Zeszyty czasopisma

Tom 83 (2022): Zeszyt 1 (August 2022)

Tom 82 (2022): Zeszyt 1 (April 2022)

Tom 81 (2022): Zeszyt 1 (January 2022)

Tom 80 (2021): Zeszyt 1 (October 2021)

Tom 79 (2021): Zeszyt 1 (July 2021)

Tom 78 (2021): Zeszyt 1 (March 2021)

Tom 77 (2021): Zeszyt 1 (January 2021)

Tom 76 (2021): Zeszyt 1 (January 2021)

Tom 75 (2020): Zeszyt 1 (October 2020)

Tom 74 (2020): Zeszyt 1 (August 2020)

Tom 73 (2020): Zeszyt 1 (July 2020)

Tom 72 (2020): Zeszyt 1 (March 2020)

Tom 71 (2020): Zeszyt 1 (January 2020)

Tom 70 (2019): Zeszyt 1 (November 2019)

Tom 69 (2019): Zeszyt 1 (October 2019)

Tom 68 (2019): Zeszyt 1 (August 2019)

Tom 67 (2019): Zeszyt 1 (June 2019)

Tom 66 (2019): Zeszyt 1 (March 2019)

Tom 65 (2018): Zeszyt 1 (December 2018)

Tom 64 (2018): Zeszyt 1 (September 2018)

Tom 63 (2018): Zeszyt 1 (August 2018)

Tom 62 (2018): Zeszyt 1 (June 2018)

Tom 61 (2018): Zeszyt 1 (March 2018)

Tom 60 (2017): Zeszyt 1 (December 2017)

Tom 59 (2017): Zeszyt 1 (October 2017)

Tom 58 (2017): Zeszyt 1 (September 2017)

Tom 57 (2017): Zeszyt 1 (June 2017)

Tom 56 (2017): Zeszyt 1 (February 2017)

Tom 55 (2017): Zeszyt 1 (January 2017)

Tom 54 (2016): Zeszyt 1 (December 2016)

Tom 53 (2016): Zeszyt 1 (December 2016)

Tom 52 (2016): Zeszyt 1 (September 2016)

Tom 51 (2016): Zeszyt 1 (June 2016)

Tom 50 (2016): Zeszyt 1 (April 2016)

Tom 49 (2015): Zeszyt 1 (December 2015)

Tom 48 (2015): Zeszyt 1 (December 2015)

Tom 47 (2015): Zeszyt 1 (September 2015)

Tom 46 (2015): Zeszyt 1 (June 2015)

Tom 45 (2015): Zeszyt 1 (March 2015)

Tom 44 (2014): Zeszyt 1 (December 2014)

Tom 43 (2014): Zeszyt 1 (November 2014)

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

Tom 41 (2014): Zeszyt 1 (June 2014)

Tom 40 (2014): Zeszyt 1 (March 2014)

Tom 39 (2013): Zeszyt 1 (December 2013)

Tom 38 (2013): Zeszyt 2013 (September 2013)

Tom 37 (2013): Zeszyt 1 (June 2013)

Tom 36 (2013): Zeszyt 1 (March 2013)

Tom 35 (2012): Zeszyt 1 (December 2012)

Tom 34 (2012): Zeszyt 1 (October 2012)

Tom 33 (2012): Zeszyt 2012 (June 2012)

Tom 32 (2012): Zeszyt 2012 (May 2012)
Aquatic Sports and Activities

Tom 31 (2012): Zeszyt 2012 (March 2012)

Tom 30 (2011): Zeszyt 2011 (December 2011)

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

Tom 29 (2011): Zeszyt 2011 (September 2011)

Tom 28 (2011): Zeszyt 2011 (June 2011)

Tom 27 (2011): Zeszyt 2011 (March 2011)

Tom 26 (2010): Zeszyt 2010 (December 2010)

Tom 25 (2010): Zeszyt 2010 (September 2010)

Tom 24 (2010): Zeszyt 2010 (June 2010)

Tom 23 (2010): Zeszyt 2010 (March 2010)

Tom 22 (2009): Zeszyt 2009 (December 2009)

Tom 21 (2009): Zeszyt 2009 (June 2009)

Tom 20 (2008): Zeszyt 2008 (December 2008)

Tom 19 (2008): Zeszyt 2008 (June 2008)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
ISSN
1640-5544
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

Tom 38 (2013): Zeszyt 2013 (September 2013)

Informacje o czasopiśmie
Format
Czasopismo
eISSN
1899-7562
ISSN
1640-5544
Pierwsze wydanie
13 Jan 2009
Częstotliwość wydawania
5 razy w roku
Języki
Angielski

Wyszukiwanie

23 Artykułów
Otwarty dostęp

Lower-Limb Power cannot be Estimated Accurately from Vertical Jump Tests

Data publikacji: 08 Oct 2013
Zakres stron: 5 - 13

Abstrakt

Abstract

The countermovement jump test is often adopted to monitor lower-limb power of an individual. Despite several studies on the validity of this test, there is still a need to determine the minimal difference needed to be confident that a difference in power between two individuals is present or that a true change in the performance of an individual has occurred. In this study, power was measured from ground reaction forces and compared to that obtained from predictive equations for two groups of subjects (67 trained and 20 highly trained individuals). The height of each jump was determined with kinematic techniques. The main outcome is a large discrepancy between power calculated from ground reaction forces and that calculated from predictive equations. For the trained group, the R-square value between power and predicted power was 0.53 and the minimal difference to consider that two individuals were different was 821.7 W. For the highly trained individuals, a much larger R-square value was obtained (0.94). Despite this, the minimal difference to consider that two individuals were different was still large (689.3 W). The large minimal differences obtained raise serious concerns about using countermovement jumps for appraisal and monitoring of lower-limb power of an individual.

Słowa kluczowe

  • Countermovement jump
  • force
  • validity
  • minimal difference
Otwarty dostęp

Kinematic Variables Evolution During a 200-m Maximum Test in Young Paddlers

Data publikacji: 08 Oct 2013
Zakres stron: 15 - 22

Abstrakt

Abstract

The objective of this research was to determine the kinematic variables evolution in a sprint canoeing maximal test over 200 m, comparing women and men kayak paddlers and men canoeists. Speed evolution, cycle frequency, cycle length and cycle index were analysed each 50 m section in fifty-two young paddlers (20 male kayakers, 17 female kayakers and 15 male canoeists; 13-14 years-old). Recordings were taken from a boat which followed each paddler trial in order to measure the variables cited above. Kinematic evolution was similar in the three categories, the speed and cycle index decreased through the test after the first 50 m. Significant differences were observed among most of the sections in speed and the cycle index (p<0.05 and <0.01, respectively). Cycle length remained stable showing the lowest values in the first section when compared with the others (p<0.01). Cycle frequency progressively decreased along the distance. Significant differences were identified in the majority of the sections (p<0.01). Men kayakers attained higher values in all the variables than women kayakers and men canoeists, but only such variables as speed, cycle length and cycle index were observed to be significantly higher (p<0.01). Moreover, lower kinematic values were obtained from men canoeists. The study of the evolution of kinematic variables can provide valuable information for athletes and coaches while planning training sessions and competitions.

Słowa kluczowe

  • Speed evolution
  • cycle frequency
  • cycle length
  • cycle index
  • kayakers
  • canoeists
Otwarty dostęp

The Development of a Repetition-Load Scheme for the Eccentric- Only Bench Press Exercise

Data publikacji: 08 Oct 2013
Zakres stron: 23 - 31

Abstrakt

Abstract

The purpose of the present study was to develop a repetition-load scheme for the eccentric-only bench press exercise. Nine resistance trained men (age: 21.6 ± 1.0 years; 1-repetition maximum [RM] bench press: 137.7 ± 30.4 kg) attended four testing sessions during a four week period. During the first session each subject’s 1-RM bench press load utilizing the stretch-shortening cycle was determined. During the remaining sessions they performed eccentric-only repetitions to failure using supra-maximal loads equivalent to 110%, 120% and 130% of their 1-RM value with a constant cadence (30 reps·min-1). Force plates and a three dimensional motion analysis system were used during these final three sessions in order to evaluate kinematic and kinetic variables. More repetitions were completed during the 110% 1-RM condition compared to the 130% 1-RM condition (p=0.01). Mean total work (p=0.046) as well as vertical force (p=0.049), vertical work (p=0.017), and vertical power output (p=0.05) were significantly greater during the 130% 1-RM condition compared to the 110% 1-RM condition. A linear function was fitted to the number of repetitions completed under each load condition that allowed the determination of the maximum number of repetitions that could be completed under other supra-maximal loads. This linear function predicted an eccentric-only 1-RM in the bench press with a load equivalent to 164.8% 1-RM, producing a load of 227.0 ± 50.0 kg. The repetition-load scheme presented here should provide a starting point for researchers to investigate the kinematic, kinetic and metabolic responses to eccentric-only bench press workouts.

Słowa kluczowe

  • bench press
  • eccentric contraction
  • repetition-load scheme
Otwarty dostęp

Body Posture Stability in Ski Boots Under Conditions of Unstable Supporting Surface

Data publikacji: 08 Oct 2013
Zakres stron: 33 - 44

Abstrakt

Abstract

The authors attempted to determine whether: (1) there are differences in stability between the conditions of standing in ski boots and barefoot, (2) the type of surface affects stability, and, (3) the level of stability differs between the frontal and sagittal planes. The study included 35 young male recreational skiers aged 20.71 ±0.63 years. Measurements of stability were taken by means of a Libra seesaw balance board. The conditions of soft surface were created by attaching an inflated cushion to the board. The experiment was carried out on both rigid and soft surface for both movement planes and two different conditions: maintaining the seesaw balance board in the horizontal position and performance of a particular balancing task. All the tests were performed with visual feedback. Restricted ankle joint mobility that results from wearing ski boots caused a reduction of stability in studied subjects, particularly in the sagittal plane. The differences found in the study were likely to be caused by the difficulty the beginners experienced in re-organizing muscular coordination in hip joint strategy and effectively using mechanical support of ski boots that reduces lower limb muscle tone. The use of the soft surface improved stability exhibited by the subjects in the frontal plane without compromising the stability in the sagittal plane. The soft surface might have contributed to a reduction in excessive corrective movements, thus improving stability in studied subjects.The aim of this study was to determine the effect of limitation of foot mobility and disturbances in afferent information from the plantar mechanoreceptors due to wearing ski boots on the level of postural stability in beginner skiers under conditions of the unstable support surface.

Słowa kluczowe

  • dynamic balance
  • compliant surface
  • ski boots
  • beginner skiers
Otwarty dostęp

Postural Adaptations in Preadolescent Karate Athletes Due to a One Week Karate Training Camp

Data publikacji: 08 Oct 2013
Zakres stron: 45 - 52

Abstrakt

Abstract

The aim of this study was to investigate the effect of an increasing number of training hours of specific highintensity karate training on postural sway in preadolescent karate athletes. Seventy-four karatekas were randomly assigned to 1 of 2 groups: Karate Group (KG=37): age 10.29±1.68 yrs; or Control Group (CG= 37): age 10.06±1.77 yrs. The KG performed two sessions per day for 1 week in total, while the CG performed only 3 sessions during the same period. The center-of-pressure length (COPL) and velocity (COPV) were recorded under four different experimental conditions: open eyes (EO), closed eyes (EC), open eyes monopodalic left (EOL), open eyes monopodalic right (EOR), pre as well as post training intervention. Post-camp results indicated significant differences between the groups in the COPL p<0.001; an interaction of training type×time in the COPV (p<0.001) and an interaction of training type×time (p=0.020). The KG revealed an improvement in the COPL from pre to post-camp under conditions of EO [-37.26% (p<0.001)], EC [-31.72% (p<0.001)], EOL [-27.27% (p<0.001)], EOR [-21.44% (p<0.001)], while CG revealed small adaptations in conditions of EO (3.16%), EC (0.93%), EOL (-3.03%), EOR (-0.97%). Furthermore, in the KG an improvement in the COPV from pre to post-camp was observed in conditions of EO [-37.92% (p<0.001)], EC [-32.52% (p<0.001)], EOL [-29.11% (p<0.001)], EOR [-21.49% (p<0.001)]. In summary, one-week of high intensity karate training induced a significant improvement in static body balance in preadolescent karate athletes. Karate performance requires high-levels of both static and dynamic balance. Further research dealing with the effect of karate practice on dynamic body balance in young athletes is required.

Słowa kluczowe

  • physical exercise
  • karate training
  • training and testing
  • centre of pressure
  • postural sway
  • proprioception
Otwarty dostęp

Are Various Forms of Locomotion-Speed Diverse or Unique Performance Quality?

Data publikacji: 08 Oct 2013
Zakres stron: 53 - 61

Abstrakt

Abstract

The forward-sprint is considered to be, and is regularly performed as, a unique measure of “on-ground” linearspeed performance. Thus far, no investigation has simultaneously studied different forms of linear-speed or investigated whether different forms of linear-speed should be observed as unique performance quality. The purpose of this study was to determine (I) the achievements (i.e. execution time), and (II) the reliability and inter-relationships between various linear-speed performances. The participants were 42 male physical education students with substantial sport-specific backgrounds. We applied a total of six tests: three quadrupedal (supine backward, supine forward, and pronate backward locomotion) and three bipedal-performances (forward sprinting, backward sprinting, lateral shuffling). All of the tests showed appropriate reliability parameters (Cronbach Alpha ranged from 0.91 to 0.97; Inter-Item-R 0.78-0.92; Coefficient-of-Variation 1.3-9.1). The tests used in this study shared between 9% and 50% of the common variance. Our results suggest that different activities require activity-specific tests of linear-speed. This is particularly significant in those sports and activities in which quadrupedal locomotion patterns are highly important (wrestling, physically trained military services, law enforcement, fire and rescue, protective services).

Słowa kluczowe

  • specific testing
  • factor analysis
  • bipedal locomotion
  • quadrupedal locomotion
Otwarty dostęp

A Comparison of Muscle Activity in Concentric and Counter Movement Maximum Bench Press

Data publikacji: 08 Oct 2013
Zakres stron: 63 - 71

Abstrakt

Abstract

The purpose of this study was to compare the kinematics and muscle activation patterns of regular free-weight bench press (counter movement) with pure concentric lifts in the ascending phase of a successful one repetition maximum (1-RM) attempt in the bench press. Our aim was to evaluate if diminishing potentiation could be the cause of the sticking region. Since diminishing potentiation cannot occur in pure concentric lifts, the occurrence of a sticking region in this type of muscle actions would support the hypothesis that the sticking region is due to a poor mechanical position. Eleven male participants (age 21.9 ~ 1.7 yrs, body mass 80.7 ~ 10.9 kg, body height 1.79 ~ 0.07 m) conducted 1-RM lifts in counter movement and in pure concentric bench presses in which kinematics and EMG activity were measured. In both conditions, a sticking region occurred. However, the start of the sticking region was different between the two bench presses. In addition, in four of six muscles, the muscle activity was higher in the counter movement bench press compared to the concentric one. Considering the findings of the muscle activity of six muscles during the maximal lifts it was concluded that the diminishing effect of force potentiation, which occurs in the counter movement bench press, in combination with a delayed muscle activation unlikely explains the existence of the sticking region in a 1-RM bench press. Most likely, the sticking region is the result of a poor mechanical force position.

Słowa kluczowe

  • kinematics
  • EMG
  • muscle
  • potentiation
  • bench press
Otwarty dostęp

Mechanical Work and Long-Distance Performance Prediction: the Influence of Allometric Scaling

Data publikacji: 08 Oct 2013
Zakres stron: 73 - 82

Abstrakt

Abstract

The purpose of this study was to examine the effect of allometric scaling on the relationship between mechanical work and long-distance running performance in recreational runners. Fourteen recreational long-distance runners (male, mean ± SD - age: 29 ± 7 years; body mass: 70.0 ± 10.2 kg; body height: 1.71 ± 0.07 m; maximal oxygen uptake: VO2max 52.0 ± 4.9 ml.kg-1.min-1) performed two tests: a continuous incremental test to volitional exhaustion in order to determine VO2max, and a 6-minute running submaximal test at 3.1 m.s-1, during which segments in the sagittal plane were recorded using a digital camera and the internal (Wint), external (Wext) and total (Wtot) mechanic work, in J.kg-1.m-1, was subsequently calculated. The results indicated a significant correlation between mechanical work and performance, however, the strongest correlations were observed when allometric exponents were used (respectively for Wint, Wext and Wtot; non allometric vs. allometric scaling defined by literature (0.75) or determined mathematically (0.49): r = 0.38 vs. r = 0.44 and r = 0.50; r = 0.80 vs. r = 0.83 and r = 0.82; r = 0.70 vs. r = 0.77 and r = 0.78). These results indicate that mechanical work could be used as a predictor of recreational long-distance performance and an allometric model may improve this prediction.

Słowa kluczowe

  • allometry
  • body size
  • cost of running
  • human locomotion
  • mechanical efficiency
  • running economy
Otwarty dostęp

Potentiation Increases Peak Twitch Torque by Enhancing Rates of Torque Development and Relaxation

Data publikacji: 08 Oct 2013
Zakres stron: 83 - 94

Abstrakt

Abstract

The aim of this study was to measure the extent to which potentiation changes in response to an isometric maximal voluntary contraction. Eleven physically active subjects participated in two separate studies. Single stimulus of electrical stimulation of the femoral nerve was used to measure torque at rest in unpotentiated quadriceps muscles (study 1 and 2), and potentiated quadriceps muscles torque in a 10 min period after a 5 s isometric maximal voluntary contraction of the quadriceps muscles (study 1). Additionally, potentiated quadriceps muscles torque was measured every min after a further 10 maximal voluntary contractions repeated every min (study 2). Electrical stimulation repeated several times without previous maximal voluntary contraction showed similar peak twitch torque. Peak twitch torque 4 s after a 5 s maximal voluntary contraction increased by 45±13% (study 1) and by 56±10% (study 2), the rate of torque development by 53±13% and 82±29%, and the rate of relaxation by 50±17% and 59±22%, respectively, but potentiation was lost already two min after a 5 s maximal voluntary contraction. There was a tendency for peak twitch torque to increase for the first five repeated maximal voluntary contractions, suggesting increased potentiation with additional maximal voluntary contractions. Correlations for peak twitch torque vs the rate of torque development and for the rate of relaxation were r2= 0.94 and r2=0.97. The correlation between peak twitch torque, the rate of torque development and the rate of relaxation suggests that potentiation is due to instantaneous changes in skeletal muscle contractility and relaxation.

Keywords

  • Maximal isometric voluntary contraction
  • quadriceps muscles
  • electrical stimulation
  • decay
  • fatigue
Otwarty dostęp

Cardiovascular Responses, Perceived Exertion and Technical Actions During Small-Sided Recreational Soccer: Effects of Pitch Size and Number of Players

Data publikacji: 08 Oct 2013
Zakres stron: 95 - 105

Abstrakt

Abstract

The aim of this study was to determine the cardiovascular, perceived exertion and technical effects of altering pitch size and number of players in recreational soccer match-play. The further aim was to evaluate to what extent exercise intensity during various game formats corresponds to the recommended intensity level for cardiovascular fitness improvement. Ten male recreational players aged 31.7±7.6 years (mean ± SD) completed four variations of smallsided games (except for goalkeepers, 5-a-side and 7-a-side on small and large pitches) during which heart rate, perceived exertion and technical actions were evaluated. Two-way analysis of variance on repeated measures was applied to collected data. The results indicated that an average workload expressed as heart rate and percentage of heart rate reserve during 5-a-side games was higher than for 7-a-side games. The rate of perceived exertion values were moderate and similar for all formats of games. The players performed more dribbling and successful passes, but fewer unsuccessful passes during 5-a-side games. Furthermore, the number of ball possessions and unsuccessful passes was higher on a small pitch than on a large one. Consequently, the current findings suggest that, independent of pitch size, the cardiovascular demands imposed on participants increase when the game is played with fewer players. However, all formats of recreational soccer can be used as an effective activity to promote cardiovascular fitness. Finally, participants may have more chance to perform basic technical actions during 5-a-side games on small and large pitches.

Keywords

  • Exercise intensity
  • heart rate
  • rate of perceived exertion
  • notation analysis
  • recreational soccer
Otwarty dostęp

Estimating the Energy Costs of Intermittent Exercise

Data publikacji: 08 Oct 2013
Zakres stron: 107 - 113

Abstrakt

Abstract

To date, steady state models represent the only acceptable methodology for the estimation of exercise energy costs. Conversely, comparisons made between continuous and intermittent exercise generally reveal major physiological discrepancies, leading to speculation as to why steady state energy expenditure models should be applied to intermittent exercise. Under intermittent conditions, skeletal muscle invokes varying aerobic and anaerobic metabolic responses, each with the potential to make significant contributions to overall energy costs. We hypothesize that if the aerobic-only energetic profile of steady state exercise can be used to estimate the energetics of non-steady state and intermittent exercise, then the converse also must be true. In fact, reasonable estimates of energy costs to work volumes or work rates can be demonstrated under steady state, non-steady state and intermittent conditions; the problem with the latter two is metabolic variability. Using resistance training as a model, estimates of both aerobic and anaerobic energy cost components, as opposed to one or the other, have reduced the overall energetic variability that appears inherent to brief, intense, intermittent exercise models.

Keywords

  • resistance training
  • intense exercise
  • total energy expenditure
  • work volume
Otwarty dostęp

Physical and Physiological Characteristics of Elite Male Handball Players from Teams with a Different Ranking

Data publikacji: 08 Oct 2013
Zakres stron: 115 - 124

Abstrakt

Abstract

The aim of this study was to examine possible discriminant physical and physiological characteristics between elite male handball players from elite teams with different league rankings. Players from three teams (A, B and C), which competed in the first league of the Greek championship during the season 2011-2012 participated in the study. Team A finished first, B came second and C came eighth out of eleven clubs. Teams A and B also participated in European Cups, and team A won the European Challenge Cup. The players (n=44) were examined for anthropometric characteristics and performed a series of physical fitness tests. Players from teams A and B were taller (6.2 cm (0.7;11.7), mean difference (95% CI) and 9.2 cm (4.0;14.5), respectively), and had a higher amount of fat free mass (6.4 kg (1.1;11.8) and 5.4 kg (0.2;10.5)) compared to those of team C. Players from team A performed better than players from team C in the squat jump (5.5 cm (1.0;10.0)), the countermovement jump without (5.5 cm (0.4;10.6)) and with armswing (6.0 cm (0.7;11.3)) and in the 30 s Bosco test (5.7 W.kg-1 (1.2;10.2)). Also, players from team A outperformed team B in mean power during the Wingate anaerobic test (WAnT, 0.5 W.kg-1(0;0.9)) and in the Bosco test (7.8 W.kg-1 (3.4;12.2)). Overall, players from the best ranked team performed better than the lowest ranked team on WAnT, vertical jumps and the Bosco test. Stepwise discriminant analysis showed that stature and mean power during the Bosco test were the most important characteristics in TH players, accounting for 54.6% of the variance in team ranking. These findings indicate the contribution of particular physical fitness components (stature, fat free mass and anaerobic power) to excellence in TH. In addition, the use of the Bosco test as an assessment tool in talent identification and physical fitness monitoring in this sport is further recommended.

Keywords

  • physical fitness
  • anthropometry
  • anaerobic power
  • discriminant variables
  • sport excellence
  • handball
Otwarty dostęp

Competitive Performance, Training Load and Physiological Responses During Tapering in Young Swimmers

Data publikacji: 08 Oct 2013
Zakres stron: 125 - 134

Abstrakt

Abstract

The study examined the changes of training load and physiological parameters in relation to competitive performance during a period leading to a national championship. The training content of twelve swimmers (age: 14.2±1.3 yrs) was recorded four weeks before the national championship (two weeks of normal training and two weeks of the taper). The training load was calculated: i) by the swimmer’s session-RPE score (RPE-Load), ii) by the training intensity levels adjusted after a 7x200-m progressively increasing intensity test (LA-Load). Swimmers completed a 400- m submaximal intensity test, a 15 s tethered swimming and hand-grip strength measurements 34-35 (baseline: Test 1), 20-21 (before taper: Test 2) and 6-7 (Test 3) days before the national championship. Performance during the national championship was not significantly changed compared to season best (0.1±1.6%; 95% confidence limits: -0.9, 1.1%; Effect Size: 0.02, p=0.72) and compared to performance before the start of the two-week taper period (0.9±1.7%; 95% confidence limits: 0.3, 2.1%; Effect size: 0.12, p=0.09). No significant changes were observed in all measured physiological and performance related variables between Test 1, Test 2, and Test 3. Changes in RPE-Load (week-4 vs. week-1) were correlated with changes in performance (r=0.63, p=0.03) and the RPE-Load was correlated with the LALoad (r=0.80, p=0.01). The estimation of the session-RPE training load may be helpful for taper planning of young swimmers. Increasing the difference between the normal and last week of taper training load may facilitate performance improvements.

Keywords

  • training loads
  • tethered swimming force
  • arm strength
  • periodization
Otwarty dostęp

An Evaluation of the Levels of Vitamin D and Bone Turnover Markers After the Summer and Winter Periods in Polish Professional Soccer Players

Data publikacji: 08 Oct 2013
Zakres stron: 135 - 140

Abstrakt

Abstract

Vitamin D is synthesised in the skin during exposure to sunlight. The fundamental roles of vitamin D are the regulation of calcium and phosphate metabolism and bone mineralisation. Low vitamin D levels in athletes may adversely affect their exercise capabilities. The aim of our study was to investigate changes in serum levels of 25(OH)D3, calcium and bone turnover markers in football players in two training periods differing in the exposure to sunlight (after the summer period and after the winter period). We investigated 24 Polish professional soccer players. Serum levels of the following parameters were determined: 25(OH)D3, calcium, osteocalcin (OC), parathormone (PTH), procollagen type I N - terminal peptide (P1NP), and beta - CrossLaps (beta - CTx). We showed significantly higher levels of 25(OH)D3 and calcium and lower levels of PTH after the summer period versus the winter period. No significant differences in the levels of bone turnover markers were found. Furthermore, we did not observe any significant correlations between the levels of 25(OH)D3 and other parameters. Normal levels of 25(OH)D3 were observed in 50% of the players after the summer period and only in 16.7% of the players after the winter period. It is justified to measure the levels of 25(OH)D3, calcium and PTH in soccer players, especially after the winter period, when the exposure to sunlight is limited.

Keywords

  • 25(OH)D3
  • bone metabolism
  • professional soccer players
Otwarty dostęp

Calculating Home Advantage in the First Decade of the 21th Century UEFA Soccer Leagues

Data publikacji: 08 Oct 2013
Zakres stron: 141 - 150

Abstrakt

Abstract

Home advantage has been studied in different sports, establishing its existence and its possible causes. This article analyzes the home advantage in soccer leagues of UEFA countries in the first part of the 21st century. The sample of 52 countries monitored during a period of 10 years allows us to study 520 leagues and 111,030 matches of the highest level in each country associated with UEFA. Home advantage exists and is significant in 32 of the 52 UEFA countries, where it equals 55.6%. A decrease can be observed in the tendency towards home advantage between the years 2000 and 2010. Values between 55 and 56 were observed for home advantage in the top ten leagues in Europe. It has also been observed that home advantage depends on the level of the league evaluated using UEFA’s 2010/11 Country coefficients. The home advantage is calculated taking into account the teams’ position and the points obtained in each of the leagues. A direct relationship was observed with the number of points gained and an inverse relationship was observed with the team position.

Keywords

  • Home advantage
  • football
  • UEFA
  • performance analysis
Otwarty dostęp

The Importance of Sports Performance Factors and Training Contents From the Perspective of Futsal Coaches

Data publikacji: 08 Oct 2013
Zakres stron: 151 - 160

Abstrakt

Abstract

The aim of this study was to identify the importance assigned by futsal coaches with different education levels to the sports performance factors (technical, tactical, physical and psychological) and to the training contents. The sample was divided into three groups (novice: n=35, intermediate: n=42; and elite coaches: n=15) depending on the degree of specific education, coaching experience and the level of the teams trained. To achieve this goal, the coaches answered a questionnaire previously validated by specialists in sport sciences. The results showed significant differences between the novice and elite group in small-sided games, inferiority games, opposition and execution timing of the training and drill items. The analyses also showed significant differences between the novice and intermediate group in inferiority games and opposition of the training and drill items. Although, no differences were identified between groups for the remaining performance factors and training and drill items considered, the identified trends provide a baseline related to the knowledge that contributes to the development of expertise of futsal coaches.

Słowa kluczowe

  • coaching
  • experience
  • futsal
  • performance
  • training
Otwarty dostęp

Appropriate Loads for Peak-Power During Resisted Sprinting on a Non-Motorized Treadmill

Data publikacji: 08 Oct 2013
Zakres stron: 161 - 167

Abstrakt

Abstract

The purpose of this study was to determine the load which allows the highest peak power for resisted sprinting on a non-motorized treadmill and to determine if other variables are related to individual differences. Thirty college students were tested for vertical jump, vertical jump peak and mean power, 10 m sprint, 20 m sprint, leg press 1 RM, leg press 1 RM relative to body weight, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM. Participants performed eight resisted sprints on a non-motorized treadmill, with increasing relative loads expressed as percent of body weight. Sprint peak power was measured for each load. Pearson correlations were used to determine if relationships between the sprint peak power load and the other variables were significant. The sprint peak power load had a mode of 35% with 73% of all participants having a relative sprint peak power load between 25-35%. Significant correlations occurred between sprint peak power load and body weight, lean body mass, vertical jump peak and mean power, leg press 1 RM, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM (r = 0.44, 0.43, 0.39, 0.37, 0.47, 0.39, 0.46, and 0.47, respectively). Larger, stronger, more powerful athletes produced peak power at a higher relative load during resisted sprinting on a nonmotorized treadmill.

Keywords

  • resistance
  • speed
  • performance
  • sprint
  • running
Otwarty dostęp

Relationship Between Fatigue Index and Number of Repetition Maxima with Sub-Maximal Loads in Biceps Curl

Data publikacji: 08 Oct 2013
Zakres stron: 169 - 181

Abstrakt

Abstract

The aim of this study was to investigate the relationship between the number of repetition maxima to volitional failure (RM) at 60%, 75%, 90% of 1RM and fatigue index (FI), a determinant of the muscular endurance level. Thirty four resistance trained male participants attended two testing sessions. The first session was conducted to assess 1RM load and RM at 60%, 75% and 90% of 1RM in the supine biceps curl (SBC) exercise. In the second session, a FI test protocol consisting of five sets of SBC with 90 s rest between sets was performed to determine FI values. Each set was performed to volitional failure using a sub-maximal load in the range of 15-20RM. Hypothetical high FI and low FI groups (17 participants with the highest and lowest FI values, respectively) were formed for statistical analyses. ANOVA results revealed that RM at 60%, 75%, 90% of 1RM were not significantly different between FI groups when controlled for mean repetition tempo (p=0.11, p=0.38, p=0.13, respectively). Pearson’s correlation coefficients revealed that no significant relationship was present between FI values and RM at 60%, 75%, 90% of 1RM (p=0.40, p=0.46, p=0.14, respectively). In conclusion, the muscular endurance level of participants defined in terms of FI value was not an indicator of RM in SBC. Therefore, athletes with different muscular endurance levels can use similar percentages of 1RM in biceps curl exercise in their training programs when the aim is to elicit training adaptations related to specific RM zones.

Słowa kluczowe

  • resistance exercise
  • relative load
  • volitional failure
  • muscular endurance
Otwarty dostęp

A Decade of Euroleague Basketball: an Analysis of Trends and Recent Rule Change Effects

Data publikacji: 08 Oct 2013
Zakres stron: 183 - 189

Abstrakt

Abstract

The International Basketball Federation (FIBA) recently introduced major rule changes that came into effect with the 2010/11 season. Most notably, moving the three-point arc and changing the shot-clock. The purpose of this study was to investigate and quantify how these changes affect the game performance of top-level European basketball players. In order to better understand these changes, we also investigated past seasons and showed the presence of several trends, even in the absence of significant rule changes. A large set of game statistics for 10 seasons and 2198 Euroleague basketball games in which top European clubs competed was analyzed. Results show that the effects of the rule changes are contrary to trends in recent years

Keywords

  • FIBA
  • basketball
  • statistics
  • three-point arc
  • shot-clock
Otwarty dostęp

The Influence of an Additional Load on Time and Force Changes in the Ground Reaction Force During the Countermovement Vertical Jump

Data publikacji: 08 Oct 2013
Zakres stron: 191 - 200

Abstrakt

Abstract

The aim of this study was to determine how an additional load influences the force-vs-time relationship of the countermovement vertical jump (CMVJ). The participants that took part in the experiment were 18 male university students who played sport recreationally, including regular games of volleyball. They were asked to perform a CMVJ without involving the arms under four conditions: without and with additional loads of 10%, 20%, and 30% of their body weight (BW). The vertical component of the ground reaction force (GRF) was measured by a force plate. The GRF was used to calculate the durations of the preparatory, braking, and acceleration phases, the total duration of the jump, force impulses during the braking and acceleration phases, average forces during the braking and acceleration phases, and the maximum force of impact at landing. Results were evaluated using repeated-measures ANOVA. Increasing the additional load prolonged both the braking and acceleration phases of the jump, with statistically significant changes in the duration of the acceleration phase found for an additional load of 20% BW. The magnitude of the force systematically and significantly increased with the additional load. The force impulse during the acceleration phase did not differ significantly between jumps performed with loads of 20% and 30% BW. The results suggest that the optimal additional load for developing explosive strength in vertical jumping ranges from 20% to 30% of BW, with this value varying between individual subjects.

Słowa kluczowe

  • strength training
  • SSC
  • kinetic analysis
  • force plate
  • vertical jump
Otwarty dostęp

Activity Profiles of Soccer Players During the 2010 World Cup

Data publikacji: 08 Oct 2013
Zakres stron: 201 - 211

Abstrakt

Abstract

The main objective of this study was to analyse the distance covered and the activity profile that players presented at the FIFA World Cup in 2010. Complementarily, the distance covered by each team within the same competition was analysed. For the purposes of this study 443 players were analysed, of which 35 were goalkeepers, 84 were external defenders, 77 were central defenders, 182 were midfielders, and 65 were forwards. Afterwards, a thorough analysis was performed on 16 teams that reached the group stage, 8 teams that achieved the round of 16, 4 teams that reached the quarter-finals, and 4 teams that qualified for the semi-finals and finals. A comparison of the mean distance covered per minute among the playing positions showed statistically significant differences (F(4,438) = 559.283; p < 0.001; 2 = 0.836; Power = 1.00). A comparison of the activity time among tactical positions also resulted in statistically significant differences, specifically, low activity (F(4,183.371) = 1476.844; p < 0.001; 2 = 0.742; Power = 1.00), medium activity (F(4,183.370) = 1408.106; p < 0.001; 2 = 0.731; Power = 1.00), and high activity (F(4,182.861) = 1152.508; p < 0.001; 2 = 0.703; Power = 1.00). Comparing the mean distance covered by teams, differences that are not statistically significant were observed (F(3,9.651) = 4.337; p < 0.035; 2 = 0.206; Power = 0.541). In conclusion, the tactical positions of the players and their specific tasks influence the activity profile and physical demands during a match.

Keywords

  • Soccer
  • match analysis
  • activity profile
  • player’s position
Otwarty dostęp

Performance Consistency of International Soccer Teams in Euro 2012: a Time Series Analysis

Data publikacji: 08 Oct 2013
Zakres stron: 213 - 226

Abstrakt

Abstract

The purpose of this study was to examine the consistency of performance in successive matches for international soccer teams from Europe which qualified for the quarter final stage of EURO 2012 in Poland and Ukraine. The eight teams that reached the quarter final stage and beyond were the sample teams for this time series analysis. The autocorrelation and cross-correlation functions were used to analyze the consistency of play and its association with the result of match in sixteen performance indicators of each team. The results of autocorrelation function showed that based on the number of consistent performance indicators, Spain and Italy demonstrated more consistency in successive matches in relation to other teams. This appears intuitive given that Spain played Italy in the final. However, it is arguable that other teams played at a higher performance levels at various parts of the competition, as opposed to performing consistently throughout the tournament. The results of the cross-correlation analysis showed that in relation to goal-related indicators, these had higher associations with the match results of Spain and France. In relation to the offensive-related indicators, France, England, Portugal, Greece, Czech Republic and Spain showed a positive correlation with the match result. In relation to the defensive-related indicators, France, England, Greece and Portugal showed a positive correlation with match results. In conclusion, in an international soccer tournament, the successful teams displayed a greater degree of performance consistency across all indicators in comparison to their competitors who occasionally would show higher levels of performance in individual games, yet not consistently across the overall tournament. The authors therefore conclude that performance consistency is more significant in international tournament soccer, versus occasionally excelling in some metrics and indicators in particular games.

Słowa kluczowe

  • consistency of play
  • match result
  • performance indicators
  • soccer
Otwarty dostęp

Ball Possession Effectiveness in Men’s Elite Floorball According to Quality of Opposition and Game Period

Data publikacji: 08 Oct 2013
Zakres stron: 227 - 237

Abstrakt

Abstract

The aim of the present study was to identify the importance of floorball tactical variables to predict ball possession effectiveness, when controlling quality of opposition and game periods. The sample was composed by 1500 ball possessions, corresponding to 14 games randomly selected from the International Championships played during 2008 and 2010 (World Championship, Four nations tournament and classificatory phases for World Championship) by teams from different competition levels (HIGH, INTERMEDIATE and LOW). The effects of the predictor variables on successful ball possessions according to the three game contexts (HIGH vs. HIGH; HIGH vs. LOW; LOW vs. LOW games) were analyzed using Binomial Logistic Regressions. The results showed no interaction with the game period. In HIGH vs. HIGH games, quality of opposition showed an association with ball possession effectiveness with ending zone, offensive system, possession duration, height of shooting and defensive pressures previous to the shot. In HIGH vs. LOW games the important factors were the starting zone, possession duration, defensive pressure previous to the last pass and to the shot, technique of shooting and the number players involved in each ball possession. Finally, in LOW vs. LOW games, the results emphasized the importance of starting and ending zones, the number of passes used and the technique of shooting. In conclusion, elite floorball performance is mainly affected by quality of opposition showing different game patterns in each context that should be considered by coaches when preparing practices and competitions.

Słowa kluczowe

  • notational analysis
  • situational variables
  • team sports
  • performance analysis
23 Artykułów
Otwarty dostęp

Lower-Limb Power cannot be Estimated Accurately from Vertical Jump Tests

Data publikacji: 08 Oct 2013
Zakres stron: 5 - 13

Abstrakt

Abstract

The countermovement jump test is often adopted to monitor lower-limb power of an individual. Despite several studies on the validity of this test, there is still a need to determine the minimal difference needed to be confident that a difference in power between two individuals is present or that a true change in the performance of an individual has occurred. In this study, power was measured from ground reaction forces and compared to that obtained from predictive equations for two groups of subjects (67 trained and 20 highly trained individuals). The height of each jump was determined with kinematic techniques. The main outcome is a large discrepancy between power calculated from ground reaction forces and that calculated from predictive equations. For the trained group, the R-square value between power and predicted power was 0.53 and the minimal difference to consider that two individuals were different was 821.7 W. For the highly trained individuals, a much larger R-square value was obtained (0.94). Despite this, the minimal difference to consider that two individuals were different was still large (689.3 W). The large minimal differences obtained raise serious concerns about using countermovement jumps for appraisal and monitoring of lower-limb power of an individual.

Słowa kluczowe

  • Countermovement jump
  • force
  • validity
  • minimal difference
Otwarty dostęp

Kinematic Variables Evolution During a 200-m Maximum Test in Young Paddlers

Data publikacji: 08 Oct 2013
Zakres stron: 15 - 22

Abstrakt

Abstract

The objective of this research was to determine the kinematic variables evolution in a sprint canoeing maximal test over 200 m, comparing women and men kayak paddlers and men canoeists. Speed evolution, cycle frequency, cycle length and cycle index were analysed each 50 m section in fifty-two young paddlers (20 male kayakers, 17 female kayakers and 15 male canoeists; 13-14 years-old). Recordings were taken from a boat which followed each paddler trial in order to measure the variables cited above. Kinematic evolution was similar in the three categories, the speed and cycle index decreased through the test after the first 50 m. Significant differences were observed among most of the sections in speed and the cycle index (p<0.05 and <0.01, respectively). Cycle length remained stable showing the lowest values in the first section when compared with the others (p<0.01). Cycle frequency progressively decreased along the distance. Significant differences were identified in the majority of the sections (p<0.01). Men kayakers attained higher values in all the variables than women kayakers and men canoeists, but only such variables as speed, cycle length and cycle index were observed to be significantly higher (p<0.01). Moreover, lower kinematic values were obtained from men canoeists. The study of the evolution of kinematic variables can provide valuable information for athletes and coaches while planning training sessions and competitions.

Słowa kluczowe

  • Speed evolution
  • cycle frequency
  • cycle length
  • cycle index
  • kayakers
  • canoeists
Otwarty dostęp

The Development of a Repetition-Load Scheme for the Eccentric- Only Bench Press Exercise

Data publikacji: 08 Oct 2013
Zakres stron: 23 - 31

Abstrakt

Abstract

The purpose of the present study was to develop a repetition-load scheme for the eccentric-only bench press exercise. Nine resistance trained men (age: 21.6 ± 1.0 years; 1-repetition maximum [RM] bench press: 137.7 ± 30.4 kg) attended four testing sessions during a four week period. During the first session each subject’s 1-RM bench press load utilizing the stretch-shortening cycle was determined. During the remaining sessions they performed eccentric-only repetitions to failure using supra-maximal loads equivalent to 110%, 120% and 130% of their 1-RM value with a constant cadence (30 reps·min-1). Force plates and a three dimensional motion analysis system were used during these final three sessions in order to evaluate kinematic and kinetic variables. More repetitions were completed during the 110% 1-RM condition compared to the 130% 1-RM condition (p=0.01). Mean total work (p=0.046) as well as vertical force (p=0.049), vertical work (p=0.017), and vertical power output (p=0.05) were significantly greater during the 130% 1-RM condition compared to the 110% 1-RM condition. A linear function was fitted to the number of repetitions completed under each load condition that allowed the determination of the maximum number of repetitions that could be completed under other supra-maximal loads. This linear function predicted an eccentric-only 1-RM in the bench press with a load equivalent to 164.8% 1-RM, producing a load of 227.0 ± 50.0 kg. The repetition-load scheme presented here should provide a starting point for researchers to investigate the kinematic, kinetic and metabolic responses to eccentric-only bench press workouts.

Słowa kluczowe

  • bench press
  • eccentric contraction
  • repetition-load scheme
Otwarty dostęp

Body Posture Stability in Ski Boots Under Conditions of Unstable Supporting Surface

Data publikacji: 08 Oct 2013
Zakres stron: 33 - 44

Abstrakt

Abstract

The authors attempted to determine whether: (1) there are differences in stability between the conditions of standing in ski boots and barefoot, (2) the type of surface affects stability, and, (3) the level of stability differs between the frontal and sagittal planes. The study included 35 young male recreational skiers aged 20.71 ±0.63 years. Measurements of stability were taken by means of a Libra seesaw balance board. The conditions of soft surface were created by attaching an inflated cushion to the board. The experiment was carried out on both rigid and soft surface for both movement planes and two different conditions: maintaining the seesaw balance board in the horizontal position and performance of a particular balancing task. All the tests were performed with visual feedback. Restricted ankle joint mobility that results from wearing ski boots caused a reduction of stability in studied subjects, particularly in the sagittal plane. The differences found in the study were likely to be caused by the difficulty the beginners experienced in re-organizing muscular coordination in hip joint strategy and effectively using mechanical support of ski boots that reduces lower limb muscle tone. The use of the soft surface improved stability exhibited by the subjects in the frontal plane without compromising the stability in the sagittal plane. The soft surface might have contributed to a reduction in excessive corrective movements, thus improving stability in studied subjects.The aim of this study was to determine the effect of limitation of foot mobility and disturbances in afferent information from the plantar mechanoreceptors due to wearing ski boots on the level of postural stability in beginner skiers under conditions of the unstable support surface.

Słowa kluczowe

  • dynamic balance
  • compliant surface
  • ski boots
  • beginner skiers
Otwarty dostęp

Postural Adaptations in Preadolescent Karate Athletes Due to a One Week Karate Training Camp

Data publikacji: 08 Oct 2013
Zakres stron: 45 - 52

Abstrakt

Abstract

The aim of this study was to investigate the effect of an increasing number of training hours of specific highintensity karate training on postural sway in preadolescent karate athletes. Seventy-four karatekas were randomly assigned to 1 of 2 groups: Karate Group (KG=37): age 10.29±1.68 yrs; or Control Group (CG= 37): age 10.06±1.77 yrs. The KG performed two sessions per day for 1 week in total, while the CG performed only 3 sessions during the same period. The center-of-pressure length (COPL) and velocity (COPV) were recorded under four different experimental conditions: open eyes (EO), closed eyes (EC), open eyes monopodalic left (EOL), open eyes monopodalic right (EOR), pre as well as post training intervention. Post-camp results indicated significant differences between the groups in the COPL p<0.001; an interaction of training type×time in the COPV (p<0.001) and an interaction of training type×time (p=0.020). The KG revealed an improvement in the COPL from pre to post-camp under conditions of EO [-37.26% (p<0.001)], EC [-31.72% (p<0.001)], EOL [-27.27% (p<0.001)], EOR [-21.44% (p<0.001)], while CG revealed small adaptations in conditions of EO (3.16%), EC (0.93%), EOL (-3.03%), EOR (-0.97%). Furthermore, in the KG an improvement in the COPV from pre to post-camp was observed in conditions of EO [-37.92% (p<0.001)], EC [-32.52% (p<0.001)], EOL [-29.11% (p<0.001)], EOR [-21.49% (p<0.001)]. In summary, one-week of high intensity karate training induced a significant improvement in static body balance in preadolescent karate athletes. Karate performance requires high-levels of both static and dynamic balance. Further research dealing with the effect of karate practice on dynamic body balance in young athletes is required.

Słowa kluczowe

  • physical exercise
  • karate training
  • training and testing
  • centre of pressure
  • postural sway
  • proprioception
Otwarty dostęp

Are Various Forms of Locomotion-Speed Diverse or Unique Performance Quality?

Data publikacji: 08 Oct 2013
Zakres stron: 53 - 61

Abstrakt

Abstract

The forward-sprint is considered to be, and is regularly performed as, a unique measure of “on-ground” linearspeed performance. Thus far, no investigation has simultaneously studied different forms of linear-speed or investigated whether different forms of linear-speed should be observed as unique performance quality. The purpose of this study was to determine (I) the achievements (i.e. execution time), and (II) the reliability and inter-relationships between various linear-speed performances. The participants were 42 male physical education students with substantial sport-specific backgrounds. We applied a total of six tests: three quadrupedal (supine backward, supine forward, and pronate backward locomotion) and three bipedal-performances (forward sprinting, backward sprinting, lateral shuffling). All of the tests showed appropriate reliability parameters (Cronbach Alpha ranged from 0.91 to 0.97; Inter-Item-R 0.78-0.92; Coefficient-of-Variation 1.3-9.1). The tests used in this study shared between 9% and 50% of the common variance. Our results suggest that different activities require activity-specific tests of linear-speed. This is particularly significant in those sports and activities in which quadrupedal locomotion patterns are highly important (wrestling, physically trained military services, law enforcement, fire and rescue, protective services).

Słowa kluczowe

  • specific testing
  • factor analysis
  • bipedal locomotion
  • quadrupedal locomotion
Otwarty dostęp

A Comparison of Muscle Activity in Concentric and Counter Movement Maximum Bench Press

Data publikacji: 08 Oct 2013
Zakres stron: 63 - 71

Abstrakt

Abstract

The purpose of this study was to compare the kinematics and muscle activation patterns of regular free-weight bench press (counter movement) with pure concentric lifts in the ascending phase of a successful one repetition maximum (1-RM) attempt in the bench press. Our aim was to evaluate if diminishing potentiation could be the cause of the sticking region. Since diminishing potentiation cannot occur in pure concentric lifts, the occurrence of a sticking region in this type of muscle actions would support the hypothesis that the sticking region is due to a poor mechanical position. Eleven male participants (age 21.9 ~ 1.7 yrs, body mass 80.7 ~ 10.9 kg, body height 1.79 ~ 0.07 m) conducted 1-RM lifts in counter movement and in pure concentric bench presses in which kinematics and EMG activity were measured. In both conditions, a sticking region occurred. However, the start of the sticking region was different between the two bench presses. In addition, in four of six muscles, the muscle activity was higher in the counter movement bench press compared to the concentric one. Considering the findings of the muscle activity of six muscles during the maximal lifts it was concluded that the diminishing effect of force potentiation, which occurs in the counter movement bench press, in combination with a delayed muscle activation unlikely explains the existence of the sticking region in a 1-RM bench press. Most likely, the sticking region is the result of a poor mechanical force position.

Słowa kluczowe

  • kinematics
  • EMG
  • muscle
  • potentiation
  • bench press
Otwarty dostęp

Mechanical Work and Long-Distance Performance Prediction: the Influence of Allometric Scaling

Data publikacji: 08 Oct 2013
Zakres stron: 73 - 82

Abstrakt

Abstract

The purpose of this study was to examine the effect of allometric scaling on the relationship between mechanical work and long-distance running performance in recreational runners. Fourteen recreational long-distance runners (male, mean ± SD - age: 29 ± 7 years; body mass: 70.0 ± 10.2 kg; body height: 1.71 ± 0.07 m; maximal oxygen uptake: VO2max 52.0 ± 4.9 ml.kg-1.min-1) performed two tests: a continuous incremental test to volitional exhaustion in order to determine VO2max, and a 6-minute running submaximal test at 3.1 m.s-1, during which segments in the sagittal plane were recorded using a digital camera and the internal (Wint), external (Wext) and total (Wtot) mechanic work, in J.kg-1.m-1, was subsequently calculated. The results indicated a significant correlation between mechanical work and performance, however, the strongest correlations were observed when allometric exponents were used (respectively for Wint, Wext and Wtot; non allometric vs. allometric scaling defined by literature (0.75) or determined mathematically (0.49): r = 0.38 vs. r = 0.44 and r = 0.50; r = 0.80 vs. r = 0.83 and r = 0.82; r = 0.70 vs. r = 0.77 and r = 0.78). These results indicate that mechanical work could be used as a predictor of recreational long-distance performance and an allometric model may improve this prediction.

Słowa kluczowe

  • allometry
  • body size
  • cost of running
  • human locomotion
  • mechanical efficiency
  • running economy
Otwarty dostęp

Potentiation Increases Peak Twitch Torque by Enhancing Rates of Torque Development and Relaxation

Data publikacji: 08 Oct 2013
Zakres stron: 83 - 94

Abstrakt

Abstract

The aim of this study was to measure the extent to which potentiation changes in response to an isometric maximal voluntary contraction. Eleven physically active subjects participated in two separate studies. Single stimulus of electrical stimulation of the femoral nerve was used to measure torque at rest in unpotentiated quadriceps muscles (study 1 and 2), and potentiated quadriceps muscles torque in a 10 min period after a 5 s isometric maximal voluntary contraction of the quadriceps muscles (study 1). Additionally, potentiated quadriceps muscles torque was measured every min after a further 10 maximal voluntary contractions repeated every min (study 2). Electrical stimulation repeated several times without previous maximal voluntary contraction showed similar peak twitch torque. Peak twitch torque 4 s after a 5 s maximal voluntary contraction increased by 45±13% (study 1) and by 56±10% (study 2), the rate of torque development by 53±13% and 82±29%, and the rate of relaxation by 50±17% and 59±22%, respectively, but potentiation was lost already two min after a 5 s maximal voluntary contraction. There was a tendency for peak twitch torque to increase for the first five repeated maximal voluntary contractions, suggesting increased potentiation with additional maximal voluntary contractions. Correlations for peak twitch torque vs the rate of torque development and for the rate of relaxation were r2= 0.94 and r2=0.97. The correlation between peak twitch torque, the rate of torque development and the rate of relaxation suggests that potentiation is due to instantaneous changes in skeletal muscle contractility and relaxation.

Keywords

  • Maximal isometric voluntary contraction
  • quadriceps muscles
  • electrical stimulation
  • decay
  • fatigue
Otwarty dostęp

Cardiovascular Responses, Perceived Exertion and Technical Actions During Small-Sided Recreational Soccer: Effects of Pitch Size and Number of Players

Data publikacji: 08 Oct 2013
Zakres stron: 95 - 105

Abstrakt

Abstract

The aim of this study was to determine the cardiovascular, perceived exertion and technical effects of altering pitch size and number of players in recreational soccer match-play. The further aim was to evaluate to what extent exercise intensity during various game formats corresponds to the recommended intensity level for cardiovascular fitness improvement. Ten male recreational players aged 31.7±7.6 years (mean ± SD) completed four variations of smallsided games (except for goalkeepers, 5-a-side and 7-a-side on small and large pitches) during which heart rate, perceived exertion and technical actions were evaluated. Two-way analysis of variance on repeated measures was applied to collected data. The results indicated that an average workload expressed as heart rate and percentage of heart rate reserve during 5-a-side games was higher than for 7-a-side games. The rate of perceived exertion values were moderate and similar for all formats of games. The players performed more dribbling and successful passes, but fewer unsuccessful passes during 5-a-side games. Furthermore, the number of ball possessions and unsuccessful passes was higher on a small pitch than on a large one. Consequently, the current findings suggest that, independent of pitch size, the cardiovascular demands imposed on participants increase when the game is played with fewer players. However, all formats of recreational soccer can be used as an effective activity to promote cardiovascular fitness. Finally, participants may have more chance to perform basic technical actions during 5-a-side games on small and large pitches.

Keywords

  • Exercise intensity
  • heart rate
  • rate of perceived exertion
  • notation analysis
  • recreational soccer
Otwarty dostęp

Estimating the Energy Costs of Intermittent Exercise

Data publikacji: 08 Oct 2013
Zakres stron: 107 - 113

Abstrakt

Abstract

To date, steady state models represent the only acceptable methodology for the estimation of exercise energy costs. Conversely, comparisons made between continuous and intermittent exercise generally reveal major physiological discrepancies, leading to speculation as to why steady state energy expenditure models should be applied to intermittent exercise. Under intermittent conditions, skeletal muscle invokes varying aerobic and anaerobic metabolic responses, each with the potential to make significant contributions to overall energy costs. We hypothesize that if the aerobic-only energetic profile of steady state exercise can be used to estimate the energetics of non-steady state and intermittent exercise, then the converse also must be true. In fact, reasonable estimates of energy costs to work volumes or work rates can be demonstrated under steady state, non-steady state and intermittent conditions; the problem with the latter two is metabolic variability. Using resistance training as a model, estimates of both aerobic and anaerobic energy cost components, as opposed to one or the other, have reduced the overall energetic variability that appears inherent to brief, intense, intermittent exercise models.

Keywords

  • resistance training
  • intense exercise
  • total energy expenditure
  • work volume
Otwarty dostęp

Physical and Physiological Characteristics of Elite Male Handball Players from Teams with a Different Ranking

Data publikacji: 08 Oct 2013
Zakres stron: 115 - 124

Abstrakt

Abstract

The aim of this study was to examine possible discriminant physical and physiological characteristics between elite male handball players from elite teams with different league rankings. Players from three teams (A, B and C), which competed in the first league of the Greek championship during the season 2011-2012 participated in the study. Team A finished first, B came second and C came eighth out of eleven clubs. Teams A and B also participated in European Cups, and team A won the European Challenge Cup. The players (n=44) were examined for anthropometric characteristics and performed a series of physical fitness tests. Players from teams A and B were taller (6.2 cm (0.7;11.7), mean difference (95% CI) and 9.2 cm (4.0;14.5), respectively), and had a higher amount of fat free mass (6.4 kg (1.1;11.8) and 5.4 kg (0.2;10.5)) compared to those of team C. Players from team A performed better than players from team C in the squat jump (5.5 cm (1.0;10.0)), the countermovement jump without (5.5 cm (0.4;10.6)) and with armswing (6.0 cm (0.7;11.3)) and in the 30 s Bosco test (5.7 W.kg-1 (1.2;10.2)). Also, players from team A outperformed team B in mean power during the Wingate anaerobic test (WAnT, 0.5 W.kg-1(0;0.9)) and in the Bosco test (7.8 W.kg-1 (3.4;12.2)). Overall, players from the best ranked team performed better than the lowest ranked team on WAnT, vertical jumps and the Bosco test. Stepwise discriminant analysis showed that stature and mean power during the Bosco test were the most important characteristics in TH players, accounting for 54.6% of the variance in team ranking. These findings indicate the contribution of particular physical fitness components (stature, fat free mass and anaerobic power) to excellence in TH. In addition, the use of the Bosco test as an assessment tool in talent identification and physical fitness monitoring in this sport is further recommended.

Keywords

  • physical fitness
  • anthropometry
  • anaerobic power
  • discriminant variables
  • sport excellence
  • handball
Otwarty dostęp

Competitive Performance, Training Load and Physiological Responses During Tapering in Young Swimmers

Data publikacji: 08 Oct 2013
Zakres stron: 125 - 134

Abstrakt

Abstract

The study examined the changes of training load and physiological parameters in relation to competitive performance during a period leading to a national championship. The training content of twelve swimmers (age: 14.2±1.3 yrs) was recorded four weeks before the national championship (two weeks of normal training and two weeks of the taper). The training load was calculated: i) by the swimmer’s session-RPE score (RPE-Load), ii) by the training intensity levels adjusted after a 7x200-m progressively increasing intensity test (LA-Load). Swimmers completed a 400- m submaximal intensity test, a 15 s tethered swimming and hand-grip strength measurements 34-35 (baseline: Test 1), 20-21 (before taper: Test 2) and 6-7 (Test 3) days before the national championship. Performance during the national championship was not significantly changed compared to season best (0.1±1.6%; 95% confidence limits: -0.9, 1.1%; Effect Size: 0.02, p=0.72) and compared to performance before the start of the two-week taper period (0.9±1.7%; 95% confidence limits: 0.3, 2.1%; Effect size: 0.12, p=0.09). No significant changes were observed in all measured physiological and performance related variables between Test 1, Test 2, and Test 3. Changes in RPE-Load (week-4 vs. week-1) were correlated with changes in performance (r=0.63, p=0.03) and the RPE-Load was correlated with the LALoad (r=0.80, p=0.01). The estimation of the session-RPE training load may be helpful for taper planning of young swimmers. Increasing the difference between the normal and last week of taper training load may facilitate performance improvements.

Keywords

  • training loads
  • tethered swimming force
  • arm strength
  • periodization
Otwarty dostęp

An Evaluation of the Levels of Vitamin D and Bone Turnover Markers After the Summer and Winter Periods in Polish Professional Soccer Players

Data publikacji: 08 Oct 2013
Zakres stron: 135 - 140

Abstrakt

Abstract

Vitamin D is synthesised in the skin during exposure to sunlight. The fundamental roles of vitamin D are the regulation of calcium and phosphate metabolism and bone mineralisation. Low vitamin D levels in athletes may adversely affect their exercise capabilities. The aim of our study was to investigate changes in serum levels of 25(OH)D3, calcium and bone turnover markers in football players in two training periods differing in the exposure to sunlight (after the summer period and after the winter period). We investigated 24 Polish professional soccer players. Serum levels of the following parameters were determined: 25(OH)D3, calcium, osteocalcin (OC), parathormone (PTH), procollagen type I N - terminal peptide (P1NP), and beta - CrossLaps (beta - CTx). We showed significantly higher levels of 25(OH)D3 and calcium and lower levels of PTH after the summer period versus the winter period. No significant differences in the levels of bone turnover markers were found. Furthermore, we did not observe any significant correlations between the levels of 25(OH)D3 and other parameters. Normal levels of 25(OH)D3 were observed in 50% of the players after the summer period and only in 16.7% of the players after the winter period. It is justified to measure the levels of 25(OH)D3, calcium and PTH in soccer players, especially after the winter period, when the exposure to sunlight is limited.

Keywords

  • 25(OH)D3
  • bone metabolism
  • professional soccer players
Otwarty dostęp

Calculating Home Advantage in the First Decade of the 21th Century UEFA Soccer Leagues

Data publikacji: 08 Oct 2013
Zakres stron: 141 - 150

Abstrakt

Abstract

Home advantage has been studied in different sports, establishing its existence and its possible causes. This article analyzes the home advantage in soccer leagues of UEFA countries in the first part of the 21st century. The sample of 52 countries monitored during a period of 10 years allows us to study 520 leagues and 111,030 matches of the highest level in each country associated with UEFA. Home advantage exists and is significant in 32 of the 52 UEFA countries, where it equals 55.6%. A decrease can be observed in the tendency towards home advantage between the years 2000 and 2010. Values between 55 and 56 were observed for home advantage in the top ten leagues in Europe. It has also been observed that home advantage depends on the level of the league evaluated using UEFA’s 2010/11 Country coefficients. The home advantage is calculated taking into account the teams’ position and the points obtained in each of the leagues. A direct relationship was observed with the number of points gained and an inverse relationship was observed with the team position.

Keywords

  • Home advantage
  • football
  • UEFA
  • performance analysis
Otwarty dostęp

The Importance of Sports Performance Factors and Training Contents From the Perspective of Futsal Coaches

Data publikacji: 08 Oct 2013
Zakres stron: 151 - 160

Abstrakt

Abstract

The aim of this study was to identify the importance assigned by futsal coaches with different education levels to the sports performance factors (technical, tactical, physical and psychological) and to the training contents. The sample was divided into three groups (novice: n=35, intermediate: n=42; and elite coaches: n=15) depending on the degree of specific education, coaching experience and the level of the teams trained. To achieve this goal, the coaches answered a questionnaire previously validated by specialists in sport sciences. The results showed significant differences between the novice and elite group in small-sided games, inferiority games, opposition and execution timing of the training and drill items. The analyses also showed significant differences between the novice and intermediate group in inferiority games and opposition of the training and drill items. Although, no differences were identified between groups for the remaining performance factors and training and drill items considered, the identified trends provide a baseline related to the knowledge that contributes to the development of expertise of futsal coaches.

Słowa kluczowe

  • coaching
  • experience
  • futsal
  • performance
  • training
Otwarty dostęp

Appropriate Loads for Peak-Power During Resisted Sprinting on a Non-Motorized Treadmill

Data publikacji: 08 Oct 2013
Zakres stron: 161 - 167

Abstrakt

Abstract

The purpose of this study was to determine the load which allows the highest peak power for resisted sprinting on a non-motorized treadmill and to determine if other variables are related to individual differences. Thirty college students were tested for vertical jump, vertical jump peak and mean power, 10 m sprint, 20 m sprint, leg press 1 RM, leg press 1 RM relative to body weight, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM. Participants performed eight resisted sprints on a non-motorized treadmill, with increasing relative loads expressed as percent of body weight. Sprint peak power was measured for each load. Pearson correlations were used to determine if relationships between the sprint peak power load and the other variables were significant. The sprint peak power load had a mode of 35% with 73% of all participants having a relative sprint peak power load between 25-35%. Significant correlations occurred between sprint peak power load and body weight, lean body mass, vertical jump peak and mean power, leg press 1 RM, leg press 1 RM relative to lean body mass, leg press 1 RM power, and leg press power at 80% of 1 RM (r = 0.44, 0.43, 0.39, 0.37, 0.47, 0.39, 0.46, and 0.47, respectively). Larger, stronger, more powerful athletes produced peak power at a higher relative load during resisted sprinting on a nonmotorized treadmill.

Keywords

  • resistance
  • speed
  • performance
  • sprint
  • running
Otwarty dostęp

Relationship Between Fatigue Index and Number of Repetition Maxima with Sub-Maximal Loads in Biceps Curl

Data publikacji: 08 Oct 2013
Zakres stron: 169 - 181

Abstrakt

Abstract

The aim of this study was to investigate the relationship between the number of repetition maxima to volitional failure (RM) at 60%, 75%, 90% of 1RM and fatigue index (FI), a determinant of the muscular endurance level. Thirty four resistance trained male participants attended two testing sessions. The first session was conducted to assess 1RM load and RM at 60%, 75% and 90% of 1RM in the supine biceps curl (SBC) exercise. In the second session, a FI test protocol consisting of five sets of SBC with 90 s rest between sets was performed to determine FI values. Each set was performed to volitional failure using a sub-maximal load in the range of 15-20RM. Hypothetical high FI and low FI groups (17 participants with the highest and lowest FI values, respectively) were formed for statistical analyses. ANOVA results revealed that RM at 60%, 75%, 90% of 1RM were not significantly different between FI groups when controlled for mean repetition tempo (p=0.11, p=0.38, p=0.13, respectively). Pearson’s correlation coefficients revealed that no significant relationship was present between FI values and RM at 60%, 75%, 90% of 1RM (p=0.40, p=0.46, p=0.14, respectively). In conclusion, the muscular endurance level of participants defined in terms of FI value was not an indicator of RM in SBC. Therefore, athletes with different muscular endurance levels can use similar percentages of 1RM in biceps curl exercise in their training programs when the aim is to elicit training adaptations related to specific RM zones.

Słowa kluczowe

  • resistance exercise
  • relative load
  • volitional failure
  • muscular endurance
Otwarty dostęp

A Decade of Euroleague Basketball: an Analysis of Trends and Recent Rule Change Effects

Data publikacji: 08 Oct 2013
Zakres stron: 183 - 189

Abstrakt

Abstract

The International Basketball Federation (FIBA) recently introduced major rule changes that came into effect with the 2010/11 season. Most notably, moving the three-point arc and changing the shot-clock. The purpose of this study was to investigate and quantify how these changes affect the game performance of top-level European basketball players. In order to better understand these changes, we also investigated past seasons and showed the presence of several trends, even in the absence of significant rule changes. A large set of game statistics for 10 seasons and 2198 Euroleague basketball games in which top European clubs competed was analyzed. Results show that the effects of the rule changes are contrary to trends in recent years

Keywords

  • FIBA
  • basketball
  • statistics
  • three-point arc
  • shot-clock
Otwarty dostęp

The Influence of an Additional Load on Time and Force Changes in the Ground Reaction Force During the Countermovement Vertical Jump

Data publikacji: 08 Oct 2013
Zakres stron: 191 - 200

Abstrakt

Abstract

The aim of this study was to determine how an additional load influences the force-vs-time relationship of the countermovement vertical jump (CMVJ). The participants that took part in the experiment were 18 male university students who played sport recreationally, including regular games of volleyball. They were asked to perform a CMVJ without involving the arms under four conditions: without and with additional loads of 10%, 20%, and 30% of their body weight (BW). The vertical component of the ground reaction force (GRF) was measured by a force plate. The GRF was used to calculate the durations of the preparatory, braking, and acceleration phases, the total duration of the jump, force impulses during the braking and acceleration phases, average forces during the braking and acceleration phases, and the maximum force of impact at landing. Results were evaluated using repeated-measures ANOVA. Increasing the additional load prolonged both the braking and acceleration phases of the jump, with statistically significant changes in the duration of the acceleration phase found for an additional load of 20% BW. The magnitude of the force systematically and significantly increased with the additional load. The force impulse during the acceleration phase did not differ significantly between jumps performed with loads of 20% and 30% BW. The results suggest that the optimal additional load for developing explosive strength in vertical jumping ranges from 20% to 30% of BW, with this value varying between individual subjects.

Słowa kluczowe

  • strength training
  • SSC
  • kinetic analysis
  • force plate
  • vertical jump
Otwarty dostęp

Activity Profiles of Soccer Players During the 2010 World Cup

Data publikacji: 08 Oct 2013
Zakres stron: 201 - 211

Abstrakt

Abstract

The main objective of this study was to analyse the distance covered and the activity profile that players presented at the FIFA World Cup in 2010. Complementarily, the distance covered by each team within the same competition was analysed. For the purposes of this study 443 players were analysed, of which 35 were goalkeepers, 84 were external defenders, 77 were central defenders, 182 were midfielders, and 65 were forwards. Afterwards, a thorough analysis was performed on 16 teams that reached the group stage, 8 teams that achieved the round of 16, 4 teams that reached the quarter-finals, and 4 teams that qualified for the semi-finals and finals. A comparison of the mean distance covered per minute among the playing positions showed statistically significant differences (F(4,438) = 559.283; p < 0.001; 2 = 0.836; Power = 1.00). A comparison of the activity time among tactical positions also resulted in statistically significant differences, specifically, low activity (F(4,183.371) = 1476.844; p < 0.001; 2 = 0.742; Power = 1.00), medium activity (F(4,183.370) = 1408.106; p < 0.001; 2 = 0.731; Power = 1.00), and high activity (F(4,182.861) = 1152.508; p < 0.001; 2 = 0.703; Power = 1.00). Comparing the mean distance covered by teams, differences that are not statistically significant were observed (F(3,9.651) = 4.337; p < 0.035; 2 = 0.206; Power = 0.541). In conclusion, the tactical positions of the players and their specific tasks influence the activity profile and physical demands during a match.

Keywords

  • Soccer
  • match analysis
  • activity profile
  • player’s position
Otwarty dostęp

Performance Consistency of International Soccer Teams in Euro 2012: a Time Series Analysis

Data publikacji: 08 Oct 2013
Zakres stron: 213 - 226

Abstrakt

Abstract

The purpose of this study was to examine the consistency of performance in successive matches for international soccer teams from Europe which qualified for the quarter final stage of EURO 2012 in Poland and Ukraine. The eight teams that reached the quarter final stage and beyond were the sample teams for this time series analysis. The autocorrelation and cross-correlation functions were used to analyze the consistency of play and its association with the result of match in sixteen performance indicators of each team. The results of autocorrelation function showed that based on the number of consistent performance indicators, Spain and Italy demonstrated more consistency in successive matches in relation to other teams. This appears intuitive given that Spain played Italy in the final. However, it is arguable that other teams played at a higher performance levels at various parts of the competition, as opposed to performing consistently throughout the tournament. The results of the cross-correlation analysis showed that in relation to goal-related indicators, these had higher associations with the match results of Spain and France. In relation to the offensive-related indicators, France, England, Portugal, Greece, Czech Republic and Spain showed a positive correlation with the match result. In relation to the defensive-related indicators, France, England, Greece and Portugal showed a positive correlation with match results. In conclusion, in an international soccer tournament, the successful teams displayed a greater degree of performance consistency across all indicators in comparison to their competitors who occasionally would show higher levels of performance in individual games, yet not consistently across the overall tournament. The authors therefore conclude that performance consistency is more significant in international tournament soccer, versus occasionally excelling in some metrics and indicators in particular games.

Słowa kluczowe

  • consistency of play
  • match result
  • performance indicators
  • soccer
Otwarty dostęp

Ball Possession Effectiveness in Men’s Elite Floorball According to Quality of Opposition and Game Period

Data publikacji: 08 Oct 2013
Zakres stron: 227 - 237

Abstrakt

Abstract

The aim of the present study was to identify the importance of floorball tactical variables to predict ball possession effectiveness, when controlling quality of opposition and game periods. The sample was composed by 1500 ball possessions, corresponding to 14 games randomly selected from the International Championships played during 2008 and 2010 (World Championship, Four nations tournament and classificatory phases for World Championship) by teams from different competition levels (HIGH, INTERMEDIATE and LOW). The effects of the predictor variables on successful ball possessions according to the three game contexts (HIGH vs. HIGH; HIGH vs. LOW; LOW vs. LOW games) were analyzed using Binomial Logistic Regressions. The results showed no interaction with the game period. In HIGH vs. HIGH games, quality of opposition showed an association with ball possession effectiveness with ending zone, offensive system, possession duration, height of shooting and defensive pressures previous to the shot. In HIGH vs. LOW games the important factors were the starting zone, possession duration, defensive pressure previous to the last pass and to the shot, technique of shooting and the number players involved in each ball possession. Finally, in LOW vs. LOW games, the results emphasized the importance of starting and ending zones, the number of passes used and the technique of shooting. In conclusion, elite floorball performance is mainly affected by quality of opposition showing different game patterns in each context that should be considered by coaches when preparing practices and competitions.

Słowa kluczowe

  • notational analysis
  • situational variables
  • team sports
  • performance analysis

Zaplanuj zdalną konferencję ze Sciendo