Heart rate recovery after exercise in adults with the Down syndrome

The main purpose of this study was to evaluate heart rate recovery (HRR) in patients with the Down syndrome (DS) after peak dynamic exercise and compare their responses to those of nondisabled subjects of similar age, gender, and body mass index. Eighteen participants with the DS (14 men, 4 women; mean age 33.6 +/- 7.6 years) and 18 nondisabled controls (14 men, 4 women; mean age 33.8 +/- 8.5 years) performed peak treadmill tests with metabolic and heart rate measurements. Compared to controls, subjects with the DS presented lower peak values of heart rate, oxygen uptake, and minute ventilation (p <0.05). In contrast, the 2 groups attained similar respiratory exchange ratio values at peak exercise. Even after controlling for the effects of reduced peak heart rate and body mass index, participants with the DS showed slower HRR than controls at 1 minute (DS: 25.3 +/- 7.2 beats/min; controls: 34.1 +/- 12.1 beats/min) and 2 minutes (DS: 36.3 +/- 5.8 beats/min; controls: 53.6 +/- 14.1 beats/min) of recovery (p <0.05). In conclusion, adults with the DS had reduced HRR (at 1 and 2 minutes of recovery) compared to nondisabled controls, and this was independent of their lower chronotropic response to peak exercise. Additionally, despite showing attenuated HRR from peak exercise, adults with the DS did not present increased cardiovascular risk by general diagnostic criteria (HRR >12 and 22 beats/min, respectively).