Time-efficient Sprint Interval Exercise Improves 24-h Glycaemic Control In Men With Type 2 Diabetes

Abstract

PURPOSE: Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient exercise intervention that has been shown to improve aerobic capacity and blood pressure in men with type 2 diabetes. However, the acute effects of REHIT on 24 h glycaemic control in type 2 diabetes have not been determined. METHODS: Eleven men with type 2 diabetes (mean ± SD: age, 52±6 years; BMI, 29.7±3.1 kg/m2; HbA , 7.0±0.8 %) participated in a randomised four-trial crossover study, with continual interstitial glucose measurements captured during a 24 h period including either: (1) no exercise (CON); (2) 30 min of continuous exercise (CE); (3) 10 x 1 min at ~90 HRmax (HIIT; time commitment, ~25 min); and (4) 2 x 20 s ‘all-out’ sprints (REHIT; time commitment, 10 min). Nutritional intake and timings of consumption were standardised within participants. The 24 h monitoring period started prior to breakfast and the exercise was performed 30 min after breakfast. Comparisons for 24 glycaemic variables were made using one-way repeated measures ANOVA and Holm-Sidak corrected t-tests for pre-planned contrasts (exercise conditions versus control). Cohens d was used as a measure of effect size with the following thresholds: small (d = 0.2), medium (d = 0.5) and large (d = 0.8) effect. RESULTS: Compared with CON (8.1±1.1 mmol/l), both REHIT (7.5±0.9 mmol/l, p<0.05, d=0.55) and CE (7.7±1.1 mmol/l, p=0.06, d=0.35) lowered mean 24 h glucose, and this was largely driven by a markedly lower glycaemic response (AUC) to dinner in both instances (-11%, p<0.05 and d>0.8 for both). The prevalence of hyperglycaemia was reduced with all three exercise bouts compared with CON (REHIT: -112 min; CE: -115 min; HIIT -125 min, all p<0.05, all d>0.5), whilst measures of glycaemic variability were not significantly altered. CONCLUSIONS: These data suggest that REHIT may offer a genuinely time-efficient alternative exercise option for improving 24 h glycaemic control in men with type 2 diabetes.