Effect of metformin on exercise capacity: A meta-analysis.

AIMS: To evaluate the effect of metformin on various parameters of exercise capacity [oxygen consumption (VO2 ), peak oxygen consumption (VO2peak ), heart rate (HR), exercise test duration, respiratory exchange ratio (RER), rating of perceived exertion (RPE), lactate and ventilatory anaerobic threshold (VAT)].

METHODS: Studies reporting change in VO2 or VO2peak after metformin administration were included. Subgroup analyses were performed as applicable. Mean difference with 95% CIs were pooled using random-effects model [RevMan (v5.3)].

RESULTS: There were no changes in VO2 and VO2peak in the overall population [VO2 : n = 388, mean difference: -0.12 ml/kg/min, 95% CI: -0.74, 0.51, p = 0.71 (i2  = 0%, p = 0.99); VO2peak : n = 345, mean difference: 0.41 ml/kg/min, 95% CI: -0.51, 1.33, p = 0.38 (i2  = 0%, p = 0.89)], healthy volunteers and patients (type 2 diabetes mellitus, insulin resistance, impaired glucose tolerance/impaired fasting glucose and metabolic syndrome). For patients with insulin resistance, there was a decrease in VO2peak , but not VO2 . In the overall population, there was a significant decrease in HR and RER, a significant increase in RPE, and no changes in exercise test duration and VAT. In addition, there was an increased VAT in the healthy volunteers.

CONCLUSIONS: In the overall population, metformin did not affect VO2 , VO2peak , exercise test duration and VAT, although it significantly decreased HR, RER and increased RPE.