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

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 localised 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 hyperinsulinaemia). 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 x 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 7 studies (11 intervention arms) measuring the suppression of circulating non-esterified fatty acid in response to insulin infusion (1.51 [-0.12 to – 3.14] %); however, sub-group analysis identified an enhanced suppression post-training in trials reporting weight loss. From four microdialysis studies, consensus indicates no effect of exercise training on localised (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.