Article

Arginine and antioxidant supplement on performance in elderly male cyclists: a randomized controlled trial

Journal of the International Society of Sports Nutrition (Impact Factor: 1.83). 01/2010; 7(1):1-7. DOI: 10.1186/1550-2783-7-13
Source: PubMed

ABSTRACT BackgroundHuman exercise capacity declines with advancing age. These changes often result in loss of physical fitness and more rapid
senescence. Nitric oxide (NO) has been implicated in improvement of exercise capacity through vascular smooth muscle relaxation
in both coronary and skeletal muscle arteries, as well as via independent mechanisms. Antioxidants may prevent nitric oxide
inactivation by oxygen free radicals. The purpose of this study was to investigate the effects of an L-arginine and antioxidant
supplement on exercise performance in elderly male cyclists.

MethodsThis was a two-arm prospectively randomized double-blinded and placebo-controlled trial. Sixteen male cyclists were randomized
to receive either a proprietary supplement (Niteworks®, Herbalife International Inc., Century City, CA) or a placebo powder. Exercise parameters were assessed by maximal incremental
exercise testing performed on a stationary cycle ergometer using breath-by-breath analysis at baseline, week one and week
three.

ResultsThere was no difference between baseline exercise parameters. In the supplemented group, anaerobic threshold increased by
16.7% (2.38 ± 0.18 L/min, p < 0.01) at week 1, and the effect was sustained by week 3 with a 14.2% (2.33 ± 0.44 L/min, p <
0.01). In the control group, there was no change in anaerobic threshold at weeks 1 and 3 compared to baseline (1.88 ± 0.20
L/min at week 1, and 1.86 ± 0.21 L/min at week 3). The anaerobic threshold for the supplement groups was significantly higher
than that of placebo group at week 1 and week 3. There were no significant changes noted in VO2 max between control and intervention groups at either week 1 or week 3 by comparison to baseline.

ConclusionAn arginine and antioxidant-containing supplement increased the anaerobic threshold at both week one and week three in elderly
cyclists. No effect on VO2 max was observed. This study indicated a potential role of L-arginine and antioxidant supplementation in improving exercise
performance in elderly.

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