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Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

Tom 42 (2014): Zeszyt 1 (September 2014)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

28 Artykułów
Otwarty dostęp

Inconsistencies of the Evaluation of Home Advantage in Sports Competitions Under the Three Points Per Victory System

Data publikacji: 10 Oct 2014
Zakres stron: 5 - 6

Abstrakt

Abstract

A recent letter sent to the Journal of Human Kinetics’ editor (Gómez & Pollard, 2014) warned about a supposed methodology error in the calculation of home advantage in football leagues used in Saavedra et al. (2013) and took the liberty of modifying the research’s data. The aim of this letter is to demonstrate that the evaluation system of the home advantage proposed by Pollard (1986) contains serious inconsistencies when applied to competitions which give three points for a win and one point for a draw, as it is the case of the UEFA football leagues in the 21th century

Otwarty dostęp

Asymmetry of Anticipatory Postural Adjustment During Gait Initiation

Data publikacji: 10 Oct 2014
Zakres stron: 7 - 14

Abstrakt

Abstract

The purpose of this study was to investigate the asymmetry of anticipatory postural adjustment (APA) during gait initiation and to determine whether the process of choosing the initial swing leg affects APA during gait initiation. The participants initiated gait with the leg indicated by a start tone or initiated gait with the leg spontaneously chosen. The dependent variables of APA were not significantly different among the condition of initiating gait with the preferred leg indicated by the start tone, the condition of initiating gait with the non-preferred leg indicated by the start tone, and the condition of initiating gait with the leg spontaneously chosen. These findings fail to support the view that the process of choosing the initial swing leg affects APA during gait initiation. The lateral displacement of the center of pressure in the period in which shifting the center of pressure to the initial swing phase before initiating gait with the left leg indicated by the external cue was significantly larger than that when initiating gait with the right leg indicated by the external cue, and significantly larger than that when initiating gait with the leg spontaneously chosen. Weight shift to the initial swing side during APA during gait initiation was found to be asymmetrical when choosing the leg in response to an external cue

Słowa kluczowe

  • gait initiation
  • anticipatory postural adjustment
  • asymmetry
  • center of pressure
Otwarty dostęp

Body Composition and Kinematic Analysis of the Grab Start in Youth Swimmers

Data publikacji: 10 Oct 2014
Zakres stron: 15 - 26

Abstrakt

Abstract

The purposes of this study were to compare the kinematic variables in youth swimmers during the grab start between sexes and to investigate the relationship between body composition and kinematic variables of the participants. Six female (Mage = 13.71 ± 0.49 yrs) and seven male (Mage = 14.00 ± 1.07 yrs) swimmers participated in this study. All participants were required to perform grab start tests in random order (three trials by each participant), while the best attempt was analyzed. Nineteen kinematic parameters consisting of block time, flight time, flight distance, total time, total distance, horizontal and vertical displacement of the center of mass (CM) at take-off, horizontal and vertical displacement of the CM at entry, height of take-off and entry, relative height of take-off, horizontal and vertical velocity of the CM at take-off, horizontal and vertical velocity of the CM at entry, angle of take-off, angle of entry and angle of knee at block were analyzed. Out of the 19 evaluated kinematic parameters, a statistical difference between the female and male group was found only in the total distance. Therefore, both female and male groups are considered as only one group and merged after analyzing the results. Statistical analysis showed positive and negative correlations between horizontal / vertical velocity of CM at take-off and several kinematic variables (e.g. angle of entry (rhorizontal = -.868, p=.000 / rvertical = .591, p=.02), total distance (rhorizontal = .594, p=.02 / rvertical = .54, p=.04), and height of take-off (rvertical = .888, p=.000), respectively). On the other hand, positive and negative correlations were found between somatotype components and several kinematic variables (e.g. horizontal displacement of CM at entry (rendomorphy = -.626, p=.013), angle of entry (rmesomorphy = -.686, p=.005 / rectomorphy = .52, p=.047), total distance (rendomorphy = -.626, p=.012), and height of take-off (rendomorphy = -.633, p=.011 / rectomorphy = .515, p=.05)). In conclusion, results show that in order to be successful at grab start performance, a swimmer should target to get higher horizontal velocity of CM at take-off and optimize the angle of take-off so this movement form supplies more total distance to the swimmer. Coaches should consider improving start performance and adding start training to regular training sessions. Moreover, youth male and female swimmers can participate together in the grab start training

Słowa kluczowe

  • swimming
  • grab start
  • kinematic analysis
  • somatotype
  • youth swimmers
Otwarty dostęp

The Backstroke Swimming Start: State of the Art

Data publikacji: 10 Oct 2014
Zakres stron: 27 - 40

Abstrakt

Abstract

As sprint swimming events can be decided by margins as small as .01 s, thus, an effective start is essential. This study reviews and discusses the ‘state of the art’ literature regarding backstroke start biomechanics from 23 documents. These included two swimming specific publications, eight peer-reviewed journal articles, three from the Biomechanics and Medicine in Swimming Congress series, eight from the International Society of Biomechanics in Sports Conference Proceedings, one from a Biomechanics Congress and one academic (PhD) thesis. The studies had diverse aims, including swimmers’ proficiency levels and data collection settings. There was no single consensus for defining phase descriptions; and kinematics, kinetics and EMG approaches were implemented in laboratory settings. However, researchers face great challenges in improving methods of quantifying valid, reliable and accurate data between laboratory and competition conditions. For example, starting time was defined from the starting signal to distances as disparate as ~5 m to 22.86 m in several studies. Due to recent rule changes, some of the research outcomes now refer to obsolete backstroke start techniques, and only a few studies considered the actual international rules. This literature review indicated that further research is required, in both laboratory and competition settings focusing on the combined influences of the current rules and block configuration on backstroke starting performances

Słowa kluczowe

  • Biomechanics
  • dorsal starts
  • starting technique
  • starting variant
  • literature review
Otwarty dostęp

Shoulder Rotator Muscle Dynamometry Characteristics: Side Asymmetry and Correlations with Ball-Throwing Speed in Adolescent Handball Players

Data publikacji: 10 Oct 2014
Zakres stron: 41 - 50

Abstrakt

Abstract

The aim of the investigation was to: 1) compare shoulder external/internal rotator muscles’ peak torques and average power values and their ratios in the dominant and non-dominant arm; 2) determine correlations between shoulder rotator muscles’ peak torques, average power and ball-throwing speed in handball players. Fourteen 14 to 15- year-old male athletes with injury-free shoulders participated in the study (body height: 176 ± 7 cm, body mass 63 ± 9 kg). The tests were carried out by an isokinetic dynamometer system in the shoulder internal and external rotation movements at angular velocities of 60°/s, 90°/s and 240°/s during concentric contractions. The eccentric external- concentric internal rotator muscle contractions were performed at the velocity of 90°/s. The player threw a ball at maximal speed keeping both feet on the floor. The speed was recorded with reflected light rays. Training in handball does not cause significant side asymmetry in shoulder external/internal rotator muscle peak torques or the average power ratio. Positive correlations between isokinetic characteristics of the shoulder internal and external rotator muscles and ball-throwing speed were determined. The power produced by internal rotator muscles during concentric contractions after eccentric contractions of external rotator muscles was significantly greater in the dominant than in the non-dominant arm. Thus, it may be concluded that the shoulder eccentric external/concentric internal rotator muscle power ratio is significantly greater than this ratio in the concentric contractions of these muscles

Słowa kluczowe

  • shoulder
  • internal and external rotator muscles
  • isokinetic dynamometry
  • handball
  • throwing speed
Otwarty dostęp

Effect of Leg Dominance on The Center-of-Mass Kinematics During an Inside-of-the-Foot Kick in Amateur Soccer Players

Data publikacji: 10 Oct 2014
Zakres stron: 51 - 61

Abstrakt

Abstract

Soccer kicking kinematics has received wide interest in literature. However, while the instep-kick has been broadly studied, only few researchers investigated the inside-of-the-foot kick, which is one of the most frequently performed techniques during games. In particular, little knowledge is available about differences in kinematics when kicking with the preferred and non-preferred leg. A motion analysis system recorded the three-dimensional coordinates of reflective markers placed upon the body of nine amateur soccer players (23.0 ± 2.1 years, BMI 22.2 ± 2.6 kg/m2), who performed 30 pass-kicks each, 15 with the preferred and 15 with the non-preferred leg. We investigated skill kinematics while maintaining a perspective on the complete picture of movement, looking for laterality related differences. The main focus was laid on: anatomical angles, contribution of upper limbs in kick biomechanics, kinematics of the body Center of Mass (CoM), which describes the whole body movement and is related to balance and stability. When kicking with the preferred leg, CoM displacement during the ground-support phase was 13% higher (p<0.001), normalized CoM height was 1.3% lower (p<0.001) and CoM velocity 10% higher (p<0.01); foot and shank velocities were about 5% higher (p<0.01); arms were more abducted (p<0.01); shoulders were rotated more towards the target (p<0.01, 6° mean orientation difference).

We concluded that differences in motor control between preferred and non-preferred leg kicks exist, particularly in the movement velocity and upper body kinematics. Coaches can use these results to provide effective instructions to players in the learning process, moving their focus on kicking speed and upper body behavior

Słowa kluczowe

  • soccer biomechanics
  • laterality
  • joint angle
  • postural control
  • technical skills
Otwarty dostęp

The Existence of a Sticking Region in Free Weight Squats

Data publikacji: 10 Oct 2014
Zakres stron: 63 - 71

Abstrakt

Abstract

The aim of this study was to investigate the existence of the sticking region in two legged free weight squats. Fifteen resistance-training males (age 24 ± 4 years, body mass 82 ± 11 kg, body height 179 ± 6 cm) with 6 ± 3 years of resistance-training experience performed 6-RM in free weight squats. The last repetition was analyzed for the existence of a sticking region. Only in 10 out of 15 participants a sticking region was observed. The observed sticking region was much shorter than in the bench press. Furthermore, rectus femoris decreased the EMG activity in contrast to increased EMG activity in biceps femoris around the sticking and surrounding region. No significant change in EMG activity was found for the lateral and medial vastus muscles. It is suggested that a combination of these muscle activity changes could be one of the causes of the existence of the sticking region in free weight squats

Słowa kluczowe

  • EMG
  • muscle activity
  • kinematics
  • strength
Otwarty dostęp

Biomechanical Analysis of the Jump Shot in Basketball

Data publikacji: 10 Oct 2014
Zakres stron: 73 - 79

Abstrakt

Abstract

Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player’s jumping ability

Słowa kluczowe

  • basketball
  • jump shot
  • countermovement jump
  • power
  • soft landing
Otwarty dostęp

Kinematic Analysis of the Instep Kick in Youth Soccer Players

Data publikacji: 10 Oct 2014
Zakres stron: 81 - 90

Abstrakt

Abstract

We attempted to establish which applied kinematic variables significantly contributed to the efficiency of the instep kick motion in soccer. The study sample comprised 13 boys (age: 13 ± 0.5 yrs; body mass: 41.50 ± 8.40 kg; body height: 151.46 ± 5.93 cm) from the FC Sloboda school of soccer. Each participant performed three kicks with maximum strength that were video recorded with two synchronized cameras (Casio Ex-F1) positioned 12 m away from the place of the kick. Data were collected by analyzing the video recordings of each kick. Data processing was performed using the APAS motion analysis system (Ariel Dynamics Inc., San Diego, CA). On the basis of the forward selection method of multiple regression analysis, we determined the correlations between the prediction variables and the selected criteria (speed of the ball; p = 0.01). On the basis of the regression coefficients, it was concluded that two variables significantly contributed to the speed of the ball: speed of the foot of the kicking leg at the time of contact with the ball (p = 0.01) and the distance between the angle support leg and center of the ball (“foot posterior displacement”) (p = 0.01). In order to achieve the best possible technical performance and, therefore, a higher speed of the ball, soccer players must pay attention to two important elements during training. First, it is necessary to position the support leg as close to the ball as possible and, second, maximize the force used in the initial phases of the kick to achieve a high speed of the kicking foot

Słowa kluczowe

  • knee angle
  • biomechanics
  • velocity
  • foot
  • support leg
  • kicking technique
Otwarty dostęp

Potentiation and Electrical Stimulus Frequency During Self-Paced Exercise and Recovery

Data publikacji: 10 Oct 2014
Zakres stron: 91 - 101

Abstrakt

Abstract

The aim of this study was to investigate the effect of potentiation on stimulation-induced muscle function during and after an intense bout of self-paced dynamic exercise. Ten active subjects performed a time trial involving repetitive concentric extension-flexion of the right knee using a Biodex dynamometer. Electrical stimulation before and after a 5 s maximal isometric voluntary contraction was performed before the start of the time trial and immediately (< 5 s) after each 20% of the time trial as well as 1, 2, 4 and 8 min after time trial termination. Potentiation was observed before the time trial and as early as 1-2 min after the time trial, but no potentiation was detected during or immediately after the time trial for neither single or paired stimuli. At termination of the time trial, “potentiated” peak torque was significantly more reduced than “unpotentiated" peak torque for single stimulus (-65 ± 10% and -42 ± 18%, respectively) and paired stimuli at 100 Hz (-51 ± 10% and -33 ± 15%, respectively). Faster recovery for “potentiated” compared to “unpotentiated” peak torque indicate that potentiate peak torque measurements or delay the post-exercise measurements more than a few seconds, will underestimate peripheral fatigue. In conclusion, the potentiation after maximal contraction disappears during intense exercise. Whether the muscle is already potentiated during intense contraction or fatiguing mechanisms inhibits potentiation remains to be clarified

Słowa kluczowe

  • Electrical stimulation
  • twitch
  • peripheral fatigue
  • potentiation
  • time trial
Otwarty dostęp

Tracking Changes in Maximal Oxygen Consumption with the Heart Rate Index in Female Collegiate Soccer Players

Data publikacji: 10 Oct 2014
Zakres stron: 103 - 111

Abstrakt

Abstract

The purpose of this study was to determine if the HRindex Method (VO2max = [6 x HRindex - 5] x 3.5, where HRindex = HRmax/HRrest) was accurate for tracking changes in VO2max following 8-weeks of endurance training among collegiate female soccer players. Predicted VO2max via the HRindex Method and observed VO2max from a maximal exercise test on a treadmill were determined for a group of female soccer athletes (n = 15) before and following an 8-week endurance training protocol. The predicted (pVO2max) and observed (aVO2max) values were compared at baseline and within 1-week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference between aVO2max before (43.2 ± 2.8 ml.kg.min-1) and following (46.2 ± 2.1 ml.kg.min-1) the 8-week training program (p < 0.05). However, pVO2max did not significantly change following training (pre = 43.4 ± 4.6 ml.kg.min-1, post = 42.9 ± 4.1 ml.kg.min-1, p = 0.53). Furthermore, the correlation between the change in aVO2max and the change in pVO2max was trivial and non-significant (r = 0.30, p = 0.28). The HRindex Method does not appear to be suitable for predicting changes in VO2max following 8-weeks of endurance training in female collegiate soccer players

Słowa kluczowe

  • athletes
  • women
  • sports
  • aerobic fitness
Otwarty dostęp

Posture, Flexibility and Grip Strength in Horse Riders

Data publikacji: 10 Oct 2014
Zakres stron: 113 - 125

Abstrakt

Abstract

Since the ability to train the horse to be ambidextrous is considered highly desirable, rider asymmetry is recognized as a negative trait. Acquired postural and functional asymmetry can originate from numerous anatomical regions, so it is difficult to suggest if any is developed due to riding. The aim of this study was therefore to assess symmetry of posture, strength and flexibility in a large population of riders and to determine whether typical traits exist due to riding. 127 right handed riders from the UK and USA were categorized according to years riding (in 20 year increments) and their competition level (using affiliated test levels). Leg length, grip strength and spinal posture were measured and recorded by a physiotherapist. Standing and sitting posture and trunk flexibility were measured with 3-D motion capture technology. Right-left differences were explored in relation to years riding and rider competitive experience. Significant anatomical asymmetry was found for the difference in standing acromion process height for a competition level (-0.07±1.50 cm Intro/Prelim; 0.02±1.31 cm Novice; 0.43±1.27 cm Elementary+; p=0.048) and for sitting iliac crest height for years riding (-0.23±1.36 cm Intro/Prelim; 0.01±1.50 cm Novice; 0.86±0.41 cm Elementary+; p=0.021). For functional asymmetry, a significant interaction was found for lateral bending ROM for years riding x competition level (p=0.047). The demands on dressage riders competing at higher levels may predispose these riders to a higher risk of developing asymmetry and potentially chronic back pain rather than improving their symmetry

Słowa kluczowe

  • asymmetry
  • leg length
  • equine
  • back pain
  • laterality
  • equestrian
Otwarty dostęp

Interaction Between ACE I/D and ACTN3 R557X Polymorphisms in Polish Competitive Swimmers

Data publikacji: 10 Oct 2014
Zakres stron: 127 - 136

Abstrakt

Abstract

We hypothesized that the ACE ID / ACTN3 R577X genotype combination was associated with sprint and endurance performance. Therefore, the purpose of the present study was to determine the interaction between both ACE ID and ACTN3 R577X polymorphisms and sprint and endurance performance in swimmers. Genomic DNA was extracted from oral epithelial cells using GenElute Mammalian Genomic DNA Miniprep Kit (Sigma, Germany). All samples were genotyped using a real-time poly- merase chain reaction. The ACE I/D and the ACTN3 R577X genotype frequencies met Hardy-Weinberg expectations in both swimmers and controls. When the two swimmer groups, long distance swimmers (LDS) and short distance swimmers (SDS), were compared with control subjects in a single test, a significant association was found only for the ACE polymorphism, but not for ACTN3. Additionally, four ACE/ACTN3 combined genotypes (ID/RX, ID/XX, II/RX and II/XX) were statistically significant for the LDS versus Control comparison, but none for the SDS versus Control comparison. The ACE I/D and the ACTN3 R577X polymorphisms did not show any association with sprint swimming, taken individually or in combination. In spite of numerous previous reports of associations with athletic status or sprint performance in other sports, the ACTN3 R577X polymorphism, in contrast to ACE I/D, was not significantly associated with elite swimming status when considered individually. However, the combined analysis of the two loci suggests that the co-occurrence of the ACE I and ACTN3 X alleles may be beneficial to swimmers who compete in long distance races

Słowa kluczowe

  • ACE
  • ACTN3
  • gene polymorphism
  • swimming
Otwarty dostęp

Anaerobic and Aerobic Performances in Elite Basketball Players

Data publikacji: 10 Oct 2014
Zakres stron: 137 - 147

Abstrakt

Abstract

The purpose of this study was to propose a specific lactate minimum test for elite basketball players considering the: Running Anaerobic Sprint Test (RAST) as a hyperlactatemia inductor, short distances (specific distance, 20 m) during progressive intensity and mathematical analysis to interpret aerobic and anaerobic variables. The basketball players were assigned to four groups: All positions (n=26), Guard (n= 7), Forward (n=11) and Center (n=8). The hyperlactatemia elevation (RAST) method consisted of 6 maximum sprints over 35 m separated by 10 s of recovery. The progressive phase of the lactate minimum test consisted of 5 stages controlled by an electronic metronome (8.0, 9.0, 10.0, 11.0 and 12.0 km/h) over a 20 m distance. The RAST variables and the lactate values were analyzed using visual and mathematical models. The intensity of the lactate minimum test, determined by a visual method, reduced in relation to polynomial fits (2nd degree) for the Small Forward positions and General groups. The Power and Fatigue Index values, determined by both methods, visual and 3rd degree polynomial, were not significantly different between the groups. In conclusion, the RAST is an excellent hyperlactatemia inductor and the progressive intensity of lactate minimum test using short distances (20 m) can be specifically used to evaluate the aerobic capacity of basketball players. In addition, no differences were observed between the visual and polynomial methods for RAST variables, but lactate minimum intensity was influenced by the method of analysis

Słowa kluczowe

  • lactate minimum
  • sprint
  • mathematical model
  • polynomial adjust
Otwarty dostęp

Effect of a MAST Exercise Program on Anthropometric Parameters, Physical Fitness, and Serum Lipid Levels in Obese Postmenopausal Women

Data publikacji: 10 Oct 2014
Zakres stron: 149 - 155

Abstrakt

Abstract

The purpose of this study was to examine an influence of a mixed aerobic and strength training program (MAST) on anthropometry, serum lipid levels, physical performance, and functional fitness in obese postmenopausal women. The MAST sessions were held three times per week, and the exercise program lasted for 10 weeks. The exercise group demonstrated a statistically significant improvement in maximal oxygen uptake, a waist/hip ratio, and strength of the upper and lower body. An increase in LDL-C levels was observed in the control group. A 10-week MAST program encompassing Nordic-walking as an aerobic component, and strength exercises, induces positive changes in functional fitness, HDL-C, LDL-C and a waist/hip ratio in obese postmenopausal women. The observed changes implicate an increase in a health-related quality of life among the women administered to the physical exercise program

Słowa kluczowe

  • exercise
  • postmenopause
  • physical fitness
  • obesity
  • serum lipids
  • nordic-walking
Otwarty dostęp

Effects of Pre-Exhausting the Biceps Brachii Muscle on the Performance of the Front Lat Pull-Down Exercise Using Different Handgrip Positions

Data publikacji: 10 Oct 2014
Zakres stron: 157 - 163

Abstrakt

Abstract

The aim of the present study was to investigate the effects of pre-exhaustion (PE) of the biceps brachii muscle (BB) on the number of repetitions and the rate of perceived exertion (RPE) in the front lat pull-down (FLPD) using different handgrip positions. Additionally, the effect of sex and its interaction with performance and the RPE were also examined. The participants were 19 healthy subjects: 8 men (age: 27.13±2.85 years; body height: 180.63±6.65 cm; body mass: 82.05±8.92 kg; and body fat: 14.67±6.09%); and 11 women (age: 28.81±3.68 years; body height: 162.91±6.51 cm; body mass 59.63±6.47 kg; and body fat: 24.11±4.33%). The number of repetitions and the RPE in the FLPD exercise with different handgrip positions, with and without PE of the BB, was documented. The following main significant effects were seen: i) PE of the BB decreased the number of repetitions (p<0.001) and increased the RPE (p<0.001); ii) the narrow handgrip width elicited a higher RPE (p<0.001) and iii) women performed fewer repetitions than men in all FLPD exercise variations (p=0.023). Significant interactions were also observed between: i) PE or sex and the RPE (p=0.024); and ii) PE or handgrip width and the number of repetitions (p<0.001). In conclusion, PE of the BB promotes a decreased performance in the FLPD exercise along with a greater RPE, especially when using a narrow handgrip position

Słowa kluczowe

  • resistance training
  • front lat pull-down
  • handgrip width
  • biceps brachii
  • perceived exertion
Otwarty dostęp

Effect of 16 Weeks of Resistance Training on Fatigue Resistance in Men and Women

Data publikacji: 10 Oct 2014
Zakres stron: 165 - 174

Abstrakt

Abstract

The purpose of this study was to investigate the effect of hypertrophy-type resistance training (RT) on upper limb fatigue resistance in young adult men and women. Fifty-eight men (22.7±3.7 years, 70.6±9.3 kg, and 176.8±6.4 cm) and 65 women (21.6±3.7 years, 58.8±11.9 kg, and 162.6±6.2 cm) underwent RT for 16 weeks. Training consisted of 10-12 whole body exercises with 3 sets of 8-12 repetitions maximum performed 3 times per week. Before and after the RT intervention participants were submitted to 1RM testing, as well as a fatigue protocol consisting of 4 sets at 80% 1RM on bench press (BP) and arm curl (AC). The sum of the number of repetitions accomplished in the 4 sets in each exercise was used to indicate fatigue resistance. There was a significant (p<0.05) time-by-group interaction in 1RM BP (men=+16%, women=+26%), however in 1RM AC no significant time-by-group interaction was observed (men=+14%, women=+23%). For the total number of repetitions, men and women showed a significant increase in BP (men=+16.3%, women=+10.5%) with no time-by-group interaction. The results suggest that the adaptation in maximal strength is influenced by sex in BP. On the other hand, for fatigue resistance, the individual’s sex does not seem to influence outcomes either in BP or AC

Słowa kluczowe

  • resistance training
  • one-repetition maximum
  • muscular endurance
  • sex
Otwarty dostęp

Changes in Muscle Strength in U19 Soccer Players During an Annual Training Cycle

Data publikacji: 10 Oct 2014
Zakres stron: 175 - 185

Abstrakt

Abstract

The aim of the study was to investigate the seasonal variation in isokinetic strength of the knee flexors and extensors, and conventional (H/QCONV) and functional (H/QFUNC) hamstring to quadriceps strength ratios in highly trained adolescent soccer players. The players (n=11; age 17.8±0.3) were measured at the end of the competitive season (autumn), at the beginning and the end of pre-season (winter) and during the sixth week of a new competitive season. Isokinetic peak torque (concentric and eccentric) was measured at 60°•s-1 in a sitting position with the hip flexed at 100°. The testing range of motion was set from 10 - 90° of knee flexion. The players performed a set of five maximum repetitions for both the dominant and non-dominant leg. Statistically significant differences (p<0.001) between the four seasonal measurements were noted for peak torque of the dominant leg knee flexors in concentric muscle action only. A post hoc analysis revealed a statistically significant increase in peak torque from the 1st to the 4th measurement (p<0.001; d=0.692) and from the 2nd to the 4th (p<0.01; d=0.564). The differences in the changes of peak torque of the knee flexors and extensors depending on type of muscle action and tendencies found in the H/Q ratios throughout the annual training cycle indicate that strength assessment of the knee flexors and extensors and their balance throughout the annual training cycle could be beneficial for elite male adolescent soccer players both in terms of performance and risk of injury.

Słowa kluczowe

  • adolescents
  • H/Q ratio
  • isokinetic
  • torque
  • training
Otwarty dostęp

The Effect of Course Length on Individual Medley Swimming Performance in National and International Athletes

Data publikacji: 10 Oct 2014
Zakres stron: 187 - 200

Abstrakt

Abstract

Effects of course length (25 m versus 50 m) and advances in performance of individual medley swimming were examined for men and women in Swiss national competitions and FINA World Championships during 2000-2011. Linear regression and analysis of variance (ANOVA) were used to analyse 200 m and 400 m race results for 26,081 swims on the Swiss high score list and 382 FINA finalists. Swiss and FINA swimmers of both sexes were, on average, 4.3±3.2% faster on short courses for both race distances. Sex-related differences in swim speed were significantly greater for FINA swimmers competing in short-course events than in long-course events (10.3±0.2% versus 9.7±0.3%, p<0.01), but did not differ for Swiss swimmers (p>0.05). Sex-related differences in swimming speed decreased with increasing race distance for both short- and long-course events for Swiss athletes, and for FINA athletes in long-course events. Performance improved significantly (p<0.05) during 2000-2011 for FINA men competing in either course length and FINA females competing in short-course events, but not for Swiss swimmers. Overall, the results showed that men and women individual medley swimmers, competing at both national and international levels, have faster average swimming speeds on short courses than on long courses, for both 200 m and 400 m distances. FINA athletes demonstrate an improving performance in the vast majority of individual medley events, while performance at national level seems to have reached a plateau during 2000-2011

Słowa kluczowe

  • swim speed
  • pool length
  • sex-related difference
  • temporal trends
Otwarty dostęp

Avoiding Systematic Errors in Isometric Squat-Related Studies without Pre-Familiarization by Using Sufficient Numbers of Trials

Data publikacji: 10 Oct 2014
Zakres stron: 201 - 213

Abstrakt

Abstract

There is no scientific evidence in the literature indicating that maximal isometric strength measures can be assessed within 3 trials. We questioned whether the results of isometric squat-related studies in which maximal isometric squat strength (MISS) testing was performed using limited numbers of trials without pre-familiarization might have included systematic errors, especially those resulting from acute learning effects. Forty resistance-trained male participants performed 8 isometric squat trials without pre-familiarization. The highest measures in the first “n” trials (3 ≤ n ≤ 8) of these 8 squats were regarded as MISS obtained using 6 different MISS test methods featuring different numbers of trials (The Best of n Trials Method [BnT]). When B3T and B8T were paired with other methods, high reliability was found between the paired methods in terms of intraclass correlation coefficients (0.93-0.98) and coefficients of variation (3.4-7.0%). The Wilcoxon’s signed rank test indicated that MISS obtained using B3T and B8T were lower (p < 0.001) and higher (p < 0.001), respectively, than those obtained using other methods. The Bland- Altman method revealed a lack of agreement between any of the paired methods. Simulation studies illustrated that increasing the number of trials to 9-10 using a relatively large sample size (i.e., ≥ 24) could be an effective means of obtaining the actual MISS values of the participants. The common use of a limited number of trials in MISS tests without pre-familiarization appears to have no solid scientific base. Our findings suggest that the number of trials should be increased in commonly used MISS tests to avoid learning effect-related systematic errors

Słowa kluczowe

  • isometric testing standards
  • learning effect
  • number of trials
  • maximal isometric strength
  • testing study assumptions
Otwarty dostęp

A Single-Unit Design Structure and Gender Differences in the Swimming World Championships

Data publikacji: 10 Oct 2014
Zakres stron: 215 - 222

Abstrakt

Abstract

Four 50 meter male/female finals - the freestyle, butterfly, breaststroke, and backstroke - swum during individual events at the Swimming World Championships (SWCs) can be defined in four clusters. The aim of the present study was to use a single-unit design structure, in which the swimmer was defined at only one scale, to evaluate gender differences in start reaction times among elite swimmers in 50 m events. The top six male and female swimmers in the finals of four swimming stroke final events in six SWCs were analyzed. An unpaired t-test was used. The p-values were evaluated using Neo-Fisherian significance assessments (Hurlbert and Lombardi, 2012). For the freestyle, gender differences in the start reaction times were positively identified for five of the six SWCs. For the backstroke, gender differences in the start reaction times could be dismissed for five of the six SWCs. For both the butterfly and breaststroke, gender differences in the start reaction times yielded inconsistent statistical differences. Pooling all swimmers together (df = 286) showed that an overall gender difference in the start reaction times could be positively identified: p = 0.00004. The contrast between the gender differences in start reaction times between the freestyle and backstroke may be associated with different types of gender adaptations to swimming performances. When the natural groupings of swimming stroke final events were ignored, sacrificial pseudoreplication occurred, which may lead to erroneous statistical differences

Słowa kluczowe

  • Clusters
  • designing studies
  • statistical analysis
  • nondemonic intrusion
  • sample size
  • sacrificial pseudoreplication
Otwarty dostęp

Assessment of Secondary School Students’ Game Performance Related to Tactical Contexts

Data publikacji: 10 Oct 2014
Zakres stron: 223 - 234

Abstrakt

Abstract

Certain limitations remain unaddressed when utilizing the Teaching Games for Understanding approach, suggesting the need for more research on authentic assessment of skill development and tactical awareness in order to guide the design of developmentally appropriate curriculum materials. This study investigated physical education students’ (n=19; age: 13.71 ± 0.4) game performance during an invasion game, specifically the relationship between their skill execution and decision-making ability. The purpose of the study was twofold: (a) to devise and implement a ‘game context’ approach to assess the game performance components and in doing so, (b) to provide information that could be used to design suitable learning progressions within tactical teaching approaches. Students’ game performance was videotaped, and measures of skill execution and decision-making were developed from observational analyses. Decision-making was measured at two levels: a) decision making restricted to the selection of technical-tactical skills (i.e., passing, moving with the ball, getting free, marking, tackling, double teaming and interception; and b) decisionmaking in the adaptation to the tactical contexts of the game. Participants played a 5 vs. 5 modified eight-minute team handball game. Participants scored significantly higher in penetrating-the-defense context adaptation than in keepingthe- ball context adaptation. Participants showed a higher efficiency in decision-making than in execution in most of the technical-tactical skills; including on-the-ball over off-the-ball decision-making, and in attack compared to defensive execution. The findings also revealed significant relationships between decision-making and skill execution in shooting, tackling and passing

Słowa kluczowe

  • teaching games for understanding
  • performance based assessment
  • physical education
  • invasion games
  • small sided games
  • constraints
Otwarty dostęp

Oxygen Uptake and Heart Rate Kinetics after Different Types of Resistance Exercise

Data publikacji: 10 Oct 2014
Zakres stron: 235 - 244

Abstrakt

Abstract

Oxygen uptake (VO2) and heart rate (HR) kinetics after exercise are important indicators of fitness and cardiovascular health. However, these variables have been little investigated in resistance exercise (RE). The current study compared post-exercise kinetics of VO2 and the HR among different types of REs. The study included 14 males (age: 26.5±5.4 years, body mass: 80.1±11.4 kg, body height: 1.77±0.07 m, fat content: 11.3±4.6%) with RE experience. Dynamic muscle strength was measured using one repetition maximum (1RM) with regard to the half-squat, bench press, pull-down, and triceps pushdown exercises. The participants performed a maximum number of repetitions at 80% of 1RM for each exercise, separated by a recovery period of 60 minutes. VO2 was measured using ergospirometry. VO2 and HR kinetics were assessed using the time constant of the recovery curves, and excess oxygen consumption (EPOC) was calculated afterward. Significant differences were not observed across the exercises with regard to VO2 kinetics. However, the half-squat exercise elicited a greater EPOC than the bench press and triceps pushdown exercises (p<.05). HR kinetics was slower for the half-squat exercise than for the other exercises (p<.05). These findings confirm that the type of RE influences both the cardiac autonomic response post-exercise and EPOC, but not VO2 kinetics

Słowa kluczowe

  • strength training
  • oxygen uptake
  • energy metabolism
  • energy expenditure
Otwarty dostęp

Qualitative Task Analysis to Enhance Sports Characterization: A Surfing Case Study

Data publikacji: 10 Oct 2014
Zakres stron: 245 - 257

Abstrakt

Abstract

The aim of this study was to develop a Matrix of Analysis for Sports Tasks (MAST), regardless of the sports activity, based on practice classification and task analysis. Being this a qualitative research our main question was: in assessing sports’ structure is it possible to make the characterization of any discipline through context and individuals’ behaviours? The sample was within a surf discipline in a competition flowing having 5 of the top 16 Portuguese surfers training together. Based on a qualitative method, studying the surf as the main activity was an interpretative study case. The MAST was applied in four phases: taxonomy; tasks and context description; task analysis; teaching and performance strategies. Its application allowed the activities’ characterization through the observation, surfer’s opinions and bibliographical support. The triangulation of the data was used as an information data treatment. The elements were classified by the challenges proposed to the practitioners and the taxonomy was constituted by the sport activities, group, modality and discipline. Surf is a discipline of surfing which is a sliding sport modality, therefore, a nature sport. In the context description, we had the wave’s components and constraints and the surfboards’ qualities. Through task analysis we obtained a taxonomy of surf manoeuvres. The structural and functional analysis allowed finding solutions for learning of surf techniques with trampoline and skateboards because these fit in sliding sports. MAST makes possible the development of strategies that benefit teaching and performance intervention

Słowa kluczowe

  • qualitative research
  • taxonomy
  • structural analysis
  • functional analysis
  • nature sports
  • sliding sports
Otwarty dostęp

Somatotype of Competitive Youth Soccer Players From Brazil

Data publikacji: 10 Oct 2014
Zakres stron: 259 - 266

Abstrakt

Abstract

The aim of this study was to identify the morphological configuration of youth athletes from professional soccer clubs and to verify their differences according to the tactical position on the field. Overall, 67 male players aged 15 to 17 years were evaluated. The examined anthropometric measurements included body mass, body height, skinfolds (triceps, subscapular, supraspinal and medial calf), girths (flexed and tensed arm and calf) and breadths (humerus and femur). For statistical purposes, analysis of variance and post hoc Bonferroni and Kruskal-Wallis tests were used. We concluded that goalkeepers were heavier and taller than center backs (p = 0.015 and p = 0.001), midfielders (p = 0.005 and p <0.001) and center forward players (p = 0.024 and p <0.001). The average somatotype for defense, forward and goalkeeper positions was a balanced mesomorph. Midfield players showed ectomorphic-mesomorph characteristics. It was concluded that goalkeepers were characterized as being taller and heavier and that somatotype features of athletes were similar between positions, except for midfield players

Słowa kluczowe

  • athletes
  • anthropometry
  • male
  • soccer
  • youth
Otwarty dostęp

Analysis of Experts’ Quantitative Assessment of Adolescent Basketball Players and the Role of Anthropometric and Physiological Attributes

Data publikacji: 10 Oct 2014
Zakres stron: 267 - 276

Abstrakt

Abstract

In this paper, we investigated two questions: (1) can measurements of anthropometric and physiological attributes substitute for expert assessment of adolescent basketball players, and (2) how much does the quantitative assessment of a player vary among experts? The first question is relevant to the potential simplification of the player selection process. The second question pertains directly to the validity of expert quantitative assessment. Our research was based on data from 148 U14 female and male basketball players. For each player, an array of anthropometric and physiological attributes was recorded, including body height, body mass, BMI, and several motor skill tests. Furthermore, each player's current ability and potential ability were quantitatively evaluated by two different experts from a group of seven experts. Analysis of the recorded data showed that the anthropometric and physiological attributes explained between 15% and 40% of the variance in experts’ scores. The primary predictive attributes were speed and agility (for predicting current ability) and body height and growth potential (for predicting potential ability). We concluded that these attributes were not sufficiently informative to act as a substitute for expert assessment of the players’ current or potential ability. There is substantial variability in different experts' scores of the same player’s ability. However, the differences between experts are mostly in scale, and the relationships between experts’ scores are monotonic. That is, different experts rank players on ability very similarly, but their scores are not well calibrated.

Słowa kluczowe

  • sports
  • coaching
  • morphology
  • motor skills
  • performance evaluation
  • players’ selection
Otwarty dostęp

Height and Body Composition Determine Arm Propulsive Force in Youth Swimmers Independent of a Maturation Stage

Data publikacji: 10 Oct 2014
Zakres stron: 277 - 284

Abstrakt

Abstract

The aim of this study was to examine the relationship between anthropometric variables, body composition and propulsive force in swimmers aged 9-17 years. Anthropometric characteristics (body height and mass, sitting height, arm span, arm muscle area and body composition) and the propulsive force of the arm (tethered swimming test) were evaluated in 56 competitive male swimmers. Tanner’s stages of genital maturation (P1-5) were used. The data analysis included correlations and multiple linear regression. The propulsive force of the arm was correlated with body height (r = 0.34; p =0.013), arm span (r = 0.29; p =0.042), sitting height (r = 0.36; p =0.009), % body fat (r = 0.33; p =0.016), lean body mass (r = 0.34; p =0.015) and arm muscle area (r = 0.31; p =0.026). Using multiple linear regression models, the percent body fat and height were identified as significant predictors of the propulsive force of the arm after controlling for the maturation stage. This model explained 22% (R2 = 0.22) of associations. In conclusion, the propulsive force of swimmers was related to body height and percent body fat

Słowa kluczowe

  • body composition
  • performance
  • swimming
  • anthropometric variables
  • propulsive force
Otwarty dostęp

Mark Pitkin “Practical Sanomechanics®: Exercising for a Healthy Skeleton”

Data publikacji: 10 Oct 2014
Zakres stron: 285 - 286

Abstrakt

Słowa kluczowe

  • sanomechanics
  • floating skeleton theory
  • rehabilitation
28 Artykułów
Otwarty dostęp

Inconsistencies of the Evaluation of Home Advantage in Sports Competitions Under the Three Points Per Victory System

Data publikacji: 10 Oct 2014
Zakres stron: 5 - 6

Abstrakt

Abstract

A recent letter sent to the Journal of Human Kinetics’ editor (Gómez & Pollard, 2014) warned about a supposed methodology error in the calculation of home advantage in football leagues used in Saavedra et al. (2013) and took the liberty of modifying the research’s data. The aim of this letter is to demonstrate that the evaluation system of the home advantage proposed by Pollard (1986) contains serious inconsistencies when applied to competitions which give three points for a win and one point for a draw, as it is the case of the UEFA football leagues in the 21th century

Otwarty dostęp

Asymmetry of Anticipatory Postural Adjustment During Gait Initiation

Data publikacji: 10 Oct 2014
Zakres stron: 7 - 14

Abstrakt

Abstract

The purpose of this study was to investigate the asymmetry of anticipatory postural adjustment (APA) during gait initiation and to determine whether the process of choosing the initial swing leg affects APA during gait initiation. The participants initiated gait with the leg indicated by a start tone or initiated gait with the leg spontaneously chosen. The dependent variables of APA were not significantly different among the condition of initiating gait with the preferred leg indicated by the start tone, the condition of initiating gait with the non-preferred leg indicated by the start tone, and the condition of initiating gait with the leg spontaneously chosen. These findings fail to support the view that the process of choosing the initial swing leg affects APA during gait initiation. The lateral displacement of the center of pressure in the period in which shifting the center of pressure to the initial swing phase before initiating gait with the left leg indicated by the external cue was significantly larger than that when initiating gait with the right leg indicated by the external cue, and significantly larger than that when initiating gait with the leg spontaneously chosen. Weight shift to the initial swing side during APA during gait initiation was found to be asymmetrical when choosing the leg in response to an external cue

Słowa kluczowe

  • gait initiation
  • anticipatory postural adjustment
  • asymmetry
  • center of pressure
Otwarty dostęp

Body Composition and Kinematic Analysis of the Grab Start in Youth Swimmers

Data publikacji: 10 Oct 2014
Zakres stron: 15 - 26

Abstrakt

Abstract

The purposes of this study were to compare the kinematic variables in youth swimmers during the grab start between sexes and to investigate the relationship between body composition and kinematic variables of the participants. Six female (Mage = 13.71 ± 0.49 yrs) and seven male (Mage = 14.00 ± 1.07 yrs) swimmers participated in this study. All participants were required to perform grab start tests in random order (three trials by each participant), while the best attempt was analyzed. Nineteen kinematic parameters consisting of block time, flight time, flight distance, total time, total distance, horizontal and vertical displacement of the center of mass (CM) at take-off, horizontal and vertical displacement of the CM at entry, height of take-off and entry, relative height of take-off, horizontal and vertical velocity of the CM at take-off, horizontal and vertical velocity of the CM at entry, angle of take-off, angle of entry and angle of knee at block were analyzed. Out of the 19 evaluated kinematic parameters, a statistical difference between the female and male group was found only in the total distance. Therefore, both female and male groups are considered as only one group and merged after analyzing the results. Statistical analysis showed positive and negative correlations between horizontal / vertical velocity of CM at take-off and several kinematic variables (e.g. angle of entry (rhorizontal = -.868, p=.000 / rvertical = .591, p=.02), total distance (rhorizontal = .594, p=.02 / rvertical = .54, p=.04), and height of take-off (rvertical = .888, p=.000), respectively). On the other hand, positive and negative correlations were found between somatotype components and several kinematic variables (e.g. horizontal displacement of CM at entry (rendomorphy = -.626, p=.013), angle of entry (rmesomorphy = -.686, p=.005 / rectomorphy = .52, p=.047), total distance (rendomorphy = -.626, p=.012), and height of take-off (rendomorphy = -.633, p=.011 / rectomorphy = .515, p=.05)). In conclusion, results show that in order to be successful at grab start performance, a swimmer should target to get higher horizontal velocity of CM at take-off and optimize the angle of take-off so this movement form supplies more total distance to the swimmer. Coaches should consider improving start performance and adding start training to regular training sessions. Moreover, youth male and female swimmers can participate together in the grab start training

Słowa kluczowe

  • swimming
  • grab start
  • kinematic analysis
  • somatotype
  • youth swimmers
Otwarty dostęp

The Backstroke Swimming Start: State of the Art

Data publikacji: 10 Oct 2014
Zakres stron: 27 - 40

Abstrakt

Abstract

As sprint swimming events can be decided by margins as small as .01 s, thus, an effective start is essential. This study reviews and discusses the ‘state of the art’ literature regarding backstroke start biomechanics from 23 documents. These included two swimming specific publications, eight peer-reviewed journal articles, three from the Biomechanics and Medicine in Swimming Congress series, eight from the International Society of Biomechanics in Sports Conference Proceedings, one from a Biomechanics Congress and one academic (PhD) thesis. The studies had diverse aims, including swimmers’ proficiency levels and data collection settings. There was no single consensus for defining phase descriptions; and kinematics, kinetics and EMG approaches were implemented in laboratory settings. However, researchers face great challenges in improving methods of quantifying valid, reliable and accurate data between laboratory and competition conditions. For example, starting time was defined from the starting signal to distances as disparate as ~5 m to 22.86 m in several studies. Due to recent rule changes, some of the research outcomes now refer to obsolete backstroke start techniques, and only a few studies considered the actual international rules. This literature review indicated that further research is required, in both laboratory and competition settings focusing on the combined influences of the current rules and block configuration on backstroke starting performances

Słowa kluczowe

  • Biomechanics
  • dorsal starts
  • starting technique
  • starting variant
  • literature review
Otwarty dostęp

Shoulder Rotator Muscle Dynamometry Characteristics: Side Asymmetry and Correlations with Ball-Throwing Speed in Adolescent Handball Players

Data publikacji: 10 Oct 2014
Zakres stron: 41 - 50

Abstrakt

Abstract

The aim of the investigation was to: 1) compare shoulder external/internal rotator muscles’ peak torques and average power values and their ratios in the dominant and non-dominant arm; 2) determine correlations between shoulder rotator muscles’ peak torques, average power and ball-throwing speed in handball players. Fourteen 14 to 15- year-old male athletes with injury-free shoulders participated in the study (body height: 176 ± 7 cm, body mass 63 ± 9 kg). The tests were carried out by an isokinetic dynamometer system in the shoulder internal and external rotation movements at angular velocities of 60°/s, 90°/s and 240°/s during concentric contractions. The eccentric external- concentric internal rotator muscle contractions were performed at the velocity of 90°/s. The player threw a ball at maximal speed keeping both feet on the floor. The speed was recorded with reflected light rays. Training in handball does not cause significant side asymmetry in shoulder external/internal rotator muscle peak torques or the average power ratio. Positive correlations between isokinetic characteristics of the shoulder internal and external rotator muscles and ball-throwing speed were determined. The power produced by internal rotator muscles during concentric contractions after eccentric contractions of external rotator muscles was significantly greater in the dominant than in the non-dominant arm. Thus, it may be concluded that the shoulder eccentric external/concentric internal rotator muscle power ratio is significantly greater than this ratio in the concentric contractions of these muscles

Słowa kluczowe

  • shoulder
  • internal and external rotator muscles
  • isokinetic dynamometry
  • handball
  • throwing speed
Otwarty dostęp

Effect of Leg Dominance on The Center-of-Mass Kinematics During an Inside-of-the-Foot Kick in Amateur Soccer Players

Data publikacji: 10 Oct 2014
Zakres stron: 51 - 61

Abstrakt

Abstract

Soccer kicking kinematics has received wide interest in literature. However, while the instep-kick has been broadly studied, only few researchers investigated the inside-of-the-foot kick, which is one of the most frequently performed techniques during games. In particular, little knowledge is available about differences in kinematics when kicking with the preferred and non-preferred leg. A motion analysis system recorded the three-dimensional coordinates of reflective markers placed upon the body of nine amateur soccer players (23.0 ± 2.1 years, BMI 22.2 ± 2.6 kg/m2), who performed 30 pass-kicks each, 15 with the preferred and 15 with the non-preferred leg. We investigated skill kinematics while maintaining a perspective on the complete picture of movement, looking for laterality related differences. The main focus was laid on: anatomical angles, contribution of upper limbs in kick biomechanics, kinematics of the body Center of Mass (CoM), which describes the whole body movement and is related to balance and stability. When kicking with the preferred leg, CoM displacement during the ground-support phase was 13% higher (p<0.001), normalized CoM height was 1.3% lower (p<0.001) and CoM velocity 10% higher (p<0.01); foot and shank velocities were about 5% higher (p<0.01); arms were more abducted (p<0.01); shoulders were rotated more towards the target (p<0.01, 6° mean orientation difference).

We concluded that differences in motor control between preferred and non-preferred leg kicks exist, particularly in the movement velocity and upper body kinematics. Coaches can use these results to provide effective instructions to players in the learning process, moving their focus on kicking speed and upper body behavior

Słowa kluczowe

  • soccer biomechanics
  • laterality
  • joint angle
  • postural control
  • technical skills
Otwarty dostęp

The Existence of a Sticking Region in Free Weight Squats

Data publikacji: 10 Oct 2014
Zakres stron: 63 - 71

Abstrakt

Abstract

The aim of this study was to investigate the existence of the sticking region in two legged free weight squats. Fifteen resistance-training males (age 24 ± 4 years, body mass 82 ± 11 kg, body height 179 ± 6 cm) with 6 ± 3 years of resistance-training experience performed 6-RM in free weight squats. The last repetition was analyzed for the existence of a sticking region. Only in 10 out of 15 participants a sticking region was observed. The observed sticking region was much shorter than in the bench press. Furthermore, rectus femoris decreased the EMG activity in contrast to increased EMG activity in biceps femoris around the sticking and surrounding region. No significant change in EMG activity was found for the lateral and medial vastus muscles. It is suggested that a combination of these muscle activity changes could be one of the causes of the existence of the sticking region in free weight squats

Słowa kluczowe

  • EMG
  • muscle activity
  • kinematics
  • strength
Otwarty dostęp

Biomechanical Analysis of the Jump Shot in Basketball

Data publikacji: 10 Oct 2014
Zakres stron: 73 - 79

Abstrakt

Abstract

Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player’s jumping ability

Słowa kluczowe

  • basketball
  • jump shot
  • countermovement jump
  • power
  • soft landing
Otwarty dostęp

Kinematic Analysis of the Instep Kick in Youth Soccer Players

Data publikacji: 10 Oct 2014
Zakres stron: 81 - 90

Abstrakt

Abstract

We attempted to establish which applied kinematic variables significantly contributed to the efficiency of the instep kick motion in soccer. The study sample comprised 13 boys (age: 13 ± 0.5 yrs; body mass: 41.50 ± 8.40 kg; body height: 151.46 ± 5.93 cm) from the FC Sloboda school of soccer. Each participant performed three kicks with maximum strength that were video recorded with two synchronized cameras (Casio Ex-F1) positioned 12 m away from the place of the kick. Data were collected by analyzing the video recordings of each kick. Data processing was performed using the APAS motion analysis system (Ariel Dynamics Inc., San Diego, CA). On the basis of the forward selection method of multiple regression analysis, we determined the correlations between the prediction variables and the selected criteria (speed of the ball; p = 0.01). On the basis of the regression coefficients, it was concluded that two variables significantly contributed to the speed of the ball: speed of the foot of the kicking leg at the time of contact with the ball (p = 0.01) and the distance between the angle support leg and center of the ball (“foot posterior displacement”) (p = 0.01). In order to achieve the best possible technical performance and, therefore, a higher speed of the ball, soccer players must pay attention to two important elements during training. First, it is necessary to position the support leg as close to the ball as possible and, second, maximize the force used in the initial phases of the kick to achieve a high speed of the kicking foot

Słowa kluczowe

  • knee angle
  • biomechanics
  • velocity
  • foot
  • support leg
  • kicking technique
Otwarty dostęp

Potentiation and Electrical Stimulus Frequency During Self-Paced Exercise and Recovery

Data publikacji: 10 Oct 2014
Zakres stron: 91 - 101

Abstrakt

Abstract

The aim of this study was to investigate the effect of potentiation on stimulation-induced muscle function during and after an intense bout of self-paced dynamic exercise. Ten active subjects performed a time trial involving repetitive concentric extension-flexion of the right knee using a Biodex dynamometer. Electrical stimulation before and after a 5 s maximal isometric voluntary contraction was performed before the start of the time trial and immediately (< 5 s) after each 20% of the time trial as well as 1, 2, 4 and 8 min after time trial termination. Potentiation was observed before the time trial and as early as 1-2 min after the time trial, but no potentiation was detected during or immediately after the time trial for neither single or paired stimuli. At termination of the time trial, “potentiated” peak torque was significantly more reduced than “unpotentiated" peak torque for single stimulus (-65 ± 10% and -42 ± 18%, respectively) and paired stimuli at 100 Hz (-51 ± 10% and -33 ± 15%, respectively). Faster recovery for “potentiated” compared to “unpotentiated” peak torque indicate that potentiate peak torque measurements or delay the post-exercise measurements more than a few seconds, will underestimate peripheral fatigue. In conclusion, the potentiation after maximal contraction disappears during intense exercise. Whether the muscle is already potentiated during intense contraction or fatiguing mechanisms inhibits potentiation remains to be clarified

Słowa kluczowe

  • Electrical stimulation
  • twitch
  • peripheral fatigue
  • potentiation
  • time trial
Otwarty dostęp

Tracking Changes in Maximal Oxygen Consumption with the Heart Rate Index in Female Collegiate Soccer Players

Data publikacji: 10 Oct 2014
Zakres stron: 103 - 111

Abstrakt

Abstract

The purpose of this study was to determine if the HRindex Method (VO2max = [6 x HRindex - 5] x 3.5, where HRindex = HRmax/HRrest) was accurate for tracking changes in VO2max following 8-weeks of endurance training among collegiate female soccer players. Predicted VO2max via the HRindex Method and observed VO2max from a maximal exercise test on a treadmill were determined for a group of female soccer athletes (n = 15) before and following an 8-week endurance training protocol. The predicted (pVO2max) and observed (aVO2max) values were compared at baseline and within 1-week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference between aVO2max before (43.2 ± 2.8 ml.kg.min-1) and following (46.2 ± 2.1 ml.kg.min-1) the 8-week training program (p < 0.05). However, pVO2max did not significantly change following training (pre = 43.4 ± 4.6 ml.kg.min-1, post = 42.9 ± 4.1 ml.kg.min-1, p = 0.53). Furthermore, the correlation between the change in aVO2max and the change in pVO2max was trivial and non-significant (r = 0.30, p = 0.28). The HRindex Method does not appear to be suitable for predicting changes in VO2max following 8-weeks of endurance training in female collegiate soccer players

Słowa kluczowe

  • athletes
  • women
  • sports
  • aerobic fitness
Otwarty dostęp

Posture, Flexibility and Grip Strength in Horse Riders

Data publikacji: 10 Oct 2014
Zakres stron: 113 - 125

Abstrakt

Abstract

Since the ability to train the horse to be ambidextrous is considered highly desirable, rider asymmetry is recognized as a negative trait. Acquired postural and functional asymmetry can originate from numerous anatomical regions, so it is difficult to suggest if any is developed due to riding. The aim of this study was therefore to assess symmetry of posture, strength and flexibility in a large population of riders and to determine whether typical traits exist due to riding. 127 right handed riders from the UK and USA were categorized according to years riding (in 20 year increments) and their competition level (using affiliated test levels). Leg length, grip strength and spinal posture were measured and recorded by a physiotherapist. Standing and sitting posture and trunk flexibility were measured with 3-D motion capture technology. Right-left differences were explored in relation to years riding and rider competitive experience. Significant anatomical asymmetry was found for the difference in standing acromion process height for a competition level (-0.07±1.50 cm Intro/Prelim; 0.02±1.31 cm Novice; 0.43±1.27 cm Elementary+; p=0.048) and for sitting iliac crest height for years riding (-0.23±1.36 cm Intro/Prelim; 0.01±1.50 cm Novice; 0.86±0.41 cm Elementary+; p=0.021). For functional asymmetry, a significant interaction was found for lateral bending ROM for years riding x competition level (p=0.047). The demands on dressage riders competing at higher levels may predispose these riders to a higher risk of developing asymmetry and potentially chronic back pain rather than improving their symmetry

Słowa kluczowe

  • asymmetry
  • leg length
  • equine
  • back pain
  • laterality
  • equestrian
Otwarty dostęp

Interaction Between ACE I/D and ACTN3 R557X Polymorphisms in Polish Competitive Swimmers

Data publikacji: 10 Oct 2014
Zakres stron: 127 - 136

Abstrakt

Abstract

We hypothesized that the ACE ID / ACTN3 R577X genotype combination was associated with sprint and endurance performance. Therefore, the purpose of the present study was to determine the interaction between both ACE ID and ACTN3 R577X polymorphisms and sprint and endurance performance in swimmers. Genomic DNA was extracted from oral epithelial cells using GenElute Mammalian Genomic DNA Miniprep Kit (Sigma, Germany). All samples were genotyped using a real-time poly- merase chain reaction. The ACE I/D and the ACTN3 R577X genotype frequencies met Hardy-Weinberg expectations in both swimmers and controls. When the two swimmer groups, long distance swimmers (LDS) and short distance swimmers (SDS), were compared with control subjects in a single test, a significant association was found only for the ACE polymorphism, but not for ACTN3. Additionally, four ACE/ACTN3 combined genotypes (ID/RX, ID/XX, II/RX and II/XX) were statistically significant for the LDS versus Control comparison, but none for the SDS versus Control comparison. The ACE I/D and the ACTN3 R577X polymorphisms did not show any association with sprint swimming, taken individually or in combination. In spite of numerous previous reports of associations with athletic status or sprint performance in other sports, the ACTN3 R577X polymorphism, in contrast to ACE I/D, was not significantly associated with elite swimming status when considered individually. However, the combined analysis of the two loci suggests that the co-occurrence of the ACE I and ACTN3 X alleles may be beneficial to swimmers who compete in long distance races

Słowa kluczowe

  • ACE
  • ACTN3
  • gene polymorphism
  • swimming
Otwarty dostęp

Anaerobic and Aerobic Performances in Elite Basketball Players

Data publikacji: 10 Oct 2014
Zakres stron: 137 - 147

Abstrakt

Abstract

The purpose of this study was to propose a specific lactate minimum test for elite basketball players considering the: Running Anaerobic Sprint Test (RAST) as a hyperlactatemia inductor, short distances (specific distance, 20 m) during progressive intensity and mathematical analysis to interpret aerobic and anaerobic variables. The basketball players were assigned to four groups: All positions (n=26), Guard (n= 7), Forward (n=11) and Center (n=8). The hyperlactatemia elevation (RAST) method consisted of 6 maximum sprints over 35 m separated by 10 s of recovery. The progressive phase of the lactate minimum test consisted of 5 stages controlled by an electronic metronome (8.0, 9.0, 10.0, 11.0 and 12.0 km/h) over a 20 m distance. The RAST variables and the lactate values were analyzed using visual and mathematical models. The intensity of the lactate minimum test, determined by a visual method, reduced in relation to polynomial fits (2nd degree) for the Small Forward positions and General groups. The Power and Fatigue Index values, determined by both methods, visual and 3rd degree polynomial, were not significantly different between the groups. In conclusion, the RAST is an excellent hyperlactatemia inductor and the progressive intensity of lactate minimum test using short distances (20 m) can be specifically used to evaluate the aerobic capacity of basketball players. In addition, no differences were observed between the visual and polynomial methods for RAST variables, but lactate minimum intensity was influenced by the method of analysis

Słowa kluczowe

  • lactate minimum
  • sprint
  • mathematical model
  • polynomial adjust
Otwarty dostęp

Effect of a MAST Exercise Program on Anthropometric Parameters, Physical Fitness, and Serum Lipid Levels in Obese Postmenopausal Women

Data publikacji: 10 Oct 2014
Zakres stron: 149 - 155

Abstrakt

Abstract

The purpose of this study was to examine an influence of a mixed aerobic and strength training program (MAST) on anthropometry, serum lipid levels, physical performance, and functional fitness in obese postmenopausal women. The MAST sessions were held three times per week, and the exercise program lasted for 10 weeks. The exercise group demonstrated a statistically significant improvement in maximal oxygen uptake, a waist/hip ratio, and strength of the upper and lower body. An increase in LDL-C levels was observed in the control group. A 10-week MAST program encompassing Nordic-walking as an aerobic component, and strength exercises, induces positive changes in functional fitness, HDL-C, LDL-C and a waist/hip ratio in obese postmenopausal women. The observed changes implicate an increase in a health-related quality of life among the women administered to the physical exercise program

Słowa kluczowe

  • exercise
  • postmenopause
  • physical fitness
  • obesity
  • serum lipids
  • nordic-walking
Otwarty dostęp

Effects of Pre-Exhausting the Biceps Brachii Muscle on the Performance of the Front Lat Pull-Down Exercise Using Different Handgrip Positions

Data publikacji: 10 Oct 2014
Zakres stron: 157 - 163

Abstrakt

Abstract

The aim of the present study was to investigate the effects of pre-exhaustion (PE) of the biceps brachii muscle (BB) on the number of repetitions and the rate of perceived exertion (RPE) in the front lat pull-down (FLPD) using different handgrip positions. Additionally, the effect of sex and its interaction with performance and the RPE were also examined. The participants were 19 healthy subjects: 8 men (age: 27.13±2.85 years; body height: 180.63±6.65 cm; body mass: 82.05±8.92 kg; and body fat: 14.67±6.09%); and 11 women (age: 28.81±3.68 years; body height: 162.91±6.51 cm; body mass 59.63±6.47 kg; and body fat: 24.11±4.33%). The number of repetitions and the RPE in the FLPD exercise with different handgrip positions, with and without PE of the BB, was documented. The following main significant effects were seen: i) PE of the BB decreased the number of repetitions (p<0.001) and increased the RPE (p<0.001); ii) the narrow handgrip width elicited a higher RPE (p<0.001) and iii) women performed fewer repetitions than men in all FLPD exercise variations (p=0.023). Significant interactions were also observed between: i) PE or sex and the RPE (p=0.024); and ii) PE or handgrip width and the number of repetitions (p<0.001). In conclusion, PE of the BB promotes a decreased performance in the FLPD exercise along with a greater RPE, especially when using a narrow handgrip position

Słowa kluczowe

  • resistance training
  • front lat pull-down
  • handgrip width
  • biceps brachii
  • perceived exertion
Otwarty dostęp

Effect of 16 Weeks of Resistance Training on Fatigue Resistance in Men and Women

Data publikacji: 10 Oct 2014
Zakres stron: 165 - 174

Abstrakt

Abstract

The purpose of this study was to investigate the effect of hypertrophy-type resistance training (RT) on upper limb fatigue resistance in young adult men and women. Fifty-eight men (22.7±3.7 years, 70.6±9.3 kg, and 176.8±6.4 cm) and 65 women (21.6±3.7 years, 58.8±11.9 kg, and 162.6±6.2 cm) underwent RT for 16 weeks. Training consisted of 10-12 whole body exercises with 3 sets of 8-12 repetitions maximum performed 3 times per week. Before and after the RT intervention participants were submitted to 1RM testing, as well as a fatigue protocol consisting of 4 sets at 80% 1RM on bench press (BP) and arm curl (AC). The sum of the number of repetitions accomplished in the 4 sets in each exercise was used to indicate fatigue resistance. There was a significant (p<0.05) time-by-group interaction in 1RM BP (men=+16%, women=+26%), however in 1RM AC no significant time-by-group interaction was observed (men=+14%, women=+23%). For the total number of repetitions, men and women showed a significant increase in BP (men=+16.3%, women=+10.5%) with no time-by-group interaction. The results suggest that the adaptation in maximal strength is influenced by sex in BP. On the other hand, for fatigue resistance, the individual’s sex does not seem to influence outcomes either in BP or AC

Słowa kluczowe

  • resistance training
  • one-repetition maximum
  • muscular endurance
  • sex
Otwarty dostęp

Changes in Muscle Strength in U19 Soccer Players During an Annual Training Cycle

Data publikacji: 10 Oct 2014
Zakres stron: 175 - 185

Abstrakt

Abstract

The aim of the study was to investigate the seasonal variation in isokinetic strength of the knee flexors and extensors, and conventional (H/QCONV) and functional (H/QFUNC) hamstring to quadriceps strength ratios in highly trained adolescent soccer players. The players (n=11; age 17.8±0.3) were measured at the end of the competitive season (autumn), at the beginning and the end of pre-season (winter) and during the sixth week of a new competitive season. Isokinetic peak torque (concentric and eccentric) was measured at 60°•s-1 in a sitting position with the hip flexed at 100°. The testing range of motion was set from 10 - 90° of knee flexion. The players performed a set of five maximum repetitions for both the dominant and non-dominant leg. Statistically significant differences (p<0.001) between the four seasonal measurements were noted for peak torque of the dominant leg knee flexors in concentric muscle action only. A post hoc analysis revealed a statistically significant increase in peak torque from the 1st to the 4th measurement (p<0.001; d=0.692) and from the 2nd to the 4th (p<0.01; d=0.564). The differences in the changes of peak torque of the knee flexors and extensors depending on type of muscle action and tendencies found in the H/Q ratios throughout the annual training cycle indicate that strength assessment of the knee flexors and extensors and their balance throughout the annual training cycle could be beneficial for elite male adolescent soccer players both in terms of performance and risk of injury.

Słowa kluczowe

  • adolescents
  • H/Q ratio
  • isokinetic
  • torque
  • training
Otwarty dostęp

The Effect of Course Length on Individual Medley Swimming Performance in National and International Athletes

Data publikacji: 10 Oct 2014
Zakres stron: 187 - 200

Abstrakt

Abstract

Effects of course length (25 m versus 50 m) and advances in performance of individual medley swimming were examined for men and women in Swiss national competitions and FINA World Championships during 2000-2011. Linear regression and analysis of variance (ANOVA) were used to analyse 200 m and 400 m race results for 26,081 swims on the Swiss high score list and 382 FINA finalists. Swiss and FINA swimmers of both sexes were, on average, 4.3±3.2% faster on short courses for both race distances. Sex-related differences in swim speed were significantly greater for FINA swimmers competing in short-course events than in long-course events (10.3±0.2% versus 9.7±0.3%, p<0.01), but did not differ for Swiss swimmers (p>0.05). Sex-related differences in swimming speed decreased with increasing race distance for both short- and long-course events for Swiss athletes, and for FINA athletes in long-course events. Performance improved significantly (p<0.05) during 2000-2011 for FINA men competing in either course length and FINA females competing in short-course events, but not for Swiss swimmers. Overall, the results showed that men and women individual medley swimmers, competing at both national and international levels, have faster average swimming speeds on short courses than on long courses, for both 200 m and 400 m distances. FINA athletes demonstrate an improving performance in the vast majority of individual medley events, while performance at national level seems to have reached a plateau during 2000-2011

Słowa kluczowe

  • swim speed
  • pool length
  • sex-related difference
  • temporal trends
Otwarty dostęp

Avoiding Systematic Errors in Isometric Squat-Related Studies without Pre-Familiarization by Using Sufficient Numbers of Trials

Data publikacji: 10 Oct 2014
Zakres stron: 201 - 213

Abstrakt

Abstract

There is no scientific evidence in the literature indicating that maximal isometric strength measures can be assessed within 3 trials. We questioned whether the results of isometric squat-related studies in which maximal isometric squat strength (MISS) testing was performed using limited numbers of trials without pre-familiarization might have included systematic errors, especially those resulting from acute learning effects. Forty resistance-trained male participants performed 8 isometric squat trials without pre-familiarization. The highest measures in the first “n” trials (3 ≤ n ≤ 8) of these 8 squats were regarded as MISS obtained using 6 different MISS test methods featuring different numbers of trials (The Best of n Trials Method [BnT]). When B3T and B8T were paired with other methods, high reliability was found between the paired methods in terms of intraclass correlation coefficients (0.93-0.98) and coefficients of variation (3.4-7.0%). The Wilcoxon’s signed rank test indicated that MISS obtained using B3T and B8T were lower (p < 0.001) and higher (p < 0.001), respectively, than those obtained using other methods. The Bland- Altman method revealed a lack of agreement between any of the paired methods. Simulation studies illustrated that increasing the number of trials to 9-10 using a relatively large sample size (i.e., ≥ 24) could be an effective means of obtaining the actual MISS values of the participants. The common use of a limited number of trials in MISS tests without pre-familiarization appears to have no solid scientific base. Our findings suggest that the number of trials should be increased in commonly used MISS tests to avoid learning effect-related systematic errors

Słowa kluczowe

  • isometric testing standards
  • learning effect
  • number of trials
  • maximal isometric strength
  • testing study assumptions
Otwarty dostęp

A Single-Unit Design Structure and Gender Differences in the Swimming World Championships

Data publikacji: 10 Oct 2014
Zakres stron: 215 - 222

Abstrakt

Abstract

Four 50 meter male/female finals - the freestyle, butterfly, breaststroke, and backstroke - swum during individual events at the Swimming World Championships (SWCs) can be defined in four clusters. The aim of the present study was to use a single-unit design structure, in which the swimmer was defined at only one scale, to evaluate gender differences in start reaction times among elite swimmers in 50 m events. The top six male and female swimmers in the finals of four swimming stroke final events in six SWCs were analyzed. An unpaired t-test was used. The p-values were evaluated using Neo-Fisherian significance assessments (Hurlbert and Lombardi, 2012). For the freestyle, gender differences in the start reaction times were positively identified for five of the six SWCs. For the backstroke, gender differences in the start reaction times could be dismissed for five of the six SWCs. For both the butterfly and breaststroke, gender differences in the start reaction times yielded inconsistent statistical differences. Pooling all swimmers together (df = 286) showed that an overall gender difference in the start reaction times could be positively identified: p = 0.00004. The contrast between the gender differences in start reaction times between the freestyle and backstroke may be associated with different types of gender adaptations to swimming performances. When the natural groupings of swimming stroke final events were ignored, sacrificial pseudoreplication occurred, which may lead to erroneous statistical differences

Słowa kluczowe

  • Clusters
  • designing studies
  • statistical analysis
  • nondemonic intrusion
  • sample size
  • sacrificial pseudoreplication
Otwarty dostęp

Assessment of Secondary School Students’ Game Performance Related to Tactical Contexts

Data publikacji: 10 Oct 2014
Zakres stron: 223 - 234

Abstrakt

Abstract

Certain limitations remain unaddressed when utilizing the Teaching Games for Understanding approach, suggesting the need for more research on authentic assessment of skill development and tactical awareness in order to guide the design of developmentally appropriate curriculum materials. This study investigated physical education students’ (n=19; age: 13.71 ± 0.4) game performance during an invasion game, specifically the relationship between their skill execution and decision-making ability. The purpose of the study was twofold: (a) to devise and implement a ‘game context’ approach to assess the game performance components and in doing so, (b) to provide information that could be used to design suitable learning progressions within tactical teaching approaches. Students’ game performance was videotaped, and measures of skill execution and decision-making were developed from observational analyses. Decision-making was measured at two levels: a) decision making restricted to the selection of technical-tactical skills (i.e., passing, moving with the ball, getting free, marking, tackling, double teaming and interception; and b) decisionmaking in the adaptation to the tactical contexts of the game. Participants played a 5 vs. 5 modified eight-minute team handball game. Participants scored significantly higher in penetrating-the-defense context adaptation than in keepingthe- ball context adaptation. Participants showed a higher efficiency in decision-making than in execution in most of the technical-tactical skills; including on-the-ball over off-the-ball decision-making, and in attack compared to defensive execution. The findings also revealed significant relationships between decision-making and skill execution in shooting, tackling and passing

Słowa kluczowe

  • teaching games for understanding
  • performance based assessment
  • physical education
  • invasion games
  • small sided games
  • constraints
Otwarty dostęp

Oxygen Uptake and Heart Rate Kinetics after Different Types of Resistance Exercise

Data publikacji: 10 Oct 2014
Zakres stron: 235 - 244

Abstrakt

Abstract

Oxygen uptake (VO2) and heart rate (HR) kinetics after exercise are important indicators of fitness and cardiovascular health. However, these variables have been little investigated in resistance exercise (RE). The current study compared post-exercise kinetics of VO2 and the HR among different types of REs. The study included 14 males (age: 26.5±5.4 years, body mass: 80.1±11.4 kg, body height: 1.77±0.07 m, fat content: 11.3±4.6%) with RE experience. Dynamic muscle strength was measured using one repetition maximum (1RM) with regard to the half-squat, bench press, pull-down, and triceps pushdown exercises. The participants performed a maximum number of repetitions at 80% of 1RM for each exercise, separated by a recovery period of 60 minutes. VO2 was measured using ergospirometry. VO2 and HR kinetics were assessed using the time constant of the recovery curves, and excess oxygen consumption (EPOC) was calculated afterward. Significant differences were not observed across the exercises with regard to VO2 kinetics. However, the half-squat exercise elicited a greater EPOC than the bench press and triceps pushdown exercises (p<.05). HR kinetics was slower for the half-squat exercise than for the other exercises (p<.05). These findings confirm that the type of RE influences both the cardiac autonomic response post-exercise and EPOC, but not VO2 kinetics

Słowa kluczowe

  • strength training
  • oxygen uptake
  • energy metabolism
  • energy expenditure
Otwarty dostęp

Qualitative Task Analysis to Enhance Sports Characterization: A Surfing Case Study

Data publikacji: 10 Oct 2014
Zakres stron: 245 - 257

Abstrakt

Abstract

The aim of this study was to develop a Matrix of Analysis for Sports Tasks (MAST), regardless of the sports activity, based on practice classification and task analysis. Being this a qualitative research our main question was: in assessing sports’ structure is it possible to make the characterization of any discipline through context and individuals’ behaviours? The sample was within a surf discipline in a competition flowing having 5 of the top 16 Portuguese surfers training together. Based on a qualitative method, studying the surf as the main activity was an interpretative study case. The MAST was applied in four phases: taxonomy; tasks and context description; task analysis; teaching and performance strategies. Its application allowed the activities’ characterization through the observation, surfer’s opinions and bibliographical support. The triangulation of the data was used as an information data treatment. The elements were classified by the challenges proposed to the practitioners and the taxonomy was constituted by the sport activities, group, modality and discipline. Surf is a discipline of surfing which is a sliding sport modality, therefore, a nature sport. In the context description, we had the wave’s components and constraints and the surfboards’ qualities. Through task analysis we obtained a taxonomy of surf manoeuvres. The structural and functional analysis allowed finding solutions for learning of surf techniques with trampoline and skateboards because these fit in sliding sports. MAST makes possible the development of strategies that benefit teaching and performance intervention

Słowa kluczowe

  • qualitative research
  • taxonomy
  • structural analysis
  • functional analysis
  • nature sports
  • sliding sports
Otwarty dostęp

Somatotype of Competitive Youth Soccer Players From Brazil

Data publikacji: 10 Oct 2014
Zakres stron: 259 - 266

Abstrakt

Abstract

The aim of this study was to identify the morphological configuration of youth athletes from professional soccer clubs and to verify their differences according to the tactical position on the field. Overall, 67 male players aged 15 to 17 years were evaluated. The examined anthropometric measurements included body mass, body height, skinfolds (triceps, subscapular, supraspinal and medial calf), girths (flexed and tensed arm and calf) and breadths (humerus and femur). For statistical purposes, analysis of variance and post hoc Bonferroni and Kruskal-Wallis tests were used. We concluded that goalkeepers were heavier and taller than center backs (p = 0.015 and p = 0.001), midfielders (p = 0.005 and p <0.001) and center forward players (p = 0.024 and p <0.001). The average somatotype for defense, forward and goalkeeper positions was a balanced mesomorph. Midfield players showed ectomorphic-mesomorph characteristics. It was concluded that goalkeepers were characterized as being taller and heavier and that somatotype features of athletes were similar between positions, except for midfield players

Słowa kluczowe

  • athletes
  • anthropometry
  • male
  • soccer
  • youth
Otwarty dostęp

Analysis of Experts’ Quantitative Assessment of Adolescent Basketball Players and the Role of Anthropometric and Physiological Attributes

Data publikacji: 10 Oct 2014
Zakres stron: 267 - 276

Abstrakt

Abstract

In this paper, we investigated two questions: (1) can measurements of anthropometric and physiological attributes substitute for expert assessment of adolescent basketball players, and (2) how much does the quantitative assessment of a player vary among experts? The first question is relevant to the potential simplification of the player selection process. The second question pertains directly to the validity of expert quantitative assessment. Our research was based on data from 148 U14 female and male basketball players. For each player, an array of anthropometric and physiological attributes was recorded, including body height, body mass, BMI, and several motor skill tests. Furthermore, each player's current ability and potential ability were quantitatively evaluated by two different experts from a group of seven experts. Analysis of the recorded data showed that the anthropometric and physiological attributes explained between 15% and 40% of the variance in experts’ scores. The primary predictive attributes were speed and agility (for predicting current ability) and body height and growth potential (for predicting potential ability). We concluded that these attributes were not sufficiently informative to act as a substitute for expert assessment of the players’ current or potential ability. There is substantial variability in different experts' scores of the same player’s ability. However, the differences between experts are mostly in scale, and the relationships between experts’ scores are monotonic. That is, different experts rank players on ability very similarly, but their scores are not well calibrated.

Słowa kluczowe

  • sports
  • coaching
  • morphology
  • motor skills
  • performance evaluation
  • players’ selection
Otwarty dostęp

Height and Body Composition Determine Arm Propulsive Force in Youth Swimmers Independent of a Maturation Stage

Data publikacji: 10 Oct 2014
Zakres stron: 277 - 284

Abstrakt

Abstract

The aim of this study was to examine the relationship between anthropometric variables, body composition and propulsive force in swimmers aged 9-17 years. Anthropometric characteristics (body height and mass, sitting height, arm span, arm muscle area and body composition) and the propulsive force of the arm (tethered swimming test) were evaluated in 56 competitive male swimmers. Tanner’s stages of genital maturation (P1-5) were used. The data analysis included correlations and multiple linear regression. The propulsive force of the arm was correlated with body height (r = 0.34; p =0.013), arm span (r = 0.29; p =0.042), sitting height (r = 0.36; p =0.009), % body fat (r = 0.33; p =0.016), lean body mass (r = 0.34; p =0.015) and arm muscle area (r = 0.31; p =0.026). Using multiple linear regression models, the percent body fat and height were identified as significant predictors of the propulsive force of the arm after controlling for the maturation stage. This model explained 22% (R2 = 0.22) of associations. In conclusion, the propulsive force of swimmers was related to body height and percent body fat

Słowa kluczowe

  • body composition
  • performance
  • swimming
  • anthropometric variables
  • propulsive force
Otwarty dostęp

Mark Pitkin “Practical Sanomechanics®: Exercising for a Healthy Skeleton”

Data publikacji: 10 Oct 2014
Zakres stron: 285 - 286

Abstrakt

Słowa kluczowe

  • sanomechanics
  • floating skeleton theory
  • rehabilitation

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