The effect of different resistance exercise training intensities on cardiovascular risk factors: a systematic review and meta-analysis

Resistance training effectively reduces cardiovascular risk factors (CVRFs). However, the optimal training intensity remains unclear. Firstly, this systematic review investigated the effects of different resistance training intensities on glycated haemoglobin (HbA1c), systolic blood pressure (SBP), low-density lipoprotein (LDL), and waist-to-hip ratio (WHR). Secondly, we aimed to compare the effect of different resistance training intensities with each other. We identified randomized controlled trials ( n = 59) investigating progressive ( n = 9), low ( n = 15), moderate ( n = 33), and high intensity ( n = 4) resistance training in adults with CVRFs. We used random-effects models to investigate the effects of each intensity on CVRFs compared to non-active controls and meta-regression analyses to investigate differences in effect between training intensities. Meta-analyses showed statistically significant effects of low to moderate certainty. Progressive intensity reduced SBP {-14.70 mm/Hg, 95% confidence interval [CI] (-16.40; -13.00)} and LDL [-0.16 mmol/L, 95% CI (-0.19; -0.13)]. High intensity reduced HbA1c [-0.81%, 95% CI (-1.52; -0.10)], low intensity LDL [-0.10 mmol/L, 95% CI (-0.16; -0.04)], and moderate intensity WHR [-0.02, 95% CI (-0.03; -0.01)] and HbA1c [-0.40%, 95% CI (-0.66; -0.14)]. Meta-regression analyses showed high intensity was significantly more effective in reducing WHR than low intensity. No significant differences were found between resistance training intensities for HbA1c, SBP, and LDL. In one study, high intensity was more effective than low intensity in reducing WHR. However, the limited number of studies investigating high and progressive intensity and the certainty of evidence limits the ability for definitive conclusions. More research is needed for clarification on the effect of different resistance training intensities on multiple CVRFs.