The effect of exercise training on adipose tissue insulin sensitivity: A systematic review and meta-analysis

Abstract

This systematic review and meta-analysis determined the impact of exercise training on adipose tissue insulin sensitivity in adults. Its scope extended to studies measuring whole-body and localized subcutaneous adipose tissue insulin sensitivity using validated techniques. Consensus from four studies demonstrates that exercise training improved whole-body adipose tissue insulin sensitivity when measured via stable-isotope lipid tracers (rate of appearance suppression in response to hyperinsulinemia). Meta-analysis of 20 studies (26 intervention arms) employing the adipose tissue insulin resistance index (ADIPO-IR) supported these findings (−10.63 [−14.12 to −7.15] pmol·L−1 × mmol·L−1). With ADIPO-IR, this response was greater in studies documenting weight loss and shorter sampling time (≤48 h) post-training. Overall, exercise training did not affect whole-body adipose tissue insulin sensitivity in seven studies (11 intervention arms) measuring the suppression of circulating non-esterified fatty acids in response to insulin infusion (1.51 [−0.12 to 3.14]%); however, subgroup analysis identified an enhanced suppression post-training in trials reporting weight loss. From four microdialysis studies, consensus indicates no effect of exercise training on localized (abdominal/femoral) adipose tissue insulin sensitivity, potentially suggesting that enhanced whole-body responses are related to improvements in central adipose depots. However, heterogeneity within microdialysis protocols dictates that findings must be viewed with caution.