Heart Rate Variability Metrics from Commercial Devices Predicts Strength and Cardiovascular Performance in a Military Cohort

Abstract

Heart rate variability (HRV) has become popular for assessing improvements in physical fitness, performance, and recovery. The purpose of this study was to assess the ability of HRV metrics to predict strength and cardiovascular performance in a military cohort using data obtained from commercial off-the-shelf (COTS) wearables. (1) Methods: Twenty-four active-duty military personnel (17 males; 7 females), ranging from age 23 to 41 (32.70 ± 4.65), were equipped with a Whoop Strap 3.0, a Garmin Fenix 5, and an Omegawave during a 12-week exercise intervention study. For this experiment researchers focused solely on HRV metrics obtained on scheduled “Gameday” competitions that occurred periodically during the intervention and contained a battery for strength, power, and cardiovascular performance tests. (2) Statistical Analysis: HRV metrics fitted with linear mixed models and applied to a composite strength variable derived following interrogation of performance tests with principal component analysis (PCA). Akaike’s information criterion (AIC) was also used to compare cardiovascular and strength metrics. (3) Results: Results indicated that standard deviation of NN intervals (SDNN)] obtained from Omegawave was the best overall predictor of performance (AIC > 5.00). (4) Conclusion: Our analyses demonstrated that traditional metrics obtained with the Omegawave were the best performance predictors. HRV measured by Omegawave immediately prior to Gameday assessment was inversely related with strength performance, suggesting that a lower HRV was associated with higher performance (p = 0.002). These findings demonstrate the potential influence of timing and raw values utilized on HRV interpretation to predict strength and cardiovascular performance.