Determinants of Heart Rate Recovery following Exercise in Children

Abstract

Purpose: Heart rate (HR) recovery during the first minute after cessation of exercise is predominantly modulated by reactivation of vagal tone. Attenuated 1-min HR recovery is a cardiovascular risk factor in adults. The purpose of this study was to determine predictors of 1-min HR recovery after a maximum-effort exercise test in healthy children. Methods: HR recovery after cessation of a maximal treadmill exercise test (Bruce protocol) was assessed in 485 children (197 girls, 288 boys) who underwent an exercise test during their clinical evaluation to exclude cardiac disease and who were discharged as normal. The first-minute cool-down period (1.5 mph, 0% inclination on treadmill) was consistent for all subjects. Age- and gender-specific 25th, 50th, and 75th percentile values of 1-min HR recovery were generated. Multivariable linear regression analyses were performed to determine predictors of 1-min HR recovery. Results: One-minute HR recovery was higher in boys and correlated inversely with age and with age-adjusted BMI in both boys and girls. In a multivariable linear regression model, age, gender, BMI, and baseline HR were significant predictors of 1-min HR recovery and explained 39% of variance. Exercise duration and peak HR were also significant predictors when added to the model, but they improved the explained variance by only 2%. Conclusion: One-minute HR recovery after exercise is attenuated with age in children. Children with higher BMI, particularly those who are overweight, and those with lower exercise endurance, have slower 1-min HR recovery.