Abstract

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.

Keywords: Heart rate; performance; supplementation; thresholds; velocity