title: Exercise and improved insulin sensitivity in older women: evidence of the enduring benefits of higher intensity training.
abstract: Few studies have compared the relative benefits of moderate- vs. higher intensity exercise training on improving insulin sensitivity in older people while holding exercise volume constant. Healthy older (73 +/- 10 yr) women (N = 25) who were inactive, but not obese, were randomized into one of three training programs (9-mo duration): 1) high-intensity [80% peak aerobic capacity (V(O2)peak); T(H)] aerobic training; 2) moderate-intensity (65% V(O2)peak; T(M)) aerobic training; or 3) low-intensity (stretching) placebo control (50% V(O2)peak); C(TB)). Importantly, exercise volume (300 kcal/session) was held constant for subjects in both the T(H) and the T(M) groups. V(O2)peak was determined by using a graded exercise challenge on a treadmill. Total body fat and lean mass were determined with dual-energy X-ray absorptiometry. The rate of insulin-stimulated glucose utilization as well as the suppression of lipolysis were determined approximately 72 h after the final exercise bout by using a two-step euglycemic-hyperinsulinemic clamp. We observed improved glucose utilization at the higher insulin dose with training, but these improvements were statistically significant only in the T(H) (21%; P = 0.02) compared with the T(M) (16%; P = 0.17) and C(TB) (8%; P = 0.37) groups and were observed without changes in either body composition or V(O2)peak. Likewise in the T(H) group, we detected a significant improvement in insulin-stimulated suppression (%) of adipose tissue lipolysis at the low-insulin dose (38-55%, P < 0.05). Our findings suggest that long-term higher intensity exercise training provides more enduring benefits to insulin action compared with moderate- or low-intensity exercise, likely due to greater transient effects.
authors.affiliation: The John B. Pierce Laboratory, Yale University School of Medicine, 290 Congress Ave., New Haven, Connecticut 06519, USA. ldipietro@jbpierce.org
authors.forename: Loretta
authors.initials: L
authors.lastname: DiPietro
authors.forename: James
authors.initials: J
authors.lastname: Dziura
authors.forename: Catherine W
authors.initials: CW
authors.lastname: Yeckel
authors.forename: P Darrell
authors.initials: PD
authors.lastname: Neufer
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance / Q000502:physiology*; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D016896:Treatment Outcome
chemical_list: D007328:Insulin