Resistance exercise training improves heart rate variability and muscle performance: a randomized controlled trial in coronary artery disease patients.

BACKGROUND: Resistance exercise (RE) is an important part of cardiac rehabilitation. However, it is not known about the low intensity of RE training that could modify the heart rate variability (HRV), muscular strength and endurance in patients with coronary artery disease (CAD). AIM: To investigate the effects of high repetition/low load resistance training (HR/LL-RT) program on HRV and muscular strength and endurance in CAD patients. DESIGN: Randomized and controlled trial. SETTING: Patients seen at the Cardiopulmonary Physical Therapy Laboratory between May 2011 and November 2013. POPULATION: Twenty male patients with CAD were randomized to a training group (61.3±5.2 years) or control group (61±4.4 years). METHODS: 1 repetition maximum (1-RM) maneuver, discontinuous exercise test on the leg press (DET-L), and resting HRV were performed before and after 8 weeks of HR/LL-RT on a 45° leg press. RMSSD, SD1, mean HR and ApEn indices were calculated. The HR/LL-RT program consisted of a lower limb exercise using a 45° leg press; 3 sets of 20 repetitions, two times a week. The initial load was set at 30% of the 1-RM load and the duration of the HR/LL-RT program was performed for 8 weeks. RESULTS: After 8 weeks of HR/LL-RT there were significant increases of RMSSD and SD1 indices in the training group only (P<0.05). There was a significant decrease in mean HR after HR/LL-RT in the training group (P<0.05). There was a significantly higher ApEn after in the training group (P<0.05). There were significantly higher values in the training group in contrast to the control group (P<0.05). CONCLUSION: These results show positive improvements on HRV, as well as muscle strength and endurance in CAD patients. CLINICAL REHABILITATION IMPACT: Eight weeks of HR/LL-RT is an effective sufficient to beneficially modify important outcomes as HRV, muscle strength and endurance in CAD patients.

Lactate and heart rate variability threshold during resistance exercise in the young and elderly.

This purpose of this study was to: 1) determine the intensity corresponding to anaerobic threshold (AT) during a discontinuous resistance exercise protocol in healthy young and elderly subjects by analyzing heart rate variability (HRV) and blood lactate (BL) and 2) investigate the effect of aging on these variables. A total of 28 individuals, 14 young and 14 elderly healthy men underwent one-repetition maximum (1RM) testing to determine maximum load on the leg press. Discontinuous resistance exercise testing was initiated at 10% of the 1RM with subsequent increases of 10%. The load corresponding to AT was approximately 30% 1RM in both groups. The determination of AT by HRV was associated with BL responses (p<0.01). While HRV indexes decreased with increasing of loads in both groups, the elderly had lower values at loads below AT (p<0.05). Additionally, BL increased sharply after the load corresponding to AT in both groups, although elderly subjects showed the lowest values (p<0.05). In conclusion, HRV is an effective tool for determining AT, which was approximately 30% 1RM under the testing procedures included in the present study. Furthermore, there was a marked change in autonomic function, with gradual vagal withdrawal followed by sympathetic activation. These responses were lower in elderly subjects.