Plain language summary
The insulin response is known to decline with age, which puts older people at risk of hyperglycaemia after eating. Insulin and exercise stimulate the uptake of glucose into skeletal muscle so exercise could aid insulin in age-related impaired glucose tolerance (IGT). This small randomised controlled trial (RCT) used a multiple crossover design to compare the effect of exercise timing and frequency on glycaemia control in older people. The ten trial subjects were at risk of impaired glucose tolerance (IGT), but were otherwise healthy with an average age of sixty-nine years old. Subjects were housed in whole room calorimeters, fed three standardised meals a day and glucose levels were monitored. Subjects were randomly assigned to walk on a treadmill for either fifteen minutes after each of the three meals, or walk for forty-five minutes either at mid-morning or mid-afternoon. It was found that that both the morning walk and the post-meal walking decreased 24 hour glucose concentration, whilst the afternoon walk had little impact. Post-meal walking was effective at lowering glucose levels after each meal including dinner, where the other exercise protocols were not. The author concluded that the timing of the exercise may be as important, if not more, than volume. Short (15 minute) bouts of post-meal walking could be manageable for older people and appears to be an effective way of controlling post eating hyperglycaemia.
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.
Methodological quality
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Not applicable
