Creatine is a popular ergogenic aid among athletic populations with consistent evidence indicating that creatine supplementation also continues to be commonly used among adolescent populations. In addition, the evidence base supporting the therapeutic benefits of creatine supplementation for a plethora of clinical applications in both adults and children continues to grow. Among pediatric populations, a strong rationale exists for creatine to afford therapeutic benefits pertaining to multiple neuromuscular and metabolic disorders, with preliminary evidence for other subsets of clinical populations as well. Despite the strong evidence supporting the efficacy and safety of creatine supplementation among adult populations, less is known as to whether similar physiological benefits extend to children and adolescent populations, and in particular those adolescent populations who are regularly participating in high-intensity exercise training. While limited in scope, studies involving creatine supplementation and exercise performance in adolescent athletes generally report improvements in a number of ergogenic outcomes with limited evidence of ergolytic properties and consistent reports indicating no adverse events associated with supplementation. The purpose of this article is to summarize the rationale, prevalence of use, performance benefits, clinical applications, and safety of creatine use in children and adolescents.

Literature on the use of nutritional supplements (NS) in tennis players is scarce. The objective of the present study was to evaluate NS consumption in a group of men's tennis players who participated in the 2016 Andalusian team championship. A total of 70 questionnaires from 7 different clubs were registered. The questionnaire was previously designed and evaluated through piloting in which the validity of the content, its application, its structure and its presentation were observed. The results showed that 100% of the sample group was in favor of NS consumption within the law, 88.6% claimed to have consumed them at some time and 61.4% presently consume them. The NS most consumed by study participants were sports drinks (69.35%), energy bars (29%), a vitamin complex (19.35%), protein (serum) (17.74%) and creatine (14.51%). A high percentage of NS consumers thought that they had obtained positive results from NS consumption. The percentages and the findings regarding NS consumption in the present study were similar to the contributions made by other studies which evaluated supplementation in athletes, although with some subtle differences.

Background: Caffeine is an ergogenic aid that still needs to be investigated in female sports per-formance. Methods: Eight semi-professional female volleyball (Heigth=1.63±0.08 m; Weigth= 66.67 ± 4,.74 kg) players voluntarily participated in this study. A randomised crossover design was carried out. Players went through the caffeine and placebo condition. In the caffeine condi-tion, participants consumed 5 mg/kg of caffeine. The evaluations were performed over two weeks of training. In both conditions, the countermovement jump test, repeated jumps for 15s and hand-grip were performed. Change of direction was assessed using the 505 test. Well-being was also assessed by a wellness questionnaire. A repeated measures Anova and correlation analysis were performed. Results: The repeated-measures ANOVA revealed a main effect of supplementation (F (1.7) = 8.41, p = 0.02, η2 = 0.54) across the training week on physical performance. Besides, there was a positive effect on perceived fatigue (F (1.7) = 7.29, p = 0.03, η2 = 0.51). Conclusions: Caf-feine improved performance and fatigue parameters over one week of training.

We investigated whether post-exercise capsinoids (CSN) supplementation could enhance muscle glycogen resynthesis via GLUT4/Akt expressions in human skeletal muscle. Nine male college students (aged 21.4±0.2 years, BMI 21.9±1.3 kg/m2, VO2max 47.1±1.8 ml/kg/min) participated in this crossover designed study, and completed a 60-min cycling exercise at 70% VO2max. Immediately after exercise, participants consumed high-carbohydrate diet (2 g carb/kg bodyweight) with CSN (12 mg, single dosage) or placebo. Biopsied muscle samples (vastus lateralis) were obtained immediately (0h) and 3h after exercise. Blood and expired gas samples were collected before and after exercise. We found oral CSN supplementation immediately after exercise was unable to enhance glycogen resynthesis in exercised human skeletal muscle. Despite, CSN could alter the energy reliance on fat oxidation during post-exercise recovery, based on gaseous exchange measurement (NEFA and glycerol). We further identified no significant differences in postprandial glucose/insulin area under curve in both trials. Western blot data showed no significant response of p-Akt/Akt ratio with CSN during post-exercise recovery. Inconsistent with glycogen levels, muscle GLUT4 expression was significantly elevated at 3h in CSN trial. Our findings emphasize the necessity of further evidences to confirm the ergogenic properties of CSN in connection with glycogen recovery in exercised human skeletal muscle.

The aim of this study was to observe the nutritional supplement practices of highly trained swimmers on a national talent pathway, since it is often reported that swimmers engage in widespread supplement use at the elite level. Thus, this study conducted short interviews based on a validated supplement intake questionnaire with forty-four swimmers from a high-performance swimming club, which had three distinct talent stages: development (aged 11–14 years, n = 20), age-group (aged 13 – 17 years, n = 13), and national level (aged ≥16 years, n = 11). Ninety-eight percent of the interviewed swimmers reported using at least one supplement, with performance (34%) and recovery (19%) cited as the primary reasons. National swimmers used more total supplements (8.1 ± 3.4 supplements) compared to age-group (4.8 ± 2.0 supplements, p = 0.003, g = 1.17) and development (3.9 ± 1.7 supplements, p <0.001, g = 1.69) swimmers, mostly because of a greater intake of ergogenic aids (2.4 ± 1.4 supplements vs. age-group: 0.5 ± 0.5 sup-plements, p <0.001, g = 1.12; vs. development: 0.1 ± 0.2 supplements, p <0.001, g = 1.81). Par-ents/guardians were the primary supplement informants of development swimmers (74%, p <0.001, V = 0.50), whereas performance nutritionists informed ~50% of supplements used by age-group and national swimmers (p <0.001, V = 0.51). Based on these results, supplement edu-cation and greater focus on basic sport nutrition practices may be required for parents/guardians at the development level. Moreover, further research is needed to support the high number of ergogenic aids used by national swimmers, with the efficacy of these supplements currently equivocal in the applied setting.

Adiposity is associated with adverse health conditions such as obesity, cardiovascular disease and type 2 diabetes. The combination of resistance exercise and creatine supplementation has been shown to decrease body fat % in adults ≥ 50 years of age. However, the effects in adults < 50 years of age is unknown. To address this limitation, we systematically reviewed the literature and performed several meta-analyses comparing studies that included resistance exercise and creatine supplementation to resistance exercise and placebo. Twelve studies were included involving 266 participants. Adults (< 50 years of age) that supplemented with creatine and performed resistance exercise experienced a significant reduction in body fat % (-1.19%, p=0.006) and a non-significant reduction in absolute fat mass (-0.09 kg, p=0.88). Collectively, the combination of resistance exercise and creatine supplementation produces a very small reduction in body fat % in adults < 50 years of age.

It has been demonstrated that brief cycles of ischemia followed by reperfusion (IR) applied before exercise can improve performance and, IR intervention, applied immediately after exercise (post-exercise ischemic conditioning – PEIC) exerts a potential ergogenic effect to accelerate recovery. Thus, the purpose of this systematic review with meta-analysis was to identify the effects of PEIC on exercise performance, recovery and the responses of associated physiological parameters, such as creatine kinase, perceived recovery and muscle soreness, over 24 h after its application. From 3281 studies, six involving 106 subjects fulfilled the inclusion criteria. Compared to sham (cuff administration with low pressure) and control interventions (no cuff administration), PEIC led to faster performance recovery (p=0.004; ES=-0.49) and lower increase in creatine kinase (p&lt;0.001; ES=-0.71) and muscle soreness (p&lt;0.001; ES=-0.89) over 24 h. The effectiveness of this intervention is more pronounced in subjects with low/moderate fitness level and at least a total time of 10 min of ischemia (e.g. 2 cycles of 5 min) is necessary to promote positive effects.

The use of isolated supplements to enhance performance is widespread among athletes. The aim of this study was to increase knowledge about the combined effects of caffeine and New Zealand blackcurrant (NZBC) dietary supplements. In this study, two subjects each underwent four phases of four sessions in a double-blind and randomized alternating treatment single-case design. After a 3-week pre-test phase, the supplement combinations of placebo/placebo, caffeine/placebo (5 mg/kg), NZBC/placebo (600 mg), and caffeine/NZBC (5 mg/kg + 600 mg) were taken and weekly performance tests were conducted to examine their effects on relative power (W/kg) during a 20-minute time trial on a bicycle. Data were analyzed descriptively and using the Tau-U calculator from Single Case Research. The ergogenic effect of caffeine was confirmed in both subjects, with increases of 3.3% and 6.5%, while the positive effect of NZBC on performance was only seen in one subject (13.4%). The combination of caffeine and NZBC again increased performance in both subjects (2.2% and 19.2%), but the data only showed an additive effect of the supplements in one subject. Further studies are required to confirm or refute this evidence of the synergistic effects of these supplements.