‘Exercise Snacks’ Before Meals: A Novel Strategy to Improve Glycaemic Control in Individuals With Insulin Resistance
Do small amounts of intense exercise prior to meals improve blood glucose control among patients with insulin resistance?
Adults (ages 18-55 years) were recruited for this study. Participants had to have insulin resistance by documented oral glucose tolerance testing after a controlled diet and overnight fast. Patients on medications for glucose control or for high blood pressure were excluded. Of the 16 volunteers recruited, seven men and two women had impaired fasting glucose and/or impaired glucose tolerance and were enrolled in the study. The individuals were randomized to one of three exercise interventions across a 3-day period, with exercise performed on the middle day, as either: 1) traditional continuous exercise, comprising 30-minute moderate-intensity (60% of maximal heart rate [HRmax]) incline walking before dinner; 2) exercise snacking, consisting of 6×1 minute intense (90% HRmax) incline walking intervals 30 minutes before each meal; or 3) composite exercise snacking, encompassing 6×1 minute intervals alternating between walking and resistance-based exercise, 30 minutes before meals. Meal timing and composition were controlled within participants for exercise interventions.
Exercise snacking attenuated mean 3-hour postprandial glucose concentration following breakfast (by 1.4 ± 1.5 mmol/L, p = 0.02), but not lunch (0.4 ± 1.0 mmol/L, p = 0.22), and was more effective than continuous exercise following dinner (0.7 ± 1.5 mmol/L below continuous exercise; p = 0.04). Exercise snacking also reduced 24-hour mean glucose concentration by 0.7 ± 0.6 mmol/L (p = 0.01), and this reduction persisted for the subsequent 24 hours (lower by 0.6 ± 0.4 mmol/L vs. continuous exercise, relative to baseline; p = 0.01). Composite exercise snacking was just as effective as exercise snacking (p > 0.05 for all glycemic variables) at improving glycemic control.
The investigators concluded that dosing exercise as brief, intense ‘exercise snacks’ before main meals is a time-efficient and effective approach to improve glycemic control in individuals with insulin resistance.
This small study provides novel information on exercise type and glucose control. The improvement in glucose control associated with short bouts of intense exercise (which last for up to 24 hours post-intervention) merits further study in larger and more diverse cohorts.
Keywords: Prediabetic State, Heart Rate, Insulin Resistance, Meals, Glucose Intolerance, Walking, Postprandial Period, Glucose Tolerance Test, Blood Glucose, Cardiovascular Diseases, Physical Exertion, Fasting, Hypertension
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