Effects of Exercise on Circulating Muscle-related Cytokines in Adults with Type 2 Diabetes and/or Obesity.

Abstract

Skeletal muscle is an endocrine organ that plays an important role in metabolic health by secreting a variety of myokines. Recent studies have shown that exercise significantly decreases interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in patients with type 2 diabetes (T2D). This paper explores the effect of chronic exercise on myokines in patients with T2D and/or obesity. The author searched for relevant English-language articles in PubMed. A total of 14 randomized controlled studies were found to be eligible for this short review. It has been observed that chronic exercise does not change brain-derived neurotrophic factor (BDNF), irisin, and secreted protein acidic and rich in cysteine levels, whereas it decreases TNF-α levels in patients with T2D. Combined aerobic exercise (AE) and resistance training (RT) or sprint interval training increase insulin-like growth factor 1 (IGF-1) levels and decrease IL-6 and IL-15 levels in patients with T2D. Combined AE and RT may also increase IL-15 levels in obese individuals. In addition, RT alone may increase BDNF, IGF-1, and IL-7 levels in overweight individuals. However, AE alone does not change circulating myokine levels in patients with T2D, while it may increase myonectin levels in obese individuals. This short review demonstrated that exercise appears to have favorable effects on some myokines in patients with T2D and/or obesity. However, it remains inconclusive due to the heterogeneity in subject characteristics and exercise modalities.