Heart Rate Responses at Rest, during Exercise and after Exercise Periods in Relation to Adiposity Levels among Young Nigerian Adults.

Background: There is a dearth of comparative studies on heart rate (HR) abnormalities at rest, chronotropic responses during submaximal exercise, and such responses during recovery from submaximal exercise between healthy-weight and overweight/obese young adults.

Methods: Eighty healthy young adults (30 men and 50 women) aged 19 to 33 years participated in the present study. A symptom-limited, submaximal, cycle ergometer exercise test of intensity targeted at 60% to 70% of the subject's age-predicted maximum HR was performed. The HR, blood pressure, and minute ventilation were measured at rest and during exercise. Post-exercise, HR was first measured at 1 minute of recovery and then every 2 minutes until the 5th minute.

Results: Our results showed significantly higher resting HR (P<0.001), lower percentage HR reserve during exercise (P<0.001), and slower HR recovery after exercise (P<0.05, P<0.01, or P<0.001) in overweight/obese men and women than in the non-overweight/obese controls. The prevalence of high resting HR, submaximal chronotropic incompetence, and blunted HR recovery were more common in the overweight/obese individuals than in the healthy-weight controls. Peak VO₂ and ventilatory equivalent for oxygen were associated with resting HR, exercise HR parameters, and post-exercise HR recovery indices in both men and women.

Conclusion: High resting HR, submaximal chronotropic incompetence, and blunted HR recovery in overweight/obese individuals in this study may be attributed to poor cardiorespiratory fitness and low respiratory efficiency.