Acute effects of psychological relaxation techniques between two physical tasks.

The concept of recovery strategies includes various ways to achieve a state of well-being, prevent underrecovery syndromes from occurring and re-establish pre-performance states. A systematic application of individualised relaxation techniques is one of those. Following a counterbalanced cross-over design, 27 sport science students (age 25.22 ± 1.08 years; sports participation 8.08 ± 3.92 h/week) were randomly assigned to series of progressive muscle relaxation, systematic breathing, power nap, yoga, and a control condition. Once a week, over the course of five weeks, their repeated sprint ability was tested. Tests (6 sprints of 4 s each with 20 s breaks between them) were executed on a non-motorised treadmill twice during that day intermitted by 25 min breaks. RM-ANOVA revealed significant interaction effects between the relaxation conditions and the two sprint sessions with regard to average maximum speed over all six sprints, F(4,96) = 4.06, P = 0.004, [Formula: see text] = 0.15. Post-hoc tests indicated that after systematic breathing interventions, F(1,24) = 5.02, P = 0.033, [Formula: see text] = 0.18, participants performed significantly better compared to control sessions. As the focus of this study lied on basic mechanisms of relaxation techniques in sports, this randomised controlled trial provides us with distinct knowledge on their effects, i.e., systematic breathing led to better performances, and therefore, seems to be a suited relaxation method during high-intensity training.

Acute responses and muscle damage in different high-intensity interval running protocols.

AIM: Our study aimed to evaluate the acute responses and exercise--induced muscle damage of five different high--intensity interval training (HIT) protocols adjusted by the maximum velocity obtained in the 30--15 Intermittent Fitness Test (V IFT ). METHODS: Sixteen well--trained intermittent sport players (mean ± SD;; age, 24.6 ± 2.7 years; V̇O 2max , 58.3 ± 5.9 ml∙min∙kg --1 ) participated in five different HIT protocols separated by six days in between (P 240 : 4×4 min at 80% V IFT ; P 120 : 7×2 min at 85%; P 30 : 2×10×30 s at 90%; P 15 : 3×9×15 s at 95%; P 5 : 4×6×5 s sprints). Blood lactate (La), blood pH, serum creatinkinase (CK), heart rate (HR), session rating of perceived exertion (session--RPE), delayed onset muscle soreness (DOMS) and countermovement jump (CMJ) height were measured. RESULTS: A significant main effect for protocol ( p < 0.05) was found for the acute responses of HR, session-RPE and La with values increasing in longer intervals from P 15 to P 120 and P 240 while blood pH responded inversely. In contrast, P 5 produced the highest La concentration and blood pH decreases. 24 h post exercise CK, DOMS and the decrease in CMJ height were significantly higher after P 5 compared to all other protocols ( p < 0.05). CONCLUSION: HIT protocols of different interval duration and intensity result in varying acute physiological and perceptual demands and exercise--induced muscle damage. Longer intervals with submaximal intensity lead to higher acute cardio circulatory responses, whereas sprint protocols induce the highest muscle damage and muscle soreness.

Changes in phosphocreatine concentration of skeletal muscle during high-intensity intermittent exercise in children and adults.

PURPOSE: The aim of the present study was to test the hypotheses that a greater oxidative capacity in children results in a lower phosphocreatine (PCr) depletion, a faster PCr resynthesis and a lower muscle acidification during high-intensity intermittent exercise compared to adults. METHODS: Sixteen children (9.4 ± 0.5 years) and 16 adults (26.1 ± 0.3 years) completed a protocol consisting of a dynamic plantar flexion (10 bouts of 30-s exercise at 25 % of one repetition maximum separated by 20-s recovery), followed by 10 min of passive recovery. Changes of PCr, ATP, inorganic phosphate, and phosphomonoesters were measured by means of (31)Phosphorous-magnetic resonance spectroscopy during and post-exercise. RESULTS: Average PCr (percentage of [PCr] at initial rest (%[PCr]i)) at the end of the exercise (adults 17 ± 12 %[PCr]i, children 38 ± 17 %[PCr]i, P < 0.01) and recovery periods (adults 37 ± 14 %[PCr]i, children 57 ± 17 %[PCr]i, P < 0.01) was significantly lower in adults compared to children, induced by a stronger PCr decrease during the first exercise interval (adults -73 ± 10 %[PCr]i, children -55 ± 15 %[PCr]i, P < 0.01). End-exercise pH was significantly higher in children compared to adults (children 6.90 + 0.20, -0.14; adults 6.67 + 0.23, -0.15, P < 0.05). CONCLUSIONS: From our results we suggest relatively higher rates of oxidative ATP formation in children's muscle for covering the ATP demand of high-intensity intermittent exercise compared to adults, enabling children to begin each exercise interval with significantly higher PCr concentrations and leading to an overall lower muscle acidification.

The effects of creatine supplementation on selected factors of tennis specific training.

BACKGROUND: Creatine supplementation is popular among tennis players but it is not clear whether it actually enhances tennis performance. OBJECTIVES: To examine the effects of creatine supplementation on tennis specific performance indices. METHODS: In a randomised, double blind design, 36 competitive male tennis players (24 creatine, mean (SD) age, 22.5 (4.9) years; 12 placebo, 22.8 (4.8) years) were tested at baseline, after six days of creatine loading, and after a maintenance phase of four weeks (14 creatine, 10 placebo). Serving velocity (10 serves), forehand and backhand velocity (three series of 5x8 strokes), arm and leg strength (bench press and leg press), and intermittent running speed (three series of five 20 metre sprints) were measured. RESULTS: Compared with placebo, neither six days nor five weeks of creatine supplementation had a significant effect on serving velocity (creatine: +2 km/h; placebo: +2 km/h, p = 0.90); forehand velocity (creatine: +4 km/h; placebo: +4 km/h, p = 0.80), or backhand velocity (creatine: +3 km/h; placebo: +1 km/h, p = 0.38). There was also no significant effect of creatine supplementation on repetitive sprint power after 5, 10, and 20 metres, (creatine 20 m: -0.03 m/s; placebo 20 m: +0.01 m/s, p = 0.18), or in the strength of the upper and lower extremities. CONCLUSIONS: Creatine supplementation is not effective in improving selected factors of tennis specific performance and should not be recommended to tennis players.

Blood glucose responses and incidence of hypoglycaemia in elite tennis under practice and tournament conditions.

The purpose of the study was to specify the changes in blood glucose concentrations in the course of repeated tournament and practice matches, and to quantify the Incidence of hypoglycaemia in elite tennis players. The study consisted of two parts. In the first, 147 tournament players completed a questionnaire about the incidence of hypoglycaemic symptoms during repeated tennis matches. In the second part of the study, the players participated in two subsequent matches (one singles match followed by a doubles) under (T) tournament (n = 57) and (P) practice (n = 20) conditions. Of the 147 players consulted, 94 (63.9%) reported experiences with hypoglycaemic symptoms during a tennis tournament (n = 80) and/or tennis practice (n = 62). The warm-up period for the second match day was identified as the most sensitive point for the occurrence of hypoglycaemic symptoms (n = 29), compared to the final stages of the first (n = 11) or second match (n = 7). Under both practice and tournament conditions, a significant (p < 0.01) drop in blood glucose concentration was found during the warm-up period for the second match per day (T: from 5.8 +/- 1.4 mmol x L(-1) to 4.3 +/- 0.8 mmol x L(-1) and P: from 5.4 +/- 1.1 mmol x L(-1) to 4.1 +/- 1.5 mmol x L(-1)). In conclusion, precautions should be taken to prevent a sudden drop in blood glucose concentration and hypoglycaemic symptoms during the early stages of a player's second tennis match in one day.

Physiological responses in tennis and running with similar oxygen uptake.

The purpose of the study was to compare selected physiological responses during singles tennis match play and continuous running at a similar mean oxygen uptake (VO2). The study consisted of two main parts, which were separated by 1 week. In the first part, 12 nationally ranked senior tennis players [six females and six males; 47.2 (6.6) years old and 47.0 (5.4) years old, respectively] each completed a 2-h singles tennis match (TE). Mean VO2 during TE [23.1 (3.1) ml.kg(-1). min(-1) for the women and 25.6 (2.8) ml.kg(-1).min(-1) for the men] was measured by a portable spirometry-telemetry system and corresponded to 56% (women) or 54% (men) of their respective maximum VO2. In the second part, the relative VO2 data measured during TE were used to set a similar workload during a 2-h treadmill run at a constant level (RU). At the measured time points, heart rate [140.1 (15.5) beats.min(-1) vs 126.4 (15.1) beats. min(-1)], lactate concentration [1.53 (0.65) mmol.l(-1) vs 1.01 (0.38) mmol.l(-1)] and glucose concentration [5.45 (0.84) mmol.l(-1) vs 4.34 (0.56) mmol.l(-1)] in capillary blood, as well as the respiratory exchange ratio [0.93 (0.03) vs 0.88 (0.03)], were higher (P<0.05) in TE compared to RU. Serum concentrations of free fatty acids increased (P < 0.05) during both work loads [from 0.25 (0.15) mmol.l(-1) to 1.31 (0.44) mmol.l(-1) in TE and from 0.22 (0.17) mmol.l(-1) to 1.24 (0.35) mmol.l(-1) in RU]. Post-exercise urine concentrations of epinephrine [0.17 (0.14) micromol.l(-1) vs 0.08 (0.04) micromol.l(-1)] and norepinephrine [1.27 (0.59) micromol.l(-1) vs. 0.55 (0.33) micromol.l(-1)] were higher in TE (P<0.05). These results indicate a stronger metabolic emphasis on glycolysis and glycogenolysis and an overall enhanced sympathoadrenal activity during tennis match play compared to continuous running exercise at a similar mean VO2.

Urine catecholamine concentrations and psychophysical stress in elite tennis under practice and tournament conditions.

BACKGROUND: The purpose of the study was to specify and define the differences of psychophysical stress in elite tennis players under practice and tournament conditions. METHODS: Basal, pre- and postcompetition urine samples of 26 nationally ranked players (NR) were analysed for concentrations of epinephrine (EPI) and norepinephrine (NE) under practice (P) and tournament conditions (T). Results were completed by the values obtained from two internationally ranked players (IR) competing in 6 (player A) and 5 (player B) Davis-Cup matches, respectively. RESULTS: In NR, pre- and postcompetition concentrations for EPI were significantly higher under tournament conditions (T: 1.33+/-0.65 and 3.66+/-2.51 microg/100 mg creatinine vs P: 0.61+/-0.39 and 0.97+/-0.59 microg/100 mg creatinine). The NE/EPI ratio showed significantly inverse results (T: 3.53+/-1.87 and 3.58+/-1.59 vs P: 8.08+/-6.99 and 10.03+/-6.58), whereas the concentration of NE did not differ between the two conditions. Significant correlations were found between the level of perceived nervousness (ten-point-likert scale) and the postcompetition concentration of EPI (r=0.491, p<0.05) and the NE/EPI ratio (r=-0.595, p<0.01). Players who felt affected by nervousness in their performance outcome showed significantly lower NE/EPI ratios (2.73+/-1.44 vs 4.49+/-2.54, p<0.05). The Davis-Cup-Players showed intra-individually constant but inter-individually different concentrations of EPI (A= 2.2+/-0.5 vs B= 7.0+/-0.8 microg/100 mg creatinine), NE (A= 7.4+/-2.2 vs B= 15.5+/-3.2 microg/100 mg creatinine) and the ratio of NE/EPI (A= 3.7+/-2.2 vs B= 2.2+/-0.7). CONCLUSIONS: In tennis tournaments, sympathetic activity is increased due to a higher psychological stress which may impair performance. Practical efforts should focus on psycho-regulative methods and psychophysical regeneration for players dealing with a chronic sympathetic hyper-activation.

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.

Effect of Carbohydrates and Caffeine on Plasma Amino Acids, Neuroendocrine Responses and Performance in Tennis.

Effects of carbohydrate (CHO) and caffeine (CAF) in amounts typically found in sports-drinks on plasma metabolites, neuroendocrine responses and performance in tennis were investigated in 8 skilled players during a 4 h tennis match. In 3 trials players ingested a placebo (T I), a CAF (T II) or a CHO (T III) drink during court changeover. Total intake consisted of 2.81 of fluid, supplemented with 243 g CHO or with 364 mg CAF, respectively. Self-perceived "drive/motivation" and post-exercise hitting accuracy were evaluated. Plasma free fatty acids increments were lower after CHO while CAF administration had no effect. In all trials, plasma branched-chain amino acids (BCAA) concentrations decreased as a result of exercise; however, no differences were observed between trials. Plasma free tryptophan (TRP) to BCAA ratio was augmented in T I and T II while no change from basal level was found in T III. Plasma prolactin (PRL) and growth hormone (HGH) concentrations after cessation of exercise were lower in T III compared with T I and T II. No main effect for treatment was found for plasma ACTH, COR and ß-endorphin. Neither supplement affected number of won games. We conclude that CAF ingestion did not affect the plasma large neutral amino acids concentrations, neuroendocrine system responses or tennis performance. Lower plasma free TRP/BCAA ratio induced by CHO occurred concomitant with reduced plasma PRL and HGH concentrations, suggesting that the brain monoaminergic system might be affected if CHO-containing drinks are consumed during tennis match play. However, the data do not point towards an ergogenic value of reduced plasma free TRP/BCAA ratio.

Effect of exercise intensity on free tryptophan to branched-chain amino acids ratio and plasma prolactin during endurance exercise.

The potential of exercise-induced changes in peripheral amino acids to alter blood prolactin levels through a serotonergic system modification was investigated in 8 male athletes. In two trials, subjects (N = 8) exercised on a cycle ergometer for 5 hr. The intensity of exercise corresponded to 55% VO2max (T55) or 75% VO2max (T75), respectively. In each trial, each subject received a 25-g energy bar (111 kcal) every 60 min, as well as 300 ml of a 6% carbohydrate solution (90 kcal) every 30 min of exercise duration. Plasma glucose and insulin declined (p < or = .05) in both trials during exercise. Ammonia was augmented (p < or = .05) above the baseline concentration after 120 min in both trials. During the last 2 hr of exercise, plasma free fatty acids were higher (p < or = .05) in T75 than in T55. During this time, the plasma free TRP/BCAA ratio was also augmented (p < or = .05) in T75, while no change was induced in T55. Plasma prolactin did not change in T55, while an increase (p < or = .05) was found in T75. The findings may further support the hypothesis that during endurance exercise changes in peripheral amino acid concentration may influence prolactin response via serotonergic system modifications.

Metabolic and ergogenic effects of carbohydrate and caffeine beverages in tennis.

OBJECTIVE: Metabolic and ergogenic effects of carbohydrate and caffeine concentrations, common in commercial available beverages, were investigated in 16 tournament players (8 males and 8 females) during a 4 hrs interrupted tennis match (30 min rest after 150 min). METHODS: On three double-blind occasions players ingested a placebo (PLA), carbohydrate (CHO) or caffeine drink (CAF) at court changeover and during the resting period. In men (women) total intake consisted of 2.8 l (2.0 l) fluid, supplemented with 243 g (182 g) carbohydrates (CHO) or with 364 mg (260 mg) caffeine (CAF), respectively. Postexercise all players performed a ball-machine test (BMT) and a tennis-sprint test (TST). RESULTS: During match play blood glucose (GLU) was higher in CHO and did not differ between CAF and PLA. Immediately after the resting period GLU temporary declined in CHO and PLA, while no significant changes occurred in CAF. Increases of serum FFA and glycerol as well as the decrease of insulin were similar during the PLA and CAF trials and less pronounced in CHO. Postexercise urine concentrations of epinephrine and caffeine were significantly higher in CAF. Perception ratings and hitting accuracy (BMT) were not affected by treatment. CHO resulted in higher blood lactate levels during match play and a better post-exercise sprint performance (TST). Under CAF women won significantly more games than during both other treatments. CONCLUSIONS: CHO enhances tennis-specific running-speed but has no ergogenic effect on tennis performance under the conditions of our study. CAF improves glucose homeostasis at the beginning of work load after rest and may increase tennis success in women.

Effects of tennis training on lipid metabolism and lipoproteins in recreational players.

OBJECTIVE: To investigate the short term effects of tennis training on lipid metabolism and to find out if a typical tennis training programme has positive longitudinal effects on cardiovascular risk factors in recreational players. METHODS: The experimental design consisted of an exercise study and a subsequent longitudinal study. In the exercise study the short term metabolic effects of a two hour technically orientated tennis training (TT) session and a running intensive tennis training (RIT) session were investigated in 16 recreational tennis players (eight men: 46 (SD 7) years, 177 (6) cm, 81 (10) kg; and eight women: 44 (5) years, 165 (5) cm, 64 (6) kg). In the longitudinal study the long term effects of a six week RIT programme in 22 players (11 men and 11 women) of similar characteristics were compared with those in 16 control subjects (eight men and eight women). The results of the exercise study (higher lipolytic activity and cardiopulmonary demand, as well as acceptance by the players) led to the RIT method being chosen for all training sessions in the longitudinal study. RESULTS: In RIT, significantly higher values for heart rate (148 (SD 10) v 124 (11) beats/minute) and lactate (2.8 (1.1) v 1.5 (0.6) mmol/l), significantly higher post exercise concentrations of serum glycerol (0.37 (0.15) v 0.29 (0.14) mmol/l) and high density lipoprotein cholesterol (1.31 (0.55) v 1.20 (0.50) mmol/l) and a higher acceptance than in TT (15 of the 16 players preferred RIT) were found. During the six week tennis training programme the changes in body weight (-1.41 (1.56) v 0.00 (1.50) kg) and anaerobic threshold (1.04 (0.84) v -0.08 (0.92) km/h) were significantly different between the training and control group. In the training group several parameters of the lipoprotein profile tended to change in an antiatherosclerotic direction. CONCLUSIONS: The results indicate that typical regular tennis training influences cardiovascular risk factors in a positive manner and can be suggested as an attractive alternative to other current health orientated sports programmes. A more frequent use of running intensive exercises during tennis training is recommended.