The effects of high-load and low-load resistance training on insulin resistance, lipids and inflammation in coronary artery disease patients

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Javna agencija za raziskovalno dejavnost Republike Slovenije. Background Prevalence of diabetes and dysmetabolism is high in patients with coronary artery disease (CAD), therefore, the combination of resistance training (RT) and aerobic training (AT) is advised to provide optimal control of insulin metabolism, dyslipidaemia, and inflammation. Since previous studies examined only the effects of low load (LL) to moderate load resistance training (RT) (<60% of one repetition maximum [1-RM]), the effects of high load (HL) RT remains to be investigated. Purpose This study aimed to examine the effects of HL-RT and LL-RT combined with AT in comparison to solely AT on insulin resistance, lipids, and inflammation in patients with CAD. Methods Seventy-nine patients with CAD were randomised to combined AT and LL-RT (30%-40% of 1-RM), combined AT and HL-RT (70%-80% of 1-RM) or AT alone (50%-80% of peak power output). The study was completed by 59 patients, with [mean (SD)] age = 61 (8) years, height = 172.1 (8.4) cm, weight = 85.47 (15.43) kg and left ventricular ejection fraction = 53 (9) %. Patients in all three groups performed the same progressive AT consisted of 3-5 min of work-load interval cycling separated by 2 min of unloaded cycling progressing from 50% to 80% maximal workload achieved at baseline cardiopulmonary exercise test. In RT groups, the training load progressed from 70% of 1-RM (6–11 reps/set) to 80% of 1-RM (6–8 reps/set) in HL-RT group and from 35% of 1-RM (12–22 reps/set) to 40% of 1-RM (12–16 reps/set) in LL-RT group in the first seven weeks of the intervention. After 1-RM re-evaluation, training load progressed from 70% 1-RM (11 reps/set) to 80% 1-RM (6–8 reps/set) in HL-RT group, and from 35% 1-RM (22 reps/set) to 40% 1-RM (12–16 reps/set) in LL-RT group. We collected blood samples after overnight fast (≥10 hours) at baseline (prior to first training session) and post-training (prior to last training session) for analysis of glucose, insulin, homeostatic model of insulin resistance, total cholesterol, triglycerides, HDL and LDL cholesterol and C-reactive protein levels. Results Two-way analysis of variance showed only significant time effect on total cholesterol and LDL cholesterol (both p < 0.001) and C-reactive protein (p = 0.017), while there was no significant effect of time x group interaction on any of the blood biomarkers. When compared with baseline, total cholesterol and LDL levels were significantly lower after AT (total cholesterol: -0.4 mmol/l, p = 0.013; LDL: -0.4 mmol/l, p = 0.006) and HL-RT (total cholesterol: -0.5 mmol/l, p = 0.002; LDL: -0.5 mol/l, p = 0.002). In addition, there was a borderline decrease in triglycerides (AT group: -0.18 mmol/l, p = 0.053), glucose (LL-group: -0.6 mmol/l, p = 0.065) and C-reactive protein (HL-RT group: -0.9 mmol/l, p = 0.069) levels. Conclusions The combination of AT and RT, regardless of the RT load, was not superior to AT alone in improvement of insulin and lipids metabolism, and inflammation in patients with CAD.