Increase in Maximal Cycling Power With Acute Dietary Nitrate Supplementation

Abstract

Muscle shortening velocity and hence power has 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. PURPOSE This study determined if NO3− supplementation could acutely enhance maximal power in trained athletes. METHODS 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 (i.e., 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. RESULTS 2×2 repeated measures ANOVA indicated a greater increase in PMAX from PRE to POST NO3 (PRE: 1160±301 to POST: 1229±317 W) compared to PLA (PRE: 1191±298 to POST: 1213±300 W) (p=0.009; ή2=0.45). A paired t-test verified a greater relative change in PMAX after NO3 (6.0±2.6%) compared to PLA (2.0±3.8%) (p=0.014; d=1.21). RPMOPT remained unchanged from PRE (123±14) to POST PLA (122±14 rpm) but increased from PRE (120±14) to POST NO3 (127±13 rpm) (p=0.043; ή2=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=0.049; d=0.79). No differences were observed between the 30 s isokinetic trials. CONCLUSIONS Acute NO3− supplementation can enhance maximal muscle power in trained athletes. These findings may particularly benefit power-sports athletes who perform brief explosive actions.

Effects of Natural Nutritional Beverages on Anaerobic Exercise Performance

“…One of the few groups to examine performance across 4 individual short (3-4 s) sprints, found performance benefits following an acute dose of beet juice (Rimer et al, 2015). This study utilized a higher NO3-dose (~11.3 mmol) than the present study (~8 mmol).…”

“…Improvements have been seen during both aerobic and anaerobic exercise, but NO3-'s effects on the oxygen cost of exercise and exercise tolerance during aerobic work have been the focus of most of the research in this area. Current evidence suggests that shorter bouts of mostly anaerobic type activity may improve with NO3-supplementation, but the research in this area is scarce (Kramer et al, 2016;Rimer et al, 2015). As suggested by some, dietary NO3-'s ability to produce performance benefits during short duration, high power activity may be mechanistically different than the benefits yielded from NO3-supplementation with aerobic exercise (Thompson et al, 2015).…”

“…Recent studies have focused more specifically on isolated bouts of anaerobic activity, yielding preliminary evidence that NO3-supplementation can produce performance benefits during this type of exercise (Kramer et al, 2016;Rimer et al, 2015). Rimer et al (2015) examined the role of an acute dose of ~11.2 mmol of NO3-(beet juice) on maximal power (Pmax) and optimal pedaling (RPMoptimal) rate during short bouts (3-4 s) of maximal effort cycling.…”

“…Rimer et al (2015) examined the role of an acute dose of ~11.2 mmol of NO3-(beet juice) on maximal power (Pmax) and optimal pedaling (RPMoptimal) rate during short bouts (3-4 s) of maximal effort cycling. They also examined the effects of NO3-supplementation on maximal power during a 30 s fatiguing cycling task.…”

“…A review of the evidence suggests that NO3-supplementation may improve anaerobic performance by increasing peak power output Kramer, Baur, Spicer, Vukovich & Ormsbee, 2016;Larsen et al, 2007;Rimer, Peterson, Coggan & Martin, 2015). Dietary NO3-'s effects on the 30-s Wingate test, specifically utilizing beets as the NO3-source, has not been studied.…”