In that exercise capacity declines with advancing age, previous studies have observed that nitric oxide (NO) is implicated in improving exercise capacity, by relaxing vascular smooth muscles in both coronary and skeletal muscle arteries, as well as via independent mechanisms. Zhaoping Li, from University of California/Los Angeles (UCLA; California, USA), and colleagues investigated the effects of a dietary supplement containing antioxidant vitamins and L-arginine, an amino acid, on exercise performance in a group of 16 male cyclists, average age 57.6 years.  The combination supplement was found to increase the anaerobic threshold – the amount of work done before lactic acid begins to accumulate in the blood – by 16.7%.  No changes to VO2 max were observed. The team concludes that: “This study indicated a potential role of L-arginine and antioxidant supplementation in improving exercise performance in elderly.”