Acute Nitrate Supplementation Affects Transition Points in Progressive Incremental Testing?

Introduction: Nitrate supplementation has shown promising results in endurance sports. Objective: This study aims to use heart rate (HR) and its derivatives—the heart rate inflection point (HRIP) and heart rate deflection point (HRDP)—to detect metabolic transition points (MTPs) and peak velocity (Vpeak) in amateur runners after acute nitrate (NO3-) supplementation with sugar beet juice. Methodology: We administered 70 ml of concentrated beet juice rich in NO-3 (~6.4 mmol NO3- - 400 mg) or a NO-3 depleted placebo (0.04 mmol NO-3 >0.8 g/L) to thirteen male amateur athletes two hours before they underwent progressive incremental testing (PIT) on a treadmill until exhaustion, with a 7-day washout period. We plotted HR data every 2 minutes to identify HRIP and HRDP, and subjects needed to reach at least 90% of their HRMÁX for the test to be considered maximal. We calculated Vpeak using Kuipers’ formula and set the threshold for statistical significance at p<0.05. Results: HRMAX values after supplementation with either placebo or beet juice did not differ significantly (p=0.573). Similarly, MTP data, including HRIP (p=0.252) and HRDP values (p=0.508), showed no significant differences after supplementation. No differences were observed in Vpeak or the velocities at HRIP and HRDP post-supplementation (p=0.562; p=0.340, respectively). Conclusions: Nitrate supplementation did not enhance performance as evidenced by HRMAX, HRIP, HRDP, and Vpeak metrics remaining unchanged post-supplementation.