Effects of 6 weeks of quercetin supplementation on energy, fatigue, and sleep in ROTC cadets.

PURPOSE: To investigate the effects of 6 weeks of quercetin supplementation on energy, fatigue, and sleep quality in young persons conducting military physical training. METHODS: Using a randomized, double-blind, repeated-measures, placebo-controlled design, 58 healthy, moderately trained men and women were assigned to quercetin group and placebo group. Energy, fatigue, and sleep quality were evaluated before, in the middle, at the end, and 2 weeks following 42 to 54 days of supplementation with 1 g/day of quercetin in a soft chew or a placebo. RESULTS: Changes in energy and fatigue, assessed by the Profile of Mood States-Brief and the Mental and Physical State Energy and Fatigue Scales, and changes in sleep quality, measured by the Pittsburgh Sleep Quality Index were not significantly different (p > 0.05) in quercetin and placebo groups. CONCLUSION: Six weeks of quercetin supplementation in young persons conducting military physical training does not influence energy, fatigue, or sleep quality.

Effect of sprint interval training on circulatory function during exercise in sedentary, overweight/obese women.

Very high-intensity, low-volume, sprint interval training (SIT) increases muscle oxidative capacity and may increase maximal oxygen uptake ([Formula: see text]), but whether circulatory function is improved, and whether SIT is feasible in overweight/obese women is unknown. To examine the effects of SIT on [Formula: see text] and circulatory function in sedentary, overweight/obese women. Twenty-eight women with BMI > 25 were randomly assigned to SIT or control (CON) groups. One week before pre-testing, subjects were familarized to [Formula: see text] testing and the workload that elicited 50% [Formula: see text] was calculated. Pre- and post-intervention, circulatory function was measured at 50% of the pre-intervention [Formula: see text], and a GXT was performed to determine [Formula: see text]. During the intervention, SIT training was given for 3 days/week for 4 weeks. Training consisted of 4-7, 30-s sprints on a stationary cycle (5% body mass as resistance) with 4 min active recovery between sprints. CON maintained baseline physical activity. Post-intervention, heart rate (HR) was significantly lower and stroke volume (SV) significantly higher in SIT (-8.1 and 11.4%, respectively; P < 0.05) during cycling at 50% [Formula: see text]; changes in CON were not significant (3 and -4%, respectively). Changes in cardiac output ([Formula: see text]) and arteriovenous oxygen content difference [(a - v)O(2) diff] were not significantly different for SIT or CON. The increase in [Formula: see text] by SIT was significantly greater than by CON (12 vs. -1%). Changes by SIT and CON in HR(max) (-1 vs. -1%) were not significantly different. Four weeks of SIT improve circulatory function during submaximal exercise and increases [Formula: see text] in sedentary, overweight/obese women.

Effects of six weeks of quercetin supplementation on physical performance in ROTC cadets.

OBJECTIVE: To investigate the effects of 6 weeks of quercetin supplementation on physical performance during military physical training. METHODS: Using a randomized, double-blind, repeated-measures, placebo-controlled design, 58 healthy, moderately trained men and women were randomly assigned to quercetin (Q) or placebo (P) groups. Peak oxygen uptake (VO(2peak)) during maximal effort uphill treadmill running and four physical performance measures (Army Physical Fitness Test, [APFT], Baumgartner Modified Pull-Up Test [BMPU], Wingate Anaerobic Test [WanT], and a 36.6-m sprint) were evaluated before and after 42-54 days of supplementation with 1 g/d of quercetin with vitamins and other substances in a soft chew or placebo chew. RESULTS: Pretreatment-to-posttreatment changes in VO(2peak) and physical performance were not significantly different (p > 0.05) in Q and P. CONCLUSIONS: Six weeks of dietary quercetin supplementation in moderately trained individuals conducting military physical training did not improve VO(2peak) or performance on the APFT, BMPU, WAnT, and 36.6-m sprint.

Dietary quercetin supplementation is not ergogenic in untrained men.

Quercetin supplementation increases muscle oxidative capacity and endurance in mice, but its ergogenic effect in humans has not been established. Our study investigates the effects of short-duration chronic quercetin supplementation on muscle oxidative capacity; metabolic, perceptual, and neuromuscular determinants of performance in prolonged exercise; and cycling performance in untrained men. Using a double-blind, pretest-posttest control group design, 30 recreationally active, but not endurance-trained, young men were randomly assigned to quercetin and placebo groups. A noninvasive measure of muscle oxidative capacity (phosphocreatine recovery rate using magnetic resonance spectroscopy), peak oxygen uptake (Vo(2peak)), metabolic and perceptual responses to submaximal exercise, work performed on a 10-min maximal-effort cycling test following the submaximal cycling, and voluntary and electrically evoked strength loss following cycling were measured before and after 7-16 days of supplementation with 1 g/day of quercetin in a sports hydration beverage or a placebo beverage. Pretreatment-to-posttreatment changes in phosphocreatine recovery time constant, Vo(2peak,) substrate utilization, and perception of effort during submaximal exercise, total work done during the 10-min maximal effort cycling trial, and voluntary and electrically evoked strength loss were not significantly different (P > 0.05) in the quercetin and placebo groups. Short duration, chronic dietary quercetin supplementation in untrained men does not improve muscle oxidative capacity; metabolic, neuromuscular and perceptual determinants of performance in prolonged exercise; or cycling performance. The null findings indicate that metabolic and physical performance consequences of quercetin supplementation observed in mice should not be generalized to humans.

Effect of intensity of resistance exercise on postprandial lipemia.

The purpose of this study is to determine whether moderate-intensity resistance exercise (MOD) lowers postprandial lipemia (PPL) as much as high-intensity resistance exercise (HI) of equal work. Ten healthy men performed three trials, each conducted over 2 days. On day 1 of each treatment, they either did not exercise (CON), performed 3 sets of 16 repetitions of 10 exercises at 50% of 8 repetitions maximum (MOD), or performed 3 sets of 8 repetitions of 10 exercises at 100% of 8 repetitions maximum (HI). On the morning of day 2 at 15.5 h postexercise, participants ate a high-fat meal. Venous blood samples were collected, and metabolic rate was measured at rest and 3 h postprandial. HI reduced fasting triglyceride (TG) and TG area under the curve (AUC) (36%, P = 0.011 and 35%, P = 0.014) compared with CON. MOD tended to reduce fasting TG and TG AUC (21%, P = 0.054 and 26%, P = 0.052) compared with CON, but MOD and HI did not differ in fasting TG or TG AUC. Incremental TG AUC did not differ among treatments. MOD and HI did not change resting metabolic rate. HI increased fat oxidation at rest (21%, P = 0.021) and at 3 h postprandial (39%, P = 0.009) relative to CON. MOD tended to increase fat oxidation at rest (18%, P = 0.060) relative to CON. Fat oxidation and metabolic rate did not differ in MOD and HI. MOD and HI increased the fasting quantitative insulin-sensitivity check index (4%, P = 0.001 and P = 0.004) relative to CON. As MOD and HI resulted in similar reductions in PPL and increases in fat oxidation, resistance exercise intensity does not influence PPL.