Three 15-min bouts of moderate postmeal walking significantly improves 24-h glycemic control in older people at risk for impaired glucose tolerance

Abstract

Objective: The 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 and methods: Inactive 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 dL(-1). Participants completed three randomly ordered exercise protocols spaced 4 weeks 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 continuous glucose monitor. Substrate utilization was measured continuously by respiratory exchange (VCO2/VO2).

Results: Both sustained morning walking (127±23 vs. 118±14 mg dL(-1)) and postmeal walking (129±24 vs. 116±13 mg dL(-1)) significantly improved 24-h glycemic control relative to the control day (P<0.05). Moreover, postmeal walking was significantly (P<0.01) more effective than 45 min of sustained morning or afternoon walking in lowering 3-h postdinner glucose between the control and experimental day.

Conclusions: Short, intermittent bouts of postmeal walking appear to be an effective way to control postprandial hyperglycemia in older people.

Figure 1

Mean continuous glucose concentrations from CGM over the exercise day according to exercise condition. Data represent exercise at 10:30 a.m. for 45 min (solid line), at 4:30 p.m. for 45 min (dotted line), and postmeal (broken line). To convert to Système International units (µmol/kg min⁻¹), multiply glucose values by 5.5.

Figure 2

Differences in mean 24-h averaged glucose concentrations between the control day (hashed bars) and the exercise day (solid bars) (N = 10). All walking was performed on a treadmill at a 3.0 MET exertion level. *P < 0.05 between control and exercise day. To convert to Système International units (µmol/kg min⁻¹), multiply glucose values by 5.5.

Figure 3

Differences in 3-h postlunch (A) and postdinner (B) glucose concentrations between the control day (hashed bars) and the exercise day (solid bars) (N = 10). All walking was performed on a treadmill at a 3.0 MET exertion level. *P < 0.01 between control and exercise day; §P < 0.05 compared with sustained exercise in the morning or afternoon. To convert to Système International units (µmol/kg min⁻¹), multiply glucose values by 5.5.