Effects of Exercise on Insulin Resistance and Body Composition in Overweight and Obese Women with and without Polycystic Ovary Syndrome

Abstract

Polycystic ovary syndrome (PCOS) is an insulin-resistant (IR) state. Visceral fat (VF) is independently associated with IR. The objectives of the study were to explore mechanisms underpinning IR by assessing the effect of exercise training on IR and body composition in overweight PCOS and non-PCOS women. This was a prospective exercise intervention study. The study was conducted at an academic medical center. Participants included 20 overweight PCOS and 14 overweight non-PCOS women. The intervention included 12 wk of intensified aerobic exercise (3 h/wk). IR on euglycemic hyperinsulinemic clamp, body composition including abdominal visceral and sc fat distribution by computer tomography and lipids was measured. PCOS subjects were more IR (P = 0.02) and had more VF (P = 0.04 age adjusted) than non-PCOS women. In PCOS women, IR correlated with VF (r = -0.78, P < 0.01). With exercise training, both groups maintained weight but within PCOS, VF (-12.0 cm(2), P = 0.03) and within non-PCOS abdominal sc fat (-40.2 cm(2), P = 0.02) decreased. Despite exercise-induced improvement in IR within PCOS (+27.9 mg · m(-2) · min(-1), P = 0.03), no relationship with decreased VF (r = -0.08, P = 0.84) and no differential changes in IR and VF between groups were noted. Triglycerides decreased within PCOS (-0.27 mmol/liter, P = 0.02) and decreased differentially between groups (P < 0.01). Higher IR was related to increased VF in PCOS, suggesting an etiological role for VF in intrinsic IR in PCOS; however, changes with exercise intervention did not support a causal relationship. Triglycerides were modulated more by exercise training in PCOS than non-PCOS women. Within-group exercise-induced reductions in cardiometabolic risk factors including IR, triglycerides, and VF in PCOS were observed without significant weight loss and if confirmed in future controlled trials, suggest weight loss should not be the sole focus of exercise programs.