A 2-wk reduction of ambulatory activity attenuates peripheral insulin sensitivity

J Appl Physiol (1985). 2010 May;108(5):1034-40. doi: 10.1152/japplphysiol.00977.2009. Epub 2009 Dec 31.

Abstract

US adults take between approximately 2,000 and approximately 12,000 steps per day, a wide range of ambulatory activity that at the low range could increase risk for developing chronic metabolic diseases. Dramatic reductions in physical activity induce insulin resistance; however, it is uncertain if and how low ambulatory activity would influence peripheral insulin sensitivity. We aimed to explore if healthy, nonexercising subjects who went from a normal to a low level of ambulatory activity for 2 wk would display metabolic alterations including reduced peripheral insulin sensitivity. To do this, ten healthy young men decreased their daily activity level from a mean of 10,501+/-808 to 1,344+/-33 steps/day for 2 wk. Hyperinsulinemic-euglycemic clamps with stable isotopes and muscle biopsies, maximal oxygen consumption (VO2 max) tests, and blood samples were performed pre- and postintervention. A reduced number of daily steps induced a significant reduction of 17% in the glucose infusion rate (GIR) during the clamp. This reduction was due to a decline in peripheral insulin sensitivity with no effect on hepatic endogenous glucose production. The insulin-stimulated ratio of pAktthr308/total Akt decreased after step reduction, with a post hoc analysis revealing the most pronounced effect after 4 h of insulin infusion. In addition, the 2-wk period induced a 7% decline in VO2 max (ml/min; cardiovascular fitness). Lean mass of legs, but not arms and trunk, decreased concurrently. Taken together, one possible biological cause for the public health problem of Type 2 diabetes has been identified. Reduced ambulatory activity for 2 wk in healthy, nonexercising young men significantly reduced peripheral insulin sensitivity, cardiovascular fitness, and lean leg mass.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actigraphy / instrumentation
  • Adult
  • Biomarkers / blood
  • Biopsy
  • Blood Glucose / metabolism*
  • Body Composition
  • Diabetes Mellitus, Type 2 / etiology*
  • Diabetes Mellitus, Type 2 / metabolism
  • Diabetes Mellitus, Type 2 / physiopathology
  • Energy Metabolism
  • Glucose Clamp Technique
  • Humans
  • Inflammation / etiology
  • Inflammation / metabolism
  • Inflammation / physiopathology
  • Inflammation Mediators / blood
  • Insulin / administration & dosage
  • Insulin / metabolism*
  • Insulin Resistance*
  • Liver / metabolism
  • Liver / physiopathology
  • Male
  • Motor Activity*
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / physiopathology
  • Oxygen Consumption
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Sedentary Behavior*
  • Time Factors
  • Young Adult

Substances

  • Biomarkers
  • Blood Glucose
  • Inflammation Mediators
  • Insulin
  • Proto-Oncogene Proteins c-akt