Limited effects of endurance or interval training on Visceral Adipose Tissue and Systemic Inflammation in sedentary middle-aged men

Purpose: Limited data exists for the comparative effects of sprint-interval training (SIT) and endurance training (ET) on total body composition, abdominal visceral adipose tissue (VAT) and plasma inflammatory markers. Further, whether active recovery SIT (A-SIT) provides a differential effect on these measures than passive recovery SIT (P-SIT) remains uncertain.Methods: Sedentary middle-aged men (n=62; 49.5±5.8y; 29.7±3.7kg·m2) were recruited and pre- and post-intervention underwent abdominal computed tomography, dual-energy x-ray absorptiometry, anthropometry, venepuncture and exercise testing. Participants were randomised into: 12-wks 3d·wk-1 ET (n=15; 50-60min cycling; 80% HRmax), SIT (4-10 × 30s sprint efforts) with passive (P-SIT; n=15) or 'active' recovery (A-SIT; n=15); or non-exercising control condition (CON; n=14). Repeated-measures analysis of covariance (pre-data as covariate) with one-way analysis of variance was used to assess changes in cardiorespiratory fitness, whole-body and visceral fat-mass, and plasma systemic inflammation (TNF-a, IL-6, CRP, IL-10, MCP-1). Results: Compared to CON, there were significant increases in interpolated power output (P-SIT, P<0.001; ET, P=0.012; A-SIT, P=0.041) and test duration (P-SIT, P=0.001; ET, P=0.012; A-SIT, P=0.046) after training. Final VO2 consumption was increased after P-SIT only (P<0.001). Despite >90% intervention compliance, there was no effect of exercise on whole-body or visceral fat-mass, or plasma inflammation (P>0.05).Conclusion: SIT was a time-effective alternative to ET in facilitating conditioning responses; yet was ineffective in altering body composition and inflammation, and evidenced diminished conditioning responses when employing active recovery. In initially sedentary middle-aged men, 150min·wk-1 of ET and commonly employed SIT was inadequate in reducing whole-body or visceral fat-mass, or systemic inflammation.