The Accuracy Of Heart Rate Monitors And Determination Of Heart Rate Percentages At Anaerobic Threshold

Abstract

PURPOSE: To examine the heart rate percentage (HR%) at the Anaerobic Threshold (AT) in order to determine the appropriate exercise intensity below or above the AT. A second goal was to assess the accuracy of different types of wearable heart rate monitors (HRMs) during a graded exercise test. METHODS: Thirty healthy individuals (n=21 male & n=9 female; aged 24.5 ± 3.5 years) participated in a single incremental exercise protocol on a cycle ergometer (CE). AT was detected through a metabolic cart by using V-slope method, which determined the point of a nonlinear increase in carbon dioxide output (VCO2) against oxygen uptake (VO2). HR was measured each minute of exercise test via two optical-based monitors (Cellular Watch [IW] & Fitness tracker [FB]) and two electrical-based monitors (traditional monitor [ECG] & heart rate monitor [PL]). Electrocardiography (ECG) was used as a “Gold Standard” for comparison in this study. RESULTS: AT was reached at the mean and standard deviation (SD) of 130 ± 16 bpm. HR% at AT was observed 67 ± 8 % of HRpeak, Heart Rate Reserve Percentages (HRR%) at AT were observed at 42 ± 15 % of HRpeak. Across all exercise testing stages (Stage 1 [S1], Stage 2 [S2], Stage 3 [S3], etc.), no significant differences were found in HR values between ECG and PL. The most statistical differences were found in HR between ECG and IW, (S5=[p=0.018], S6=[p=0.041] and S7=[p=.005], respectively). As intensity increased, FB and IW underestimated the HR values throughout all stages when compared with the ECG. CONCLUSIONS: Analysis of HR% at AT was estimated at approximately 67% of participant maximum effort as well as HRR% at AT was estimated at 42%. At the light-intensity, accurate outcomes of HR values were observed from all wearable HRMs. However, with increased intensity, the accuracy of wearable devices was varied at moderate and high-intensity exercise testing. The PL had the greatest agreement with ECG when compared to other devices. This might be due to the fact that both HRMs utilize a similar mechanism of measurement. The electrical-based HRM was found to be more accurate in comparison to the optical-based HRMs.