The Integrative Benefits Of Oral Nitrate Supplementation On Supra-Maximal Cycling Work Demands

Abstract

Reported Relationships: C.E. Broeder:Contracted Research - Including Principle Investigator; Corporate grant. PURPOSE: This study investigated the effects beet nitrate supplementation had on cycling performance (power, force, cadence (Cad) speed (Spd), distance, time to fatigue, kJ expended) during repeated high intensity intervals (HIIT). METHODS: Eight cyclists participated (Age: 41.4 ± 9.1; WT: 83.3 ± 9.6 kg; BF%: 21.7 ± 0.1; VO2 max: 4.20 ± 0.58 L/min, functional threshold power (FTP): 245.4 ± 43.6 watts). This study was a randomized, double-blind, crossover, matched pair design. Prior to the HIIT sessions, subjects consumed for 7-days placebo (PL) or an oral beet nitrate (BN) supplement. On the day of testing, after completing baseline measurements & 45-mins prior to the HIIT session, 10g of the treatment week’s supplement was consumed by each rider. The HIIT workload was set at a wattage 1.5 times greater than a cyclist’s baseline FTP, e.g., FTP = 200 watts; HIIT work interval = 300 watts. Each HIIT segment was 75-secs and followed by a 2-min recovery at 50% of FTP. Cyclists were instructed to do as many intervals as possible. A matched paired t-test was used to compare each treatment for the summary data (i.e., total secs completed under the placebo versus beet supplementation conditions), HIIT trial total work data, and HIIT trial total recovery data. When a significant difference was observed, Cohen’s d effect size (ES) procedures were used to determine the magnitude. RESULTS: BN supplementation improved time to exhaustion (PL: 1,251 ± 562 secs, BN: 1,475 ± 504 secs; p = 0.02; ES = 0.423) and total energy expended (PL: 251.3 ± 48.6 secs, BN: 306.6 ± 55.2 kJ; p = 0.01; ES = 1.079) compared to PL. Subjects during the BN trials completed more intervals (BN = 8.14 ± 2.4, PL = 7.00 ± 2.5, p = 0.03, ES = 0.42) and cycled 23.9% further (BN = 13.5 ± 3.9 km, PL = 10.9 ± 4.0 km, p = 0.01, ES = 0.65). During the work segments, BN enhanced cadence and speed by 2.0% at the same force compared to PL (Cad: p = 0.02; ES = 0.20; Spd; p = 0.02; ES = 0.20). During recovery, comparing BN to PL, force was lower (PL: 68.2 ± 15.6 N, BN: 65.5 ± 13.7 N, p = 0.01, ES = 0.23), Cad was higher (PL: 91.8 ± 10.9 rpm, BN: 93.9 ± 7.4 rpm, p = 0.01, ES = 0.23), Spd was greater (PL: 30.7 ± 3.3 kph, BN: 31.4 ± 1.9 kph, p = 0.02, ES = 0.27). CONCLUSIONS: BN enhanced HIIT work and recovery performance allowing a more efficient maintenance of Cad, force, & Spd.