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Background: The benefits of oral caffeine intake to enhance several aspects of physical performance, such as aerobic endurance, strength, power, and muscle endurance performance, are well supported. However, how the physical performance benefits of caffeine supplementation are translated into better specific actions in intermittent sports during real or simulated competition has been the topic of fewer investigations, and their results need to be appropriately reviewed and meta-analyzed. Objective: The aim of the study was to investigate the effects of acute caffeine intake on specific actions in intermittent sports involving decision making and high-intensity efforts (eg, team, racket, and combat sports) during real or simulated competitions. Methods: All studies included had blinded and crossover experimental designs, and we conducted a risk-of-bias analysis. In total, we included 24 studies. A meta-analysis was performed using the random-effects model to calculate the standardized mean difference (SMD) estimated by Hedges g and 95% CIs. Results: Caffeine ingestion increased high-intensity sport-specific actions during competition, such as the number of sprints (SMD: 0.48; 95% CI, 0.23–0.74), body impacts (SMD: 0.28; 95% CI, 0.08–0.49), accelerations (SMD: 0.35; 95% CI, 0.06–0.63), decelerations (SMD: 0.63; 95% CI, 0.12–1.14), and high-intensity offensive efforts (SMD: 0.36; 95% CI, 0.11–0.61). Additionally, caffeine ingestion induced a higher positive or success rate of actions during real or simulated competition (SMD: 0.44; 95% CI, 0.19–0.69). Conclusion: The current meta-analysis provides evidence of caffeine supplementation in increasing high-intensity efforts and the success rate of sport-specific actions during real or simulated competition. [ABSTRACT FROM AUTHOR]

There are no scientific data about the effects of caffeine intake on volleyball performance. The aim of this study was to investigate the effect of a caffeine-containing energy drink to enhance physical performance in male volleyball players. A double-blind, placebo-controlled, randomized experimental design was used. In 2 different sessions separated by 1 wk, 15 college volleyball players ingested 3 mg of caffeine per kg of body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60 min, participants performed volleyball-specific tests: standing spike test, maximal squat jump (SJ), maximal countermovement jump (CMJ), 15-s rebound jump test (15RJ), and agility T-test. Later, a simulated volleyball match was played and recorded. In comparison with the placebo drink, the ingestion of the caffeinated energy drink increased ball velocity in the spike test (73 ± 9 vs 75 ± 10 km/h, P < .05) and the mean jump height in SJ (31.1 ± 4.3 vs 32.7 ± 4.2 cm, P < .05), CMJ (35.9 ± 4.6 vs 37.7 ± 4.4 cm, P < .05), and 15RJ (29.0 ± 4.0 vs 30.5 ± 4.6 cm, P < .05). The time to complete the agility test was significantly reduced with the caffeinated energy drink (10.8 ± 0.7 vs 10.3 ± 0.4 s, P < .05). In addition, players performed successful volleyball actions more frequently (24.6% ± 14.3% vs 34.3% ± 16.5%, P < .05) with the ingestion of the caffeinated energy drink than with the placebo drink during the simulated game. A caffeine-containing energy drink, with a dose equivalent to 3 mg of caffeine per kg body mass, might be an effective ergogenic aid to improve physical performance and accuracy in male volleyball players. [ABSTRACT FROM AUTHOR]

The aim was to analyze the influence of competitive round on muscle strength, body-fluid balance, and renal function in elite badminton players during a real competition. Body mass, jump height during a countermovement jump, handgrip force, and urine samples were obtained from 13 elite badminton players (6 men and 7 women) before and after the 2nd-round and quarterfinal matches of the national Spanish badminton championship. Sweat rate was determined by using prematch-to-postmatch body-mass change and by weighing individually labeled fluid bottles. Sweat rates were 1.04 ± 0.62 and 0.98 ± 0.43 L/h, while rehydration rate was 0.69 ± 0.26 and 0.91 ± 0.52 L/h for the 2nd round and quarterfinals, respectively. Thus, dehydration was 0.47% ± 1.03% after the 2nd round and 0.23% ± 0.43% after the quarterfinals. There were no differences in prematch-to-postmatch jump height, but jump height was reduced from 37.51 ± 8.83 cm after the 2nd-round game to 34.82 ± 7.37 cm after the quarterfinals (P < .05). No significant differences were found in handgrip force when comparing prepost matches or rounds, although there were significant differences between dominant and nondominant hands (P < .05). The succession of rounds caused the appearance of proteinuria, hematuria, glycosuria, and higher nitrite and ketone concentrations in urine. Rehydration patterns during a real badminton competition were effective to prevent dehydration. A badminton match did not affect jump height or handgrip force, but jump height was progressively reduced by the competitive round. Badminton players’ renal responses reflected diminished renal flux due to the high-intensity nature of this racket sport. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Case-control study; ecological study, OBJECTIVES: To examine the efficacy of wearing compression stockings to prevent muscle damage and to maintain running performance during a marathon competition. BACKGROUND: Exercise-induced muscle damage has been identified as one of the main causes of the progressive decrease in running and muscular performance found during marathon races, METHODS: Thirty-four experienced runners were pair-matched for age, anthropometric data, and best race time in the marathon, and randomly assigned to a control group (n = 17) of runners who wore conventional socks or to a group of runners who wore foot-to-knee graduated compression stockings (n = 17). Before and after the race, a sample of venous blood was obtained, and jump height and leg muscle power were measured during a countermovement jump. Serum myoglobin and creatine kinase concentrations were determined as blood markers of muscle fiber damage. RESULTS: Total race time was not different between the control group and the compression stockings group (210 ± 23 and 214 ± 22 minutes, respectively; P = .58). Between the control group and the compression stockings group, postrace reductions in leg muscle power (-19.8% ± 17.7% versus -24.8% ± 18.4%, respectively; P = .37) and jump height (-25.3% ± 14.1% versus -32.5% ± 20.4%, respectively; P = .27) were similar. At the end of the race, there were no differences between the control group and the compression stockings group in serum myoglobin (568 ± 347 ng⋅mL-1 versus 573 ± 270 ng⋅mL-1 respectively; P = .97) and creatine kinase concentration (390 ± 166 U⋅L-1 versus 487 ± 227 U⋅L-1, respectively; P = .16). CONCLUSION: The use of compression stockings did not improve running pace and did not prevent exercise-induced muscle damage during the marathon. Wearing compression stockings during long-distance running events is an ineffective strategy to avoid the deleterious effects of muscle damage on running performance. LEVEL OF EVIDENCE: Therapy, level 2b. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effectiveness of a caffeine-containing energy drink to enhance physical and match performance in elite badminton players. Sixteen male and elite badminton players (25.4 ± 7.3 year; 71.8 ± 7.9 kg) participated in a double-blind, placebo-controlled and randomised experiment. On two different sessions, badminton players ingested 3 mg of caffeine per kg of body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60 min, participants performed the following tests: handgrip maximal force production, smash jump without and with shuttlecock, squat jump, countermovement jump and the agilityT-test. Later, a 45-min simulated badminton match was played. Players’ number of impacts and heart rate was measured during the match. The ingestion of the caffeinated energy drink increased squat jump height (34.5 ± 4.7 vs. 36.4 ± 4.3 cm;P < 0.05), squat jump peak power (P < 0.05), countermovement jump height (37.7 ± 4.5 vs. 39.5 ± 5.1 cm;P < 0.05) and countermovement jump peak power (P < 0.05). In addition, an increased number of total impacts was found during the badminton match (7395 ± 1594 vs. 7707 ± 2033 impacts;P < 0.05). In conclusion, the results show that the use of caffeine-containing energy drink may be an effective nutritional aid to increase jump performance and activity patterns during game in elite badminton players. [ABSTRACT FROM PUBLISHER]

The use of caffeine containing energy drinks has dramatically increased in the last few years, especially in the sport context because of its reported ergogenic effect. The ingestion of low to moderate doses of caffeinated energy drinks has been associated with adverse side effects such as insomnia or increased nervousness. The aim of the present study was to assess psycho-physiological changes and the prevalence of side effects resulting from the ingestion of 3 mg caffeine/kg body mass in the form of an energy drink. In a double-blind and placebo controlled experimental design, ninety experienced and low-caffeine-consuming athletes (fifty-three male and thirty-seven female) in two different sessions were provided with an energy drink that contained 3 mg/kg of caffeine or the same decaffeinated energy drink (placebo; 0 mg/kg). At 60 min after the ingestion of the energy drink, participants completed a training session. The effects of ingestion of these beverages on psycho-physiological variables during exercise and the rate of adverse side effects were measured using questionnaires. The caffeinated energy drink increased self-perceived muscle power during exercise compared with the placebo beverage (6·41 (sd 1·7) v. 5·66 (sd 1·51); P= 0·001). Moreover, the energy drink produced a higher prevalence of side effects such as insomnia (31·2 v. 10·4 %; P< 0·001), nervousness (13·2 v. 0 %; P= 0·002) and activeness (16·9 v. 3·9 %; P= 0·007) than the placebo energy drink. There were no sex differences in the incidence of side effects (P>0·05). The ingestion of an energy drink with 3 mg/kg of caffeine increased the prevalence of side effects. The presence of these side effects was similar between male and female participants. [ABSTRACT FROM PUBLISHER]

Triathlon is a popular outdoor endurance sport performed under a variety of environmental conditions. The aim of this study was to assess physiological variables before and after a half-ironman triathlon in the heat and to analyse their relationship with performance. Thirty-four well-trained triathletes completed a half-ironman triathlon in a mean dry temperature of 29 ± 3ºC. Before and within 1 min after the end of the race, body mass, core temperature, maximal jump height and venous blood samples were obtained. Mean race time was 315 ± 40 min, with swimming (11 ± 1%), cycling (49 ± 2%) and running (40 ± 3%) representing different amounts of the total race time. At the end of the competition, body mass changed by −3.8 ± 1.6% and the change in body mass correlated positively with race time (r = 0.64;P < 0.001). Core temperature increased from 37.5 ± 0.6ºC to 38.8 ± 0.7ºC (P < 0.001) and post-race core temperature correlated negatively with race time (r = −0.47;P = 0.007). Race time correlated positively with the decrease in jump height (r = 0.38;P = 0.043), post-race serum creatine kinase (r = 0.55;P = 0.001) and myoglobin concentrations (r = 0.39;P = 0.022). In a half-ironman triathlon in the heat, greater reductions in body mass and higher post-competition core temperatures were present in faster triathletes. In contrast, slower triathletes presented higher levels of muscle damage and decreased muscle performance. [ABSTRACT FROM AUTHOR]

Dorsiflexion sport shoes aim to increase jumping capacity and speed by means of a lower position of the heel in comparison with the forefoot, favouring additional stretching of the ankle plantar flexors. In previous studies, contradictory results have been found on the benefits of using this type of shoe. With the aim of comparing a dorsiflexion sport shoe model (DF) with a conventional sport shoe (CS), 41 participants performed a countermovement jump (CMJ) test and an agility test (MAT) with both models of shoe. There were no significant differences in the jump test [CS=35.3 cm (6.4) and DF=35.6 cm (6.4), P>0.05]. In the agility test, the conventional shoe obtained better results than the model with dorsiflexion with regard to time taken to complete the circuit [CS=6236 ms (540) and DF=6377 ms (507), P<0.05)]. In spite of producing pre-stretching of the plantar muscles, the DF sport shoes were not effective for improving either jump power or agility in a specific test. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Randomized clinical trial. To compare the effects of thrust and nonthrust manipulation and exercises with and without the addition of myofascial therapy for the treatment of acute inversion ankle sprain. BACKGROUND: Studies have reported that thrust and nonthrust manipulations of the ankle joint are effective for the management of patients post-ankle sprain. However, it is not known whether the inclusion of soft tissue myofascial therapy could further improve clinical and functional outcomes. METHODS: Fifty patients (37 men and 13 women; mean ± SD age, 33 ± 10 years) post-acute inversion ankle sprain were randomly assigned to 2 groups: a comparison group that received a thrust and nonthrust manipulation and exercise intervention, and an experimental group that received the same protocol and myofascial therapy. The primary outcomes were ankle pain at rest and functional ability. Additionally, ankle mobility and pressure pain threshold over the ankle were assessed by a clinician who was blinded to the treatment allocation. Outcomes of interest were captured at baseline, immediately after the treatment period, and at a 1-month follow-up. The primary analysis was the group-by-time interaction. RESULTS: The 2-by-3 mixed-model analyses of variance revealed a significant group-by-time interaction for ankle pain (P<.001) and functional score (P = .002), with the patients who received the combination of nonthrust and thrust manipulation and myofascial intervention experiencing a greater improvement in pain and function than those who received the nonthrust and thrust manipulation intervention alone. Significant group-by-time interactions were also observed for ankle mobility (P<.001) and pressure pain thresholds (all, P<.01), with those in the experimental group experiencing greater increases in ankle mobility and pressure pain thresholds. Between-group effect sizes were large (d>0.85) for all outcomes. CONCLUSION: This study provides evidence that, in the treatment of individuals post-inversion ankle sprain, the addition of myofascial therapy to a plan of care consisting of thrust and nonthrust manipulation and exercise may further improve outcomes compared to a plan of care solely consisting of thrust and nonthrust manipulation and exercise. However, though statistically significant, the difference in improvement in the primary outcome between groups was not greater than what would be considered a minimal clinically important difference. Future studies should examine the long-term effects of these interventions in this population. LEVEL OF EVIDENCE: Therapy, level lb- [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study is to determine the effects of a caffeine-containing energy drink on female volleyball players' performance. Methods: Thirteen elite female volleyball players ingested 3 mg·kg-1 of caffeine with an energy drink or the same drink without caffeine (placebo drink) in a double-blind and randomized study. Then, participants performed the following: standing spike, jumping spike, spike jump, blocking jump, squat jump, counter movement jump, manual dynamometry, and the agility t-test. A simulated volleyball game was played, videotaped, and notated afterward. Results: In comparison to the placebo drink, the ingestion of the caffeinated energy drink increased the ball velocity in the standing spike (19.2 ± 2.1 vs 19.7 ± 1.9 m.s-1, P = 0.023) and in the jumping spike (17.9 ± 2.2 vs 18.8 ± 2.2 m.s-1, P = 0.038) and the jump height in the squat jump (28.1 ± 3.2 vs 29.4 ± 3.6 cm, P = 0.028), countermovement jump (32.0 ± 4.6 vs 33.1 ± 4.5 cm, P = 0.018), spike jump (43.3 ± 4.7 vs 44.4 ± 5.0 cm, P = 0.025), and block jump (35.2 ± 5.1 vs 36.1 ± 5.1 cm, P = 0.044). Furthermore, the caffeinated energy drink decreased the time needed to complete the agility t-test (11.1 ± 0.5 vs 10.9 ± 0.3 s, P = 0.036). During the game, the volleyball actions categorized as successful were more frequent with the caffeinated energy drink (34% ± 9% vs 45% ± 9%, P < 0.001), whereas imprecise actions decreased (28% ± 7% vs 14% ± 9%, P < 0.001) when compared with the placebo drink. Conclusion: Commercially available energy drinks can significantly improve physical performance in female volleyball players. Increased physical performance led to improved accuracy during an actual volleyball match. [ABSTRACT FROM AUTHOR]