Dose-response of acute capsiate supplementation on muscle endurance performance during CrossFit® in trained men: A randomized, crossover and double-blind study

Objectives: This study aimed to verify the acute effect of Capsiate (CAP) on muscle endurance resistance training during CrossFit® and to compare the effects of two acute doses of CAP supplementation (12 vs. 24 mg) in trained men during this workout. Methods: Using a randomized, crossover and double-blind design, 17 trained males with at least 1 year of CrossFit® (CF) experience were supplemented with 12 or 24 mg of CAP or placebo 45 min before the workout. The participant performed three random sessions separated by seven days, where they should complete as many repetitions as possible in 20 min, consisting of five pull-ups, 10 push-ups, and 15 air squats. The rate of perceived effort (RPE) was analyzed immediately after exercise and the heart rate at rest, five, 10, 15 and 20 min. Results: There was no significant difference between doses for the number of repetitions (Placebo = 620.5 ± 137.8 vs. 12 mg = 627.7 ± 99.8 vs. 24 mg = 631.3 ± 120.1 repetitions, p = 0.768, η2 = 0.02) and RPE (Placebo = 7.4 ± 1.3 vs. 12 mg = 7.5 ± 0.9 vs. 24 mg = 7.3 ± 1.5, p = 0.772, η2 = 0.02). The heart rate increased across workouts (p < 0.001) but no significant dose time interaction was observed (p = 0.109, η2 = 0.09). Conclusion: In summary, 12 and 24 mg of CAP did not improve muscle endurance performance, RPE and heart rate during CF performance in trained men.