To examine the effect of a nutritional supplement (ATP-E) on high intensity exercise performance, 23 physically active males volunteered to perform six Wingate Anaerobic Power tests. Tests were performed prior to and at 14 and 21 days during ATP-E or placebo ingestion. The experiment followed a double-blind and random-order design. Twelve subjects (responders, R) showed an increase in preexercise blood ATP on Day 14 of ATP-E ingestion compared to control measures. The remaining 11 subjects (nonresponders, NR) had no change in preexercise blood ATP. Peak power and mean power were unchanged for both R and NR subjects across the exercise tests, but R experienced a decrease (p < 0.05) in immediate post-exercise plasma lactate on Day 14 of ATP-E testing compared to their control measures. NR had no change in peak plasma lactate at any time during the study. The results suggest that short-term high intensity exercise performance was maintained in R with less reliance on anaerobic metabolism, and that response was evident following 14 days of ATP-E ingestion.