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Exercise ‘snacks’ controlled blood glucose better than prolonged workouts
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Brief and intense exercise “snacks” before main meals are an effective approach to improve glycemic control in patients with insulin resistance, suggesting the potential to prevent cardiometabolic disease, according to research published in Diabetologia.
Monique Francois, MPhEd, of the University of Otago in New Zealand, along with other exercise science and medicine researchers, enrolled nine participants (two women, seven men) to a crossover study to investigate how bursts of exercise affect blood glucose control compared with prolonged, continuous, moderate-intensity exercise.
“In those with insulin resistance, both the timing and intensity of exercise are important and can be used to control blood glucose,” Francois told Endocrine Today. “Moderate-low intensity exercise may not be a big enough stimulus to improve blood glucose control, especially if the rest of the day is spent sedentary.”
The individuals (aged 18 to 55 years; mean BMI, 36) had blood tests showing insulin resistance and were not on cardiovascular or diabetic medication; two were diagnosed with type 2 diabetes during the screening. Exercise interventions, to be performed midday, were randomly assigned and measures were recorded for 3 days.
The traditional continuous exercise (CONT) group participated in 30-minute moderate-intensity (60% of maximal heart rate) sessions of incline walking before an evening meal only. The exercise snacking (ES) cohort completed six 1-minute intense (90% maximal heart rate) incline walking intervals that ended 30 minutes before breakfast, lunch and dinner; 1 minute of slow walking followed as recovery. The composite exercise snacking (CES) group engaged in six 1-minute intervals that alternated between walking and resistance-based exercise; this also included 1 minute of slow walking recovery and finished 30 minutes before breakfast, lunch and dinner.
The timing and composition of meals were the same for each cohort — monitored using diet records, daily discussion and dietary analysis software.
Individuals in the ES group showed reduced postprandial glucose concentration after breakfast (by 1.4 ± 1.5 mmol/L, P=.02) but not lunch (0.4 ± 1 mmol/L, P=.22); ES was found more effective than CONT after dinner (0.7 ± 1.5 mmol/L below CONT, P=.04). The ES group also reduced 24-hour mean glucose concentration by 0.7 ± 0.6 mmol/L (P=.01) and stayed low for 24 hours after (lower by 0.6 ± 0.4 mmol/L vs. CONT, relative to their baselines; P=.01). Glycemic control improvements corresponded in the CES group (P>.05 for all glycemic variables).
“Intense short bursts of exercise before meals can lower the postprandial blood glucose responses to meals, particularly before breakfast and dinner,” Francois said. “It doesn’t matter whether it is walking up hill or resistance exercise, as long as the intensity is above what we normally do across the day.”
Disclosure: This study was supported by the School of Physical Education, Sport and Exercise Sciences and Dunedin School of Medicine, University of Otago.
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