Rivista e Edizione

Volume 84 (2022): Edizione 1 (October 2022)

Volume 83 (2022): Edizione 1 (August 2022)

Volume 82 (2022): Edizione 1 (April 2022)

Volume 81 (2022): Edizione 1 (January 2022)

Volume 80 (2021): Edizione 1 (October 2021)

Volume 79 (2021): Edizione 1 (July 2021)

Volume 78 (2021): Edizione 1 (March 2021)

Volume 77 (2021): Edizione 1 (January 2021)

Volume 76 (2021): Edizione 1 (January 2021)

Volume 75 (2020): Edizione 1 (October 2020)

Volume 74 (2020): Edizione 1 (August 2020)

Volume 73 (2020): Edizione 1 (July 2020)

Volume 72 (2020): Edizione 1 (March 2020)

Volume 71 (2020): Edizione 1 (January 2020)

Volume 70 (2019): Edizione 1 (November 2019)

Volume 69 (2019): Edizione 1 (October 2019)

Volume 68 (2019): Edizione 1 (August 2019)

Volume 67 (2019): Edizione 1 (June 2019)

Volume 66 (2019): Edizione 1 (March 2019)

Volume 65 (2018): Edizione 1 (December 2018)

Volume 64 (2018): Edizione 1 (September 2018)

Volume 63 (2018): Edizione 1 (August 2018)

Volume 62 (2018): Edizione 1 (June 2018)

Volume 61 (2018): Edizione 1 (March 2018)

Volume 60 (2017): Edizione 1 (December 2017)

Volume 59 (2017): Edizione 1 (October 2017)

Volume 58 (2017): Edizione 1 (September 2017)

Volume 57 (2017): Edizione 1 (June 2017)

Volume 56 (2017): Edizione 1 (February 2017)

Volume 55 (2017): Edizione 1 (January 2017)

Volume 54 (2016): Edizione 1 (December 2016)

Volume 53 (2016): Edizione 1 (December 2016)

Volume 52 (2016): Edizione 1 (September 2016)

Volume 51 (2016): Edizione 1 (June 2016)

Volume 50 (2016): Edizione 1 (April 2016)

Volume 49 (2015): Edizione 1 (December 2015)

Volume 48 (2015): Edizione 1 (December 2015)

Volume 47 (2015): Edizione 1 (September 2015)

Volume 46 (2015): Edizione 1 (June 2015)

Volume 45 (2015): Edizione 1 (March 2015)

Volume 44 (2014): Edizione 1 (December 2014)

Volume 43 (2014): Edizione 1 (November 2014)

Volume 42 (2014): Edizione 1 (September 2014)

Volume 41 (2014): Edizione 1 (June 2014)

Volume 40 (2014): Edizione 1 (March 2014)

Volume 39 (2013): Edizione 1 (December 2013)

Volume 38 (2013): Edizione 2013 (September 2013)

Volume 37 (2013): Edizione 1 (June 2013)

Volume 36 (2013): Edizione 1 (March 2013)

Volume 35 (2012): Edizione 1 (December 2012)

Volume 34 (2012): Edizione 1 (October 2012)

Volume 33 (2012): Edizione 2012 (June 2012)

Volume 32 (2012): Edizione 2012 (May 2012)
Aquatic Sports and Activities

Volume 31 (2012): Edizione 2012 (March 2012)

Volume 30 (2011): Edizione 2011 (December 2011)

Volume 29A (2011): Edizione Special-Edizione (September 2011)
Presentation of the 1st International Symposium on Strength & Conditioning (ISSC 2011)

Volume 29 (2011): Edizione 2011 (September 2011)

Volume 28 (2011): Edizione 2011 (June 2011)

Volume 27 (2011): Edizione 2011 (March 2011)

Volume 26 (2010): Edizione 2010 (December 2010)

Volume 25 (2010): Edizione 2010 (September 2010)

Volume 24 (2010): Edizione 2010 (June 2010)

Volume 23 (2010): Edizione 2010 (March 2010)

Volume 22 (2009): Edizione 2009 (December 2009)

Volume 21 (2009): Edizione 2009 (June 2009)

Volume 20 (2008): Edizione 2008 (December 2008)

Volume 19 (2008): Edizione 2008 (June 2008)

Dettagli della rivista
Formato
Rivista
eISSN
1899-7562
Pubblicato per la prima volta
13 Jan 2009
Periodo di pubblicazione
5 volte all'anno
Lingue
Inglese

Cerca

Volume 41 (2014): Edizione 1 (June 2014)

Dettagli della rivista
Formato
Rivista
eISSN
1899-7562
Pubblicato per la prima volta
13 Jan 2009
Periodo di pubblicazione
5 volte all'anno
Lingue
Inglese

Cerca

28 Articoli
Accesso libero

Effect of a Short Time Concentric Versus Eccentric Training Program on Electromyography Activity and Peak Torque of Quadriceps

Pubblicato online: 08 Jul 2014
Pagine: 5 - 13

Astratto

Abstract

The purpose of this study was to examine the effect of an 8-week concentric (CON) versus eccentric (ECC) isokinetic training program on the electromyography (EMG) signal amplitude of vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF). Also, the isometric (ISO) and dynamic maximum strength of the knee extensors were assessed. Eighteen physically healthy male subjects (age 22 ± 1 years, body height 177 ± 4 cm, body mass 73 ± 7 kg) performed four weeks of unilateral CON isokinetic training for the quadriceps of the dominant leg on a REV9000 dynamometer. At the end of the fourth week, the sample was divided into two groups, with one group performing additional four weeks of unilateral ECC training and the other continuing with CON training. The training sessions consisted of three sets of ten maximal repetitions at a velocity of 60°s-1, three days per week for eight weeks. The results showed that CON and ECC groups improved the peak torque in all types of contractions. Also, both groups presented increases in the avgEMG for VL, VM and RF. The present investigation showed that CON training elicited increases of the ISO peak torque and VM avgEMG in the CON contraction. Additionally, significant gains were reported after the ECC training on the VM avgEMG in all contractions and RM avgEMG in CON contraction.

Parole chiave

  • Isokinetic training
  • quadriceps
  • hamstring
  • peak torque
  • imbalance ratios
Accesso libero

Lower Extremity Muscle Activity During a Women's Overhand Lacrosse Shot

Pubblicato online: 08 Jul 2014
Pagine: 15 - 22

Astratto

Abstract

The purpose of this study was to describe lower extremity muscle activity during the lacrosse shot. Participants (n=5 females, age 22±2 years, body height 162.6±15.2 cm, body mass 63.7±23.6 kg) were free from injury and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG) leads to measure muscle activity of the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (GA). Participants completed five trials of a warm-up speed shot (Slow) and a game speed shot (Fast). Video analysis was used to identify the discrete events defining specific movement phases. Full-wave rectified data were averaged per muscle per phase (Crank Back Minor, Crank Back Major, Stick Acceleration, Stick Deceleration). Average EMG per muscle was analyzed using a 4 (Phase) x 2 (Speed) ANOVA. BF was greater during Fast vs. Slow for all phases (p<0.05), while TA was not influenced by either Phase or Speed (p>0.05). RF and GA were each influenced by the interaction of Phase and Speed (p<0.05) with GA being greater during Fast vs. Slow shots during all phases and RF greater during Crank Back Minor and Major as well as Stick Deceleration (p<0.05) but only tended to be greater during Stick Acceleration (p=0.076) for Fast vs. Slow. The greater muscle activity (BF, RF, GA) during Fast vs. Slow shots may have been related to a faster approach speed and/or need to create a stiff lower extremity to allow for faster upper extremity movements.

Parole chiave

  • electromyography
  • sport skill
  • technique
  • biomechanics
Accesso libero

Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

Pubblicato online: 08 Jul 2014
Pagine: 23 - 32

Astratto

Abstract

This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.

Parole chiave

  • electromyography
  • elite performance
  • roller skate jumps
Accesso libero

Comparison of Static Balance and the Role of Vision in Elite Athletes

Pubblicato online: 08 Jul 2014
Pagine: 33 - 41

Astratto

Abstract

When prescribing balance exercises to athletes in different sports, it may be important to recognize performance variations. Indeed, how athletes from different sports perform on balance tests is not well understood. The goal of the present study was to compare static balance and the role of vision among elite sprinters, jumpers and rugby players. The modified clinical test of sensory interaction on balance (mCTSIB) was used to assess the velocity of the center-of-pressure (CoP) on a force platform during a 30 s bipedal quiet standing posture in 4 conditions: firm surface with opened and closed eyes, foam surface with opened and closed eyes. Three-factor ANOVA indicated a significant main effect for groups (F=21.69, df=2, p<0.001, η2 = 0.34). Significant main effect of vision (F=43.20, df=1, p<0.001, η2 = 0.34) and surface (F=193.41, df=1, p<0.001, η2 = 0.70) as well as an interaction between vision (eyes open, eyes closed) and surface (firm and foam) (F=21.79, df=1, p=0.001) were reported in all groups. The subsequent Bonferroni-Dunn post hoc test indicated that rugby players displayed better static balance than sprinters and jumpers (p=0.001). The comparison of sprinters and jumpers did not reveal significant differences (p>0.05). The nature of the sport practiced and the absence of visual control are linked to modify static balance in elite athletes. Coaches and strength and conditioning professionals are recommended to use a variety of exercises to improve balance, including both exercises with opened and closed eyes on progressively challenging surfaces in order to make decisions about tasks and sensory availability during assessment and training.

Parole chiave

  • Athletes
  • surface
  • vision
  • static balance
Accesso libero

Effect of Training Mode on Post-Exercise Heart Rate Recovery of Trained Cyclists

Pubblicato online: 08 Jul 2014
Pagine: 43 - 49

Astratto

Abstract

The sympathetic nervous system dominates the regulation of body functions during exercise. Therefore after exercise, the sympathetic nervous system withdraws and the parasympathetic nervous system helps the body return to a resting state. In the examination of this relationship, the purpose of this study was to compare recovery heart rates (HR) of anaerobically versus aerobically trained cyclists. With all values given as means ± SD, anaerobically trained track cyclists (n=10, age=25.9 ± 6.0 yrs, body mass=82.7 ± 7.1 kg, body fat=10.0 ± 6.3%) and aerobically trained road cyclists (n=15, age=39.9 ± 8.5 yrs, body mass=75.3 ± 9.9 kg, body fat=13.1 ± 4.5%) underwent a maximal oxygen uptake test. Heart rate recovery was examined on a relative basis using heart rate reserve as well as the absolute difference between maximum HR and each of two recovery HRs. The post-exercise change in HR at minute one for the track cyclists and road cyclists respectively were 22 ± 8 bpm and 25 ± 12 bpm. At minute two, the mean drop for track cyclists was significantly (p<0.05) greater than the road cyclists (52 ± 15 bpm and 64 ± 11 bpm). Training mode showed statistically significant effects on the speed of heart rate recovery in trained cyclists. Greater variability in recovery heart rate at minute two versus minute one suggests that the heart rate should be monitored longer than one minute of recovery for a better analysis of post-exercise autonomic shift.

Parole chiave

  • performance
  • autonomic shift
  • aerobic and anaerobic exercise
Accesso libero

The Kinematic Control During the Backward Gait and Knee Proprioception: Insights from Lesions of the Anterior Cruciate Ligament

Pubblicato online: 08 Jul 2014
Pagine: 51 - 57

Astratto

Abstract

An already existing large volume of work on kinematics documents a reduction of step length during unusual gaits, such as backward walking. This is mainly explained in terms of modifications of some biomechanical properties. In the present study, we propose that the proprioceptive information from the knee may be involved in this change of motor strategy. Specifically, we show that a non-automated condition such as backward walking can elicit different motor strategies in subjects with reduced proprioceptive feedback after anterior cruciate ligament lesion (ACL). For this purpose, the kinematic parameters during forward and backward walking in subjects with ACL deficit were compared to two control groups: a group with intact ACL and a group with surgically reconstructed ACL. The knee proprioception was tested measuring the threshold for detection of passive knee motion. Subjects were asked to walk on a level treadmill at five different velocities (1-5km/h) in forward and backward direction, thereby calculating the cadence and step length. Results showed that forward walking parameters were largely unaffected in subjects with ACL damage. However, they failed to reduce step length during backward walking, a correction that was normally observed in all control subjects and in subjects with normal proprioceptive feedback after ACL reconstruction. The main result of the present study is that knee proprioception is an important signal used by the brain to reduce step length during the backward gait. This can have a significant impact on clinical evaluation and rehabilitation.

Parole chiave

  • backward walking
  • treadmill
  • knee joint
  • step length
  • ligament reconstruction
Accesso libero

Effectiveness of Selected Fitness Exercises on Stress of Femoral Neck using Musculoskeletal Dynamics Simulations and Finite Element Model

Pubblicato online: 08 Jul 2014
Pagine: 59 - 70

Astratto

Abstract

The purpose of the study was to establish a dynamics model and a three-dimensional (3D) finite element model to analyze loading characteristics of femoral neck during walking, squat, single-leg standing, and forward and lateral lunges. One male volunteer performed three trials of the five movements. The 3D kinematic data were captured and imported into the LifeMOD to establish a musculoskeletal dynamics model to obtain joint reaction and muscle forces of iliacus, gluteus medius, gluteus maximus, psoas major and adductor magnus. The loading data LfeMOD were imported and transformed into a hip finite-element model. The results of the finite element femur model showed that stress was localized along the compression arc and the tension arc. In addition, the trabecular bone and tension lines of the Ward's triangle also demonstrated high stress. The compact bone received the greatest peak stress in the forward lunge and the least stress in the squat. However, the spongy bone in the femoral neck region had the greatest stress during the walk and the least stress in the squat. The results from this study indicate that the forward lunge may be an effective method to prevent femoral neck fractures. Walking is another effective and simple method that may improve bone mass of the Ward's triangle and prevent osteoporosis and femoral neck fracture.

Parole chiave

  • femoral neck fracture
  • finite-element model
  • LifeMOD
  • exercise
  • compression
  • tension
Accesso libero

Effects of Regular Physical Exercises in the Water on the Metabolic Profile of Women with Abdominal Obesity

Pubblicato online: 08 Jul 2014
Pagine: 71 - 79

Astratto

Abstract

Recreational physical exercise in the water is predominantly based on aerobic metabolism. Since it involves both carbohydrate and lipid sources of energy, aqua aerobics has a beneficial effect on metabolism of these substrates. The aim of the study was to assess the impact of a 3 month aqua aerobics training program on the metabolic profile of women with abdominal obesity. The study sample comprised 32 women aged 41-72 years. Somatic characteristics and variables characterizing carbohydrate and lipid metabolism were measured before the commencement and after the completion of the training program. During the 2nd measurement all mean anthropometric variables were found to be significantly lower (p<0.01). In the blood lipid profile, the concentrations of total cholesterol, LDL-cholesterol and HOMAIR were significantly lower (p<0.01). Furthermore, the levels of fasting triglycerides, glucose and insulin were reduced significantly (p<0.05) after the training program. The aqua aerobics program contributed to positive changes in lipid metabolism, anthropometric variables, as well as the fasting insulin, glucose levels and insulin resistance index in women with abdominal obesity.

Parole chiave

  • water aerobics
  • blood lipid profile
  • OGTT
Accesso libero

Multi-Stage 20-m Shuttle Run Fitness Test, Maximal Oxygen Uptake and Velocity at Maximal Oxygen Uptake

Pubblicato online: 08 Jul 2014
Pagine: 81 - 87

Astratto

Abstract

The multi-stage 20-m shuttle run fitness test (20mMSFT) is a popular field test which is widely used to measure aerobic fitness by predicting maximum oxygen uptake (VO2 max) and performance. However, the velocity at which VO 2 max occurs (vVO 2 max) is a better indicator of performance than VO 2 max, and can be used to explain inter-individual differences in performance that VO 2 max cannot. It has been reported as a better predictor for running performance and it can be used to monitor athletes’ training for predicting optimal training intensity. This study investigated the validity and suitability of predicting VO2max and vVO2max of adult subjects on the basis of the performance of the 20mMST. Forty eight (25 male and 23 female) physical education students performed, in random order, a laboratory based continuous horizontal treadmill test to determine VO2max, vVO 2 max and a 20mMST, with an interval of 3 days between each test. The results revealed significant correlations between the number of shuttles in the 20mMSFT and directly determined VO 2 max (r = 0.87, p<0.05) and vVO 2 max (r = 0.93, p<0.05). The equation for prediction of VO 2 max was y = 0.0276x + 27.504, whereas for vVO 2 max it was y = 0.0937x + 6.890. It can be concluded that the 20mMSFT can accurately predict VO 2 max and vVO 2 max and this field test can provide useful information regarding aerobic fitness of adults. The predicted vVO 2 max can be used in monitoring athletes, especially in determining optimal training intensity.

Parole chiave

  • aerobic capacity
  • prediction
  • testing
Accesso libero

The Effect of a Single Session of Whole-Body Vibration Training in Recreationally Active Men on the Excitability of the Central and Peripheral Nervous System

Pubblicato online: 08 Jul 2014
Pagine: 89 - 98

Astratto

Abstract

Vibration training has become a popular method used in professional sports and recreation. In this study, we examined the effect of whole-body vibration training on the central nervous system and muscle excitability in a group of 28 active men. Subjects were assigned randomly to one of two experimental groups with different variables of vibrations. The chronaximetry method was used to evaluate the effect of a single session of whole-body vibration training on the excitability of the rectus femoris and brachioradialis muscles. The examination of the fusing and flickering frequencies of the light stimulus was performed. An increase in the excitability of the quadriceps femoris muscle due to low intensity vibrations (20 Hz frequency, 2 mm amplitude) was noted, and a return to the initial values was observed 30 min after the application of vibration. High intensity vibrations (60 Hz frequency, 4 mm amplitude) caused elongations of the chronaxy time; however, these differences were not statistically significant. Neither a low intensity vibration amplitude of 2 mm (frequency of 20 Hz) nor a high intensity vibration amplitude of 4 mm (frequency of 60 Hz) caused a change in the excitability of the central nervous system, as revealed by the average frequency of the fusing and flickering of the light stimulus. A single session of high intensity whole-body vibration did not significantly decrease the excitability of the peripheral nervous system while the central nervous system did not seem to be affected.

Parole chiave

  • vibration
  • chronaxy
  • excitability
  • flicker fusion
Accesso libero

Insights into Supplements with Tribulus Terrestris used by Athletes

Pubblicato online: 08 Jul 2014
Pagine: 99 - 105

Astratto

Abstract

Herbal and nutritional supplements are more and more popular in the western population. One of them is an extract of an exotic plant, named Tribulus terrestris (TT). TT is a component of several supplements that are available over-the-counter and widely recommended, generally as enhancers of human vitality. TT is touted as a testosterone booster and remedy for impaired erectile function; therefore, it is targeted at physically active men, including male athletes. Based on the scientific literature describing the results of clinical trials, this review attempted to verify information on marketing TT with particular reference to the needs of athletes. It was found that there are few reliable data on the usefulness of TT in competitive sport. In humans, a TT extract used alone without additional components does not improve androgenic status or physical performance among athletes. The results of a few studies have showed that the combination of TT with other pharmacological components increases testosterone levels, but it was not discovered which components of the mixture contributed to that effect. TT contains several organic compounds including alkaloids and steroidal glycosides, of which pharmacological action in humans is not completely explained. One anti-doping study reported an incident with a TT supplement contaminated by a banned steroid. Toxicological studies regarding TT have been carried out on animals only, however, one accidental poisoning of a man was described. The Australian Institute of Sport does not recommend athletes’ usage of TT. So far, the published data concerning TT do not provide strong evidence for either usefulness or safe usage in sport.

Parole chiave

  • Sports
  • dietary supplements
  • doping
  • placebo
  • testosterone
  • herbal supplements
Accesso libero

Changes in Urinary 8-Hydroxydeoxyguanosine Levels During Heptathlon Race in Professional Female Athletes

Pubblicato online: 08 Jul 2014
Pagine: 107 - 111

Astratto

Abstract

Acute strenuous exercise can induce a state of oxidative stress affecting the involved muscles. Heptathlon is a multi-event exercise of two days duration and can be considered an acute, intensive endurance exercise. The purpose of this study is to compare the oxidative stress response to heptathlon events day by day and to determine the impact of this type of exercise on oxidative stress biomarkers.

The study subjects included eight heptathlon athletes who participated in the National First Class Republic competition in Egypt (October 19-21, 2011). Blood samples were collected at rest after exercise for two successive days and analyzed for malondialdehyde (MDA). Morning urine samples were collected one hour after exercise for each day and were analyzed for 8-hydroxydeoxyguanosine (8-OHdG). Results revealed a significant increase (p<0.05) in both plasma MDA and urine 8-OHdG levels after exercise regardless of the day. We concluded that exercise generates higher MDA levels compared to DNA strand breaks and oxidative DNA damage in athletes with antioxidant supplementation.

Parole chiave

  • heptathlon
  • oxidative DNA damage
  • 8-hydroxydeoxyguanosine (8-OHdG)
  • malondialdehyde (MDA)
  • oxidative stress
Accesso libero

Effect of Number of Touches and Exercise Duration on the Kinematic Profile and Heart Rate Response During Small-Sided Games in Soccer

Pubblicato online: 08 Jul 2014
Pagine: 113 - 123

Astratto

Abstract

This study aimed to examine the effect of exercise duration and the number of touches allowed during possession on time-motion characteristics and the physiological responses of soccer players in 6 vs. 6 small-sided games (SSGs) lasting 12 minutes. The analysis divided each game into two 6-min periods and we compared two formats: free play (SSGfp) vs. a maximum of two touches per individual possession (SSG 2T). Participants were 12 semi-professional players (age: 22.7±4.3 years; body height: 177.5+4.9 cm; body mass: 74.9±6.3 kg) and the following variables were measured by means of heart rate monitors and GPS devices: mean heart rate (HRmean), time spent in each exercise intensity zone, total distance covered, total distance covered in different speed zones, number of accelerations at different intensities, maximum speed reached, player load, and the work-to-rest ratio. The results showed that in SSGFP there was a decrease in the intensity of physical parameters during the second 6-min period (6-12 min), whereas this decrease was not observed when a maximum of two touches per individual possession was allowed. During the second period (6-12 min) of SSG2T there was an increase in HRmean and in the time spent in high exercise intensity zones, but these differences were not observed in SSGFP. The value of these findings for soccer coaches is that they illustrate how different technical, tactical or conditioning objectives could be addressed by altering the length and format of the SSG used in training.

Parole chiave

  • soccer
  • bout duration
  • exercise intensity
  • small sided games
  • time-motion
  • GPS device
  • heart rate
Accesso libero

Effects of Strength Training Combined with Specific Plyometric exercises on body composition, vertical jump height and lower limb strength development in elite male handball players: a case study

Pubblicato online: 08 Jul 2014
Pagine: 125 - 132

Astratto

Abstract

The purpose of the present study was to identify the effects of a strength training program combined with specific plyometric exercises on body composition, vertical jump (VJ) height and strength development of lower limbs in elite male handball players. A 12-week program with combined strength and specific plyometric exercises was carried out for 7 weeks. Twelve elite male handball players (age: 21.6 ± 1.73) competing in the Portuguese Major League participated in the study. Besides the anthropometric measurements, several standardized jump tests were applied to assess VJ performance together with the strength development of the lower limbs in an isokinetic setting. No significant changes were found in body circumferences and diameters. Body fat content and fat mass decreased by 16.4 and 15.7% respectively, while lean body mass increased by 2.1%. Despite small significance, there was in fact an increase in squat jump (SJ), counter movement jump (CMJ) and 40 consecutive jumps after the training period (6.1, 3.8 and 6.8%, respectively). After the applied protocol, peak torque increased in lower limb extension and flexion in the majority of the movements assessed at 90°s-1. Consequently, it is possible to conclude that combining general strength-training with plyometric exercises can not only increase lower limb strength and improve VJ performance but also reduce body fat content.

Parole chiave

  • strength training
  • specific plyometric exercises
  • vertical jump
  • handball
Accesso libero

Prediction of Rowing Ergometer Performance from Functional Anaerobic Power, Strength and Anthropometric Components

Pubblicato online: 08 Jul 2014
Pagine: 133 - 142

Astratto

Abstract

The aim of this research was to develop different regression models to predict 2000 m rowing ergometer performance with the use of anthropometric, anaerobic and strength variables and to determine how precisely the prediction models constituted by different variables predict performance, when conducted together in the same equation or individually. 38 male collegiate rowers (20.17 ± 1.22 years) participated in this study. Anthropometric, strength, 2000 m maximal rowing ergometer and rowing anaerobic power tests were applied. Multiple linear regression procedures were employed in SPSS 16 to constitute five different regression formulas using a different group of variables. The reliability of the regression models was expressed by R2 and the standard error of estimate (SEE). Relationships of all parameters with performance were investigated through Pearson correlation coefficients. The prediction model using a combination of anaerobic, strength and anthropometric variables was found to be the most reliable equation to predict 2000 m rowing ergometer performance (R2 = 0.92, SEE= 3.11 s). Besides, the equation that used rowing anaerobic and strength test results also provided a reliable prediction (R2 = 0.85, SEE= 4.27 s). As a conclusion, it seems clear that physiological determinants which are affected by anaerobic energy pathways should also get involved in the processes and models used for performance prediction and talent identification in rowing.

Parole chiave

  • performance prediction model
  • simulated rowing
  • talent identification
Accesso libero

The Impact of Immediate Verbal Feedback on the Improvement of Swimming Technique

Pubblicato online: 08 Jul 2014
Pagine: 143 - 154

Astratto

Abstract

The present research attempts to ascertain the impact of immediate verbal feedback (IVF) on modifications of stroke length (SL). In all swimming styles, stroke length is considered an essential kinematic parameter of the swimming cycle. It is important for swimming mechanics and energetics. If SL shortens while the stroke rate (SR) remains unchanged or decreases, the temporal-spatial structure of swimming is considered erroneous. It results in a lower swimming velocity. Our research included 64 subjects, who were divided into two groups: the experimental - E (n=32) and the control - C (n=32) groups. A pretest and a post-test were conducted. The subjects swam the front crawl over the test distance of 25m at Vmax. Only the E group subjects were provided with IVF aiming to increase their SL. All tests were filmed by two cameras (50 samples•s-1). The kinematic parameters of the swimming cycle were analyzed using the SIMI Reality Motion Systems 2D software (SIMI Reality Motion Systems 2D GmbH, Germany). The movement analysis allowed to determine the average horizontal swimming velocity over 15 meters. The repeated measures analysis of variance ANOVA with a post-hoc Tukey range test demonstrated statistically significant (p<0.05) differences between the two groups in terms of SL and swimming velocity. IVF brought about a 6.93% (Simi method) and a 5.09% (Hay method) increase in SL, as well as a 2.92% increase in swimming velocity.

Parole chiave

  • motor control
  • verbal information
  • immediate verbal feedback
  • swimming technique
Accesso libero

Reliability of Tethered Swimming Evaluation in Age Group Swimmers

Pubblicato online: 08 Jul 2014
Pagine: 155 - 162

Astratto

Abstract

The aim of the present study was to examine the reliability of tethered swimming in the evaluation of age group swimmers. The sample was composed of 8 male national level swimmers with at least 4 years of experience in competitive swimming. Each swimmer performed two 30 second maximal intensity tethered swimming tests, on separate days. Individual force-time curves were registered to assess maximum force, mean force and the mean impulse of force. Both consistency and reliability were very strong, with Cronbach's Alpha values ranging from 0.970 to 0.995. All the applied metrics presented a very high agreement between tests, with the mean impulse of force presenting the highest. These results indicate that tethered swimming can be used to evaluate age group swimmers. Furthermore, better comprehension of the swimmers ability to effectively exert force in the water can be obtained using the impulse of force.

Parole chiave

  • swimming
  • training and testing
  • propulsive force
  • front crawl
Accesso libero

Effects of High-Intensity Blood Flow Restriction Exercise on Muscle Fatigue

Pubblicato online: 08 Jul 2014
Pagine: 163 - 172

Astratto

Abstract

Strength training combined with blood flow restriction (BFR) have been used to improve the levels of muscle adaptation. The aim of this paper was to investigate the acute effect of high intensity squats with and without blood flow restriction on muscular fatigue levels. Twelve athletes (aged 25.95 ± 0.84 years) were randomized into two groups: without Blood Flow Restriction (NFR, n = 6) and With Blood Flow Restriction (WFR, n = 6) that performed a series of free weight squats with 80% 1-RM until concentric failure. The strength of the quadriceps extensors was assessed in a maximum voluntary isometric contraction integrated to signals from the surface electromyogram. The average frequency showed significant reductions in the WFR group for the vastus lateralis and vastus medialis muscles, and intergroup only for the vastus medialis. In conclusion, a set of squats at high intensity with BFR could compromise muscle strength immediately after exercise, however, differences were not significant between groups.

Parole chiave

  • quadriceps
  • resistance training
  • vascular occlusion
  • athletes
Accesso libero

Game-Related Volleyball Skills that Influence Victory

Pubblicato online: 08 Jul 2014
Pagine: 173 - 179

Astratto

Abstract

The aim of the present study was to identify the volleyball skills that discriminate in favour of victory. Twenty-four games (n=24) from the Senior Men's Volleyball World Championship played in Italy in 2010 were chosen and analyzed with Data Volley software. The discriminating function was used to identify the discriminating variables, using a canonical structuring coefficient of |SC| >.30. The results suggest that service points, reception errors, and blocking errors were the discriminating variables that identify the final outcome of the match (victory/defeat). Moreover, successful service points were the major variable most likely associated with match success (victory). In this sense, increasing the effectiveness of service should be a top priority in coaching elite volleyball teams.

Parole chiave

  • volleyball
  • games-related statistics
  • performance
  • results
  • skills
Accesso libero

The Reliability of a Functional Agility Test for Water Polo

Pubblicato online: 08 Jul 2014
Pagine: 181 - 190

Astratto

Abstract

Few functional agility tests for water polo take into consideration its specific characteristics. The preliminary objective of this study was to evaluate the reliability of an agility test for water polo players. Fifteen players (16.3 ± 1.8 years old) with a minimum of two years of competitive experience were evaluated. A Functional Test for Agility Performance (FTAP) was designed to represent the context of this sport. Several trials were performed to familiarize the athlete with the movement. Two experienced coaches measured three repetitions of the FTAP. Descriptive statistics, repeated measures analysis of variance (ANOVA), 95% limit of agreement (LOA), intraclass correlation coefficient (ICC) and standard error of measurements (SEM) were used for data analysis. It was considered that certain criteria of reliability measures were met. There was no significant difference between the repetitions, which may be explained by an effect of the evaluator, the ability of the players or fatigue (p > 0.05). The ICC average from evaluators was high (0.88). The SEM varied between 0.13 s and 0.49 s. The CV average considering each individual was near 6-7%. These values depended on the condition of measurement. As the FTAP contains some characteristics that create a degree of unpredictability, the same athlete may reach different performance results, increasing variability. An adjustment in the sample, familiarization and careful selection of subjects help to improve this situation and enhance the reliability of the indicators.

Parole chiave

  • Water polo
  • agility assessment
  • reproducibility
  • testing
Accesso libero

Comparing Tactical Behaviour of Soccer Players in 3 vs. 3 and 6 vs. 6 Small-Sided Games

Pubblicato online: 08 Jul 2014
Pagine: 191 - 202

Astratto

Abstract

The present study aimed to compare players’ tactical behaviour in 3 vs. 3 and 6 vs. 6 soccer small-sided games (SSGs). The sample comprised 3,482 tactical actions performed by 18 U-11 youth soccer players from a Portuguese club, in 3 vs. 3 and 6 vs. 6 SSGs. All participants played eight minutes in both situations and field size was adapted according to the number of players involved (30 m x 19.5 m for 3 vs. 3 and 60 m x 39 m for 6 vs. 6). The System of Tactical Assessment in Soccer (FUT-SAT) was used for data collection and analyses. Descriptive analysis was conducted to verify frequencies and percentages of the variables assessed. The chi-squared (χ2) test was performed to compare the frequencies of the variables between 3 vs. 3 and 6 vs. 6 SSGs and Standardized Residuals (e) were used to examine the influence of the frequency of one or more variables within 3 vs. 3 and 6 vs. 6 SSGs. Data treatment was performed through SPSS for Windows®, version 18.0. Results indicated that players displayed safer behaviours in 6 vs. 6 SSG and more aggressive behaviours in 3 vs. 3 SSG. Findings can aid coaches and teachers to develop different players’ tactical skills according to the chosen SSG (3 vs. 3 or 6 vs. 6) form.

Parole chiave

  • Soccer
  • tactical assessment
  • tactical behaviour
  • small-sided games
Accesso libero

Effects of Match Location, Match Status and Quality of Opposition on Regaining Possession in UEFA Champions League

Pubblicato online: 08 Jul 2014
Pagine: 203 - 214

Astratto

Abstract

The present study aimed to examine the independent and interactive effects of match location, match status, and quality of opposition on regaining possession, analysed by the type and zone of ball recovery, in matches played in the 2011-2012 UEFA Champions League. Twenty-eight matches of the knockout phase were evaluated post-event using a computerized notational analysis system. Multinomial logistic regression analysis was applied to identify the effects of the previously mentioned situational variables on ball recovery type and zone. Match status and quality of opposition main effects were observed for both dependent variables, while main effects of match location were only evident for ball recovery zone. Additionally, the interactions Match location * Quality of opposition and Match status * Quality of opposition were significant for both type and zone of ball recovery. Better teams employed more proactive defensive strategies, since, even when winning, they tried to sustain their defensive success on actions that aimed to gain the ball from the opponents. Results emphasized the tendency for home and losing teams to defend in more advanced pitch zones. Better-ranked teams were also more effective than worse-ranked teams in applying defensive pressure in more advanced pitch positions. The findings of the study suggest that the defensive strategies used by better teams imply more intense and organized collective processes in order to recover the ball directly from the opposing team. Furthermore, defending away from own goal and near the opponent's one seems to be associated with success in elite soccer.

Parole chiave

  • Soccer
  • notational analysis
  • situational variables
  • team performance
  • defensive strategies
Accesso libero

The Examination of Different Tests for the Evaluation of the Efficiency of the Eggbeater Kicks

Pubblicato online: 08 Jul 2014
Pagine: 215 - 226

Astratto

Abstract

The eggbeater kick presents an important basic technical skill in water polo. The aim of this study was to examine some different tests in order to recommend the best ones for the evaluation of the eggbeater kick. Twenty eight young male water polo players performed one test (squat jump) on land and ten tests in water: tethered swimming with legs only, using alternating and simultaneous eggbeater kicks, jumps out of water from basic and vertical (arms vertically above the head) position, water start and swimming two meters and swimming horizontally with legs only five meters with a flying start. The differences between tests were checked by executing dependent t-tests, while Pearson"s correlation coefficients were calculated to evaluate the correlation between different parameters. Results showed that when performing alternate eggbeater kicks greater average forces were produced by the water polo players when compared to consecutive simultaneous eggbeater kicks. However, a short time maximal acceleration of the body in the vertical and horizontal plane was greater when the single simultaneous kick was performed. It was determined that horizontal swimming using legs only and a squat jump were less useful for the evaluation of the eggbeater kick. Therefore, the recommendation was to measure the average force of successive alternating eggbeater kicks, the height of the jump out of the water from the basic position and the water start and swim over a distance of 2 meters.

Parole chiave

  • water polo
  • testing
  • eggbeater kick
  • squat jump
Accesso libero

Isokinetic Leg Strength and Power in Elite Handball Players

Pubblicato online: 08 Jul 2014
Pagine: 227 - 233

Astratto

Abstract

Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60°/s and 180°/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60°/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180°/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60°/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180°/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.

Parole chiave

  • isokinetic
  • handball
  • peak torque
  • power
  • jumping
Accesso libero

Fitness Profiles of Elite Portuguese Rugby Union Players

Pubblicato online: 08 Jul 2014
Pagine: 235 - 244

Astratto

Abstract

The aim of this study was to describe the fitness profiles of senior elite Portuguese rugby players. Forty-six senior Portuguese rugby players, classified as backs (n=22; age 26.2±2.8) and forwards (n=24; age 26.7±2.9) were assessed during physical testing sessions carried out for the Portuguese National rugby team. The body composition, maximum strength and anaerobic capacity of players are hypothesized to be important physical characteristics as successful performance in rugby is predicated on the ability to undertake skilled behaviours both quickly and whilst withstanding large forces when in contact situations. No absolute differences were found between the backs and forwards for the speed performance variables although positional differences were found across all speeds when assessed relative to body mass since the forwards were significantly heavier. Coaches and the management team can use this information for monitoring progressive improvements in the physiological capacities of rugby players. These physical characteristics of elite rugby players provide normative profiles for specific positions and should form the basis of developmental programmes for adolescents.

Parole chiave

  • Rugby
  • physical and fitness tests
  • performance
Accesso libero

Physical Fitness Differences between Freestyle and Greco-Roman Junior Wrestlers

Pubblicato online: 08 Jul 2014
Pagine: 245 - 251

Astratto

Abstract

The aim of the present study was to examine physical fitness differences between Freestyle and Greco-Roman junior wrestlers. One hundred twenty-six junior wrestlers, comprising 70 Freestyle and 56 Greco-Roman wrestlers, participated in this study. The somatic and physical fitness profile included body mass, body height, body mass index, body composition, flexibility, maximal anaerobic power of the legs and arms, aerobic endurance, hand grip strength, leg and back strength, and speed. No significant differences were found in the anthropometric and physical features between Freestyle and Greco-Roman wrestlers. The Greco-Roman wrestlers had a significantly higher level of relative leg power, peak arm power, relative peak arm power, and relative average arm power than Freestyle wrestlers (p < 0.05). Greco-Roman wrestlers were significantly faster, had better agility, and had a greater level of leg strength than Freestyle wrestlers, but Freestyle wrestlers were more flexible than Greco-Roman wrestlers (p < 0.05). Discriminant function analysis indicated that peak arm power, agility, speed, and flexibility were selective factors for the differences between Freestyle and Greco-Roman wrestlers. In conclusion, the present study indicates that the differences between these wrestling styles promote physical fitness differences in elite wrestlers. The results reflect specific features of each wrestling style.

Parole chiave

  • Anaerobic power
  • aerobic capacity
  • body composition
  • speed
  • strength
  • wrestlers
Accesso libero

Knowledge of Errors in the Teaching-Learning Process of Judo-Techniques: Osoto-Guruma as a Case Study

Pubblicato online: 08 Jul 2014
Pagine: 253 - 263

Astratto

Abstract

The aim of this article was to suggest some changes in the teaching-learning process methodology of the judo osoto-guruma technique, establishing the action sequences and the most frequent technical errors committed when performing them. The study was carried out with the participation of 45 students with no experience regarding the fundamentals of judo (21 men and 24 women; age=24.02±3.98 years old) from the Bachelor of Science of Physical Activity and Sport Science at the University of Vigo. The proceeding consisted of a systematic observation of a video recording registered during the technique execution. Data obtained were analyzed by means of descriptive statistics and sequential analysis of T-Patterns (obtained with THEME v.5. Software), identifying: a) the presence of typical inaccuracies during the technique performance; b) a number of chained errors affecting body balance, the position of the supporting foot, the blocking action and the final action of the arms. Findings allowed to suggest some motor tasks to correct the identified inaccuracies, the proper sequential actions to make the execution more effective and some recommendations for the use of feedback. Moreover, these findings could be useful for other professionals in order to correct the key technical errors and prevent diverse injuries.

Parole chiave

  • Feedback
  • martial arts
  • observation instrument
  • knowledge of performance
  • teaching
  • T-patterns
Accesso libero

Transference of Traditional Versus Complex Strength and Power Training to Sprint Performance

Pubblicato online: 08 Jul 2014
Pagine: 265 - 273

Astratto

Abstract

The purpose of this study was to determine the effects of two different strength-power training models on sprint performance. Forty-eight soldiers of the Brazilian brigade of special operations with at least one year of army training experience were divided into a control group (CG: n = 15, age: 20.2 ± 0.7 years, body height: 1.74 ± 0.06 m, and body mass: 66.7 ± 9.8 kg), a traditional training group (TT: n = 18, age: 20.1 ± 0.7 years, body height: 1.71 ± 0.05 m, and body mass: 64.2 ± 4.7 kg), and a complex training group (CT: n = 15, age: 20.3 ± 0.8 years, body height: 1.71 ± 0.07 m; and body mass: 64.0 ± 8.8 kg). Maximum strength (25% and 26%), CMJ height (36% and 39%), mean power (30% and 35%) and mean propulsive power (22% and 28%) in the loaded jump squat exercise, and 20-m sprint speed (16% and 14%) increased significantly (p<0.05) following the TT and CT, respectively. However, the transfer effect coefficients (TEC) of strength and power performances to 20-m sprint performance following the TT were greater than the CT throughout the 9-week training period. Our data suggest that TT is more effective than CT to improve sprint performance in moderately trained subjects.

Parole chiave

  • transfer effect
  • complex training
  • traditional training
  • sprint speed performance
28 Articoli
Accesso libero

Effect of a Short Time Concentric Versus Eccentric Training Program on Electromyography Activity and Peak Torque of Quadriceps

Pubblicato online: 08 Jul 2014
Pagine: 5 - 13

Astratto

Abstract

The purpose of this study was to examine the effect of an 8-week concentric (CON) versus eccentric (ECC) isokinetic training program on the electromyography (EMG) signal amplitude of vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF). Also, the isometric (ISO) and dynamic maximum strength of the knee extensors were assessed. Eighteen physically healthy male subjects (age 22 ± 1 years, body height 177 ± 4 cm, body mass 73 ± 7 kg) performed four weeks of unilateral CON isokinetic training for the quadriceps of the dominant leg on a REV9000 dynamometer. At the end of the fourth week, the sample was divided into two groups, with one group performing additional four weeks of unilateral ECC training and the other continuing with CON training. The training sessions consisted of three sets of ten maximal repetitions at a velocity of 60°s-1, three days per week for eight weeks. The results showed that CON and ECC groups improved the peak torque in all types of contractions. Also, both groups presented increases in the avgEMG for VL, VM and RF. The present investigation showed that CON training elicited increases of the ISO peak torque and VM avgEMG in the CON contraction. Additionally, significant gains were reported after the ECC training on the VM avgEMG in all contractions and RM avgEMG in CON contraction.

Parole chiave

  • Isokinetic training
  • quadriceps
  • hamstring
  • peak torque
  • imbalance ratios
Accesso libero

Lower Extremity Muscle Activity During a Women's Overhand Lacrosse Shot

Pubblicato online: 08 Jul 2014
Pagine: 15 - 22

Astratto

Abstract

The purpose of this study was to describe lower extremity muscle activity during the lacrosse shot. Participants (n=5 females, age 22±2 years, body height 162.6±15.2 cm, body mass 63.7±23.6 kg) were free from injury and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG) leads to measure muscle activity of the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (GA). Participants completed five trials of a warm-up speed shot (Slow) and a game speed shot (Fast). Video analysis was used to identify the discrete events defining specific movement phases. Full-wave rectified data were averaged per muscle per phase (Crank Back Minor, Crank Back Major, Stick Acceleration, Stick Deceleration). Average EMG per muscle was analyzed using a 4 (Phase) x 2 (Speed) ANOVA. BF was greater during Fast vs. Slow for all phases (p<0.05), while TA was not influenced by either Phase or Speed (p>0.05). RF and GA were each influenced by the interaction of Phase and Speed (p<0.05) with GA being greater during Fast vs. Slow shots during all phases and RF greater during Crank Back Minor and Major as well as Stick Deceleration (p<0.05) but only tended to be greater during Stick Acceleration (p=0.076) for Fast vs. Slow. The greater muscle activity (BF, RF, GA) during Fast vs. Slow shots may have been related to a faster approach speed and/or need to create a stiff lower extremity to allow for faster upper extremity movements.

Parole chiave

  • electromyography
  • sport skill
  • technique
  • biomechanics
Accesso libero

Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

Pubblicato online: 08 Jul 2014
Pagine: 23 - 32

Astratto

Abstract

This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.

Parole chiave

  • electromyography
  • elite performance
  • roller skate jumps
Accesso libero

Comparison of Static Balance and the Role of Vision in Elite Athletes

Pubblicato online: 08 Jul 2014
Pagine: 33 - 41

Astratto

Abstract

When prescribing balance exercises to athletes in different sports, it may be important to recognize performance variations. Indeed, how athletes from different sports perform on balance tests is not well understood. The goal of the present study was to compare static balance and the role of vision among elite sprinters, jumpers and rugby players. The modified clinical test of sensory interaction on balance (mCTSIB) was used to assess the velocity of the center-of-pressure (CoP) on a force platform during a 30 s bipedal quiet standing posture in 4 conditions: firm surface with opened and closed eyes, foam surface with opened and closed eyes. Three-factor ANOVA indicated a significant main effect for groups (F=21.69, df=2, p<0.001, η2 = 0.34). Significant main effect of vision (F=43.20, df=1, p<0.001, η2 = 0.34) and surface (F=193.41, df=1, p<0.001, η2 = 0.70) as well as an interaction between vision (eyes open, eyes closed) and surface (firm and foam) (F=21.79, df=1, p=0.001) were reported in all groups. The subsequent Bonferroni-Dunn post hoc test indicated that rugby players displayed better static balance than sprinters and jumpers (p=0.001). The comparison of sprinters and jumpers did not reveal significant differences (p>0.05). The nature of the sport practiced and the absence of visual control are linked to modify static balance in elite athletes. Coaches and strength and conditioning professionals are recommended to use a variety of exercises to improve balance, including both exercises with opened and closed eyes on progressively challenging surfaces in order to make decisions about tasks and sensory availability during assessment and training.

Parole chiave

  • Athletes
  • surface
  • vision
  • static balance
Accesso libero

Effect of Training Mode on Post-Exercise Heart Rate Recovery of Trained Cyclists

Pubblicato online: 08 Jul 2014
Pagine: 43 - 49

Astratto

Abstract

The sympathetic nervous system dominates the regulation of body functions during exercise. Therefore after exercise, the sympathetic nervous system withdraws and the parasympathetic nervous system helps the body return to a resting state. In the examination of this relationship, the purpose of this study was to compare recovery heart rates (HR) of anaerobically versus aerobically trained cyclists. With all values given as means ± SD, anaerobically trained track cyclists (n=10, age=25.9 ± 6.0 yrs, body mass=82.7 ± 7.1 kg, body fat=10.0 ± 6.3%) and aerobically trained road cyclists (n=15, age=39.9 ± 8.5 yrs, body mass=75.3 ± 9.9 kg, body fat=13.1 ± 4.5%) underwent a maximal oxygen uptake test. Heart rate recovery was examined on a relative basis using heart rate reserve as well as the absolute difference between maximum HR and each of two recovery HRs. The post-exercise change in HR at minute one for the track cyclists and road cyclists respectively were 22 ± 8 bpm and 25 ± 12 bpm. At minute two, the mean drop for track cyclists was significantly (p<0.05) greater than the road cyclists (52 ± 15 bpm and 64 ± 11 bpm). Training mode showed statistically significant effects on the speed of heart rate recovery in trained cyclists. Greater variability in recovery heart rate at minute two versus minute one suggests that the heart rate should be monitored longer than one minute of recovery for a better analysis of post-exercise autonomic shift.

Parole chiave

  • performance
  • autonomic shift
  • aerobic and anaerobic exercise
Accesso libero

The Kinematic Control During the Backward Gait and Knee Proprioception: Insights from Lesions of the Anterior Cruciate Ligament

Pubblicato online: 08 Jul 2014
Pagine: 51 - 57

Astratto

Abstract

An already existing large volume of work on kinematics documents a reduction of step length during unusual gaits, such as backward walking. This is mainly explained in terms of modifications of some biomechanical properties. In the present study, we propose that the proprioceptive information from the knee may be involved in this change of motor strategy. Specifically, we show that a non-automated condition such as backward walking can elicit different motor strategies in subjects with reduced proprioceptive feedback after anterior cruciate ligament lesion (ACL). For this purpose, the kinematic parameters during forward and backward walking in subjects with ACL deficit were compared to two control groups: a group with intact ACL and a group with surgically reconstructed ACL. The knee proprioception was tested measuring the threshold for detection of passive knee motion. Subjects were asked to walk on a level treadmill at five different velocities (1-5km/h) in forward and backward direction, thereby calculating the cadence and step length. Results showed that forward walking parameters were largely unaffected in subjects with ACL damage. However, they failed to reduce step length during backward walking, a correction that was normally observed in all control subjects and in subjects with normal proprioceptive feedback after ACL reconstruction. The main result of the present study is that knee proprioception is an important signal used by the brain to reduce step length during the backward gait. This can have a significant impact on clinical evaluation and rehabilitation.

Parole chiave

  • backward walking
  • treadmill
  • knee joint
  • step length
  • ligament reconstruction
Accesso libero

Effectiveness of Selected Fitness Exercises on Stress of Femoral Neck using Musculoskeletal Dynamics Simulations and Finite Element Model

Pubblicato online: 08 Jul 2014
Pagine: 59 - 70

Astratto

Abstract

The purpose of the study was to establish a dynamics model and a three-dimensional (3D) finite element model to analyze loading characteristics of femoral neck during walking, squat, single-leg standing, and forward and lateral lunges. One male volunteer performed three trials of the five movements. The 3D kinematic data were captured and imported into the LifeMOD to establish a musculoskeletal dynamics model to obtain joint reaction and muscle forces of iliacus, gluteus medius, gluteus maximus, psoas major and adductor magnus. The loading data LfeMOD were imported and transformed into a hip finite-element model. The results of the finite element femur model showed that stress was localized along the compression arc and the tension arc. In addition, the trabecular bone and tension lines of the Ward's triangle also demonstrated high stress. The compact bone received the greatest peak stress in the forward lunge and the least stress in the squat. However, the spongy bone in the femoral neck region had the greatest stress during the walk and the least stress in the squat. The results from this study indicate that the forward lunge may be an effective method to prevent femoral neck fractures. Walking is another effective and simple method that may improve bone mass of the Ward's triangle and prevent osteoporosis and femoral neck fracture.

Parole chiave

  • femoral neck fracture
  • finite-element model
  • LifeMOD
  • exercise
  • compression
  • tension
Accesso libero

Effects of Regular Physical Exercises in the Water on the Metabolic Profile of Women with Abdominal Obesity

Pubblicato online: 08 Jul 2014
Pagine: 71 - 79

Astratto

Abstract

Recreational physical exercise in the water is predominantly based on aerobic metabolism. Since it involves both carbohydrate and lipid sources of energy, aqua aerobics has a beneficial effect on metabolism of these substrates. The aim of the study was to assess the impact of a 3 month aqua aerobics training program on the metabolic profile of women with abdominal obesity. The study sample comprised 32 women aged 41-72 years. Somatic characteristics and variables characterizing carbohydrate and lipid metabolism were measured before the commencement and after the completion of the training program. During the 2nd measurement all mean anthropometric variables were found to be significantly lower (p<0.01). In the blood lipid profile, the concentrations of total cholesterol, LDL-cholesterol and HOMAIR were significantly lower (p<0.01). Furthermore, the levels of fasting triglycerides, glucose and insulin were reduced significantly (p<0.05) after the training program. The aqua aerobics program contributed to positive changes in lipid metabolism, anthropometric variables, as well as the fasting insulin, glucose levels and insulin resistance index in women with abdominal obesity.

Parole chiave

  • water aerobics
  • blood lipid profile
  • OGTT
Accesso libero

Multi-Stage 20-m Shuttle Run Fitness Test, Maximal Oxygen Uptake and Velocity at Maximal Oxygen Uptake

Pubblicato online: 08 Jul 2014
Pagine: 81 - 87

Astratto

Abstract

The multi-stage 20-m shuttle run fitness test (20mMSFT) is a popular field test which is widely used to measure aerobic fitness by predicting maximum oxygen uptake (VO2 max) and performance. However, the velocity at which VO 2 max occurs (vVO 2 max) is a better indicator of performance than VO 2 max, and can be used to explain inter-individual differences in performance that VO 2 max cannot. It has been reported as a better predictor for running performance and it can be used to monitor athletes’ training for predicting optimal training intensity. This study investigated the validity and suitability of predicting VO2max and vVO2max of adult subjects on the basis of the performance of the 20mMST. Forty eight (25 male and 23 female) physical education students performed, in random order, a laboratory based continuous horizontal treadmill test to determine VO2max, vVO 2 max and a 20mMST, with an interval of 3 days between each test. The results revealed significant correlations between the number of shuttles in the 20mMSFT and directly determined VO 2 max (r = 0.87, p<0.05) and vVO 2 max (r = 0.93, p<0.05). The equation for prediction of VO 2 max was y = 0.0276x + 27.504, whereas for vVO 2 max it was y = 0.0937x + 6.890. It can be concluded that the 20mMSFT can accurately predict VO 2 max and vVO 2 max and this field test can provide useful information regarding aerobic fitness of adults. The predicted vVO 2 max can be used in monitoring athletes, especially in determining optimal training intensity.

Parole chiave

  • aerobic capacity
  • prediction
  • testing
Accesso libero

The Effect of a Single Session of Whole-Body Vibration Training in Recreationally Active Men on the Excitability of the Central and Peripheral Nervous System

Pubblicato online: 08 Jul 2014
Pagine: 89 - 98

Astratto

Abstract

Vibration training has become a popular method used in professional sports and recreation. In this study, we examined the effect of whole-body vibration training on the central nervous system and muscle excitability in a group of 28 active men. Subjects were assigned randomly to one of two experimental groups with different variables of vibrations. The chronaximetry method was used to evaluate the effect of a single session of whole-body vibration training on the excitability of the rectus femoris and brachioradialis muscles. The examination of the fusing and flickering frequencies of the light stimulus was performed. An increase in the excitability of the quadriceps femoris muscle due to low intensity vibrations (20 Hz frequency, 2 mm amplitude) was noted, and a return to the initial values was observed 30 min after the application of vibration. High intensity vibrations (60 Hz frequency, 4 mm amplitude) caused elongations of the chronaxy time; however, these differences were not statistically significant. Neither a low intensity vibration amplitude of 2 mm (frequency of 20 Hz) nor a high intensity vibration amplitude of 4 mm (frequency of 60 Hz) caused a change in the excitability of the central nervous system, as revealed by the average frequency of the fusing and flickering of the light stimulus. A single session of high intensity whole-body vibration did not significantly decrease the excitability of the peripheral nervous system while the central nervous system did not seem to be affected.

Parole chiave

  • vibration
  • chronaxy
  • excitability
  • flicker fusion
Accesso libero

Insights into Supplements with Tribulus Terrestris used by Athletes

Pubblicato online: 08 Jul 2014
Pagine: 99 - 105

Astratto

Abstract

Herbal and nutritional supplements are more and more popular in the western population. One of them is an extract of an exotic plant, named Tribulus terrestris (TT). TT is a component of several supplements that are available over-the-counter and widely recommended, generally as enhancers of human vitality. TT is touted as a testosterone booster and remedy for impaired erectile function; therefore, it is targeted at physically active men, including male athletes. Based on the scientific literature describing the results of clinical trials, this review attempted to verify information on marketing TT with particular reference to the needs of athletes. It was found that there are few reliable data on the usefulness of TT in competitive sport. In humans, a TT extract used alone without additional components does not improve androgenic status or physical performance among athletes. The results of a few studies have showed that the combination of TT with other pharmacological components increases testosterone levels, but it was not discovered which components of the mixture contributed to that effect. TT contains several organic compounds including alkaloids and steroidal glycosides, of which pharmacological action in humans is not completely explained. One anti-doping study reported an incident with a TT supplement contaminated by a banned steroid. Toxicological studies regarding TT have been carried out on animals only, however, one accidental poisoning of a man was described. The Australian Institute of Sport does not recommend athletes’ usage of TT. So far, the published data concerning TT do not provide strong evidence for either usefulness or safe usage in sport.

Parole chiave

  • Sports
  • dietary supplements
  • doping
  • placebo
  • testosterone
  • herbal supplements
Accesso libero

Changes in Urinary 8-Hydroxydeoxyguanosine Levels During Heptathlon Race in Professional Female Athletes

Pubblicato online: 08 Jul 2014
Pagine: 107 - 111

Astratto

Abstract

Acute strenuous exercise can induce a state of oxidative stress affecting the involved muscles. Heptathlon is a multi-event exercise of two days duration and can be considered an acute, intensive endurance exercise. The purpose of this study is to compare the oxidative stress response to heptathlon events day by day and to determine the impact of this type of exercise on oxidative stress biomarkers.

The study subjects included eight heptathlon athletes who participated in the National First Class Republic competition in Egypt (October 19-21, 2011). Blood samples were collected at rest after exercise for two successive days and analyzed for malondialdehyde (MDA). Morning urine samples were collected one hour after exercise for each day and were analyzed for 8-hydroxydeoxyguanosine (8-OHdG). Results revealed a significant increase (p<0.05) in both plasma MDA and urine 8-OHdG levels after exercise regardless of the day. We concluded that exercise generates higher MDA levels compared to DNA strand breaks and oxidative DNA damage in athletes with antioxidant supplementation.

Parole chiave

  • heptathlon
  • oxidative DNA damage
  • 8-hydroxydeoxyguanosine (8-OHdG)
  • malondialdehyde (MDA)
  • oxidative stress
Accesso libero

Effect of Number of Touches and Exercise Duration on the Kinematic Profile and Heart Rate Response During Small-Sided Games in Soccer

Pubblicato online: 08 Jul 2014
Pagine: 113 - 123

Astratto

Abstract

This study aimed to examine the effect of exercise duration and the number of touches allowed during possession on time-motion characteristics and the physiological responses of soccer players in 6 vs. 6 small-sided games (SSGs) lasting 12 minutes. The analysis divided each game into two 6-min periods and we compared two formats: free play (SSGfp) vs. a maximum of two touches per individual possession (SSG 2T). Participants were 12 semi-professional players (age: 22.7±4.3 years; body height: 177.5+4.9 cm; body mass: 74.9±6.3 kg) and the following variables were measured by means of heart rate monitors and GPS devices: mean heart rate (HRmean), time spent in each exercise intensity zone, total distance covered, total distance covered in different speed zones, number of accelerations at different intensities, maximum speed reached, player load, and the work-to-rest ratio. The results showed that in SSGFP there was a decrease in the intensity of physical parameters during the second 6-min period (6-12 min), whereas this decrease was not observed when a maximum of two touches per individual possession was allowed. During the second period (6-12 min) of SSG2T there was an increase in HRmean and in the time spent in high exercise intensity zones, but these differences were not observed in SSGFP. The value of these findings for soccer coaches is that they illustrate how different technical, tactical or conditioning objectives could be addressed by altering the length and format of the SSG used in training.

Parole chiave

  • soccer
  • bout duration
  • exercise intensity
  • small sided games
  • time-motion
  • GPS device
  • heart rate
Accesso libero

Effects of Strength Training Combined with Specific Plyometric exercises on body composition, vertical jump height and lower limb strength development in elite male handball players: a case study

Pubblicato online: 08 Jul 2014
Pagine: 125 - 132

Astratto

Abstract

The purpose of the present study was to identify the effects of a strength training program combined with specific plyometric exercises on body composition, vertical jump (VJ) height and strength development of lower limbs in elite male handball players. A 12-week program with combined strength and specific plyometric exercises was carried out for 7 weeks. Twelve elite male handball players (age: 21.6 ± 1.73) competing in the Portuguese Major League participated in the study. Besides the anthropometric measurements, several standardized jump tests were applied to assess VJ performance together with the strength development of the lower limbs in an isokinetic setting. No significant changes were found in body circumferences and diameters. Body fat content and fat mass decreased by 16.4 and 15.7% respectively, while lean body mass increased by 2.1%. Despite small significance, there was in fact an increase in squat jump (SJ), counter movement jump (CMJ) and 40 consecutive jumps after the training period (6.1, 3.8 and 6.8%, respectively). After the applied protocol, peak torque increased in lower limb extension and flexion in the majority of the movements assessed at 90°s-1. Consequently, it is possible to conclude that combining general strength-training with plyometric exercises can not only increase lower limb strength and improve VJ performance but also reduce body fat content.

Parole chiave

  • strength training
  • specific plyometric exercises
  • vertical jump
  • handball
Accesso libero

Prediction of Rowing Ergometer Performance from Functional Anaerobic Power, Strength and Anthropometric Components

Pubblicato online: 08 Jul 2014
Pagine: 133 - 142

Astratto

Abstract

The aim of this research was to develop different regression models to predict 2000 m rowing ergometer performance with the use of anthropometric, anaerobic and strength variables and to determine how precisely the prediction models constituted by different variables predict performance, when conducted together in the same equation or individually. 38 male collegiate rowers (20.17 ± 1.22 years) participated in this study. Anthropometric, strength, 2000 m maximal rowing ergometer and rowing anaerobic power tests were applied. Multiple linear regression procedures were employed in SPSS 16 to constitute five different regression formulas using a different group of variables. The reliability of the regression models was expressed by R2 and the standard error of estimate (SEE). Relationships of all parameters with performance were investigated through Pearson correlation coefficients. The prediction model using a combination of anaerobic, strength and anthropometric variables was found to be the most reliable equation to predict 2000 m rowing ergometer performance (R2 = 0.92, SEE= 3.11 s). Besides, the equation that used rowing anaerobic and strength test results also provided a reliable prediction (R2 = 0.85, SEE= 4.27 s). As a conclusion, it seems clear that physiological determinants which are affected by anaerobic energy pathways should also get involved in the processes and models used for performance prediction and talent identification in rowing.

Parole chiave

  • performance prediction model
  • simulated rowing
  • talent identification
Accesso libero

The Impact of Immediate Verbal Feedback on the Improvement of Swimming Technique

Pubblicato online: 08 Jul 2014
Pagine: 143 - 154

Astratto

Abstract

The present research attempts to ascertain the impact of immediate verbal feedback (IVF) on modifications of stroke length (SL). In all swimming styles, stroke length is considered an essential kinematic parameter of the swimming cycle. It is important for swimming mechanics and energetics. If SL shortens while the stroke rate (SR) remains unchanged or decreases, the temporal-spatial structure of swimming is considered erroneous. It results in a lower swimming velocity. Our research included 64 subjects, who were divided into two groups: the experimental - E (n=32) and the control - C (n=32) groups. A pretest and a post-test were conducted. The subjects swam the front crawl over the test distance of 25m at Vmax. Only the E group subjects were provided with IVF aiming to increase their SL. All tests were filmed by two cameras (50 samples•s-1). The kinematic parameters of the swimming cycle were analyzed using the SIMI Reality Motion Systems 2D software (SIMI Reality Motion Systems 2D GmbH, Germany). The movement analysis allowed to determine the average horizontal swimming velocity over 15 meters. The repeated measures analysis of variance ANOVA with a post-hoc Tukey range test demonstrated statistically significant (p<0.05) differences between the two groups in terms of SL and swimming velocity. IVF brought about a 6.93% (Simi method) and a 5.09% (Hay method) increase in SL, as well as a 2.92% increase in swimming velocity.

Parole chiave

  • motor control
  • verbal information
  • immediate verbal feedback
  • swimming technique
Accesso libero

Reliability of Tethered Swimming Evaluation in Age Group Swimmers

Pubblicato online: 08 Jul 2014
Pagine: 155 - 162

Astratto

Abstract

The aim of the present study was to examine the reliability of tethered swimming in the evaluation of age group swimmers. The sample was composed of 8 male national level swimmers with at least 4 years of experience in competitive swimming. Each swimmer performed two 30 second maximal intensity tethered swimming tests, on separate days. Individual force-time curves were registered to assess maximum force, mean force and the mean impulse of force. Both consistency and reliability were very strong, with Cronbach's Alpha values ranging from 0.970 to 0.995. All the applied metrics presented a very high agreement between tests, with the mean impulse of force presenting the highest. These results indicate that tethered swimming can be used to evaluate age group swimmers. Furthermore, better comprehension of the swimmers ability to effectively exert force in the water can be obtained using the impulse of force.

Parole chiave

  • swimming
  • training and testing
  • propulsive force
  • front crawl
Accesso libero

Effects of High-Intensity Blood Flow Restriction Exercise on Muscle Fatigue

Pubblicato online: 08 Jul 2014
Pagine: 163 - 172

Astratto

Abstract

Strength training combined with blood flow restriction (BFR) have been used to improve the levels of muscle adaptation. The aim of this paper was to investigate the acute effect of high intensity squats with and without blood flow restriction on muscular fatigue levels. Twelve athletes (aged 25.95 ± 0.84 years) were randomized into two groups: without Blood Flow Restriction (NFR, n = 6) and With Blood Flow Restriction (WFR, n = 6) that performed a series of free weight squats with 80% 1-RM until concentric failure. The strength of the quadriceps extensors was assessed in a maximum voluntary isometric contraction integrated to signals from the surface electromyogram. The average frequency showed significant reductions in the WFR group for the vastus lateralis and vastus medialis muscles, and intergroup only for the vastus medialis. In conclusion, a set of squats at high intensity with BFR could compromise muscle strength immediately after exercise, however, differences were not significant between groups.

Parole chiave

  • quadriceps
  • resistance training
  • vascular occlusion
  • athletes
Accesso libero

Game-Related Volleyball Skills that Influence Victory

Pubblicato online: 08 Jul 2014
Pagine: 173 - 179

Astratto

Abstract

The aim of the present study was to identify the volleyball skills that discriminate in favour of victory. Twenty-four games (n=24) from the Senior Men's Volleyball World Championship played in Italy in 2010 were chosen and analyzed with Data Volley software. The discriminating function was used to identify the discriminating variables, using a canonical structuring coefficient of |SC| >.30. The results suggest that service points, reception errors, and blocking errors were the discriminating variables that identify the final outcome of the match (victory/defeat). Moreover, successful service points were the major variable most likely associated with match success (victory). In this sense, increasing the effectiveness of service should be a top priority in coaching elite volleyball teams.

Parole chiave

  • volleyball
  • games-related statistics
  • performance
  • results
  • skills
Accesso libero

The Reliability of a Functional Agility Test for Water Polo

Pubblicato online: 08 Jul 2014
Pagine: 181 - 190

Astratto

Abstract

Few functional agility tests for water polo take into consideration its specific characteristics. The preliminary objective of this study was to evaluate the reliability of an agility test for water polo players. Fifteen players (16.3 ± 1.8 years old) with a minimum of two years of competitive experience were evaluated. A Functional Test for Agility Performance (FTAP) was designed to represent the context of this sport. Several trials were performed to familiarize the athlete with the movement. Two experienced coaches measured three repetitions of the FTAP. Descriptive statistics, repeated measures analysis of variance (ANOVA), 95% limit of agreement (LOA), intraclass correlation coefficient (ICC) and standard error of measurements (SEM) were used for data analysis. It was considered that certain criteria of reliability measures were met. There was no significant difference between the repetitions, which may be explained by an effect of the evaluator, the ability of the players or fatigue (p > 0.05). The ICC average from evaluators was high (0.88). The SEM varied between 0.13 s and 0.49 s. The CV average considering each individual was near 6-7%. These values depended on the condition of measurement. As the FTAP contains some characteristics that create a degree of unpredictability, the same athlete may reach different performance results, increasing variability. An adjustment in the sample, familiarization and careful selection of subjects help to improve this situation and enhance the reliability of the indicators.

Parole chiave

  • Water polo
  • agility assessment
  • reproducibility
  • testing
Accesso libero

Comparing Tactical Behaviour of Soccer Players in 3 vs. 3 and 6 vs. 6 Small-Sided Games

Pubblicato online: 08 Jul 2014
Pagine: 191 - 202

Astratto

Abstract

The present study aimed to compare players’ tactical behaviour in 3 vs. 3 and 6 vs. 6 soccer small-sided games (SSGs). The sample comprised 3,482 tactical actions performed by 18 U-11 youth soccer players from a Portuguese club, in 3 vs. 3 and 6 vs. 6 SSGs. All participants played eight minutes in both situations and field size was adapted according to the number of players involved (30 m x 19.5 m for 3 vs. 3 and 60 m x 39 m for 6 vs. 6). The System of Tactical Assessment in Soccer (FUT-SAT) was used for data collection and analyses. Descriptive analysis was conducted to verify frequencies and percentages of the variables assessed. The chi-squared (χ2) test was performed to compare the frequencies of the variables between 3 vs. 3 and 6 vs. 6 SSGs and Standardized Residuals (e) were used to examine the influence of the frequency of one or more variables within 3 vs. 3 and 6 vs. 6 SSGs. Data treatment was performed through SPSS for Windows®, version 18.0. Results indicated that players displayed safer behaviours in 6 vs. 6 SSG and more aggressive behaviours in 3 vs. 3 SSG. Findings can aid coaches and teachers to develop different players’ tactical skills according to the chosen SSG (3 vs. 3 or 6 vs. 6) form.

Parole chiave

  • Soccer
  • tactical assessment
  • tactical behaviour
  • small-sided games
Accesso libero

Effects of Match Location, Match Status and Quality of Opposition on Regaining Possession in UEFA Champions League

Pubblicato online: 08 Jul 2014
Pagine: 203 - 214

Astratto

Abstract

The present study aimed to examine the independent and interactive effects of match location, match status, and quality of opposition on regaining possession, analysed by the type and zone of ball recovery, in matches played in the 2011-2012 UEFA Champions League. Twenty-eight matches of the knockout phase were evaluated post-event using a computerized notational analysis system. Multinomial logistic regression analysis was applied to identify the effects of the previously mentioned situational variables on ball recovery type and zone. Match status and quality of opposition main effects were observed for both dependent variables, while main effects of match location were only evident for ball recovery zone. Additionally, the interactions Match location * Quality of opposition and Match status * Quality of opposition were significant for both type and zone of ball recovery. Better teams employed more proactive defensive strategies, since, even when winning, they tried to sustain their defensive success on actions that aimed to gain the ball from the opponents. Results emphasized the tendency for home and losing teams to defend in more advanced pitch zones. Better-ranked teams were also more effective than worse-ranked teams in applying defensive pressure in more advanced pitch positions. The findings of the study suggest that the defensive strategies used by better teams imply more intense and organized collective processes in order to recover the ball directly from the opposing team. Furthermore, defending away from own goal and near the opponent's one seems to be associated with success in elite soccer.

Parole chiave

  • Soccer
  • notational analysis
  • situational variables
  • team performance
  • defensive strategies
Accesso libero

The Examination of Different Tests for the Evaluation of the Efficiency of the Eggbeater Kicks

Pubblicato online: 08 Jul 2014
Pagine: 215 - 226

Astratto

Abstract

The eggbeater kick presents an important basic technical skill in water polo. The aim of this study was to examine some different tests in order to recommend the best ones for the evaluation of the eggbeater kick. Twenty eight young male water polo players performed one test (squat jump) on land and ten tests in water: tethered swimming with legs only, using alternating and simultaneous eggbeater kicks, jumps out of water from basic and vertical (arms vertically above the head) position, water start and swimming two meters and swimming horizontally with legs only five meters with a flying start. The differences between tests were checked by executing dependent t-tests, while Pearson"s correlation coefficients were calculated to evaluate the correlation between different parameters. Results showed that when performing alternate eggbeater kicks greater average forces were produced by the water polo players when compared to consecutive simultaneous eggbeater kicks. However, a short time maximal acceleration of the body in the vertical and horizontal plane was greater when the single simultaneous kick was performed. It was determined that horizontal swimming using legs only and a squat jump were less useful for the evaluation of the eggbeater kick. Therefore, the recommendation was to measure the average force of successive alternating eggbeater kicks, the height of the jump out of the water from the basic position and the water start and swim over a distance of 2 meters.

Parole chiave

  • water polo
  • testing
  • eggbeater kick
  • squat jump
Accesso libero

Isokinetic Leg Strength and Power in Elite Handball Players

Pubblicato online: 08 Jul 2014
Pagine: 227 - 233

Astratto

Abstract

Isokinetic strength evaluation of the knee flexion and extension in concentric mode of contraction is an important part of the comprehensive evaluation of athletes. The aims of this study were to evaluate the isokinetic knee peak torque in both the extension and flexion movement in the dominant and non-dominant leg, and the relationship with jumping performance. Twelve elite male handball players from the top Spanish handball division voluntary participated in the study (age 27.68 ± 4.12 years; body mass 92.89 ± 12.34 kg; body height 1.90 ± 0.05 m). The knee extensor and flexor muscle peak torque of each leg were concentrically measured at 60°/s and 180°/s with an isokinetic dynamometer. The Squat Jump and Countermovement Jump were performed on a force platform to determine power and vertical jump height. Non-significant differences were observed between legs in the isokinetic knee extension (dominant= 2.91 ± 0.53 Nm/kg vs non-dominant = 2.70 ± 0.47 Nm/kg at 60°/s; dominant = 1.90 ± 0.31 Nm/kg vs non-dominant = 1.83 ± 0.29 Nm/kg at 180°/s) and flexion peak torques (dominant = 1.76 ± 0.29 Nm/kg vs non-dominant = 1.72 ± 0.39 Nm/kg at 60°/s; dominant = 1.30 ± 0.23 Nm/kg vs non-dominant = 1.27 ± 0.35 Nm/kg at 180°/s). Low and non-significant correlation coefficients were found between the isokinetic peak torques and vertical jumping performance (SJ = 31.21 ± 4.32 cm; CMJ = 35.89 ± 4.20 cm). Similar isokinetic strength was observed between the legs; therefore, no relationship was found between the isokinetic knee flexion and extension peak torques as well as vertical jumping performance in elite handball players.

Parole chiave

  • isokinetic
  • handball
  • peak torque
  • power
  • jumping
Accesso libero

Fitness Profiles of Elite Portuguese Rugby Union Players

Pubblicato online: 08 Jul 2014
Pagine: 235 - 244

Astratto

Abstract

The aim of this study was to describe the fitness profiles of senior elite Portuguese rugby players. Forty-six senior Portuguese rugby players, classified as backs (n=22; age 26.2±2.8) and forwards (n=24; age 26.7±2.9) were assessed during physical testing sessions carried out for the Portuguese National rugby team. The body composition, maximum strength and anaerobic capacity of players are hypothesized to be important physical characteristics as successful performance in rugby is predicated on the ability to undertake skilled behaviours both quickly and whilst withstanding large forces when in contact situations. No absolute differences were found between the backs and forwards for the speed performance variables although positional differences were found across all speeds when assessed relative to body mass since the forwards were significantly heavier. Coaches and the management team can use this information for monitoring progressive improvements in the physiological capacities of rugby players. These physical characteristics of elite rugby players provide normative profiles for specific positions and should form the basis of developmental programmes for adolescents.

Parole chiave

  • Rugby
  • physical and fitness tests
  • performance
Accesso libero

Physical Fitness Differences between Freestyle and Greco-Roman Junior Wrestlers

Pubblicato online: 08 Jul 2014
Pagine: 245 - 251

Astratto

Abstract

The aim of the present study was to examine physical fitness differences between Freestyle and Greco-Roman junior wrestlers. One hundred twenty-six junior wrestlers, comprising 70 Freestyle and 56 Greco-Roman wrestlers, participated in this study. The somatic and physical fitness profile included body mass, body height, body mass index, body composition, flexibility, maximal anaerobic power of the legs and arms, aerobic endurance, hand grip strength, leg and back strength, and speed. No significant differences were found in the anthropometric and physical features between Freestyle and Greco-Roman wrestlers. The Greco-Roman wrestlers had a significantly higher level of relative leg power, peak arm power, relative peak arm power, and relative average arm power than Freestyle wrestlers (p < 0.05). Greco-Roman wrestlers were significantly faster, had better agility, and had a greater level of leg strength than Freestyle wrestlers, but Freestyle wrestlers were more flexible than Greco-Roman wrestlers (p < 0.05). Discriminant function analysis indicated that peak arm power, agility, speed, and flexibility were selective factors for the differences between Freestyle and Greco-Roman wrestlers. In conclusion, the present study indicates that the differences between these wrestling styles promote physical fitness differences in elite wrestlers. The results reflect specific features of each wrestling style.

Parole chiave

  • Anaerobic power
  • aerobic capacity
  • body composition
  • speed
  • strength
  • wrestlers
Accesso libero

Knowledge of Errors in the Teaching-Learning Process of Judo-Techniques: Osoto-Guruma as a Case Study

Pubblicato online: 08 Jul 2014
Pagine: 253 - 263

Astratto

Abstract

The aim of this article was to suggest some changes in the teaching-learning process methodology of the judo osoto-guruma technique, establishing the action sequences and the most frequent technical errors committed when performing them. The study was carried out with the participation of 45 students with no experience regarding the fundamentals of judo (21 men and 24 women; age=24.02±3.98 years old) from the Bachelor of Science of Physical Activity and Sport Science at the University of Vigo. The proceeding consisted of a systematic observation of a video recording registered during the technique execution. Data obtained were analyzed by means of descriptive statistics and sequential analysis of T-Patterns (obtained with THEME v.5. Software), identifying: a) the presence of typical inaccuracies during the technique performance; b) a number of chained errors affecting body balance, the position of the supporting foot, the blocking action and the final action of the arms. Findings allowed to suggest some motor tasks to correct the identified inaccuracies, the proper sequential actions to make the execution more effective and some recommendations for the use of feedback. Moreover, these findings could be useful for other professionals in order to correct the key technical errors and prevent diverse injuries.

Parole chiave

  • Feedback
  • martial arts
  • observation instrument
  • knowledge of performance
  • teaching
  • T-patterns
Accesso libero

Transference of Traditional Versus Complex Strength and Power Training to Sprint Performance

Pubblicato online: 08 Jul 2014
Pagine: 265 - 273

Astratto

Abstract

The purpose of this study was to determine the effects of two different strength-power training models on sprint performance. Forty-eight soldiers of the Brazilian brigade of special operations with at least one year of army training experience were divided into a control group (CG: n = 15, age: 20.2 ± 0.7 years, body height: 1.74 ± 0.06 m, and body mass: 66.7 ± 9.8 kg), a traditional training group (TT: n = 18, age: 20.1 ± 0.7 years, body height: 1.71 ± 0.05 m, and body mass: 64.2 ± 4.7 kg), and a complex training group (CT: n = 15, age: 20.3 ± 0.8 years, body height: 1.71 ± 0.07 m; and body mass: 64.0 ± 8.8 kg). Maximum strength (25% and 26%), CMJ height (36% and 39%), mean power (30% and 35%) and mean propulsive power (22% and 28%) in the loaded jump squat exercise, and 20-m sprint speed (16% and 14%) increased significantly (p<0.05) following the TT and CT, respectively. However, the transfer effect coefficients (TEC) of strength and power performances to 20-m sprint performance following the TT were greater than the CT throughout the 9-week training period. Our data suggest that TT is more effective than CT to improve sprint performance in moderately trained subjects.

Parole chiave

  • transfer effect
  • complex training
  • traditional training
  • sprint speed performance

Pianifica la tua conferenza remota con Sciendo