In this month’s MSSE, I am highlighting two articles that deal with ergogenic aids: one reports a study investigating performance effects of sodium nitrate ingestion and the other reports a study investigating the phenomenon of the placebo effect, in the context of athletic performance.
Porcelli et al. evaluated the effects of six days of supplementation with sodium nitrate on the physiological and performance responses of 21 young healthy subjects with differing aerobic fitness levels. After sodium nitrate supplementation, the O2 cost of submaximal exercise (about 80% of gas exchange threshold) was decreased and 3-km time trial performance was improved. These improvements were inversely related to individual aerobic fitness level. Notably, subjects with higher fitness showed a lower increase in plasma nitrate and nitrite in response to supplementation, suggesting that the induced changes in nitrate/nitrite concentration may predict the ergogenic benefits of nitrate supplementation. These results are consistent with recent studies suggesting that trained endurance athletes are less likely to benefit from nitrate supplementation [Bescòs et al. Sodium Nitrate Supplementation Does Not Enhance Performance of Endurance Athletes. Med Sci Sports Exerc. 2012;44(12):2400-2409; Boorsma et al. Beetroot Juice Supplementation Does Not Improve Performance of Elite 1500-m Runners. Med Sci Sports Exerc. 2014;46(12):2326-2334; Peacock et al. Dietary Nitrate Does Not Enhance Running Performance in Elite Cross-Country Skiers. Med Sci Sports Exerc. 2012;44(11):2213-2219].
Also in this month’s journal, Ross et al. report a study of the placebo effect on running performance. The placebo effect is well-documented in clinical research, and a number of studies have documented a similar effect for athletic performance when the placebo product is orally administered. However, in clinical research, there is some evidence that injections of placebo produce more pronounced effects than oral administration. Ross et al. had 15 endurance-trained club-level males (personal best 10-km running times of 39.3 ± 4.4 min) self-administer subcutaneous saline injections daily for seven days. These men were told that they were participating in a trial to investigate the effects of a legal erythropoietin-like substance (OxyRBX) designed to induce effects similar to those of recombinant human erythropoietin. In the cross-over designed study, these placebo injections resulted in significantly faster 3-km time trials (≈ -10 s) in comparison to a “control” trial in which no injections were taken (≈ -2 s). While significant, this placebo effect is smaller than those reported for actual erythropoietin administration. Nevertheless, these results serve as a cogent reminder of the often powerful effect of a placebo, and the importance of using well-designed controls for placebo effects in research on ergogenic products.
L. Bruce Gladden