On the Use of a Test to Exhaustion Specific to Tennis (TEST) with Ball Hitting by Elite Players

PurposeWe aimed to a) introduce a new Test to Exhaustion Specific to Tennis (TEST) and compare performance (test duration) and physiological responses to those obtained during the 20-m multistage shuttle test (MSST), and b) determine to which extent those variables correlate with performance level (tennis competitive ranking) for both test procedures.MethodsTwenty-seven junior players (8 males, 19 females) members of the national teams of the French Tennis Federation completed MSST and TEST, including elements of the game (ball hitting, intermittent activity, lateral displacement), in a randomized order. Cardiorespiratory responses were compared at submaximal (respiratory compensation point) and maximal loads between the two tests.ResultsAt the respiratory compensation point oxygen uptake (50.1 ± 4.7 vs. 47.5 ± 4.3 mL.min^-1.kg^-1, p = 0.02), but not minute ventilation and heart rate, was higher for TEST compared to MSST. However, load increment and physiological responses at exhaustion did not differ between the two tests. Players’ ranking correlated negatively with oxygen uptake measured at submaximal and maximal loads for both TEST (r = -0.41; p = 0.01 and -0.55; p = 0.004) and MSST (r = -0.38; P = 0.05 and -0.51; p = 0.1).ConclusionUsing TEST provides a tennis-specific assessment of aerobic fitness and may be used to prescribe aerobic exercise in a context more appropriate to the game than MSST. Results also indicate that VO₂ values both at submaximal and maximal load reached during TEST and MSST are moderate predictors of players competitive ranking.     

CATECHOLAMINES AND β2-ADRENOCEPTOR GENE EXPRESSION BEFORE AND AFTER MAXIMAL INCREMENTAL CYCLE TEST IN YOUNG ICE HOCKEY PLAYERS: RELATION TO WORK PERFORMED

The aim of this study was to assess the plasma adrenaline and noradrenaline concentrations as well as whole blood β₂-adrenoceptor gene (ADRB2) expression in young ice hockey players before and immediately after exercise in relation to performed work. Nineteen Youth National Team ice hockey players were subjected to the maximal incremental cycloergometer exercise. The test was done in the pre-competitive phase of training. Among many parameters the plasma adrenaline and noradrenaline concentrations and ADRB2 gene expression in peripheral blood mononuclear cells (PBMC) were determined before and after exercise. The average performed work was 3261.3 ± 558.3 J · kg⁻¹ and maximal oxygen consumption (VO₂max) for all players was 53.85 ± 3.91 mL · kg⁻¹ min⁻¹. The geometric mean of the ADRB2 gene expression was statistically significantly different before and after exercise (P ≤ 0.05), while adrenaline and noradrenaline levels in plasma significantly increased after exercise. In the analysed group of athletes we found that initial level of plasma noradrenaline correlated with the performed work (r = - 0.55, P < 0.014) and normalized ADRB2 expression before the exercise correlated with the work done by them (r = 0.48, P<0.039). However, no statistically significant correlations were found between the plasma adrenaline or noradrenaline concentrations and ADRB2 gene expression in peripheral blood of the players. The performed work in the maximal incremental exercise test of regularly training young ice hockey players depends on the initial levels of noradrenaline in plasma and ADRB2 mRNA in PBMC.     

Cortisol and stress responses during a game and practice in female collegiate soccer players

The purpose of this study was to compare the cortisol responses from a regular season game and a typical practice session in female National Collegiate Athletic Association Division I collegiate soccer players. Eighteen players were assigned to 2 groups, 10 starters and 8 nonstarters, depending on their playing time. Salivary cortisol concentration, as well as competitive sport anxiety (somatic and cognitive anxiety, self-confidence), was monitored before and after 1 regular season game and 1 typical practice session. Although salivary cortisol levels increased postgame for both starters (+250%) and nonstarters (+140%), they increased to a greater extent for the starters. Practice salivary cortisol did not significantly change (p > 0.05). Cognitive and somatic anxiety was greater pre- and postgame when compared with the pre- and postpractice scores, respectively. These data clearly demonstrate the psychological and physiological differences between soccer competition and practice in collegiate women. It appears that both physiological and psychological variables combine to contribute to the large stress hormone response to an actual competitive game.     

Changes in body composition, hormonal status, and physical fitness in 11-, 13-, and 15-year-old Finnish regional youth soccer players during a two-year follow-up

V?nttinen, T, Blomqvist, M, Nyman, K, and H?kkinen, K. Changes in body composition, hormonal status, and physical fitness in 11-, 13-, and 15-year-old Finnish regional youth soccer players during a two-year follow-up. J Strength Cond Res 25(12): 3342-3351, 2011-The purpose of this study was to examine the changes in body composition, hormonal status, and physical fitness in 10.8 ± 0.3-year-old (n = 13), 12.7 ± 0.2-year-old (n = 14), and 14.7 ± 0.3-year-old (n = 12) Finnish regional youth soccer players during a 2-year monitoring period and to compare physical fitness characteristics of soccer players with those of age-matched controls (10.7 ± 0.3 years, n = 13; 14.7 ± 0.3 years, n = 10) not participating in soccer. Body composition was measured in terms of height, weight, muscle mass, percentage of body fat, and lean body weight of trunk, legs, and arms. Hormonal status was monitored by concentrations of serum testosterone and cortisol. Physical fitness was measured in terms of sprinting speed, agility, isometric maximal strength (leg extensors, abdominal, back, grip), explosive strength, and endurance. Age-related development was detected in all other measured variables except in the percentage of body fat. The results showed that the physical fitness of regional soccer players was better than that of the control groups in all age groups, especially in cardiovascular endurance (p < 0.01-0.001) and in agility (p < 0.01-0.001). In conclusion, playing in a regional level soccer team seems to provide training adaptation, which is beyond normal development and which in all likelihood leads to positive health effects over a prolonged period of time.     

Studies on the immediate and delayed leucocytosis elicited by brief (30-min) strenuous exercise

Eight healthy male volunteers exercised for two 30-min sessions starting 3 h apart on an electronically braked cycle ergometer at a work load (mean 155.9 W, SD 33.4 W) which required an oxygen consumption that was 70% of their maximal rate of oxygen uptake. Venous blood samples were taken through an indwelling cannula over a period of 6 h beginning shortly before the first bout of exercise and were analysed for routine haematological parameters and for lactate, noradrenaline, adrenaline and cortisol. Both bouts of exercise induced an immediate leucocytosis due to rises in lymphocytes and neutrophils but only the first exercise bout induced a substantial delayed neutrophilia. In at least five subjects, changes in lymphocyte and platelet numbers were correlated (Spearman's rank procedure, P less than 0.05) with simultaneous changes in the plasma concentrations of lactate, noradrenaline and adrenaline over the 6-h period studied. Increases in the plasma concentration of cortisol due to exercise correlated positively with the percentage changes in neutrophil numbers at 3 h and 6 h. These results are consistent with the suggestion that the immediate and delayed leucocytosis induced by exercise are mediated respectively by catecholamine and by cortisol.     

Effects of Small-Sided Games vs. Interval Training in Aerobic Fitness and Physical Enjoyment in Young Elite Soccer Players

The purpose of this study was to compare the effects of Small-Sided Games (SSG) vs. Interval Training (IT) in soccer training on aerobic fitness and physical enjoyment in youth elite soccer players during the last 8 weeks of the season. Seventeen U-16 male soccer players (age = 15.5 ± 0.6 years, and 8.5 years of experience) of a Spanish First Division club academy were randomized to 2 different groups for 6 weeks: SSG group (n = 9) and IT group (n = 8). In addition to the usual technical and tactical sessions and competitive games, the SSG group performed 11 sessions with different SSGs, whereas the IT group performed the same number of sessions of IT. Players were tested before and after the 6-week training intervention with a continuous maximal multistage running field test and the counter movement jump test (CMJ). At the end of the study, players answered the physical activity enjoyment scale (PACES). During the study, heart rate (HR) and session perceived effort (sRPE) were assessed. SSGs were as effective as IT in maintaining the aerobic fitness in elite young soccer players during the last weeks of the season. Players in the SSG group declared a greater physical enjoyment than IT (P = 0.006; ES = 1.86 ± 1.07). Coaches could use SSG training during the last weeks of the season as an option without fear of losing aerobic fitness while promoting high physical enjoyment.     

Hormonal responses to a graded mental workload

Three mental arithmetic tests of graded difficulty were presented to eight young male volunteers on consecutive days. The effort compensation patterns were investigated using urinary catecholamines and salivary cortisol. A significant increase in adrenaline excretion was found in response to all three tests. Urinary adrenaline was partially graded according to the level of difficulty of the tests. The response patterns to mental workload also included a significantly lower noradrenaline/adrenaline ratio and a higher adrenaline/dopamine ratio after the tests. No significant increase was found after the tests for noradrenaline and dopamine. Changes in salivary cortisol concentration during the tests were graded with respect to test difficulty between the easiest and both of the more difficult tests. Salivary cortisol concentration changes are proposed as the basis for field observations involving mental workload. It is concluded that mental workload causes distinguishable effort compensation patterns and that under certain conditions urinary adrenaline and salivary cortisol allow one to distinguish different mental workload levels.     

Reliability and Discriminative Ability of a New Method for Soccer Kicking Evaluation

The study aimed to evaluate the test–retest reliability of a newly developed 356 Soccer Shooting Test (356-SST), and the discriminative ability of this test with respect to the soccer players'' proficiency level and leg dominance. Sixty-six male soccer players, divided into three groups based on their proficiency level (amateur, n = 24; novice semi-professional, n = 18; and experienced semi-professional players, n = 24), performed 10 kicks following a two-step run up. Forty-eight of them repeated the test on a separate day. The following shooting variables were derived: ball velocity (BV; measured via radar gun), shooting accuracy (SA; average distance from the ball-entry point to the goal centre), and shooting quality (SQ; shooting accuracy divided by the time elapsed from hitting the ball to the point of entry). No systematic bias was evident in the selected shooting variables (SA: 1.98±0.65 vs. 2.00±0.63 m; BV: 24.6±2.3 vs. 24.5±1.9 m s^-1; SQ: 2.92±1.0 vs. 2.93±1.0 m s^-1; all p>0.05). The intra-class correlation coefficients were high (ICC = 0.70–0.88), and the coefficients of variation were low (CV = 5.3–5.4%). Finally, all three 356-SST variables identify, with adequate sensitivity, differences in soccer shooting ability with respect to the players'' proficiency and leg dominance. The results suggest that the 356-SST is a reliable and sensitive test of specific shooting ability in men’s soccer. Future studies should test the validity of these findings in a fatigued state, as well as in other populations.     

Aerobic capacities and anthropometric characteristics of elite female soccer players

Ingebrigtsen, J, Dillern, T, and Shalfawi, SAI. Aerobic capacities and anthropometric characteristics of elite female soccer players. J Strength Cond Res 25(12): 3352-3357, 2011-This study investigated aerobic capacities and anthropometric characteristics within a group of 29 elite female soccer players. The purpose was to identify and establish aerobic capacities and anthropometric characteristics for these players and to look for possible positional differences between keepers, defenders, midfielders, and attackers. We did this by measuring standard anthropometrical variables and maximal oxygen (VO(2)max) and anaerobic threshold (AT). One-way analysis of variance revealed no significant differences among anthropometric or physiological variables. However, a trend (p = 0.062) toward positional differences was found within running speed at AT. A subsequent Tukey post hoc test showed differences (p = 0.04) between keepers and defenders, with the latter running faster (～1.7 km·h) at AT. The present results suggest that few anthropometric and physiological differences exist between playing positions in elite female soccer players. Furthermore, the current results indicate that present elite players' physiological characteristics are similar to those previously shown, despite the rapid changes of the female soccer game. Based on well-established knowledge that different playing positions within a soccer team ought to have distinct capacities, we recommend regular testing programs to be able to construct and implement tailored training programs for players' physical capacities with respect to the demands of their playing positions.     

Comparative study of field and laboratory tests for the evaluation of aerobic capacity in soccer players

The purpose of this study was to evaluate the maximal oxygen uptake (Vo(2)max) values in soccer players as assessed by field and laboratory tests. Thirty-five elite young soccer players were studied (mean age 18.1 +/- 1.0 years, training duration 8.3 +/- 1.5 years) in the middle of the playing season. All subjects performed 2 maximal field tests: the Yo-Yo endurance test (T(1)) for the estimation of Vo(2)max according to normogram values, and the Yo-Yo intermittent endurance test (T(2)) using portable telemetric ergospirometry; as well as 2 maximal exercise tests on the treadmill with continuous (T(3)) and intermittent (T(4)) protocols. The estimated Vo(2)max values of the T(1) test (56.33 ml.kg(-1).min(-1)) were 10.5%, 11.4%, and 13.3% (p < or = 0.05) lower than those of the T(2) (62.96 ml.kg(-1).min(-1)), T(3) (63.59 ml.kg(-1).min(-1)) and T(4) (64.98 ml.kg(-1).min(-1)) tests, respectively. Significant differences were also found between the intermittent exercise protocols T(1) and T(3) (p < or = 0.001) and the continuous exercise protocols T(2) and T(4) (p < or = 0.001). There was a high degree of cross correlation between the Vo(2)max values of the 3 ergospirometric tests (T(2) versus T(3), r = 0.47, p < or = 0.005; T(2) versus T(4), r = 0.59, p < or = 0.001; T(3) versus T(4) r = 0.79, p < or = 0.001). It is necessary to use ergospirometry to accurately estimate aerobic capacity in soccer players. Nevertheless, the Yo-Yo field tests should be used by coaches because they are easy and helpful tools in the training program setting and for player follow-up during the playing season.     

Effects of biogenic amines and hormones on butterfly Malpighian tubules: Dopamine stimulates fluid secretion

Isolated Malpighian tubules of Papilio demodocus, the citrus swallowtail butterfly, were stimulated by biogenic amines as well as by cyclic AMP and the naturally occuring diuretic hormone. The greatest secretory response was obtained with 5-hydroxytryptamine, and smaller responses with dopamine and noradrenaline, but none of these amines could induce the maximal secretion rates obtained with cyclic AMP and diuretic hormone. Various other biogenic amines, hormones and pharmacological agents, including adrenaline, had no effect on Papilio tubules. The blocking agents cyproheptadine, phentolamine and propranolol did not alter the tubule response to biogenic amines.     

The effects of training on hormonal concentrations in young soccer players

To test the hypothesis that football training would be accompanied by physiological adaptations and hormonal changes, we analyzed the effects of a whole football season on physical fitness and hormonal concentrations in youth football players. Male football players (n = 29, age 16.51 ± 0.7 years) in a regional professional league and male healthy control subjects (n = 30, age 17.1 ± 1 years) participated to the study. Blood cortisol, testosterone, and growth hormone (hGH) concentrations were assayed before the beginning of the training period (T0), just after the training period (T1), at the middle of the season (T2), and at the end of the season (T3). In each period physical tests and anthropometric measurements were also performed. Results showed significant differences in basal values of cortisol, testosterone, and growth hormone (hGH) in the four time points evaluated (P < 0.01). In addition, the concentrations of hGH were higher in the soccer players group than in control subjects (P < 0.001). Between the start of the training period and the end of the football season significant differences were observed in the anthropometric characteristics and in the physical form of the football players. Furthermore, the hormonal status was significantly correlated with the indicators of the lower limb power (squat-jump [SqJ], and counter-movement-jump [CMJ]) and those of aerobic performance (Yo–Yo intermittent recovery test level 1 (YYIRT1) and maximal oxygen consumption (VO_2max)).These data underscore the importance of establishing training protocols that present the potential to promote positive adaptations without, at the same time, provoking overtraining of young players.     

Effects of a caffeine-containing energy drink on simulated soccer performance

Background

To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake.

Methodology/Principal Findings

Nineteen semiprofessional soccer players ingested 630±52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7×30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7±4.7 v 35.8±5.5 cm; P<0.05), mean running speed during the sprint test (25.6±2.1 v 26.3±1.8 km · h⁻¹; P<0.05) and total distance covered at a speed higher than 13 km · h⁻¹ during the game (1205±289 v 1436±326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30±10 v 24±8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1±1.0 v 0.1±0.1 µg · mL⁻¹; P<0.05).

Conclusions/significance

A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball.     

Evaluation of a composite test of kicking performance

The aim of this study was to evaluate the reliability and sensitivity of variables for the direct assessment of kicking performance in young soccer players. One hundred and six elite young soccer players were divided into 4 age groups (12-15 years). Absolute error (AE), variable error (VE), and constant error (CE) were evaluated as the variables of kicking accuracy, whereas the kicking velocity variables involved the maximum ball velocity (BVmax) and the ball velocity during accurate kicks (BVacc). Results suggested low-to-moderate reliability of the kicking accuracy (intraclass correlation coefficient [ICC] = 0.00-0.67) and high reliability of the kicking velocity variables (ICC = 0.87-0.94). Regarding the sensitivity, most of the variables detected the differences both between the dominant and nondominant legs and among the age groups. Because the evaluated variables should have a property of face validity, the findings obtained generally suggest that AE (and perhaps VE, as the measures of kicking accuracy) and both BVmax and BVacc (as the measures of kicking velocity) could be used within a routine composite test of kicking performance in young elite soccer players. Further development of the evaluated composite test of kicking performance could be based on the involvement of other kicking techniques and on testing the athletes of different ages, levels of skill, or sport specialization.     

Does improved decision-making ability reduce the physiological demands of game-based activities in field sport athletes?

This study investigated the effects of video-based perceptual training on pattern recognition and pattern prediction ability in elite field sport athletes and determined whether enhanced perceptual skills influenced the physiological demands of game-based activities. Sixteen elite women soccer players (mean +/- SD age, 18.3 +/- 2.8 years) were allocated to either a video-based perceptual training group (N = 8) or a control group (N = 8). The video-based perceptual training group watched video footage of international women's soccer matches. Twelve training sessions, each 15 minutes in duration, were conducted during a 4-week period. Players performed assessments of speed (5-, 10-, and 20-m sprint), repeated-sprint ability (6 x 20-m sprints, with active recovery on a 15-second cycle), estimated maximal aerobic power (V O2 max, multistage fitness test), and a game-specific video-based perceptual test of pattern recognition and pattern prediction before and after the 4 weeks of video-based perceptual training. The on-field assessments included time-motion analysis completed on all players during a standardized 45-minute small-sided training game, and assessments of passing, shooting, and dribbling decision-making ability. No significant changes were detected in speed, repeated-sprint ability, or estimated V O2 max during the training period. However, video-based perceptual training improved decision accuracy and reduced the number of recall errors, indicating improved game awareness and decision-making ability. Importantly, the improvements in pattern recognition and prediction ability transferred to on-field improvements in passing, shooting, and dribbling decision-making skills. No differences were detected between groups for the time spent standing, walking, jogging, striding, and sprinting during the small-sided training game. These findings demonstrate that video-based perceptual training can be used effectively to enhance the decision-making ability of field sport athletes; however, it has no effect on the physiological demands of game-based activities.     

Determinants and importance of stress hyperglycaemia in non-diabetic patients with myocardial infarction.

Determinants of plasma glucose concentrations were studied in patients on admission to hospital with confirmed acute myocardial infarction but without previous glucose intolerance as evidenced by raised concentrations of glycosylated haemoglobin (HbAlc). Mortality in hospital increased significantly with increasing plasma concentrations of glucose in patients with both normal (p less than 0.0001, n = 311) and borderline (p less than 0.02, n = 70) concentrations of HbAlc. There was a weak relation between plasma glucose concentrations and infarct size as estimated by peak aspartate transaminase activity in both HbAlc groups (rs = 0.26, n = 101 and rs = 0.41, n = 35 respectively). A correlation was found between adrenaline and plasma glucose concentrations (r = 0.47, n = 27) and cortisol and plasma glucose concentrations (r = 0.75, n = 19), but the relation of plasma noradrenaline and plasma glucose suggested a threshold effect. Concentrations of adrenaline, but not those of noradrenaline or cortisol, correlated with infarct size as measured both by peak aspartate transaminase activity and cumulative release of creatine kinase MB isoenzyme. Multiple regression analysis showed that concentrations of cortisol, adrenaline, and noradrenaline (but not the concentration of HbAlc, infarct size, or age) are the main determinants of plasma glucose concentration measured in non-diabetic patients when admitted to hospital after acute myocardial infarction.     

Effects of 1 vs. 2 sessions per week of equal-volume sprint training on explosive,high-intensity and endurance-intensive performances in young soccer players

The study aimed to evaluate the effects of 1 vs. 2 sessions per week of equal-volume sprint training on explosive, high-intensity and endurance-intensive performances among young soccer players. Thirty-six young male soccer players were randomly divided into 2 experimental groups that performed either a single weekly sprint training session (ST1, n = 18, age: 17.2 ± 0.8 years) or two weekly sprint training sessions (ST2, n = 18; age: 17.1 ± 0.9 years) of equal weekly and total volume, in addition to their regular soccer training regimen. Linear sprinting (10 m, 20 m, 30 m, and flying 10 m), T-test agility, countermovement jump (CMJ) and maximal oxygen consumption were assessed one week before (T1), in the middle (T2) and immediately after the 10 weeks of training (T3). A large magnitude and statistically significant main effect for time was found in all the assessed variables after both training interventions (all p < 0.001; ES ≥ 0.80). No main effect was observed between the 2 groups at any time in linear sprinting, T-test or CMJ test (p > 0.05; ES < 0.20). A significant interaction effect (F = 4.05; p = 0.04, ES = 0.21) was found for maximal oxygen consumption with ST2 inducing better performance than ST1 (p = 0.001; ES = 1.11). Our findings suggested that the two sprint training frequencies were effective in enhancing explosive, high-intensity and endurance-intensive performances. However, it is recommended for coaches and fitness coaches to use a biweekly sprint training modality as it was found to be more effective in improving endurance-intensive performance.     

Lack of Selectivity Between the Uptake of [3H] Adrenaline and [3H]Noradrenaline into Rat Hypothalamic Slices

The uptake of [3H]adrenaline and [3H]noradrenaline into rat hypothalamic slices was compared for determination of whether adrenaline uptake was independent of uptake into noradrenergic neurones. Kinetic analysis revealed a similar high-affinity uptake process for both adrenaline and noradrenaline, with Km and Vmax values within similar ranges. These uptakes were inhibited by desipramine and maprotiline in a dose-dependent manner, but the selective dopamine and 5-hydroxytryptamine uptake inhibitors benztropine and fluoxetine, respectively, were without effect. Competition for uptake sites by unlabelled adrenaline with [3H]adrenaline and [3H]-noradrenaline and by unlabelled noradrenaline with [3H]-adrenaline and [3H]noradrenaline was very similar. Lesioning of the major adrenaline-containing cell group (C1 cell group) decreased the hypothalamic adrenaline concentration but had no effect on hypothalamic [3H]adrenaline or [3H]noradrenaline uptake. The results suggest that exogenous adrenaline is largely taken up by high-affinity sites on noradrenergic nerve terminals.     

Effects of speed, agility, quickness training method on power performance in elite soccer players

The purpose of this study was to evaluate the effects of the speed, agility, quickness (SAQ) training method on power performance in soccer players. Soccer players were assigned randomly to 2 groups: experimental group (EG; n = 50) and control group (n = 50). Power performance was assessed by a test of quickness--the 5-m sprint, a test of acceleration--the 10-m sprint, tests of maximal speed--the 20- and the 30-m sprint along with Bosco jump tests--squat jump, countermovement jump (CMJ), maximal CMJ, and continuous jumps performed with legs extended. The initial testing procedure took place at the beginning of the in-season period. The 8-week specific SAQ training program was implemented after which final testing took place. The results of the 2-way analysis of variance indicated that the EG improved significantly (p < 0.05) in 5-m (1.43 vs. 1.39 seconds) and in 10-m (2.15 vs. 2.07 seconds) sprints, and they also improved their jumping performance in countermovement (44.04 vs. 4.48 cm) and continuous jumps (41.08 vs. 41.39 cm) performed with legs extended (p < 0.05). The SAQ training program appears to be an effective way of improving some segments of power performance in young soccer players during the in-season period. Soccer coaches could use this information in the process of planning in-season training. Without proper planning of the SAQ training, soccer players will most likely be confronted with decrease in power performance during in-season period.     

Estimation of oxygen uptake from heart rate and ratings of perceived exertion in young soccer players

The objective of this study was to estimate the oxygen uptake (&OV0312;O2) in elite youth soccer players using measures of heart rate (HR) and ratings of perceived exertion (RPEs). Forty-six regional-level male youth soccer players (～13 years) participated in 2 VO(2)max tests. Data for HR, RPE, and VO(2) were simultaneously recorded during the VO(2)max tests with incremental running speed. Regression equations were derived from the first VO(2)max test. Two weeks later, all players performed the same VO(2)max test to validate the developed regression equations. There were no significant differences between the estimated values in the first test and actual values in the second test. During the continuous endurance exercise, the combination of percentage of maximal HR (%HRmax) and RPE measures gave similar estimation of %VO(2)max (R = 83%) in comparison to %HRmax alone (R = 81%). However, the estimation of VO(2) using combined %HRmax and RPE was not satisfactory (R = 45-46%). Therefore, the use of %HRmax (without RPE) to estimate %VO(2)max could be a useful tool in young soccer players during field-based continuous endurance testing and training. Specifically, coaches can use the %HRmax to quantify internal loads (%VO(2)max) and subsequently implement continuous endurance training at appropriate intensities. Furthermore, it seems that RPE is more useful as a measure of internal load during noncontinuous (e.g., intermittent and sprint) exercises but not to estimate %VO(2)max during continuous aerobic exercise (R = 59%).