Caffeine Caffeine is a naturally derived stimulant found in many nutritional supplements typically as gaurana, bissey nut, or kola. Caffeine can also be found in coffee, tea, soft drinks,

energy drinks, and chocolate. It has previously been made clear that caffeine can have a positive effect on energy expenditure, weight loss, and body fat. Caffeine has also been shown to be an effective ergogenic aid. Research investigating the see more effects of caffeine on a time trial in trained cyclist found that caffeine improved speed, peak power, and mean power [411]. Similar results were observed in a recent study that found cyclists who ingested a caffeine drink prior to a time trial demonstrated improvements in performance [412, 413]. Studies indicate

that ingestion of caffeine (e.g., 3-9 mg/kg taken 30 – 90 minutes before exercise) can spare carbohydrate use during exercise and thereby improve endurance exercise capacity [406, 414]. In addition to the apparent positive effects on endurance performance, caffeine has also been shown to improve repeated sprint performance benefiting the selleckchem anaerobic athlete [415, 416]. People who drink caffeinated drinks regularly, however, appear to experience less DZNeP mw ergogenic benefits from caffeine [417]. Additionally, some concern has been expressed that ingestion of caffeine prior to exercise may contribute to dehydration although recent studies have not supported this concern [414, 418, 419]. Caffeine doses above 9 mg/kg can result in urinary caffeine levels that surpass the doping threshold for many sport organizations. Suggestions that there is no ergogenic value to caffeine supplementation is not supported by the preponderance of available scientific studies. β-alanine In recent years research has begun investigating the effects of β-alanine supplementation on performance. β-alanine has ergogenic potential based on its relationship with carnosine. Carnosine is a dipeptide comprised of the amino acids, histidine and β-alanine naturally occurring in large amounts in skeletal muscles. Carnosine

is believed to be one of the primary muscle-buffering substances available in skeletal muscle. Studies have demonstrated that taking β-alanine orally over a 28-day period was effective in increasing carnosine levels [420, 421]. This proposed benefit would increase Sclareol work capacity and decrease time to fatigue. Researchers have found that β-alanine supplementation decreases rate of fatigue [422]. This could translate into definite strength gains and improved performance. A recent study [423] supplemented men with β-alanine for 10 weeks and showed that muscle carnosine levels were significantly increased after 4 and 10 weeks of β-alanine supplementation. Stout et al. [422] conducted a study that examined the effects of β-alanine supplementation on physical working capacity at fatigue threshold. The results showed decreased fatigue in the subjects tested.