Nonexercise Measurements as Predictors of Chronotropic Response to Exercise

Background: Chronotropic response to exercise is a clinically important health indicator. Direct assessment of chronotropic response to exercise is problematic in many clinical settings because of lack of access to required exercise equipment. Also, abnormal chronotropic response to exercise is often asymptomatic, which hinders the ability to identify individuals who require exercise-based chronotropic response evaluation. The purpose of this study was to investigate a set of nonexercise, contemporary assessments as predictors of chronotropic response to exercise. Methods: This prospective, cross-sectional study investigated nonexercise predictors of chronotropic response to exercise. Forty participants (19 women, 21 men; mean age = 34.3 years, SD = 14.5) performed a graded exercise work rate protocol while heart rate was continuously monitored. Chronotropic response to exercise was recorded as the heart rate-work rate slope. Data on a variety of nonexercise measures were also collected. Results: Multivariable regression analysis indicated that sex, self-reported physical activity, body mass index, waist circumference, and isometric grip strength were independent predictors of chronotropic response to exercise and, as a subset, resulted in the strongest prediction model ( R = 0.80, R 2 = 0.64, P < 0.001). Conclusion: The results of this study suggest that a group of nonexercise measurements are predictive of chronotropic response to exercise. These findings provide a basis for future research to determine if these nonexercise predictors can be used to screen for chronotropic response to exercise abnormalities. Also, exercise interventions that target physical activity, body composition, and muscle strength may improve chronotropic response to exercise.