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Aquatic Sports and Activities

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Presentation of the 1st International Symposium on Strength & Conditioning (ISSC 2011)

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Journal Details
Format
Journal
eISSN
1899-7562
ISSN
1640-5544
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

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

Journal Details
Format
Journal
eISSN
1899-7562
ISSN
1640-5544
First Published
13 Jan 2009
Publication timeframe
5 times per year
Languages
English

Search

16 Articles
Open Access

Movements that are both variable and optimal

Published Online: 23 Oct 2012
Page range: 5 - 13

Abstract

Abstract

This brief review addresses two major aspects of the neural control of multi-element systems. First, theprinciple of abundance suggests that the central nervous system unites elements into synergies (co-variation ofelemental variables across trials quantified within the framework of the uncontrolled manifold hypothesis) that stabilizeimportant performance variables. Second, a novel method, analytical inverse optimization, has been introduced tocompute cost functions that define averaged across trials involvement of individual elements over a range of values oftask-specific performance variables. The two aspects reflect two features of motor coordination: (1) using variablesolutions that allow performing secondary tasks and stabilizing performance variables; and (2) selecting combinationsof elemental variables that follow an optimization principle. We suggest that the conflict between the two approaches (asingle solution vs. families of solutions) is apparent, not real. Natural motor variability may be due to using the samecost function across slightly different initial states; on the other hand, there may be variability in the cost function itselfleading to variable solutions that are all optimal with respect to slightly different cost functions. The analysis of motorsynergies has revealed specific changes associated with atypical development, healthy aging, neurological disorders, andpractice. These have allowed formulating hypotheses on the neurophysiological mechanisms involved in the synergiccontrol of actions.

Keywords:

  • motor control
  • abundance
  • variability
  • optimization
  • synergy
Open Access

A biomechanical model correlating shoulder kinetics to pain in young baseball pitchers

Published Online: 23 Oct 2012
Page range: 15 - 20

Abstract

Abstract

Previous work has postulated that shoulder pain may be associated with increases in both peak shoulderanterior force and peak shoulder proximal force. Unfortunately these relationships have yet to be quantified. Thus, thepurpose of this study was to associate these kinetic values with reported shoulder pain in youth baseball pitchers.Nineteen healthy baseball pitchers participated in this study. Segment based reference systems and establishedcalculations were utilized to identify peak shoulder anterior force and peak shoulder proximal force. A medical historyquestionnaire was utilized to identify shoulder pain. Following collection of these data, the strength of the relationshipsbetween both peak shoulder anterior force and peak shoulder proximal force and shoulder pain were analyzed. Althoughpeak anterior force was not significantly correlated to shoulder pain, peak proximal force was. These results lead to thedevelopment of a single variable logistic regression model able to accurately predict 84.2% of all cases and 71.4% ofshoulder pain cases. This model indicated that for every 1 N increase in peak proximal force, there was a corresponding4.6% increase in the likelihood of shoulder pain. The magnitude of peak proximal force is both correlated to reportedshoulder pain and capable of being used to accurately predict the likelihood of experiencing shoulder pain. It appearsthat those pitchers exhibiting high magnitudes of peak proximal force are significantly more likely to reportexperiencing shoulder pain than those who generate lower magnitudes of peak proximal force.

Keywords:

  • baseball,
  • kinetics
  • youth
  • injury
Open Access

Biomechanical evaluation of exercises for performing a forward handspring - Case study

Published Online: 23 Oct 2012
Page range: 21 - 32

Abstract

Abstract

The aim of this study was based on the kinematic parameters, extracted at different stages of performing aforward handspring to determine the interconnection of methodological procedures of learning with the final structureof the movement. The respondent is an active competitor with years of experience, elite athlete, many times Croatianchampion, and competitor at European, World Championships and the Olympics. The team composed of six gymnasticexperts, chose one of the best performances by twelve methodological procedures and the best performance (of six) twolegforward handsprings basing their choice on a detailed review of recorded material. Assessment of quality ofperformance was done according to the defined rules prescribed by the regulations (Code of Points). The forwardhandspring technique consists of four phases based on which 45 space and time kinematic parameters were selected (30parameters in the phase of hand contact and push-off, 7 in the flight phase, and 8 parameters in the landing phase). Byextraction of space and time parameters, there was a differentiation of certain methodological procedures that are thebest for learning forward handspring in each phase of its performance. This research indicates that these methodologicalprocedures mostly coincide in space kinematic parameters by which the technique of a forward handspring is described.

Keywords

  • gymnastics
  • methodology
  • basic exercises
  • biomechanical analysis
Open Access

An acute bout of quadriceps muscle stretching has no influence on knee joint proprioception

Published Online: 23 Oct 2012
Page range: 33 - 39

Abstract

Abstract

The main objective of this study was to determine if an acute bout of static stretching of the quadriceps muscleaffects the sense of joint position, the threshold to detect passive movement, and the sense of force. Thirty young, healthymen (age : 22.1 ± 2.7 years) were randomly divided into two groups. The Stretching Group (n=15) underwentstretching of the dominant quadriceps muscle, which comprised ten passive stretches lasting 30 seconds each, while theControl Group (n=15) remained seated for the same length of time. A repeated-measures analysis of variance was usedto establish intragroup differences over time, and an independent sample t-test was used to compare the dependentvariables between groups at each moment. None of the measurements revealed any significant change between bothgroups in each assessment moment or between moments within groups (p>0.05). This study demonstrated that staticquadriceps muscle stretching has no effect on the sense of knee joint position, threshold to detect passive movement, andforce sense, suggesting that stretching does not have appreciable effect on the spindle firing characteristics and tendonorgans activation.

Keywords:

  • Intrafusal muscle fibres
  • extrafusal muscle fibres
  • sense of joint position
  • kinaesthesia
  • force sense.
Open Access

Biomechanical analysis of anticipation of elite and inexperienced goalkeepers to distance shots in handball

Published Online: 23 Oct 2012
Page range: 41 - 48

Abstract

Abstract

The objective of this study was to evaluate the anticipation time and kinematic factors in the movement ofgoalkeepers’ center of mass when making a long-distance throw in handball. The sample group was composed of 14goalkeepers and field players. A force platform was used to measure the force of the goalkeepers’ reaction movements, whilethe throwers’ movements were recorded with high-speed cameras. The expert goalkeepers began to move 193 ± 67 ms beforethe ball was released, with a 67% success rate of interception. The inexperienced goalkeepers began their movement 209 ±127 ms with a 24% success rate. The time taken by expert goalkeepers to begin a vertical movement of their CM, relative tothe moment of the ball’s release, was less than the time taken by inexperienced goalkeepers (77 ± 70 vs. 141 ± 108 msrespectively). The analysis of the velocity and movement indicates that expert goalkeepers wait longer before moving than doinexperienced goalkeepers.

Keywords:

  • biomechanics
  • anticipation
  • handball
  • goalkeeper
  • throw
Open Access

Plantar-flexor static stretch training effect on eccentric and concentric peak torque – a comparative study of trained versus untrained subjects

Published Online: 23 Oct 2012
Page range: 49 - 58

Abstract

Abstract

The aim of this study was to examine the long-term effects of static stretching of the plantar-flexor muscles oneccentric and concentric torque and ankle dorsiflexion range of motion in healthy subjects. Seventy five healthy malevolunteers, with no previous history of trauma to the calf that required surgery, absence of knee flexion contracture andno history of neurologic dysfunction or disease, systemic disease affecting the lower extremities were selected for thisstudy. The participants were divided into three equal groups. The control group did not stretch the plantar-flexormuscles. Two Experimental groups (trained and untrained) were instructed to perform static stretching exercise of 30second duration and 5 repetitions twice daily. The stretching sessions were carried out 5 days a week for 6 weeks. Thedorsiflexion range of motion was measured in all subjects. Also measured was the eccentric and concentric torque ofplantar-flexors at angular velocities of 30 and 120o/s pre and post stretching. Analysis of variance showed a significantincrease in plantar-flexor eccentric and concentric torque (p < 0.05) of trained and untrained groups, and an increase indorsiflexion range of motion (p < 0.05) at both angular velocities for the untrained group only. The static stretchingprogram of plantar-flexors was effective in increasing the concentric and eccentric plantarflexion torque at angularvelocities of 30 and 120o/s. Increases in plantar-flexors flexibility were observed in untrained subjects.

Keywords:

  • calf muscle
  • isokinetic torque
  • static stretching
Open Access

A comparison of mechanical parameters between the counter movement jump and drop jump in Biathletes

Published Online: 23 Oct 2012
Page range: 59 - 68

Abstract

Abstract

The main objective of the study was to determine to what degree higher muscular activity, achieved by increasedload in the extension phase (eccentric muscle action) of the vertical jump, affects the efficiency of the vertical jump.Sixteen elite biathletes participated in this investigation. The biathletes performed tests that consisted of five, single“maximal” vertical jumps (counter movement jump - CMJ) and five, single vertical jumps, in which the task was totouch a bar placed over the jumping biathletes (specific task counter movement jump - SCMJ). Then, they performedfive, single drop jumps from an elevation of 0.4m (DJ). Ground reaction forces were registered using the KISTLER9182C force platform. MVJ software was used for signal processing (Król, 1999) and enabling calculations forkinematic and kinetic parameters of the subject’s jump movements (on-line system). The results indicate that onlyheight of the jump (h) and mean power (Pmean) during the takeoff are statistically significant. Both h and Pmean arehigher in the DJ. The results of this study may indicate that elite biathletes are well adapted to eccentric work of thelower limbs, thus reaching greater values of power during the drop jump. These neuromuscular adaptive changes mayallow for a more dynamic and efficient running technique.

Keywords

  • biathletes
  • muscular activity
  • drop jump
  • vertical jump
Open Access

The effect of glycerol supplements on aerobic and anaerobic performance of athletes and sedentary subjects

Published Online: 23 Oct 2012
Page range: 69 - 79

Abstract

Abstract

The purpose of this study was to evaluate the effect of glycerol supplementation on aerobic and anaerobicexercise performance in sedentary subjects and athletes. The glycerol supplement treatments were as follows: 40volunteers were selected and divided into two groups, sedentary and exercise groups. These two groups were furthersubdivided into two groups. The first group, the placebo (S), only consumed water; the second group (GS) consumedglycerol followed by water. Neither of these groups did any exercise for 20 days. The third and fourth groups consistedof the exercise group subjects; they were required to perform a 20-m shuttle run test every day for 20 days. The thirdgroup’s subjects, the placebo (E), only consumed water. The last group (GE) consumed glycerol followed by water. TheAstrand Cycle Ergometer Test (ACET) was performed, and the Cosmed K4b2 portable gas analysis system was used todetermine the aerobic capacity, while the Wingate Anaerobic Power Test (WAPT) was performed to determine the levelof anaerobic power. The 20 Meter Shuttle Run Test (20MSRT) was performed after glycerol supplementationthroughout the 20 days, and the exercise periods and distances were recorded.The glycerol supplement was found to have an increasing effect on aerobic and anaerobic performance in GS, Eand GE. A similar effect was found for the covered distances and time in the same groups. However, an adverse effectwas found on body weight.

Keywords:

  • Glycerol
  • aerobic capacity
  • anaerobic power
  • athletes
  • sedentary subjects
Open Access

Anaerobic and aerobic performance of elite female and male snowboarders

Published Online: 23 Oct 2012
Page range: 81 - 88

Abstract

Abstract

The physiological adaptation to training is specific to the muscle activity, dominant energy system involved,muscle groups trained, as well as intensity and volume of training. Despite increasing popularity of snowboarding onlylittle scientific data is available on the physiological characteristics of female and male competitive snowboarders.Therefore, the purpose of this study was to compare the aerobic capacity and maximal anaerobic power of elite Polishsnowboarders with untrained subjects. Ten snowboarders and ten aged matched students of Physical Educationperformed two exercise tests. First, a 30-second Wingate test was conducted and next, a cycle ergometer exercise testwith graded intensity. In the first test, peak anaerobic power, the total work, relative peak power and relative meanpower were measured. During the second test, relative maximal oxygen uptake and lactate threshold were evaluated.There were no significant differences in absolute and relative maximal oxygen uptake between snowboarders and thecontrol group. Mean maximal oxygen uptake and lactate threshold were significantly higher in men than in women.Significant differences were found between trained men and women regarding maximal power and relative maximalpower. The elite snowboarders demonstrated a high level of anaerobic power. The level of relative peak power in trainedwomen correlated negatively with maximal oxygen uptake. In conclusion, our results seem to indicate that thedemanding competition program of elite snowboarders provides a significant training stimulus mainly for anaerobicpower with minor changes in anaerobic performance.

Keywords:

  • maximal oxygen uptake
  • anaerobic power
  • exercise training
  • snowboarding
Open Access

Sprint performance changes and determinants in Afro-Caribbean adolescents between 13 and 15 years old

Published Online: 23 Oct 2012
Page range: 89 - 98

Abstract

Abstract

Afro-Caribbean sprinters often reach high performance levels at an early age. Adolescence is a time ofmorphological and physiological changes. This study was designed to analyze the evolution in parameters of shortsprint performance during adolescence in Afro-Caribbean boys, especially the stride number/body height ratio (SN/BH),which is at the interface of technical and morphological factors. Seventy-one 13-year-old boys performed vertical jumpsand short sprint races. The races were filmed with a view to determine stride variables. Anthropometric parameterswere also measured. The same tests were performed two years later. Body height and SN/BH were the main predictorsof sprint performance. The delta of performance was principally explained by stride length and stride number. Althoughdeterioration in technical parameters was expected, the parameters related to body size and stride length were the mainsprint performance predictors rather than explosive force. These results could be useful in developing tests to detectsprint potential in youth.

Keywords

  • puberty
  • stride characteristics
  • sprinting
  • Afro-Caribbean youth
Open Access

Match duration and number of rallies in men´s and women´s 2000-2010 FIVB world tour beach volleyball

Published Online: 23 Oct 2012
Page range: 99 - 104

Abstract

Abstract

After the 2000 Olympic Games, the Fédération Internationale de Volleyball (FIVB) modified the scoringsystem used in beach volleyball from side-out to a rally point system. The goal was to facilitate the comprehension of thegame and to stabilize match duration. The purpose of this study was to assess the duration and number of rallies inmen´s and women´s beach volleyball matches (2000-2010 FIVB World Tour). Data from 14,432 men´s matches and14,175 women´s matches of the 2000-2010 World Tour were collected. The variables studied were: match duration,total rallies per set and match, number of sets, team that won the set and match, type of match (equality in score), andgender. The average match duration in beach volleyball is stable, ranging from 30 to 64 minutes, regardless of thenumber of sets, the stage of the tournament (qualifying round or main draw), or gender. The average number of ralliesper match were 78-80 for two-set matches and 94-96 for three-set matches. Matches from the main draw are morebalanced than matches from the qualifying round. More balanced matches (smaller point difference between teams) havelonger durations. It is not clear why there is no relationship between the number of rallies and match duration. Futurestudies are needed to clarify this aspect. The results can serve as a reference to guide beach volleyball training (withregard to duration and number of rallies) and to help understand the effect of the rule change.

Keywords

  • sport
  • training
  • evolution
  • rules
  • beach volleyball
Open Access

Acute effects of dropsets among different resistance training methods in upper body performance

Published Online: 23 Oct 2012
Page range: 105 - 111

Abstract

Abstract

The aim of this study was to compare the influence of including dropset exercises in different orders, both inthe pre-exhaustion, as in the post-exhaustion method, and to analyze the performance of total work on the bench pressand chest flying exercise. Twenty-two male volunteers with a recreational experience in ST were evaluated in six visitsin non-consecutive days, at approximately the same time of the day. During the first visit, subjects signed an informedconsent form and underwent an anthropometric evaluation and testing of 10RM. The second visit involved a re-test of10RM. From third to sixth visits, the subjects were randomly grouped into the following experimental situations: 3rdVisit (V3 - Post-exhaustion): Bench Press (dropset) + Chest Flying (10RM); 4th visit (V4 - Post-exhaustion): BenchPress (10RM) + Chest Flying (dropset); 5th Visit (V5 - pre-exhaustion): Chest Flying (dropset) + Bench Press (10RM);6th Visit (V6 - pre-exhaustion): Chest Flying (10RM) + Bench Press (dropset). The protocol of dropset was performedwith 3 sets and no rest intervals 10RM + 80% 10RM + 60% 10RM. An interval between sets was adopted for 2minutes. The primary results showed a significant difference in Total Work for visits V3 and V6, which was included inthe dropset multiarticular exercises. These results suggest that the exercise order with the dropset method in the preexhaustionor post-exhaustion methods had an acute influence on Total Work.

Keywords:

  • Performance
  • resistance exercise
  • number of repetitions
  • training method.
Open Access

The influence of different hand paddle size on 100-m front crawl kinematics

Published Online: 23 Oct 2012
Page range: 112 - 118

Abstract

Abstract

The purpose of this study was to determine the influence of different sizes of hand paddles on kinematicparameters during a 100 m freestyle swimming performance in elite swimmers. Nine elite swimmers (19.1 ± 1.9 years)completed three tests of 100 m without paddles, with small paddles (271.27 cm2) and with large paddles (332.67 cm2),respectively. One video camera was used to record the performance during the three trials. The mean swimmingvelocity, stroke rate and stroke length were measured in the central 10 meters of each 50 m length. The results showedthat stroke length tended to increase significantly when wearing hand paddles (p < 0.05) during both the first andsecond 50 m sections whereas the increase in swimming velocity occurred only in the second 50 m (p < 0.05).Conversely, the stroke rate showed a slight decreasing trend with increasing paddle size. During the 100 m freestyletrial the stroke kinematics were changed significantly as a result of the increase in propelling surface size when handpaddles were worn.

Keywords:

  • Hand paddles
  • kinematic parameters
  • swimming performance
Open Access

Relationship between group cohesion and anxiety in soccer

Published Online: 23 Oct 2012
Page range: 119 - 127

Abstract

Abstract

Group cohesion in sport is a widely spread theme today. Research has found cohesion to be influenced byseveral individual and group components. Among the cognitive variables that relate to cohesion we found competitiveanxiety. The purpose of this study was to examine the relation between task cohesion (ATG-T, and GI-T) andcompetitive state anxiety (A-state), and also if there would be a relation between cohesion and self-confidence.Participants were 366 football players of both genders male and female, aged between 15 to 23 years old, fromPortugal’s championships. Cohesion was measured using the Portuguese version of the Group EnvironmentQuestionnaire, and to assess competitive anxiety, we used the Portuguese version of the Competition State AnxietyInventory 2. Our results show that female athletes report experiencing more cognitive anxiety and less self-confidencethan male athletes. Only cognitive anxiety relates in a significantly negative way with the perception of cohesion (GI-Te ATG-T) in the total number of participants and in male athletes. Relatively to the somatic anxiety, it only relatesnegatively with the perception of the integration of the group in the total number of participants and in the malegender.

Keywords:

  • Group Dynamics
  • cohesion
  • anxiety
  • soccer
Open Access

Evolution of perceived cohesion and efficacy over the season and their relation to success expectations in soccer teams

Published Online: 23 Oct 2012
Page range: 129 - 138

Abstract

Abstract

The main goal of the study is to examine the evolution of players' perception of cohesion and efficacy over theseason and their relation with success expectations. The research sample comprised 146 male soccer players, agedbetween 15 and 19 years (M = 16.96, SD = .76). Diverse instruments were used to measure cohesion, perceived efficacy,and success expectations. The most noteworthy results show that players whose expectations do not match the team'sfinal performance will experience a negative evolution of their levels of perceived cohesion and efficacy, whereas playerswhose expectations at the start of the season match the team's final performance in the classification will maintain theirdegree of perceived cohesion and efficacy. The main conclusion of the study is that coaches and sport psychologistsshould attempt to clarify the players' basic goals of the season to create expectations that match what is expected fromthe team.

Keywords

  • cohesion
  • efficacy
  • success expectations
  • performance
  • soccer
Open Access

Leadership power perceptions of soccer coaches and soccer players according to their education

Published Online: 23 Oct 2012
Page range: 139 - 146

Abstract

Abstract

The purpose of this study was to analyze the leadership power perceptions of soccer coaches and soccer playersaccording to their educational levels. Data were collected from 165 male soccer coaches and 870 male soccer players.Adapted versions of the “Power in Soccer Questionnaire-Other”, the “Power in Soccer Questionnaire-Self” and an“information form” were used for data collection, and collected data were analyzed by the Kruskal-Wallis and theMann-Whitney Tests. Analysis of the Power in Soccer Questionnaire-Other revealed significant differences betweensoccer players’ level of education and their perception of Coercive Power (p<.003), and no significant differences relatedto Referent Power, Legitimate Power and Expert Power. Analysis of the Power in Soccer Questionnaire-Self alsorevealed the only significant difference between coaches’ level of education and their perception of Legitimate Power(p<.001), and no significant differences with regard to others. Different perception of leadership powers between coachesand players might create communication and performance problems in soccer.

Keywords

  • perception of leadership power
  • soccer coaches
  • soccer players
  • education.
16 Articles
Open Access

Movements that are both variable and optimal

Published Online: 23 Oct 2012
Page range: 5 - 13

Abstract

Abstract

This brief review addresses two major aspects of the neural control of multi-element systems. First, theprinciple of abundance suggests that the central nervous system unites elements into synergies (co-variation ofelemental variables across trials quantified within the framework of the uncontrolled manifold hypothesis) that stabilizeimportant performance variables. Second, a novel method, analytical inverse optimization, has been introduced tocompute cost functions that define averaged across trials involvement of individual elements over a range of values oftask-specific performance variables. The two aspects reflect two features of motor coordination: (1) using variablesolutions that allow performing secondary tasks and stabilizing performance variables; and (2) selecting combinationsof elemental variables that follow an optimization principle. We suggest that the conflict between the two approaches (asingle solution vs. families of solutions) is apparent, not real. Natural motor variability may be due to using the samecost function across slightly different initial states; on the other hand, there may be variability in the cost function itselfleading to variable solutions that are all optimal with respect to slightly different cost functions. The analysis of motorsynergies has revealed specific changes associated with atypical development, healthy aging, neurological disorders, andpractice. These have allowed formulating hypotheses on the neurophysiological mechanisms involved in the synergiccontrol of actions.

Keywords:

  • motor control
  • abundance
  • variability
  • optimization
  • synergy
Open Access

A biomechanical model correlating shoulder kinetics to pain in young baseball pitchers

Published Online: 23 Oct 2012
Page range: 15 - 20

Abstract

Abstract

Previous work has postulated that shoulder pain may be associated with increases in both peak shoulderanterior force and peak shoulder proximal force. Unfortunately these relationships have yet to be quantified. Thus, thepurpose of this study was to associate these kinetic values with reported shoulder pain in youth baseball pitchers.Nineteen healthy baseball pitchers participated in this study. Segment based reference systems and establishedcalculations were utilized to identify peak shoulder anterior force and peak shoulder proximal force. A medical historyquestionnaire was utilized to identify shoulder pain. Following collection of these data, the strength of the relationshipsbetween both peak shoulder anterior force and peak shoulder proximal force and shoulder pain were analyzed. Althoughpeak anterior force was not significantly correlated to shoulder pain, peak proximal force was. These results lead to thedevelopment of a single variable logistic regression model able to accurately predict 84.2% of all cases and 71.4% ofshoulder pain cases. This model indicated that for every 1 N increase in peak proximal force, there was a corresponding4.6% increase in the likelihood of shoulder pain. The magnitude of peak proximal force is both correlated to reportedshoulder pain and capable of being used to accurately predict the likelihood of experiencing shoulder pain. It appearsthat those pitchers exhibiting high magnitudes of peak proximal force are significantly more likely to reportexperiencing shoulder pain than those who generate lower magnitudes of peak proximal force.

Keywords:

  • baseball,
  • kinetics
  • youth
  • injury
Open Access

Biomechanical evaluation of exercises for performing a forward handspring - Case study

Published Online: 23 Oct 2012
Page range: 21 - 32

Abstract

Abstract

The aim of this study was based on the kinematic parameters, extracted at different stages of performing aforward handspring to determine the interconnection of methodological procedures of learning with the final structureof the movement. The respondent is an active competitor with years of experience, elite athlete, many times Croatianchampion, and competitor at European, World Championships and the Olympics. The team composed of six gymnasticexperts, chose one of the best performances by twelve methodological procedures and the best performance (of six) twolegforward handsprings basing their choice on a detailed review of recorded material. Assessment of quality ofperformance was done according to the defined rules prescribed by the regulations (Code of Points). The forwardhandspring technique consists of four phases based on which 45 space and time kinematic parameters were selected (30parameters in the phase of hand contact and push-off, 7 in the flight phase, and 8 parameters in the landing phase). Byextraction of space and time parameters, there was a differentiation of certain methodological procedures that are thebest for learning forward handspring in each phase of its performance. This research indicates that these methodologicalprocedures mostly coincide in space kinematic parameters by which the technique of a forward handspring is described.

Keywords

  • gymnastics
  • methodology
  • basic exercises
  • biomechanical analysis
Open Access

An acute bout of quadriceps muscle stretching has no influence on knee joint proprioception

Published Online: 23 Oct 2012
Page range: 33 - 39

Abstract

Abstract

The main objective of this study was to determine if an acute bout of static stretching of the quadriceps muscleaffects the sense of joint position, the threshold to detect passive movement, and the sense of force. Thirty young, healthymen (age : 22.1 ± 2.7 years) were randomly divided into two groups. The Stretching Group (n=15) underwentstretching of the dominant quadriceps muscle, which comprised ten passive stretches lasting 30 seconds each, while theControl Group (n=15) remained seated for the same length of time. A repeated-measures analysis of variance was usedto establish intragroup differences over time, and an independent sample t-test was used to compare the dependentvariables between groups at each moment. None of the measurements revealed any significant change between bothgroups in each assessment moment or between moments within groups (p>0.05). This study demonstrated that staticquadriceps muscle stretching has no effect on the sense of knee joint position, threshold to detect passive movement, andforce sense, suggesting that stretching does not have appreciable effect on the spindle firing characteristics and tendonorgans activation.

Keywords:

  • Intrafusal muscle fibres
  • extrafusal muscle fibres
  • sense of joint position
  • kinaesthesia
  • force sense.
Open Access

Biomechanical analysis of anticipation of elite and inexperienced goalkeepers to distance shots in handball

Published Online: 23 Oct 2012
Page range: 41 - 48

Abstract

Abstract

The objective of this study was to evaluate the anticipation time and kinematic factors in the movement ofgoalkeepers’ center of mass when making a long-distance throw in handball. The sample group was composed of 14goalkeepers and field players. A force platform was used to measure the force of the goalkeepers’ reaction movements, whilethe throwers’ movements were recorded with high-speed cameras. The expert goalkeepers began to move 193 ± 67 ms beforethe ball was released, with a 67% success rate of interception. The inexperienced goalkeepers began their movement 209 ±127 ms with a 24% success rate. The time taken by expert goalkeepers to begin a vertical movement of their CM, relative tothe moment of the ball’s release, was less than the time taken by inexperienced goalkeepers (77 ± 70 vs. 141 ± 108 msrespectively). The analysis of the velocity and movement indicates that expert goalkeepers wait longer before moving than doinexperienced goalkeepers.

Keywords:

  • biomechanics
  • anticipation
  • handball
  • goalkeeper
  • throw
Open Access

Plantar-flexor static stretch training effect on eccentric and concentric peak torque – a comparative study of trained versus untrained subjects

Published Online: 23 Oct 2012
Page range: 49 - 58

Abstract

Abstract

The aim of this study was to examine the long-term effects of static stretching of the plantar-flexor muscles oneccentric and concentric torque and ankle dorsiflexion range of motion in healthy subjects. Seventy five healthy malevolunteers, with no previous history of trauma to the calf that required surgery, absence of knee flexion contracture andno history of neurologic dysfunction or disease, systemic disease affecting the lower extremities were selected for thisstudy. The participants were divided into three equal groups. The control group did not stretch the plantar-flexormuscles. Two Experimental groups (trained and untrained) were instructed to perform static stretching exercise of 30second duration and 5 repetitions twice daily. The stretching sessions were carried out 5 days a week for 6 weeks. Thedorsiflexion range of motion was measured in all subjects. Also measured was the eccentric and concentric torque ofplantar-flexors at angular velocities of 30 and 120o/s pre and post stretching. Analysis of variance showed a significantincrease in plantar-flexor eccentric and concentric torque (p < 0.05) of trained and untrained groups, and an increase indorsiflexion range of motion (p < 0.05) at both angular velocities for the untrained group only. The static stretchingprogram of plantar-flexors was effective in increasing the concentric and eccentric plantarflexion torque at angularvelocities of 30 and 120o/s. Increases in plantar-flexors flexibility were observed in untrained subjects.

Keywords:

  • calf muscle
  • isokinetic torque
  • static stretching
Open Access

A comparison of mechanical parameters between the counter movement jump and drop jump in Biathletes

Published Online: 23 Oct 2012
Page range: 59 - 68

Abstract

Abstract

The main objective of the study was to determine to what degree higher muscular activity, achieved by increasedload in the extension phase (eccentric muscle action) of the vertical jump, affects the efficiency of the vertical jump.Sixteen elite biathletes participated in this investigation. The biathletes performed tests that consisted of five, single“maximal” vertical jumps (counter movement jump - CMJ) and five, single vertical jumps, in which the task was totouch a bar placed over the jumping biathletes (specific task counter movement jump - SCMJ). Then, they performedfive, single drop jumps from an elevation of 0.4m (DJ). Ground reaction forces were registered using the KISTLER9182C force platform. MVJ software was used for signal processing (Król, 1999) and enabling calculations forkinematic and kinetic parameters of the subject’s jump movements (on-line system). The results indicate that onlyheight of the jump (h) and mean power (Pmean) during the takeoff are statistically significant. Both h and Pmean arehigher in the DJ. The results of this study may indicate that elite biathletes are well adapted to eccentric work of thelower limbs, thus reaching greater values of power during the drop jump. These neuromuscular adaptive changes mayallow for a more dynamic and efficient running technique.

Keywords

  • biathletes
  • muscular activity
  • drop jump
  • vertical jump
Open Access

The effect of glycerol supplements on aerobic and anaerobic performance of athletes and sedentary subjects

Published Online: 23 Oct 2012
Page range: 69 - 79

Abstract

Abstract

The purpose of this study was to evaluate the effect of glycerol supplementation on aerobic and anaerobicexercise performance in sedentary subjects and athletes. The glycerol supplement treatments were as follows: 40volunteers were selected and divided into two groups, sedentary and exercise groups. These two groups were furthersubdivided into two groups. The first group, the placebo (S), only consumed water; the second group (GS) consumedglycerol followed by water. Neither of these groups did any exercise for 20 days. The third and fourth groups consistedof the exercise group subjects; they were required to perform a 20-m shuttle run test every day for 20 days. The thirdgroup’s subjects, the placebo (E), only consumed water. The last group (GE) consumed glycerol followed by water. TheAstrand Cycle Ergometer Test (ACET) was performed, and the Cosmed K4b2 portable gas analysis system was used todetermine the aerobic capacity, while the Wingate Anaerobic Power Test (WAPT) was performed to determine the levelof anaerobic power. The 20 Meter Shuttle Run Test (20MSRT) was performed after glycerol supplementationthroughout the 20 days, and the exercise periods and distances were recorded.The glycerol supplement was found to have an increasing effect on aerobic and anaerobic performance in GS, Eand GE. A similar effect was found for the covered distances and time in the same groups. However, an adverse effectwas found on body weight.

Keywords:

  • Glycerol
  • aerobic capacity
  • anaerobic power
  • athletes
  • sedentary subjects
Open Access

Anaerobic and aerobic performance of elite female and male snowboarders

Published Online: 23 Oct 2012
Page range: 81 - 88

Abstract

Abstract

The physiological adaptation to training is specific to the muscle activity, dominant energy system involved,muscle groups trained, as well as intensity and volume of training. Despite increasing popularity of snowboarding onlylittle scientific data is available on the physiological characteristics of female and male competitive snowboarders.Therefore, the purpose of this study was to compare the aerobic capacity and maximal anaerobic power of elite Polishsnowboarders with untrained subjects. Ten snowboarders and ten aged matched students of Physical Educationperformed two exercise tests. First, a 30-second Wingate test was conducted and next, a cycle ergometer exercise testwith graded intensity. In the first test, peak anaerobic power, the total work, relative peak power and relative meanpower were measured. During the second test, relative maximal oxygen uptake and lactate threshold were evaluated.There were no significant differences in absolute and relative maximal oxygen uptake between snowboarders and thecontrol group. Mean maximal oxygen uptake and lactate threshold were significantly higher in men than in women.Significant differences were found between trained men and women regarding maximal power and relative maximalpower. The elite snowboarders demonstrated a high level of anaerobic power. The level of relative peak power in trainedwomen correlated negatively with maximal oxygen uptake. In conclusion, our results seem to indicate that thedemanding competition program of elite snowboarders provides a significant training stimulus mainly for anaerobicpower with minor changes in anaerobic performance.

Keywords:

  • maximal oxygen uptake
  • anaerobic power
  • exercise training
  • snowboarding
Open Access

Sprint performance changes and determinants in Afro-Caribbean adolescents between 13 and 15 years old

Published Online: 23 Oct 2012
Page range: 89 - 98

Abstract

Abstract

Afro-Caribbean sprinters often reach high performance levels at an early age. Adolescence is a time ofmorphological and physiological changes. This study was designed to analyze the evolution in parameters of shortsprint performance during adolescence in Afro-Caribbean boys, especially the stride number/body height ratio (SN/BH),which is at the interface of technical and morphological factors. Seventy-one 13-year-old boys performed vertical jumpsand short sprint races. The races were filmed with a view to determine stride variables. Anthropometric parameterswere also measured. The same tests were performed two years later. Body height and SN/BH were the main predictorsof sprint performance. The delta of performance was principally explained by stride length and stride number. Althoughdeterioration in technical parameters was expected, the parameters related to body size and stride length were the mainsprint performance predictors rather than explosive force. These results could be useful in developing tests to detectsprint potential in youth.

Keywords

  • puberty
  • stride characteristics
  • sprinting
  • Afro-Caribbean youth
Open Access

Match duration and number of rallies in men´s and women´s 2000-2010 FIVB world tour beach volleyball

Published Online: 23 Oct 2012
Page range: 99 - 104

Abstract

Abstract

After the 2000 Olympic Games, the Fédération Internationale de Volleyball (FIVB) modified the scoringsystem used in beach volleyball from side-out to a rally point system. The goal was to facilitate the comprehension of thegame and to stabilize match duration. The purpose of this study was to assess the duration and number of rallies inmen´s and women´s beach volleyball matches (2000-2010 FIVB World Tour). Data from 14,432 men´s matches and14,175 women´s matches of the 2000-2010 World Tour were collected. The variables studied were: match duration,total rallies per set and match, number of sets, team that won the set and match, type of match (equality in score), andgender. The average match duration in beach volleyball is stable, ranging from 30 to 64 minutes, regardless of thenumber of sets, the stage of the tournament (qualifying round or main draw), or gender. The average number of ralliesper match were 78-80 for two-set matches and 94-96 for three-set matches. Matches from the main draw are morebalanced than matches from the qualifying round. More balanced matches (smaller point difference between teams) havelonger durations. It is not clear why there is no relationship between the number of rallies and match duration. Futurestudies are needed to clarify this aspect. The results can serve as a reference to guide beach volleyball training (withregard to duration and number of rallies) and to help understand the effect of the rule change.

Keywords

  • sport
  • training
  • evolution
  • rules
  • beach volleyball
Open Access

Acute effects of dropsets among different resistance training methods in upper body performance

Published Online: 23 Oct 2012
Page range: 105 - 111

Abstract

Abstract

The aim of this study was to compare the influence of including dropset exercises in different orders, both inthe pre-exhaustion, as in the post-exhaustion method, and to analyze the performance of total work on the bench pressand chest flying exercise. Twenty-two male volunteers with a recreational experience in ST were evaluated in six visitsin non-consecutive days, at approximately the same time of the day. During the first visit, subjects signed an informedconsent form and underwent an anthropometric evaluation and testing of 10RM. The second visit involved a re-test of10RM. From third to sixth visits, the subjects were randomly grouped into the following experimental situations: 3rdVisit (V3 - Post-exhaustion): Bench Press (dropset) + Chest Flying (10RM); 4th visit (V4 - Post-exhaustion): BenchPress (10RM) + Chest Flying (dropset); 5th Visit (V5 - pre-exhaustion): Chest Flying (dropset) + Bench Press (10RM);6th Visit (V6 - pre-exhaustion): Chest Flying (10RM) + Bench Press (dropset). The protocol of dropset was performedwith 3 sets and no rest intervals 10RM + 80% 10RM + 60% 10RM. An interval between sets was adopted for 2minutes. The primary results showed a significant difference in Total Work for visits V3 and V6, which was included inthe dropset multiarticular exercises. These results suggest that the exercise order with the dropset method in the preexhaustionor post-exhaustion methods had an acute influence on Total Work.

Keywords:

  • Performance
  • resistance exercise
  • number of repetitions
  • training method.
Open Access

The influence of different hand paddle size on 100-m front crawl kinematics

Published Online: 23 Oct 2012
Page range: 112 - 118

Abstract

Abstract

The purpose of this study was to determine the influence of different sizes of hand paddles on kinematicparameters during a 100 m freestyle swimming performance in elite swimmers. Nine elite swimmers (19.1 ± 1.9 years)completed three tests of 100 m without paddles, with small paddles (271.27 cm2) and with large paddles (332.67 cm2),respectively. One video camera was used to record the performance during the three trials. The mean swimmingvelocity, stroke rate and stroke length were measured in the central 10 meters of each 50 m length. The results showedthat stroke length tended to increase significantly when wearing hand paddles (p < 0.05) during both the first andsecond 50 m sections whereas the increase in swimming velocity occurred only in the second 50 m (p < 0.05).Conversely, the stroke rate showed a slight decreasing trend with increasing paddle size. During the 100 m freestyletrial the stroke kinematics were changed significantly as a result of the increase in propelling surface size when handpaddles were worn.

Keywords:

  • Hand paddles
  • kinematic parameters
  • swimming performance
Open Access

Relationship between group cohesion and anxiety in soccer

Published Online: 23 Oct 2012
Page range: 119 - 127

Abstract

Abstract

Group cohesion in sport is a widely spread theme today. Research has found cohesion to be influenced byseveral individual and group components. Among the cognitive variables that relate to cohesion we found competitiveanxiety. The purpose of this study was to examine the relation between task cohesion (ATG-T, and GI-T) andcompetitive state anxiety (A-state), and also if there would be a relation between cohesion and self-confidence.Participants were 366 football players of both genders male and female, aged between 15 to 23 years old, fromPortugal’s championships. Cohesion was measured using the Portuguese version of the Group EnvironmentQuestionnaire, and to assess competitive anxiety, we used the Portuguese version of the Competition State AnxietyInventory 2. Our results show that female athletes report experiencing more cognitive anxiety and less self-confidencethan male athletes. Only cognitive anxiety relates in a significantly negative way with the perception of cohesion (GI-Te ATG-T) in the total number of participants and in male athletes. Relatively to the somatic anxiety, it only relatesnegatively with the perception of the integration of the group in the total number of participants and in the malegender.

Keywords:

  • Group Dynamics
  • cohesion
  • anxiety
  • soccer
Open Access

Evolution of perceived cohesion and efficacy over the season and their relation to success expectations in soccer teams

Published Online: 23 Oct 2012
Page range: 129 - 138

Abstract

Abstract

The main goal of the study is to examine the evolution of players' perception of cohesion and efficacy over theseason and their relation with success expectations. The research sample comprised 146 male soccer players, agedbetween 15 and 19 years (M = 16.96, SD = .76). Diverse instruments were used to measure cohesion, perceived efficacy,and success expectations. The most noteworthy results show that players whose expectations do not match the team'sfinal performance will experience a negative evolution of their levels of perceived cohesion and efficacy, whereas playerswhose expectations at the start of the season match the team's final performance in the classification will maintain theirdegree of perceived cohesion and efficacy. The main conclusion of the study is that coaches and sport psychologistsshould attempt to clarify the players' basic goals of the season to create expectations that match what is expected fromthe team.

Keywords

  • cohesion
  • efficacy
  • success expectations
  • performance
  • soccer
Open Access

Leadership power perceptions of soccer coaches and soccer players according to their education

Published Online: 23 Oct 2012
Page range: 139 - 146

Abstract

Abstract

The purpose of this study was to analyze the leadership power perceptions of soccer coaches and soccer playersaccording to their educational levels. Data were collected from 165 male soccer coaches and 870 male soccer players.Adapted versions of the “Power in Soccer Questionnaire-Other”, the “Power in Soccer Questionnaire-Self” and an“information form” were used for data collection, and collected data were analyzed by the Kruskal-Wallis and theMann-Whitney Tests. Analysis of the Power in Soccer Questionnaire-Other revealed significant differences betweensoccer players’ level of education and their perception of Coercive Power (p<.003), and no significant differences relatedto Referent Power, Legitimate Power and Expert Power. Analysis of the Power in Soccer Questionnaire-Self alsorevealed the only significant difference between coaches’ level of education and their perception of Legitimate Power(p<.001), and no significant differences with regard to others. Different perception of leadership powers between coachesand players might create communication and performance problems in soccer.

Keywords

  • perception of leadership power
  • soccer coaches
  • soccer players
  • education.

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