The effect of exercise on the cardiovascular risk factors constituting the metabolic syndrome: a meta-analysis of controlled trials

Abstract

Background: Numerous meta-analyses have investigated the effect of exercise in different populations and for single cardiovascular risk factors, but none have specifically focused on the metabolic syndrome (MetS) patients and the concomitant effect of exercise on all associated cardiovascular risk factors.

Objective: The aim of this article was to perform a systematic review with a meta-analysis of randomized and clinical controlled trials (RCTs, CTs) investigating the effect of exercise on cardiovascular risk factors in patients with the MetS.

Methods: RCTs and CTs ≥4 weeks investigating the effect of exercise in healthy adults with the MetS and published in a peer-reviewed journal up to November 2011 were included. Primary outcome measures were changes in waist circumference (WC), systolic and diastolic blood pressure, high-density lipoprotein cholesterol (HDL-C), triglycerides and fasting plasma glucose. Peak oxygen uptake ([Formula: see text]) was a secondary outcome. Random and fixed-effect models were used for analyses and data are reported as means and 95% confidence intervals (CIs).

Results: Seven trials were included, involving nine study groups and 206 participants (128 in exercise group and 78 in control group). Significant mean reductions in WC -3.4 (95% CI -4.9, -1.8) cm, blood pressure -7.1 (95% CI -9.03, -5.2)/-5.2 (95% CI -6.2, -4.1) mmHg and a significant mean increase in HDL-C +0.06 (95% CI +0.03, +0.09) mmol/L were observed after dynamic endurance training. Mean plasma glucose levels -0.31 (95% CI -0.64, 0.01; p = 0.06) mmol/L and triglycerides -0.05 (95% CI -0.20, 0.09; p = 0.47) mmol/L remained statistically unaltered. In addition, a significant mean improvement in [Formula: see text] of +5.9 (95% CI +3.03, +8.7) mL/kg/min or 19.3% was found.

Conclusions: Our results suggest that dynamic endurance training has a favourable effect on most of the cardiovascular risk factors associated with the MetS. However, in the search for training programmes that optimally improve total cardiovascular risk, further research is warranted, including studies on the effects of resistance training and combined resistance and endurance training.

Fig. 1

Prisma 2009 flow diagram

Fig. 2

Average net changes and corresponding 95% confidence intervals for waist circumference. Tjønna et al. [18] A and B represents moderate continuous training programme and aerobic interval training programme, respectively; and Irving et al. [17] A and B represents high-intensity training and low-intensity training, respectively. CI confidence intervals, df degrees of freedom, IV intervention, χ ² Chi-squared

Fig. 3

Average net changes and corresponding 95% confidence intervals for systolic blood pressure. Tjønna et al. [18] A and B represents moderate continuous training programme and aerobic interval training programme, respectively; and Irving et al. [17] A and B represents high-intensity training and low-intensity training, respectively. CI confidence intervals, df degrees of freedom, IV intervention, χ ² Chi-squared

Fig. 4

Average net changes and corresponding 95% confidence intervals for diastolic blood pressure. Tjønna et al. [18] A and B represents moderate continuous training programme and aerobic interval training programme, respectively; and Irving et al. [17] A and B represents high-intensity training and low-intensity training, respectively. CI confidence intervals, df degrees of freedom, IV intervention, χ ² Chi-squared

Fig. 5

Average net changes and corresponding 95% confidence intervals for HDL-C. Tjønna et al. [18] A and B represents moderate continuous training programme and aerobic interval training programme, respectively; and Irving et al. [17] A and B represents high-intensity training and low-intensity training, respectively. CI confidence intervals, df degrees of freedom, IV intervention, χ ² Chi-squared

Fig. 6

Average net changes and corresponding 95% confidence intervals for triglycerides. Tjønna et al. [18] A and B represents moderate continuous training programme and aerobic interval training programme, respectively; and Irving et al. [17] A and B represents high-intensity training and low-intensity training, respectively. CI confidence intervals, df degrees of freedom, IV intervention, χ ² Chi-squared

Fig. 7

Average net changes and corresponding 95% confidence intervals for plasma glucose. Tjønna et al. [18] A and B represents moderate continuous training programme and aerobic interval training programme, respectively; and Irving et al. [17] A and B represents high-intensity training and low-intensity training, respectively. CI confidence intervals, df degrees of freedom, IV intervention, χ ² Chi-squared