Acute and chronic safety and efficacy of dose dependent creatine nitrate supplementation and exercise performance

Abstract

BackgroundCreatine monohydrate (CrM) and nitrate are popular supplements for improving exercise performance; yet have not been investigated in combination. We performed two studies to determine the safety and exercise performance-characteristics of creatine nitrate (CrN) supplementation.MethodsStudy 1 participants (N = 13) ingested 1.5 g CrN (CrN-Low), 3 g CrN (CrN-High), 5 g CrM or a placebo in a randomized, crossover study (7d washout) to determine supplement safety (hepatorenal and muscle enzymes, heart rate, blood pressure and side effects) measured at time-0 (unsupplemented), 30-min, and then hourly for 5-h post-ingestion. Study 2 participants (N = 48) received the same CrN treatments vs. 3 g CrM in a randomized, double-blind, 28d trial inclusive of a 7-d interim testing period and loading sequence (4 servings/d). Day-7 and d-28 measured Tendo™ bench press performance, Wingate testing and a 6x6-s bicycle ergometer sprint. Data were analyzed using a GLM and results are reported as mean ± SD or mean change ± 95 % CI.ResultsIn both studies we observed several significant, yet stochastic changes in blood markers that were not indicative of potential harm or consistent for any treatment group. Equally, all treatment groups reported a similar number of minimal side effects. In Study 2, there was a significant increase in plasma nitrates for both CrN groups by d-7, subsequently abating by d-28. Muscle creatine increased significantly by d-7 in the CrM and CrN-High groups, but then decreased by d-28 for CrN-High. By d-28, there were significant increases in bench press lifting volume (kg) for all groups (PLA, 126.6, 95 % CI 26.3, 226.8; CrM, 194.1, 95 % CI 89.0, 299.2; CrN-Low, 118.3, 95 % CI 26.1, 210.5; CrN-High, 267.2, 95 % CI 175.0, 359.4, kg). Only the CrN-High group was significantly greater than PLA (p < 0.05). Similar findings were observed for bench press peak power (PLA, 59.0, 95 % CI 4.5, 113.4; CrM, 68.6, 95 % CI 11.4, 125.8; CrN-Low, 40.9, 95 % CI −9.2, 91.0; CrN-High, 60.9, 95 % CI 10.8, 111.1, W) and average power.ConclusionsCreatine nitrate delivered at 3 g was well-tolerated, demonstrated similar performance benefits to 3 g CrM, in addition, within the confines of this study, there were no safety concerns.

Short-Term Effects of a Ready-to-Drink Pre-Workout Beverage on Exercise Performance and Recovery

“…Results of the present study support prior reports indicating that acute and/or short-term ingestion of supplements containing nitrates prior to exercise can affect muscular strength and/or endurance. However, in contrast to recent findings [ 9 , 12 , 23 , 29 , 46 , 51 , 52 , 53 ], we did not find that ingesting the RTD containing nitrates prior to exercise enhanced short duration time-trial performance. The contrasting results may be related to greater variability in studying non-trained cyclists, differences in the dosages and/or timing of ingestion of the nitrate containing RTD, or use of arginine nitrate rather than other forms of nitrates.…”

“…Consequently, the acute and short-term use of this RTD appears to be safe within the dosages and manner it was assessed in the current study. These findings are consistent with our prior studies with supplementation periods as long as 8 weeks [ 28 , 29 , 30 , 52 ], as well as other similar studies [ 58 , 59 ].…”

“…These studies generally demonstrate that nitrate supplementation prior to exercise can affect endurance and high-intensity intermittent exercise performance. For this reason, addition of nitrates to pre-workout supplements have also been of interest [ 9 , 12 , 23 , 28 , 29 , 30 , 46 , 49 , 50 , 51 , 52 , 53 ]. Results of the present study support prior reports indicating that acute and/or short-term ingestion of supplements containing nitrates prior to exercise can affect muscular strength and/or endurance.…”

Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8 weeks on training adaptations in resistance-trained males

“…While there is little evidence that ingesting 2 g/day of creatine for 8-weeks can markedly increase muscle creatine stores and/or affect exercise capacity, it is enough creatine to maintain creatine stores during training [7, 28]. The greater potential of ergogenic value from ingesting 2 g/day of creatine nitrate would theoretically be due to the nitrate content [46, 63]. There are a number of studies that indicate that nitrate supplementation prior to exercise (e.g., 300 mg) can improve exercise capacity [9, 11, 17–20].…”

“…A questionnaire developed in our lab and reported in numerous previously published papers [23, 46–49] was used to assess side effects in this study. Participants completed the survey every week throughout the study to determine how well participants tolerated supplementation; how well participants followed the supplementation protocol; and, if participants experienced any symptoms during the supplementation period.…”