The efficacy of high- and low-load resistance training in patients with coronary artery disease: a follow-up of a randomised controlled trial

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Slovenian Research Agency. Background Perseverance of beneficial effects of exercise training in cardiac rehabilitation remains understudied. Maximal aerobic capacity (VO2 max) and quality life were mostly maintained at 1 year follow-up after aerobic training (AT) or after a combination of AT and mostly low-load (LL) resistance training (RT), while the effects of high-load (HL) RT remain unknown in patients with coronary artery disease (CAD). Purpose This study investigated the effects of combination of AT with HL-RT or LL-RT in comparison to AT alone on maximal aerobic capacity, physical activity, and quality of life in patients with CAD at 1-year follow-up after cardiac rehabilitation. Methods We initially enrolled 79 patients with CAD to combined AT and HL-RT, combined AT and LL-RT or AT alone, and 59 patients completed the study. The assessments at 1-year follow-up were completed by 53 patients, with [mean (SD) or median (interquartile range)] age = 61 (8) years, height = 172.1 (8.4) cm, weight = 83.93 (14.03) kg and left ventricular ejection fraction = 50 (45,60) %. During the study, all patients performed the same interval aerobic cycling (40 min/session, intervals of 3-5 min of work-load cycling separated by 2 min of unloaded cycling, intensity progressed from 50% to 80% of maximal workload achieved at baseline cardiopulmonary exercise test). In HL-RT-group, the training load progressively increased from 70% of 1-RM (6–11 reps/set) to 80% of 1-RM (6–8 reps/set), while in LL-RT group the training load progressively increased from 35% of 1-RM (12–22 reps/set) to 40% of 1-RM (12–16 reps/set) in the first seven weeks of the intervention. Similar progression of RT was used after 1-RM re-evaluation following 7 weeks of training. After cardiac rehabilitation, patients were given written brochure with included advice on home-based physical activity with emphasis on aerobic and resistance exercises. Maximal aerobic performance, objectively measured physical activity and quality of life were measured after 1-year. Results At 1-year follow-up majority of the patients increased VO2max (62%). Patients increased VO2max (+0.08 l/min, p = 0.022) and had higher respiratory exchange ratio (+0.06, p < 0.001), regardless of the randomisation. There was no significant effect of time x group interaction on the outcomes. VO2max was increased in AT (+0.13 l/min, p = 0.026) and LL-RT (+0.12 l/min, p = 0.031) groups, while respiratory exchange ratio was greater in LL-RT (+0.6, p = 0.004) and HL-RT (+0.7, p = 0.003) groups at follow-up. Post-training physical activity and quality of life were high but remained unchanged after 1 year. Conclusions The combination of AT and HL-RT or LL-RT was not superior to AT alone in changes of maximal aerobic performance, physical activity and quality of life in patients with coronary artery disease at 1-year follow-up.