Strength training does not affect vagal-cardiac control or cardiovagal baroreflex sensitivity in young healthy subjects

The purpose of this study was to test the hypothesis that high-intensity strength training increases vagal-cardiac control and cardiovagal baroreflex sensitivity. Twenty-two subjects [age 22 (0.8) years] were assigned to either strength training (ST, n = 12) or control (CON, n = 10) groups. Subjects in the ST group trained each major muscle group 3 days per week for 8 weeks with three sets of 10 repetitions and 2-min rest periods. Resistance was increased progressively when possible. Subjects in the CON group were active recreationally but did not lift weights. Before and after training, resting arterial pressure was measured with an automated sphygmomanometer, and ECG, respiratory rate, and finger photoplethysmographic arterial pressures were recorded with subjects supine and breathing at a set rate (0.25 Hz) for 5 min. Data were analyzed in both time and frequency domains. Arterial baroreflex sensitivity was estimated with the sequence method and cross-spectral transfer function analysis of systolic pressures and R-R intervals. Training increased whole-body muscular strength and decreased arterial blood pressure at rest (the exercise and pressure data have been published elsewhere). R-R intervals and standard deviations, and R-R interval spectral power at the respiratory frequency were unaffected by training. Similarly, training did not affect respiratory or low-frequency systolic pressure spectral power or cardiovagal baroreflex sensitivity. Although evidence supports beneficial cardiovascular adaptations to resistance training, our results demonstrate that resistance training does not affect vagal-cardiac control or cardiovagal baroreflex sensitivity in young healthy subjects.