title: The effects of 24 weeks of moderate- or high-intensity exercise on insulin resistance.
abstract: This study was designed to investigate the effect of exercise intensity on insulin resistance by comparing moderate- and high-intensity interventions of equal energy cost. Maximum oxygen consumption (VO(2max)), insulin, glucose and triglycerides were measured in 64 sedentary men before random allocation to a non-exercise control group, a moderate-intensity exercise group (three 400-kcal sessions per week at 60% of VO(2max)) or a high-intensity exercise group (three 400-kcal sessions per week at 80% of VO(2max)). An insulin sensitivity score was derived from fasting concentrations of insulin and triglycerides, and insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). Data were available for 36 men who finished the study. After 24 weeks, insulin concentration decreased by 2.54+/-4.09 and 2.37+/-3.35 mU l(-1), insulin sensitivity score increased by 0.91+/-1.52 and 0.79+/-1.37, and HOMA-IR decreased by -0.6+/-0.8 and -0.5+/-0.8 in the moderate- and high-intensity exercise groups, respectively. When data from the exercise groups were combined, one-way analysis of variance with one-tailed post hoc comparisons indicated that these changes were significantly greater than those observed in the control group (all P<0.05). Twenty-four week changes in insulin concentration, insulin sensitivity score and HOMA-IR were not significantly different between the exercise groups. These data suggest that exercise training is accompanied by a significant reduction in insulin resistance, as indicated by well-validated surrogate measures. These data also suggest that moderate-intensity exercise is as effective as high-intensity exercise when 400 kcal are expended per session.
authors.affiliation: Department of Sport Science, Tourism and Leisure, Canterbury Christ Church, University College, Canterbury, UK.
authors.forename: Gary
authors.initials: G
authors.lastname: O'Donovan
authors.forename: Edward M
authors.initials: EM
authors.lastname: Kearney
authors.forename: Alan M
authors.initials: AM
authors.lastname: Nevill
authors.forename: Kate
authors.initials: K
authors.lastname: Woolf-May
authors.forename: Steve R
authors.initials: SR
authors.lastname: Bird
mesh_terms: D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000517:prevention & control; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D010806:Physical Education and Training / Q000379:methods*; D013997:Time Factors