The left ventricle morphologically adapts to endurance exercise training (eccentric cardiac remodeling) and strength exercise training (concentric remodeling). In addition, the acceleration of vagally mediated heart rate (HR) recovery after exercise is one of the functional adaptations of the heart in endurance-trained humans. However, the effect of strength training on HR recovery is unclear.
Purpose: The purpose of this study was to investigate whether postexercise HR recovery accelerates in strength-trained athletes.
Methods: Subjects were young strength-trained athletes (ST; N = 12), endurance-trained athletes (ET; N = 12), and age-matched sedentary control men (C; N = 12). HR and oxygen uptake were measured during submaximal exercise (cycling exercise, 40% maximal oxygen uptake for 8 min) and 30 s after the exercise (the postexercise period).
Results: Left ventricular end-diastolic dimension was higher in both types of athletes compared with C, but greater in ET than in ST (C, 4.3 ± 0.1 cm; ET, 5.0 ± 0.1 cm; ST, 4.8 ± 0.1 cm). Left ventricular average wall thickness was greater in ST in comparison with ET, although it was higher in both trained men compared with C (C, 0.85 ± 0.02 cm; ET, 0.90 ± 0.02 cm; ST, 1.00 ± 0.02 cm). The time constant of postexercise HR decay, an index of vagally mediated postexercise HR recovery, was lower in ST and ET compared with C (C, 94.4 ± 9.2 s; ET, 65.9 ± 4.3 s; ST, 69.1 ± 4.0 s). Oxygen pulse was greater in ST and ET than in C (C, 9.4 ± 0.6 mL per beat; ET, 13.0 ± 0.9 mL per beat; ST, 12.8 ± 0.4 mL per beat), and it results in increased oxygen debt for both types of athletes (C, 0.257 ± 0.024 L; ET, 0.343 ± 0.030 L; ST, 0.331 ± 0.017 L). We did not find significant differences in these indices between ST and ET.
Conclusions: These results suggest that the HR recovery immediately after exercise is accelerated in both strength- and endurance-trained athletes.