The Physiological Effects of Capsaicinoid Ingestion on Human Metabolism and Exercise Performance

Capsaicinoids (the active ingredient in hot peppers) have been shown to cause a moderate increase in energy expenditure (50 kcal/day) as well as reductions in appetite, energy intake, and (visceral) adiposity. As such, there is considerable interest in capsaicinoid for weight loss supplements. Owing to the fact that these changes are believed to be driven by catecholamine release and alterations in fat oxidation, there is growing belief that capsaicin may also offer potential ergogenic benefits (performance enhancement) during exercise, similar to the affect of caffeine, which works through similar pathways. Of particular interest are the recent findings that free-fatty acids in the blood are elevated 2-2.5hrs post ingestion, yet changes in typical cardiovascular or sympathetic nervous tone indicators (heart rate, blood pressure) were unaffected, suggesting some of the negative consequences of other stimulants may be avoided. At present, however, more in depth investigations of the effects on endothelial function, vascular autonomic tone and inflammation are lacking.

Although there are some indications that capsaicinoid ingestion may alter factors associated exercise performance (such as increased fat oxidation for glucose sparing), to date these studies have primarily used very low exercise intensities wherein these effects are typically unnecessary, and results are not generalizable to the typical race intensities of endurance sport competition. Performance measures have also been a noticeably absent outcome from research to date.

Hypotheses: 1), Exercise performance will improve, at a level similar to those demonstrated for caffeine ingestion 2) ratings of perceived exertion will go down with the effect of causing intensity to go up 3) During sustained aerobic activity approaching the aerobic threshold alterations in substrate use will be minimal (but possibly meaningful in regard to performance); alterations at rest will be more pronounced. 4) acute alterations (6o min post single dose) in blood pressure, HRV, arterial stiffness and RMR will mirror the effects observed for more prolonged exposure in phase 1.