INTRODUCTION: The present study investigated whether rugby small-sided games (SSG) could be an effective alternative to continuous stationary cycling (CYC) training at reducing clinical risk factors associated with the development of type 2 diabetes mellitus (T2DM). METHODS: Thirty-three middle-aged (48.6 +/- 6.6y), inactive men were randomized into a CYC (n = 11), SSG (n = 11), or control (CON, n = 11) group. Participants trained 3d/wk for 8 weeks, while control participants maintained normal activity and dietary patterns. Exercise duration was matched between groups, which involved CYC or SSG (four quarters, interspersed with 2-min passive recovery). Both training programs were designed to induce similar internal loads of maximal heart rate (about 80 to 85%HRmax) and rating of perceived exertion. Pre- and post-intervention testing included dual-energy x-ray absorptiometry scan, graded exercise test, fasting 2 h oral glucose tolerance test and resting muscle biopsy. Western blotting was used to assess the content of skeletal muscle proteins associated with mitochondrial biogenesis and glucose regulation. RESULTS: Both CYC and SSG increased VO2 at 80%HRmax, and reduced glycated haemoglobin, glucose area under the curve (AUC; SSG -2.3 +/- 2.4; CYC -2.2 +/- 1.6 mmol/L/120min; p < 0.05), and total body fat-mass (SSG -2.6 +/- 0.9%; CYC -2.9 +/- 1.1%), compared to no change in CON (p < 0.05). SSG reduced insulin AUC (-30.4 +/- 40.7 microlU/mL/120min; p < 0.05) and increased total body fat-free mass (1.1 +/- 1.2kg; p < 0.05), with no change in CYC or CON (p > 0.05). There were no differences within or between conditions for protein content of peroxisome proliferator-activated receptor gamma coactivator-1alpha, sirtuin-1, p53, glucose transporter-4, protein kinase AKT/PKB, myocyte enhancer factor 2A, mitochondrial transcription factor, nuclear respiratory factor (NRF)-1, NRF-2 or mitochondrial complexes I to V (p > 0.05). CONCLUSION: Rugby small-sided games is an effective alternative to continuous cycling for improving metabolic risk-factors associated with the prevention of T2DM. Despite such positive adaptations in clinical risk factors, there were no changes in the content of skeletal muscle proteins associated with glucose regulation and mitochondrial biogenesis. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry ACTRN12613000874718.

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