Purpose. To aim of this study was to analyze the effects of maltodextrin supplementation on cardiovascular and performance parameters during simulated Mountain Biking (MTB) competition as well as the cardiorespiratory and blood glucose (BG) response to a maximal test performed in a laboratory on elite MTB athletes. Methods. A total of eight male bikers [age: 28.4 ± 10.6 years; body fat: 9.46 ± 3.76 %; VO2max: 55.31 ± 4.7 mL/kg/min], participated in a double-blind study. The athletes received maltodextrin supplementation (1g/kg) or a placebo (light tangerine juice) 20 min before competition (seven 2 km laps) or before a laboratory maximal test. An incremental exercise test on a cycloergometer was performed to find any alterations in maximal HR, Watts max, VO2max, VEmax, and VO2 at the ventilatory threshold (VT), using a gas exchange analyzer. Comparisons between the simulated competition and laboratory variables (maltodextrin vs. placebo) were made using ANOVA and a two-tailed paired Student's t-test, where p < 0.05 was considered statistically significant. Results. Maltodextrin supplementation reduced 26 s in the mean time spent on completing all laps (Maltodextrin: 9 min and 16 s vs. placebo: 9 min and 35 s; p < 0.05). In laboratory testing, maltodextrin raised BG during exercise (Maltodextrin: 104.1 ± 20.9 mg/dL vs. placebo: 88.2 ± 5.3 mg/dL; p < 0.05), power output at the ventilatory threshold (Maltodextrin: 260.8 ± 12.9 vs. placebo: 150.5 ± 8.7; p < 0.05) but had no effect on cardiorespiratory variables. Conclusion. Maltodextrin was found to enhance athletic performance during MTB competition, showing that it can play an important role in supplementation strategies for these competitors.
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Purpose. The present study investigated whether L-arginine supplementation reduces blood pressure (BP) in hypertensive subjects with different ACE genotypes. Methods. Eight male hypertensive patients received L-arginine (2 or 4 g/day) or a placebo for a period of 4 days prior an exercise test. Statistical analysis consisted of one-way analysis of variance. Results. L-arginine supplementation induced a statistically significant (p ⋋ 0.05) reduction in systolic BP measured during rest (reductions of 7.8% and 12.3% with 2 and 4 g/day, respectively), exercise (reductions of 11.8% and 10.4% with 2 and 4 g/day, respectively), and recovery (reductions of 11.7% and 10.7% with 2 and 4 g/day, respectively). The observed magnitude of BP reduction suggests an association with ACE polymorphism; a larger effect was seen with the II and DI genotypes compared with the DD genotype (II: 121 mmHg and DI: 133 mmHg vs. DD: 144 mmHg). Conclusions. The results showed that L-arginine supplementation at low doses was efficient in reducing BP and that vasodilator actions that occurred through the secretion of nitric oxide might be ACE genotype dependent.
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