Muscle-shortening velocity and hence power have been shown to increase in the presence of nitric oxide (NO). NO availability increases after consuming nitrate (NO3-). Ingestion of NO3-rich beetroot juice (BRJ) has increased muscle power in untrained adults.
This study determined whether NO3- supplementation could acutely enhance maximal power in trained athletes.
In this double-blind, crossover study, 13 trained athletes performed maximal inertial-load cycling trials (3–4 s) immediately before (PRE) and after (POST) consuming either NO3-rich (NO3) or NO3-depleted (PLA) BRJ to assess acute changes (ie, within the same day) in maximal power (PMAX) and optimal pedaling rate (RPMopt). Participants also performed maximal isokinetic cycling (30 s) to assess performance differences after supplementation.
2 x 2 repeated-measures ANOVA indicated a greater increase in PMAX from PRE to POST NO3 (PRE 1160 ± 301 W to POST 1229 ± 317 W) than with PLA (PRE 1191 ± 298 W to POST 1213 ± 300 W) (P = .009; ηp2 = 0.45). A paired t-test verified a greater relative change in PMAX after NO3 (6.0% ± 2.6%) than with PLA (2.0% ± 3.8%) (P = .014; d = 1.21). RPMopt remained unchanged from PRE (123 ± 14 rpm) to POST PLA (122 ± 14 rpm) but increased from PRE (120 ± 14 rpm) to POST NO3 (127 ± 13 rpm) (P = .043; ηp2 = 0.30). There was no relative change in RPMopt after PLA (–0.3% ± 4.1%), but there was an increase after NO3 (6.5% ± 11.4%) (P = .049; d = 0.79). No differences were observed between the 30-s isokinetic trials.
Acute NO3- supplementation can enhance maximal muscle power in trained athletes. These findings may particularly benefit power-sport athletes who perform brief explosive actions.
Rimer is with the Athletics Dept, and Martin, the Dept of Exercise & Sport Science, University of Utah, Salt Lake City, UT. Peterson is with the Cardiovascular Div, and Coggan, the Mallinckrodt Inst of Radiology, Washington University School of Medicine, St Louis, MO.