Three 15-min Bouts of Moderate PostmealWalking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance

OBJECTIVEdThe purpose of this study was to compare the effectiveness of three 15-min bouts of postmeal walking with 45 min of sustained walking on 24-h glycemic control in older persons at risk for glucose intolerance. RESEARCH DESIGN ANDMETHODSdInactive older ($60 years of age) participants (N = 10) were recruited from the community and were nonsmoking, with a BMI,35 kg/m2 and a fasting blood glucose concentration between 105 and 125 mg dL21. Participants completed three randomly ordered exercise protocols spaced 4weeks apart. Each protocol comprised a 48-h stay in a whole-room calorimeter, with the first day serving as the control day. On the second day, participants engaged in either 1) postmeal walking for 15 min or 45 min of sustained walking performed at 2) 10:30 A.M. or 3) 4:30 P.M. All walking was on a treadmill at an absolute intensity of 3 METs. Interstitial glucose concentrations were determined over 48 h with a con-tinuous glucose monitor. Substrate utilization was measured continuously by respiratory ex-change (VCO2/VO2). RESULTSdBoth sustained morning walking (1276 23 vs. 1186 14 mg dL21) and postmeal walking (1296 24 vs. 1166 13mg dL21) significantly improved 24-h glycemic control relativ