Influence of Chronic Nitrate-Rich Beetroot Juice Supplementation on the Endurance Performance of Active Winter Triathletes: A Randomized Controlled Trial

Abstract

Objective:

The impact of high-nitrate beetroot juice (BRJ) supplementation has seen a recent explosion of interest in sports science. This study examined the potential influence of 7-day BRJ supplementation on the endurance performance of winter triathletes.

Methods:

Eighty young active winter triathletes (44 males, age = 21.50 ± 1.15 yrs; 36 females, age = 20.66 ± 1.45 yrs) participated in this study and were provided with either BRJ (6.5 mmol NO₃⁻/70 mL) or a placebo (PL, 0.065 mmol NO₃⁻/70 mL) for 7 days (a dose of ×3 per day) in a randomized, double-blind design. The athletes then completed a submaximal treadmill run, intraday cycling exhaustion testing, and a 10-km cross country (XC) skiing competition on the second day.

Results:

There was a significant decrease in the oxygen uptake, respiratory exchange ratio, and blood lactic acid level (p < 0.05) between the BRJ and PL treatment groups during V₃ speed running (males: 13.3 km·h⁻¹, females: 11.6 km·h⁻¹). BRJ treatment also remarkably increased the time to exhaustion (TTE) during cycling exhaustion testing (males: p = 0.02, females: p = 0.04). No significant differences were observed in medium- or low-speed submaximal treadmill runs and 10-km XC skiing performance.

Conclusions:

One week of daily nitrate-rich BRJ supplementation improved running economy at high speed during the submaximal treadmill running test and extended the TTE of athletes during cycling exhaustion testing. However, BRJ supplementation did not improve the performance in 10-km on-snow time trials in XC skiing. Regarding nutritional strategies to improve endurance performance in exercise training and competition, these results should be carefully considered owing to the different motor skill levels and competitive abilities of participants.

Keywords:

• Nitrate
• beetroot juice supplementation
• oxygen uptake
• time to exhaustion
• winter triathlon

Acknowledgments

We would like to thank all participants for their contribution to the present study. Further, we thank Binghong Gao and Gang Wang for the support in funding. This work was supported by the National Key Research and Development Program of China (Project No.: 2019YFF0301603, 2021YFF0306705) and the Shanghai Key Lab of Human Performance (Shanghai University of Sport) (No. 11DZ2261100). We thank Zheng Zhang and Xiu Wang for support in modification. We thank Yan Wang and Kun Tang for support in experiment organization and blood sample collections. All authors contributed to the article and approved the submitted version. Finally, We would like to thank Editage (www.editage.cn) for English language editing.

Disclosure statement

No potential conflict of interest was reported by the authors.