title: Effect of the volume and intensity of exercise training on insulin sensitivity.
abstract: Physical activity enhances insulin action in obese/overweight individuals. However, the exercise prescription required for the optimal enhancement is not known. The purpose of this study was to test the hypothesis that exercise training consisting of vigorous-intensity activity would enhance insulin sensitivity more substantially than moderate-intensity activity. Sedentary, overweight/obese subjects (n = 154) were randomly assigned to either control or an exercise group for 6 mo: 1) low-volume/moderate-intensity group [ approximately 12 miles walking/wk at 40-55% peak O2 consumption (Vo2 peak)], 2) low-volume/high-intensity group ( approximately 12 miles jogging/wk at 65-80% Vo2 peak), and 3) high-volume/high-intensity group ( approximately 20 miles jogging/wk at 65-80% Vo2 peak). Training volume (miles/wk) was achieved by exercising approximately 115 min/wk (low-volume/high-intensity group) or approximately 170 min/wk (low-volume/moderate-intensity and high-volume/high-intensity groups). Insulin action was measured with an insulin sensitivity index (SI) from an intravenous glucose tolerance test. In the control group, there was a decrement (P < 0.05) in SI. In contrast, all the exercise groups significantly (P < 0.05) increased SI; the relative increment in the low-volume/moderate-intensity and high-volume/high-intensity groups ( approximately 85%) were greater than in the low-volume/high-intensity group ( approximately 40%). In conclusion, physical activity encompassing a wide range of intensity and volume minimizes the insulin resistance that develops with a sedentary lifestyle. However, an exercise prescription that incorporated approximately 170 min of exercise/wk improved insulin sensitivity more substantially than a program utilizing approximately 115 min of exercise/wk, regardless of exercise intensity and volume. Total exercise duration should thus be considered when designing training programs with the intent of improving insulin action.
authors.affiliation: Department of Exercise and Sports Science, East Carolina University, Greenville, NC 27858, USA. HOUMARDJ@MAIL.ECU.EDU
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Houmard
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Tanner
authors.forename: Cris A
authors.initials: CA
authors.lastname: Slentz
authors.forename: Brian D
authors.initials: BD
authors.lastname: Duscha
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: McCartney
authors.forename: William E
authors.initials: WE
authors.lastname: Kraus
mesh_terms: D001786:Blood Glucose; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000517:prevention & control; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005215:Fasting; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity; D040242:Risk Reduction Behavior
chemical_list: D001786:Blood Glucose; D007328:Insulin