Dehydration Lowers Performance In Running Time Trial In Heat
Most studies on the effects of dehydration on endurance performance in the heat are conducted in a controlled, laboratory environment. Researchers from the University of Connecticut recently sought to determine the effects of dehydration on running performance in the heat in the field. Seventeen runners were recruited to complete 12 km trail runs on four occasions. Two of the runs were time trials; one of them was performed in a fully hydrated state, the other in a dehydrated state. The other two runs were moderate efforts; again, one was performed in a hydrated state and the other in a dehydrated state. On average, the runners completed the 12 km time trial roughly 4.5 percent faster when fully hydrated. The runners ran the same pace in the two moderate-pace runs, but their core body temperature and heart rate were higher in the dehydrated run. The authors of the study, which was published in the Journal of Athletic Training, concluded, "A small decrement in hydration status impaired physiologic function and performance while trail running in the heat."
ISSN Issues Position Stand On Caffeine And Performance
The International Society of Sports Nutrition has published a new position on the use and effectiveness of caffeine as an ergogenic aid to exercise performance. Jointly authored by a veritable Who's-Who of sports nutrition experts, the paper reaches the following conclusions: "1.) Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate dosages (~3-6 mg/kg) and overall does not result in further enhancement in performance when consumed in higher dosages (>/= 9 mg/kg). 2.) Caffeine exerts a greater ergogenic effect when consumed in an anhydrous state as compared to coffee. 3.) It has been shown that caffeine can enhance vigilance during bouts of extended exhaustive exercise, as well as periods of sustained sleep deprivation. 4.) Caffeine is ergogenic for sustained maximal endurance exercise, and has been shown to be highly effective for time-trial performance. 5.) Caffeine supplementation is beneficial for high-intensity exercise, including team sports such as soccer and rugby, both of which are categorized by intermittent activity within a period of prolonged duration. 6.) The literature is equivocal when considering the effects of caffeine supplementation on strength-power performance, and additional research in this area is warranted. 7.) The scientific literature does not support caffeine-induced diuresis during exercise, or any harmful change in fluid balance that would negatively affect performance."
Quercetin Increases VO2max, Endurance
Quercetin is a plant nutrient in the "flavanoid" class that functions as an antioxidant, anti-inflammatory, and stimulus for mitochondrial biogenesis in the human body. Researchers at the University of South Carolina recently investigated whether quercetin supplementation increases maximal aerobic capacity and endurance in untrained subjects. Twelve subjects received either 1000 mg of quercetin daily or placebo for seven days. All subjects performed indoor cycling tests before and after the supplementation period. The whole study design was then repeated with the treatments reversed. On average, the subjects exhibited a 3.9 percent increase in VO2max and a 13.2 percent increase in time to exhaustion after quercetin supplementation. The authors of the study, which was published in the International Journal of Sports Nutrition and Exercise Metabolism, concluded, "These data suggest that as little as 7 days of quercetin supplementation can increase endurance without exercise training in untrained participants. These benefits of quercetin may have important implications for enhancement of athletic and military performance. This apparent increase in fitness without exercise training may have implications beyond that of performance enhancement to health promotion and disease prevention."
What's The Shortest Race In Which Drinking Is Beneficial?
It is well known that consuming a sports drink before and during longer running races enhances performance. It is also fairly well established that drinking during short races offers no benefit, and may even do more harm than good (by causing hyperventilation or GI distress). But where is the cutoff? What is the shortest race in which drinking is beneficial? We don't know exactly, and the answer certainly also depends on the individual runner, but a new study by researchers at Loughborough University in England suggests that for moderately high-level runners, drinking a sports drink during a one-hour race is beneficial. Eight trained runners completed one-hour time trials on treadmills on three occasions. They drank flavored water before and during two of the trials and a sports drink during the other. On average, the runners were able to run 2.5 percent farther when they drank the sports drink. Interestingly, most elite male runners capable of running a half marathon under 65 minutes do not drink. They might be better off this way, however, because they are running at a very high percentage of their VO2max and would probably suffer hyperventilation or GI distress if they did try to drink at such high intensities.
