Date

5-20-2026

Department

School of Health Sciences

Degree

Doctor of Philosophy in Health Sciences (PhD)

Chair

Eric Sobolewski

Keywords

sex-based differences, male, female, athletes, aerobic exercise, cardiovascular adaptations, resting heart rate, maximal heart rate, endurance performance times/outcomes

Disciplines

Health and Physical Education

Abstract

Cardiovascular adaptations to exercise are prominent among endurance athletes. While heart rate is used to determine exercise prescription and to measure overall health, little research has explored the influence of sex-based differences on changes in heart rate and performance outcomes. The purpose of this study is to investigate and compare cardiovascular adaptations to exercise in male and female endurance athletes, with a focus on heart rate and performance times. A quasi-experimental longitudinal design was used with a sample of 19 (nine males, ten females) collegiate triathletes on a university club sports team. Data was collected at the beginning and end of the 2025-2026 season. Resting heart rates were measured for one minute following five minutes of rest, and maximal heart rates were measured using the highest heart rate value achieved during exertion. Endurance performance times were recorded via standardized institutional methods based on clocked and chip transmitter times. Statistical analyses included two-way mixed-design ANCOVAs with a covariate of training level, Pearson’s correlation, and Fisher’s r-to-z transformation. Results showed no statistical significance in preseason to postseason changes in resting and maximal heart rates among male and female triathletes. The main effect of total endurance performance times was statistically significant, however, the interaction effect with sex was not statistically significant. Lastly, there was no statistical significance when comparing the relationship between heart rate adaptations and performance outcomes in male and female triathletes. These findings suggest the observed differences in performance times may not be explained by the heart rate variables measured. The findings of this study offer valuable insights for future research.

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