Heart Rate Differences in Males and Females during Similar Physiological Work

Abstract

Physiological work refers to the amount of energy that is expended during exercise and it is related to exercise intensity. In general, exercise intensity assessment includes heart rate (HR), rate of perceived exertion (RPE), power output (PO), oxygen consumption (VO2), and blood lactate (BL) levels. These measurements are used for both males and females to evaluate exercise intensity despite their physiological differences. The purpose of this study was to determine if there are differences between sexes in different exercise intensity models when using the same physiological work. Thirty young, healthy individuals (15 males) were recruited with ages ranging from 19 to 33 y. The individuals were scheduled for two (2) lab visits within 48–72 hours of each other. A graded exercise test (GXT) on a stationary bike was conducted during the first visit. At the end of each stage, the RPE, PO, VO2, and BL were taken. After the GXT was completed, peak PO and VO2max were recorded. BL during the GXT was used to determine 3 5‐min steady‐state workloads (low: 0–2 mmol/l; medium: 2–4 mmol/l; and high: >4 mmol/l) as physiological work for the second test. The measures obtained at the end of each steady‐state physiological workload were HR, %HRmax (HR/(220‐age)), RPE, PO, %POmax, VO2, %VO2max, and BL. A two‐way repeated measurements ANOVA was performed to compare all exercise intensity variables obtained during the second test between males and females (α=0.05). Females had higher HR and %HR than males in all 3 physiological workloads (116±14 vs. 97±14 bpm and 68.7±7.5 vs. 59.4±8.8%, 143±16 vs. 128±20 bpm and 84.9±6.2 vs. 75.4±6.7%, and 164±16 vs. 149±17 bpm and 97.0±3.7 vs. 91.1±7.3%, respectively, all p<0.05). Interestingly, females had a higher %VO2max only during the lower physiological workload (554.±9.8 vs. 45.6±8.4%, p<0.05). Throughout the stages of Low (0–2mmol/l), Medium (2–4mmol/l), and High (>4mmol/l) physiological workloads %PO, RPE, and BL did not differ between sexes. Unlike previous reports, our study found that RPE was similar for both sexes within the same %PO. Our data demonstrates that HR and %HR should not be used interchangeable in males and females, especially when physiological work rate is the critical factor for increased performance.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.