title: Acute inactivity impairs glycemic control but not blood flow to glucose ingestion.
abstract: OBJECTIVE
  Insulin-stimulated increases in skeletal muscle blood flow play a role in glucose disposal. Indeed, 7 d of aerobic exercise in patients with Type 2 diabetes increased blood flow responses to an oral glucose tolerance test (OGTT) and improved insulin sensitivity. More recent work suggests that reduced daily physical activity impairs glycemic control (GC) in healthy individuals. Herein, we sought to determine whether an acute reduction in daily activity (from >10,000 to <5000 steps per day) for 5 d (RA5) in healthy individuals reduced insulin-stimulated blood flow and GC in parallel and if a 1-d return to activity (RTA1) improved these outcomes.
  
  
  METHODS
  OGTT were performed as a stimulus to increase insulin in 14 healthy, recreationally active men (24 ± 1.1 yr) at baseline, RA5, and RTA1. Measures of insulin sensitivity (Matsuda index) and femoral and brachial artery blood flow were made during the OGTT. Free-living measures of GC including peak postprandial glucose (peak PPG) were also made via continuous glucose monitoring.
  
  
  RESULTS
  Femoral and brachial artery blood flow increased during the OGTT but neither was significantly impacted by changes in physical activity (P > 0.05). However, insulin sensitivity was decreased by RA5 (11.3 ± 1.5 to 8.0 ± 1.0, P < 0.05). Likewise, free-living GC measures of peak PPG (113 ± 3 to 123 ± 5 mg·dL(-1), P < 0.05) was significantly increased at RA5. Interestingly, insulin sensitivity and GC as assessed by peak PPG were not restored after RTA1 (P > 0.05).
  
  
  CONCLUSIONS
  Thus, acute reductions in physical activity impaired GC and insulin sensitivity; however, blood flow responses to an OGTT were not affected. Further, a 1-d return to activity was not sufficient to normalize GC after 5 d of reduced daily physical activity.
authors.affiliation: 1Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO; 2Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO; and 3Division of Gastroenterology and Hepatology, Department of Medicine, University of Missouri, Columbia, MO.
authors.forename: Leryn J
authors.initials: LJ
authors.lastname: Reynolds
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Credeur
authors.forename: Seth W
authors.initials: SW
authors.lastname: Holwerda
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Leidy
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Fadel
authors.forename: John P
authors.initials: JP
authors.lastname: Thyfault
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D001916:Brachial Artery / Q000502:physiology; D004032:Diet; D005263:Femoral Artery / Q000502:physiology; D005947:Glucose / Q000008:administration & dosage*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply*; D019518:Postprandial Period / Q000502:physiology*; D012039:Regional Blood Flow; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin; D005947:Glucose