High-intensity interval training enhances markers of skeletal muscle mitochondrial capacity
FRIDAY, Dec. 16 (HealthDay News) -- Low-volume high-intensity interval training (HIT) lowers the 24-hour blood glucose concentration, and increases markers of skeletal muscle mitochondrial capacity in individuals with type 2 diabetes, according to a study published in the December issue of the Journal of Applied Physiology.
Jonathan P. Little, Ph.D., from McMaster University in Hamilton, Canada, and colleagues investigated the effects of low-volume HIT on glucose regulation and skeletal muscle metabolic capacity in eight patients with type 2 diabetes (aged 63 ± 8 years; body mass index, 32 ± 6 kg/m²; hemoglobin A1C, 6.9 ± 0.7 percent). During a two-week period, participants performed six HIT sessions (10 × 60-seconds bouts of cycling eliciting ~90 percent maximal heart rate, interspersed with 60 second rest periods). Glucose regulation was measured through continuous glucose monitoring over a 24-hour period, under standard dietary conditions, before and after training. Vastus lateralis biopsy samples were tested for markers of skeletal muscle metabolic capacity, before and after training.
The investigators found that, after training, the average 24-hour blood glucose concentration was significantly reduced. The sum of the three-hour postprandial area under the glucose curves for breakfast, lunch, and dinner was also significantly lower. Muscle mitochondrial capacity increased significantly post-training, as reflected by significant increases in citrate synthase maximal activity, and in the protein content of Complex II 70 kilodalton subunit, Complex III Core 2 protein, and Complex IV subunit IV. The protein content of mitofusin 2 and glucose transporter 4 were also significantly increased after training.
"Our findings indicate that low-volume HIT may represent a time-efficient exercise strategy for the treatment of type 2 diabetes," the authors write.
Medtronic of Canada contributed the continuous glucose monitors and sensors for the study.