Athlete perceptions of flavored, menthol-enhanced energy gels ingested prior to endurance exercise in the heat.

Background: L-menthol evokes a cooling sensation by activating cold sensing cation channels. Menthol-enhanced fluids can be ergogenic during exercise in the heat by improving thermal perception; hence, the addition of menthol to energy gels may benefit athletes. Previously, unflavored menthol gels were deemed acceptable at 0.1% concentration, but no research has been undertaken on menthol gels with additional flavoring. Therefore, we determined athlete perceptions of flavored energy gels with different menthol concentrations. Methods: With a randomized, crossover, double-blind, placebo-controlled design, 27 athletes (34.8 ± 6.7 y, 9 females) ingested an energy gel with either 0.1%, 0.3%, 0.5%, or 0.7% menthol concentration, or a non-menthol, flavor-matched placebo (CON), on separate occasions before outdoor exercise. Gels were rated for cooling sensation, irritation, flavor, and overall experience on 100-point sensory and hedonic labeled magnitude scales. The duration of any cooling sensation was also reported. Results: All menthol gels delivered a greater cooling sensation compared to CON (7.4 ± 8.1 AU) with a significantly greater response for 0.7% (59.9 ± 20.5 AU) and 0.5% (57.7 ± 21.8 AU), compared to all others. Irritation was higher for all menthol gels compared to CON (3.4 ± 7.2 AU) and for 0.7% compared to 0.1% (31.1 ± 31.0 vs. 16.3 ± 21.0 AU, p = 0.041), with none rated above a 'mild-moderate' intensity. The menthol gels delivered a significantly longer cooling sensation duration (12.3-19.6 min) versus CON (2.2 ± 4.8 min) with no difference between menthol gels. Conclusion: A flavored menthol energy gel at 0.1-0.7% concentration provides a cooling sensation for athletes when ingested before exercise. The 0.5% concentration is recommended to maximize the cooling sensation whilst minimizing irritation.

Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis.

BACKGROUND: Musculoskeletal injuries are the most common complaint in active populations. More than 50% of all injuries in sports can be classified as sprains, strains, ruptures, or breaks of musculoskeletal tissues. Nutritional and/or exercise interventions that increase collagen synthesis and strengthen these tissues could have an important effect on injury rates. OBJECTIVE: This study was designed to determine whether gelatin supplementation could increase collagen synthesis. DESIGN: Eight healthy male subjects completed a randomized, double-blinded, crossover-design study in which they consumed either 5 or 15 g of vitamin C-enriched gelatin or a placebo control. After the initial drink, blood was taken every 30 min to determine amino acid content in the blood. A larger blood sample was taken before and 1 h after consumption of gelatin for treatment of engineered ligaments. One hour after the initial supplement, the subjects completed 6 min of rope-skipping to stimulate collagen synthesis. This pattern of supplementation was repeated 3 times/d with ≥6 h between exercise bouts for 3 d. Blood was drawn before and 4, 24, 48, and 72 h after the first exercise bout for determination of amino-terminal propeptide of collagen I content. RESULTS: Supplementation with increasing amounts of gelatin increased circulating glycine, proline, hydroxyproline, and hydroxylysine, peaking 1 h after the supplement was given. Engineered ligaments treated for 6 d with serum from samples collected before or 1 h after subjects consumed a placebo or 5 or 15 g gelatin showed increased collagen content and improved mechanics. Subjects who took 15 g gelatin 1 h before exercise showed double the amino-terminal propeptide of collagen I in their blood, indicating increased collagen synthesis. CONCLUSION: These data suggest that adding gelatin to an intermittent exercise program improves collagen synthesis and could play a beneficial role in injury prevention and tissue repair. This trial was registered at the Australian New Zealand Clinical Trials Registry as ACTRN12616001092482.

Effects of lowering body temperature via hyperhydration, with and without glycerol ingestion and practical precooling on cycling time trial performance in hot and humid conditions.

BACKGROUND: Hypohydration and hyperthermia are factors that may contribute to fatigue and impairment of endurance performance. The purpose of this study was to investigate the effectiveness of combining glycerol hyperhydration and an established precooling technique on cycling time trial performance in hot environmental conditions. METHODS: Twelve well-trained male cyclists performed three 46.4-km laboratory-based cycling trials that included two climbs, under hot and humid environmental conditions (33.3 ± 1.1°C; 50 ± 6% r.h.). Subjects were required to hyperhydrate with 25 g.kg-1 body mass (BM) of a 4°C beverage containing 6% carbohydrate (CON) 2.5 h prior to the time trial. On two occasions, subjects were also exposed to an established precooling technique (PC) 60 min prior to the time trial, involving 14 g.kg-1 BM ice slurry ingestion and applied iced towels over 30 min. During one PC trial, 1.2 g.kg-1 BM glycerol was added to the hyperhydration beverage in a double-blind fashion (PC+G). Statistics used in this study involve the combination of traditional probability statistics and a magnitude-based inference approach. RESULTS: Hyperhydration resulted in large reductions (-0.6 to -0.7°C) in rectal temperature. The addition of glycerol to this solution also lowered urine output (330 ml, 10%). Precooling induced further small (-0.3°C) to moderate (-0.4°C) reductions in rectal temperature with PC and PC+G treatments, respectively, when compared with CON (0.0°C, P<0.05). Overall, PC+G failed to achieve a clear change in cycling performance over CON, but PC showed a possible 2% (30 s, P=0.02) improvement in performance time on climb 2 compared to CON. This improvement was attributed to subjects' lower perception of effort reported over the first 10 km of the trial, despite no clear performance change during this time. No differences were detected in any other physiological measurements throughout the time trial. CONCLUSIONS: Despite increasing fluid intake and reducing core temperature, performance and thermoregulatory benefits of a hyperhydration strategy with and without the addition of glycerol, plus practical precooling, were not superior to hyperhydration alone. Further research is warranted to further refine preparation strategies for athletes competing in thermally stressful events to optimize health and maximize performance outcomes.