Aim: Non-weight-bearing high-intensity interval training (HIIT) involving several muscle groups may efficiently improve metabolic health in obesity and type 2 diabetes. In a non-randomized intervention study, we examined the effect of a HIIT-protocol, recruiting both lower and upper body muscles, on insulin sensitivity, measures of metabolic health and adherence in obesity and type 2 diabetes. Methods: In 15 obese men with type 2 diabetes and age-matched obese (n=15) and lean (n=18) glucose-tolerant men, the effects of 8-weeks supervised HIIT combining rowing and cycling were examined by DXA-scan, exercise test and hyperinsulinemic-euglycemic clamp. Results: At baseline, insulin-stimulated glucose disposal rate (GDR) was ~40% reduced in the diabetic vs the non-diabetic groups (all p<0.01). In response to HIIT, insulin-stimulated GDR increased ~30-40% in all groups (all p<0.01) explained by increased glucose storage. These changes were accompanied by ~8-15% increases in VO2max, (all p<0.01), decreased fat mass and increased lean body mass in all groups (all p<0.05). There were no correlations between these training adaptations and no group-differences in these responses. HbA1c showed a clinically relevant decrease in men with type 2 diabetes (4 +/- 2 mmol/mol; p<0.05). Importantly, adherence was high (>95%) and no injuries were reported. Conclusions: A novel HIIT-protocol recruiting lower and upper body muscles efficiently improves insulin sensitivity, VO2max and body composition with intact responses in men with obesity and type 2 diabetes. The high adherence and lack of injuries show that non-weight-bearing HIIT involving several muscle groups is a promising mode of exercise training in obesity and type 2 diabetes.

The authors have declared no competing interest.

NCT03500016

Funding This study was supported by grants from the Region of Southern Denmark, Odense University Hospital, the Novo Nordisk Foundation, University of Southern Denmark, Christenson-Cesons Family Fund and from The Sawmill Owner Jeppe Juhl and wife Ovita Juhl Memorial Foundation.

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The study was approved by the Regional Scientific Ethical Committees for Southern Denmark and performed in accordance with the Helsinki Declaration II. The approval has the project-ID: Projekt-ID: S-20170142

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