Neuromuscular,metabolic and hormonal profiles of young tennis players and untrained boys

This study compared the neuromuscular, metabolic and hormonal profiles of trained prepubescent tennis players and an untrained group. The boys in the experimental group (n = 9; mean age ± S.D. = 11.4 ± 0.5 years) had participated in tennis training for 2.3 ± 1.0 years and the boys in the control group (n = 9; mean age ± S.D. = 10.9 ± 0.4 years) were normal active volunteers. The tennis players were found to be physically more active than the controls when the comparison was made for either 1 year (4.9 ± 1.8 vs 2.6 ± 2.5 times per week; P<0.05) or for 1 week (3.4 + 1.2 vs 0.4 ± 0.5 times; P < 0.001) preceding the tests. Choice reaction time was significantly (P <0.01) shorter in the experimental group (258 ± 16 ms) than in the control group (344 + 81 ms). Dropping height in the best drop jump was significantly (P< 0.05) higher in the tennis players (0.46 + 0.19 m) than in the control boys (0.27 ± 0.10 m). The tennis players had significantly lower oxygen consumption at the ‘anaerobic threshold’ than the controls (P < 0.05). There were no significant differences between the groups in serum hormone levels. The small differences that existed may have been caused by actice participation in sport by the tennis players.     

Relationships between muscle fibre characteristics and physical performance capacity in trained athletic boys

The relationships between muscle fibre characteristics and the physical performance capacity of trained athletic boys (aged 11-13 years) were studied over 2 days. The subjects were divided into two groups according to muscle fibre distribution. The 'fast' group (FG) comprised 10 subjects (sprinters, weightlifters, tennis players) with more than 50% fast-twitch fibres (type II), and the 'slow' group (SG) comprised 8 subjects (endurance runners, tennis players, one weightlifter) with more than 50% slow-twitch fibres (type I) in their vastus lateralis muscle. The 'fast' group had 59.2 +/- 6.3% and the 'slow' group had 39.4 +/- 9.8% type II fibres. Other clear differences (P less than 0.05-0.01) between the groups were observed as regards reaction time, rate of force development and rise of the body's centre of gravity in the squatting jump. For these variables, the 'fast' group was superior to the 'slow' group. Muscle fibre distribution (% type II) correlated (P less than 0.05-0.01) negatively with reaction time. Muscle fibre area (% type II) correlated negatively with reaction time (P less than 0.05-0.001) and positively with chronological age (P less than 0.05) height (P less than 0.05), mass (P less than 0.001), serum testosterone (P less than 0.05), force production (P less than 0.05-0.01) and blood lactate (P less than 0.05) in the 60-s maximal anaerobic test. There were no significant correlations between muscle fibre characteristics and maximal oxygen uptake. The present study assumes that heredity partly affects the selection of sporting event. Growth, development and training are associated with muscle fibre area, which affects the physical performance capacity of the neuromuscular system in trained young boys.     

Tennis ball diameter: the effect on performance and the concurrent physiological responses

The aim of this study was to examine the influence of a pressurized tennis ball 6% greater in diameter (Type 3) than a standard sized (Type 2) ball on performance and the physiological responses to the Loughborough Intermittent Tennis Test (LITT) (Davey et al., 2002). Eight competitive tennis players (males, n = 4, age 24.8+/-3.5 years, body mass 81.3+/-3.1 kg, height 1.74+/-0.02 m, estimated VO2max 54.4+/-2.6 ml x kg(-1) min(-1); females, n = 4, age 26.3+/-3.1 years, body mass 67.0+/-6.7 kg, height 1.68 + 0.02 m, estimated VO2max 49.9+/-3.3 ml kg(-1) min(-1); mean+/-s(x)) completed two main trials of the LITT with either the Type 2 or Type 3 tennis balls to the point of volitional fatigue. The mean time to volitional fatigue was 29.5% greater during the Type 3 trials than during the Type 2 trials (56.9+/-6.4 min vs 40.1+/-3.7 min; P < 0.05). The mean percentage accuracy and mean percentage consistency recorded for the entire LITT were greater for the Type 3 than the Type 2 trials (9.2+/-1.5 vs 4.0+/-0.3% and 61.1+/-0.6 vs 51.3+/-0.6%, respectively; P < 0.01). A significantly lower mean heart rate and blood lactate concentration were observed during the Type 3 than during the Type 2 trials. There was a clear effect of ball diameter on tennis performance and certain physiological responses.     

Height, mass and skeletal maturity of elite Portuguese soccer players aged 11-16 years

Height, mass and skeletal maturity (Fels method) were assessed in 135 elite youth soccer players aged 10.7-16.5 years (only two boys were < 11.0 years). Sample sizes, years of training and current weekly training volume by two-year age groups were: 11-12 years (n = 63), 2.6 +/- 1.0 years and 4.1 +/- 1.7 h; 13-14 years (n = 29), 3.1 +/- 1.6 years and 4.5 +/- 1.7 h; 15-16 years (n = 43), 4.7 +/- 2.4 years and 6.1 +/- 2.0 h. The oldest age group included members of the national youth team. Heights and masses were compared to US reference values, and skeletal age and chronological age were contrasted. The players were also classified as late, average ('on time') and early maturers on the basis of differences between skeletal and chronological age, with the average category including boys with skeletal ages within +/- 1 year of chronological age. The mean heights and masses of 11- to 12-year-old soccer players equalled the US reference values, while those of players aged 13-14 and 15-16 years were slightly above the reference values. The mean skeletal age approximated mean chronological age in players aged 11-12 years (12.4 +/- 1.3 and 12.3 +/- 0.5 years, respectively), while mean skeletal age was in advance of mean chronological age in the two older groups (14.3 +/- 1.2 and 13.6 +/- 0.7 years, respectively, in 13- to 14-year-olds; 16.7 +/- 1.0 and 15.8 +/- 0.4 years, respectively, in 15- to 16-year-olds). Seven boys in the oldest age group were already skeletally mature and were not included when calculating differences between skeletal and chronological age. The proportion of late maturing boys in this sample of elite soccer players decreased with increasing chronological age. Among 11- to 12-year-old players, the percentages of late and early maturing boys were equal at 21% (n = 13). Among 13- to 14-year-old players, the percentages of late and early maturing boys were 7% (n = 2) and 38% (n = 11) respectively, while among players aged 15-16 years the percentages of late and early maturing boys were 2% (n = 1) and 65% (n = 28) respectively. The results of this comparative analysis suggest that the sport of soccer systematically excludes late maturing boys and favours average and early maturing boys as chronological age and sport specialization increase. It is also possible that late maturing boys selectively drop-out of soccer as age and sport specialization increase.     

Match activity and physiological load during a clay-court tennis tournament in elite female players

The aim of this study was to determine the match activity and physiological demands of women's tennis during a 3-day clay-court tennis tournament. The activity profile of eight players was determined by filming each competitive match with video cameras. Metabolic-perceptual measurements--blood samples and individual ratings of perceived exertion (RPE)--were taken while the players were sitting during permitted changeover breaks in play. The activity profile of the players was as follows: strokes per rally, 2.5 +/- 1.6; rally duration, 7.2 +/- 5.2 s; rest time between rallies, 15.5 +/- 7.3 s; effective playing time, 21.6 +/- 6.1%; work-to-rest ratio, 1:2.1. Blood lactate concentration [2.2 +/- 0.9 mmol x l(-1) (n = 50) vs. 2.2 +/- 0.7 mmol x l(-1) (n = 48)] and RPE values [12.2 +/- 2.4 (n = 57) vs. 12 +/- 2.3 (n = 57)] were not significantly different (P = 0.65-0.78) between service and return games. The results highlight the importance of taking these factors (i.e. activity patterns and physiological profile) into account when planning training strategies for competitive females players. As such, tennis training regimes should be adapted to the specific demands imposed by match-play in female players on a clay-court surface.     

Physiological responses to maximal intermittent exercise: differences between endurance-trained runners and games players.

Six games players (GP) and six endurance-trained runners (ET) completed a standardized multiple sprint test on a non-motorized treadmill consisting of ten 6-s all-out sprints with 30-s recovery periods. Running speed, power output and oxygen uptake were determined during the test and blood samples were taken for the determination of blood lactate and pH. Games players tended to produce a higher peak power output (GP vs ET: 839 +/- 114 vs 777 +/- 89 W, N.S.) and higher peak speed (GP vs ET: 7.03 +/- 0.3 vs 6.71 +/- 0.3 m s-1, N.S.), but had a greater decrement in mean power output than endurance-trained runners (GP vs ET: 29.3 +/- 8.1% vs 14.2 +/- 11.1%, P less than 0.05). Blood lactate after the test was higher for the games players (GP vs ET: 15.2 +/- 1.9 vs 12.4 +/- 1.7 mM, P less than 0.05), but the decrease in pH was similar for both groups (GP vs ET: 0.31 +/- 0.08 vs 0.28 +/- 0.08, N.S.). Strong correlations were found between peak blood lactate and peak speed (r = 0.90, P less than 0.01) and between peak blood lactate and peak power fatigue (r = 0.92, P less than 0.01). The average increase in oxygen uptake above pre-exercise levels during the sprint test was greater for endurance-trained athletes than for the games players (ET vs GP: 35.0 +/- 2.2 vs 29.6 +/- 3.0 ml kg-1 min-1, P less than 0.05), corresponding to an average oxygen uptake per sprint (6-s sprint and 24 s of subsequent recovery) of 67.5 +/- 2.9% and 63.0 +/- 4.5% VO2 max respectively (N.S.). A modest relationship existed between the average increase in oxygen uptake above pre-exercise values during the sprint test and mean speed fatigue (r = -0.68, P less than 0.05). Thus, the greater decrement in performance for the games players may be related to higher glycolytic rates as reflected by higher lactate concentrations and to their lower oxygen uptake during the course of the 10 sprints.     

The effect of recovery duration on running speed and stroke quality during intermittent training drills in elite tennis players

The aim of this study was to assess the effect of the recovery duration in intermittent training drills on metabolism and coordination in sport games. Ten nationally ranked male tennis players (age 25.3+/-3.7 years, height 1.83+/-0.8 m, body mass 77.8+/-7.7 kg; mean +/- sx) participated in a passing-shot drill (baseline sprint with subsequent passing shot) that aimed to improve both starting speed and stroke quality (speed and precision). Time pressure for stroke preparation was individually adjusted by a ball-machine and corresponded to 80% of maximum running speed. In two trials (T10, T15) separated by 2 weeks, the players completed 30 strokes and sprints subdivided into 6 x 5 repetitions with a 1 min rest between series. The rest between each stroke-and-sprint lasted either 10 s (T10) or 15 s (T15). The sequence of both conditions was randomized between participants. Post-exercise blood lactate concentration was significantly elevated in T10 (9.04+/-3.06 vs 5.01+/-1.35 mmol x l(-1), P < 0.01). Running time for stroke preparation (1.405+/-0.044 vs 1.376+/-0.045 s, P < 0.05) and stroke speed (106+/-12 vs 114+/-8 km x h(-1), P < 0.05) were significantly decreased in T10, while stroke precision - that is, more target hits (P < 0.1) and fewer errors (P < 0.05) - tended to be higher. We conclude that running speed and stroke quality during intermittent tennis drills are highly dependent on the duration of recovery time. Optimization of training efficacy in sport games (e.g. combined improvement of conditional and technical skills) requires skilful fine-tuning of monitoring guidelines.     

Influence of physiological characteristics on selection in a semi-professional first grade rugby league team: a case study

The aim of this study was to determine whether the physiological characteristics of players influence selection in a semi-professional first grade rugby league team. Sixty-six semi-professional rugby league players aged 24+/-4 years (mean +/- s) were monitored over two competitive seasons. The players underwent measurements of body mass, muscular power (vertical jump), speed (10, 20, 30 and 40 m sprint), agility (Illinois agility run) and estimated maximal aerobic power (multi-stage fitness test) 1 week before their first competition match. After selection for either the first or second grade team, the results of all physiological tests were collated and analysed to determine if there were any physiological differences between players selected for the two teams. Players selected to play in the first grade team were significantly (P< 0.05) older (25+/-4 vs 22+/-4 years) and heavier (93+/-10 vs 86+/-10 kg) and had more playing experience (18+/-6 vs 15+/-6 years) than second grade players. Muscular power, speed, agility and estimated maximal aerobic power were not significantly different (P > 0.05) between first grade and second grade players. These results suggest that the physiological capacities of players do not influence selection in a semi-professional first grade rugby league team. Rather, player selection appears to be based on body mass, playing experience and skill. These results support the need for a standardized skills performance test for semi-professional rugby league players.     

An anthropometric analysis of elite Australian track cyclists

An anthropometric analysis was conducted on 35 elite male Australian track cyclists having a mean age of 22.6 years and who had been competing on average for 9 years. The relationship of anthropometric parameters to both bicycle saddle height and cycling performance was also investigated. Subjects were allocated, for purposes of comparison, to an endurance or sprint group on the basis of their competitive event. The group members in total were ectomorphic mesomorphs of height 178 +/- 4.8 cm and weight 72.5 +/- 6.6 kg on average. Percentage of saddle height to lower limb length averaged 99 +/- 1.6%, and significant correlations existed between strength and both body mass (r = 0.57) and thigh girth (r = 0.55). No significant correlation was seen between any anthropometric parameter and performance in an individual event. Cyclists in the spint group were heavier (76.2 +/- 7.4 vs. 70.0 +/- 4.7 kg, P less than 0.01) and stronger (258 +/- 44.4 vs. 216 +/- 30.5 Nm, P less than 0.01), and had larger chest (98.2 +/- 6.2 vs. 92.4 +/- 2.9 cm, P less than 0.01), arm (33.0 +/- 2.2 vs. 30.7 +/- 1.6 cm, P less than 0.01), thigh (57.5 +/- 3.4 vs. 54.3 +/- 2.5 cm, P less than 0.01) and calf girths (37.8 +/- 1.7 vs. 36.2 +/- 1.9 cm, P less than 0.05) than cyclists in the endurance group. They were also more mesomorphic (5.3 +/- 0.7 vs. 4.7 +/- 0.8, P less than 0.05) and less ectomorphic (2.3 +/- 0.9 vs. 2.9 +/- 0.6, P less than 0.05) than the endurance cyclists.     

The relationship between torque and joint angle during knee extension in boys and men.

The length-tension relationship of muscle contraction is well documented in adults. However, research on this relationship in children has been limited. The aim of this study was to compare differences in the torque-joint angle relationship of the quadriceps muscle in children and adults. Eight boys aged 8-10 years and eight men aged 20-26 years performed two maximal voluntary isometric contractions at six knee joint angles (20 degrees, 40 degrees, 60 degrees, 80 degrees, 90 degrees, 100 degrees). The mean of the two trials was used as the performance measure. Both groups demonstrated an expected increase in relative torque as the joint angle increased (P< 0.05). The men produced significantly greater relative torque at 20 degrees, 40 degrees and 60 degrees knee flexion (P < 0.05). The percentage of maximal torque at these angles for the men and boys respectively were: 35.2+/-4.3 vs 15.2+/-12%, 63.6+/-9.1 vs 51.8+/-16.8% and 93.6+/-6.5 vs 84.4+/-14.4%. There were no group differences at 80 degrees or 90 degrees. Peak torque was attained at 80 degrees in men, but decreased significantly (P< 0.05) at 90 degrees and 100 degrees. For boys, peak torque was attained at joint angles of 80 degrees and 90 degrees. The reduction in peak torque at 100 degrees was not statistically significant, but the relative torque at this angle was lower in men than in boys (77.9+/-13.7 vs 87.1+/-10.4%; P< 0.05). In conclusion, the relationship between torque and joint angle appears to be affected by age.     

Pre-season physiological characteristics of English first and second division soccer players.

This investigation was undertaken in an effort to establish physiological characteristics of soccer players and to relate them to positional roles. A total of 135 footballers (age 24.4 +/- 4.6 years) were assessed for body mass, % body fat, haemoglobin, maximal oxygen uptake (VO2 max), leg power, anaerobic capacity and speed prior to an English league season. The sample included 13 goalkeepers, 22 full-backs, 24 centre-backs, 35 midfield players and 41 forwards. The goalkeepers were significantly heavier (86.1 +/- 5.5 kg; P < 0.01) than all groups except the centre-backs, had significantly higher estimated body fat percentages than centre-backs, forwards, midfield players (P < 0.01) or full-backs (P < 0.05), significantly lower estimated VO2 max values (56.4 +/- 3.9 ml kg-1 min-1; P < 0.01) and were slowest over 60 m (12.71 +/- 0.42 s). The midfield players had the highest predicted VO2 max values (61.4 +/- 3.4 ml kg-1 min-1), this being significantly greater (P < 0.05) than for the centre-backs. The forwards were the fastest group over 60 m (12.19 +/- 0.30 s), being significantly quicker than goalkeepers or centre-backs (P < 0.01) and full-backs (P < 0.05). Anaerobic power, as well as knee extensor torques (corrected for body mass) and extensor-flexor ratios, were similar between groups. No difference in estimated body fat percentage was observed between any of the outfield players, and haemoglobin concentrations were similar among players of all positions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Match performance of high-standard soccer players with special reference to development of fatigue

The aim of this study was to assess physical fitness, match performance and development of fatigue during competitive matches at two high standards of professional soccer. Computerized time-motion analyses were performed 2-7 times during the competitive season on 18 top-class and 24 moderate professional soccer players. In addition, the players performed the Yo-Yo intermittent recovery test. The top-class players performed 28 and 58% more (P < 0.05) high-intensity running and sprinting, respectively, than the moderate players (2.43 +/- 0.14 vs 1.90 +/- 0.12 km and 0.65 +/- 0.06 vs 0.41 +/- 0.03 km, respectively). The top-class players were better (11%; P < 0.05) on the Yo-Yo intermittent recovery test than the moderate players (2.26 +/- 0.08 vs 2.04 +/- 0.06 km, respectively). The amount of high-intensity running, independent of competitive standard and playing position, was lower (35-45%; P < 0.05) in the last than in the first 15 min of the game. After the 5-min period during which the amount of high-intensity running peaked, performance was reduced (P < 0.05) by 12% in the following 5 min compared with the game average. Substitute players (n = 13) covered 25% more (P < 0.05) ground during the final 15 min of high-intensity running than the other players. The coefficient of variation in high-intensity running was 9.2% between successive matches, whereas it was 24.8% between different stages of the season. Total distance covered and the distance covered in high-intensity running were higher (P < 0.05) for midfield players, full-backs and attackers than for defenders. Attackers and full-backs covered a greater (P < 0.05) distance in sprinting than midfield players and defenders. The midfield players and full-backs covered a greater (P < 0.05) distance than attackers and defenders in the Yo-Yo intermittent recovery test (2.23 +/- 0.10 and 2.21 +/- 0.04 vs 1.99 +/- 0.11 and 1.91 +/- 0.12 km, respectively). The results show that: (1) top-class soccer players performed more high-intensity running during a game and were better at the Yo-Yo test than moderate professional players; (2) fatigue occurred towards the end of matches as well as temporarily during the game, independently of competitive standard and of team position; (3) defenders covered a shorter distance in high-intensity running than players in other playing positions; (4) defenders and attackers had a poorer Yo-Yo intermittent recovery test performance than midfielders and full-backs; and (5) large seasonal changes were observed in physical performance during matches.     

Effective conditioning of female soccer players

We compared the efficacy of three physical conditioning programmes provided over a 12 week period (24 h in total) on selected anthropometric and physical fitness parameters in female soccer players. Two of the groups received physical conditioning training in accordance with speed, agility and quickness (SAQ); one group used specialized resistance and speed development SAQ equipment (equipment group; n = 12), while the other group used traditional soccer coaching equipment (non-equipment group; n = 12). A third group received their regular fitness sessions (active control group; n = 12). All three interventions decreased (P < 0.001) the participants' body mass index (-3.7%) and fat percentage (-1.7%), and increased their flexibility (+14.7%) and maximal aerobic capacity (VO2max) (+18.4%). The participants in the equipment and non-equipment conditioning groups showed significantly (P < 0.005) greater benefits from their training programme than those in the active control group by performing significantly better on the sprint to fatigue (-11.6% for both the equipment and non-equipment groups versus -6.2% for the active control group), 25 m sprint (-4.4% vs -0.7%), left (-4.5% vs -1.0%) and right (-4.0% vs -1.4%) side agility, and vertical (+18.5% vs +4.8%) and horizontal (+7.7% vs +1.6%) power tests. Some of these differences in improvements in physical fitness between the equipment and non-equipment conditioning groups on the one hand and the active control group on the other hand were probably due to the specificity of the training programmes. It was concluded that SAQ training principles appear to be effective in the physical conditioning of female soccer players. Moreover, these principles can be implemented during whole team training sessions without the need for specialized SAQ equipment. Finally, more research is required to establish the relationship between physical fitness and soccer performance as well as the principles underlying the improvements seen through the implementation of SAQ training programmes.     

Height,mass and skeletal maturity of elite Portuguese soccer players aged 11–16 years

Height, mass and skeletal maturity (Fels method) were assessed in 135 elite youth soccer players aged 10.7-16.5 years (only two boys were ?11.0 years). Sample sizes, years of training and current weekly training volume by two-year age groups were: 11-12 years ( n = 63), 2.6 - 1.0 years and 4.1 - 1.7 h; 13-14 years ( n = 29), 3.1 - 1.6 years and 4.5 - 1.7 h; 15-16 years ( n = 43), 4.7 - 2.4 years and 6.1 - 2.0 h. The oldest age group included membersof the national youth team.Heights and masses were compared to US reference values,and skeletal age and chronological age were contrasted. The players were also classified as late, average ('on time') and early maturers on the basis of differences between skeletal and chronological age, with the average category including boys with skeletal ages within - 1 year of chronological age. The mean heights and masses of 11- to 12-year-old soccer players equalled the US reference values, while those of players aged 13-14 and 15-16 years were slightly above the reference values. The mean skeletal age approximated mean chronological age in players aged 11-12 years (12.4 - 1.3 and 12.3 - 0.5 years, respectively), while mean skeletal age was in advance of mean chronological age in the two older groups (14.3 - 1.2 and 13.6 - 0.7 years, respectively, in 13- to 14-year-olds; 16.7 - 1.0 and 15.8 - 0.4 years, respectively, in 15- to 16-year-olds). Seven boys in the oldest age group were already skeletally mature and were not included when calculating differences between skeletal and chronological age. The proportion of late maturing boys in this sample of elite soccer players decreased with increasing chronological age. Among 11- to 12-year-old players, the percentages of late and early maturing boys were equal at 21% ( n = 13). Among 13- to 14-year-old players, the percentages of late and early maturing boys were 7% ( n = 2) and 38% ( n = 11) respectively, while among players aged 15-16 years the percentages of late and early maturing boys were 2% ( n = 1) and 65% ( n = 28) respectively. The results of this comparative analysis suggest that the sport of soccer systematically excludes late maturing boys and favours average and early maturing boys as chronological age and sport specialization increase. It is also possible that late maturing boys selectively drop-out of soccer as age and sport specialization increase.     

Fatigue decreases skilled tennis performance

The aim of this study was to examine the effect of fatigue from maximal tennis hitting on skilled tennis performance. Eighteen senior county tennis players (9 males, 9 females) volunteered to participate in the study. Their mean (+/- s(mean)) age and body mass were as follows: males 20.7 +/- 0.9 years and 60.6 +/- 2.7 kg respectively, females 21.7 +/- 0.6 years and 71.5 +/- 1.8 kg respectively. The players undertook two performance tests, both against a tennis ball serving machine, on an indoor tennis surface: (1) a pre- and post-skill test of groundstrokes and service; (2) the Loughborough Intermittent Tennis Test (4 min work plus 40 s recovery) to volitional fatigue. Body mass decreased by 1.5% (P < 0.0001). Mean heart rates differed between rest, post-warm-up and all intermittent test values (P < 0.01), between the pre- and post-skill tests (P < 0.0001) and between bouts and recoveries (P < 0.01). Peak blood glucose and lactate concentrations were 5.9 mmol l(-1) (50% into the intermittent tennis test) and 9.6 +/- 0.9 mmol x l(-1) (25% into the test) respectively. Mean time to volitional fatigue was 35.4 +/- 4.6 min. Groundstroke hitting accuracy decreased by 69% from start to volitional fatigue in the intermittent test (P < 0.01). Service accuracy to the right court declined by 30% after the intermittent tennis test. The results of this study suggest that fatigue was accompanied by a decline in some but not all tennis skills.     

Physiological responses and time-motion characteristics of various small-sided soccer games in youth players

The aim of this study was to examine acute physiological responses and time-motion characteristics associated with three different small-sided soccer game formats in youth players. Sixteen male soccer players aged 16.3+/-0.6 years (mean+/-s) completed three variations of a small-sided game (i.e. 2 vs. 2, 4 vs. 4, and 6 vs. 6 players) in which heart rate, rating of perceived exertion (RPE), blood lactate concentration, and time-motion characteristics were recorded. The pitch size was altered to keep the relative pitch area per player consistent for each game format. The 2 vs. 2 games exhibited greater blood lactate, heart rate, and RPE responses compared with 4 vs. 4 and 6 vs. 6 games (P<0.05). The players travelled less (P<0.05) distance at speeds of 0-7 km.h(-1) in the 4 vs. 4 compared with the 2 vs. 2 games (1128+/-10 m and 1176+/-8 m, respectively). Average maximal sprint distances above 18 km.h(-1) were lower (P<0.05) in 2 vs. 2 than in 4 vs. 4 and 6 vs. 6 games (11.5+/-3.9 m, 15.3+/-5.5 m, and 19.4+/-5.9 m, respectively), and in 4 vs. 4 compared with 6 vs. 6 games. The results show that as small-sided game formats decrease in size and relative pitch area remains constant, overall physiological and perceptual workload increases.     

Upper limb joint muscle/tendon injury and anthropometric adaptations in French competitive tennis players

The purpose of this study was to examine the relationship between the upper limb anthropometric dimensions and a history of dominant upper limb injury in tennis players. Dominant and non-dominant wrist, forearm, elbow and arm circumferences, along with a history of dominant upper limb injuries, were assessed in 147 male and female players, assigned to four groups based on location of injury: wrist (n = 9), elbow (n = 25), shoulder (n = 14) and healthy players (n = 99). From anthropometric dimensions, bilateral differences in circumferences and in proportions were calculated. The wrist group presented a significant bilateral difference in arm circumference, and asymmetrical bilateral proportions between wrist and forearm, as well as between elbow and arm, compared to the healthy group (6.6 ± 3.1% vs. 4.9 ± 4.0%, P < 0.01; ?3.6 ± 3.0% vs. ?0.9 ± 2.9%, P < 0.05; and ?2.2 ± 2.2% vs. 0.1 ± 3.4%, P < 0.05, respectively). The elbow group displayed asymmetrical bilateral proportions between forearm and arm compared to the healthy group (?0.4 ± 4.3% vs. 1.5 ± 4.0%, P < 0.01). The shoulder group showed significant bilateral difference in elbow circumference, and asymmetrical bilateral proportions between forearm and elbow when compared to the healthy group (5.8 ± 4.7% vs. 3.1 ± 4.8%, P < 0.05 and ?1.7 ± 4.5% vs. 1.4 ± 4.3%, P < 0.01, respectively). These findings suggest that players with a history of injury at the upper limb joint present altered dominant upper limb proportions in comparison with the non-dominant side, and such asymmetrical proportions would appear to be specific to the location of injury. Further studies are needed to confirm the link between location of tennis injury and asymmetry in upper limb proportions using high-tech measurements in symptomatic tennis players.     

The effect of video-modelling and video-feedback on the learning of the tennis service by novices

This project is addressed to the effectiveness of video mediated instruction on the learning of the tennis service by novices. The research was carried out in an indoor tennis hall under normal training conditions. Three experimental groups were used: a video-model (VMT), a video-feedback (VFT) and a group with a combination of video modelling and video feedback (VMFT). Two control groups - based on different training periods-were also used: a traditional training group (TT1) which practised for a period of 45 min per training session and a second traditional training group (TT2) which practised for a period of only 30 min per training session. All subjects took part in five successive training sessions. No clear advantages of using video mediated instruction methods in teaching novices the tennis service could be demonstrated. Five sessions of 30 min practical training were shown to be as effective as five sessions of 45 min practical training in producing improvements in both form and achievement scores of novice tennis players. While, in the early stages, form and achievement scores were not shown to be significantly related, after five sessions a significant correlation (P less than 0.05) was shown.     

Influence of physiological characteristics on selection in a semi-professional first grade rugby league team: a case study

The aim of this study was to determine whether the physiological characteristics of players influence selection in a semi-professional first grade rugby league team. Sixty-six semi-professional rugby league players aged 24 - 4 years (mean - s ) were monitored over two competitive seasons. The players underwent measurements of body mass, muscular power (vertical jump), speed (10, 20, 30 and 40 m sprint), agility (Illinois agility run) and estimated maximal aerobic power (multi-stage fitness test) 1 week before their first competition match. After selection for either the first or second grade team, the results of all physiological tests were collated and analysed to determine if there were any physiological differences between players selected for the two teams. Players selected to play in the first grade team were significantly ( P ? 0.05) older (25 - 4 vs 22 - 4 years) and heavier (93 - 10 vs 86 - 10 kg) and had more playing experience (18 - 6 vs 15 - 6 years) than second grade players. Muscular power, speed, agility and estimated maximal aerobic power were not significantly different ( P > 0.05) between first grade and second grade players. These results suggest that the physiological capacities of players do not influence selection in a semi-professional first grade rugby league team. Rather, player selection appears to be based on body mass, playing experience and skill. These results support the need for a standardized skills performance test for semi-professional rugby league players.     

Maximal exercise performance and lean leg volume in men and women.

The purpose of this study was to compare the maximal exercise performance during cycle ergometry of 34 men and 47 women. External peak power output (OPP) and optimized pedalling rate (ORPM) were calculated from data gathered during an optimization procedure performed on a friction braked cycle ergometer. In addition, lean leg volume (LLV) and lean upper leg volume (LULV) were determined using an anthropometric technique. Both OPP and ORPM were greater in men than in women (1007 +/- 135 vs 673 +/- 109 W and 119.5 +/- 7.0 vs 104.5 +/- 8.4 rev min-1, respectively; P less than 0.001). The LLV and LULV were also greater in men than in women (7.41 +/- 0.82 vs 5.19 +/- 0.85 l and 4.96 +/- 0.63 vs 3.35 +/- 0.62 l, respectively; P less than 0.001). The ratio standards OPP/LLV and OPP/LULV did not differ significantly between men and women (136.3 +/- 14.7 vs 131.0 +/- 20.6 W l-1 and 204.4 +/- 27.1 vs 204.4 +/- 37.0 W l-1, respectively; P greater than 0.05). Peak power output was related to each of the anthropometric indices in both men and women (LLV:r = 0.614 and 0.527, P less than 0.001; LULV:r = 0.489 and 0.396, P less than 0.01). Analysis of covariance revealed no significant differences between the groups in the variance about regression and the regression coefficients (P greater than 0.05), but the elevation of the regression lines did differ (P less than 0.001). The results suggest that there are differences between maximal exercise performance in men and women that are independent of estimated lean leg volume. They also demonstrate that, in this case, consideration of ratio standards is misleading and that a comparison of regression standards is more appropriate.