The High-intensity interval training group was instructed to complete exercise sessions of 4x4-minutes intervals at 85-95% of maximal heart rate, 3 times a week for 8 weeks. This type of exercise include 10 minutes warm-up, followed by four intervals of four minutes high-intensity (85-95% of HRmax), with three minutes active breaks (70% of HRmax) between each interval, and ending with seven minutes cool-down. An exercise session last for 42 minutes, where the participants should breathe heavily and feel exhausted four times.

The moderate training group was instructed to complete exercise sessions of 50 minutes at 70% of maximal heart rate, 3 times a week for 8 weeks.

The control group followed the baseline and follow-up tests, and was asked to live normally and not change their dietary pattern or exercise habits during their participation in this project. Based on the well-known beneficial effects of exercise on general health, it was regarded unethical to demand the control group to desist from any types of physical activity during the project period. They got no further follow-up on exercise.

Interval training 3 times a week for 8 weeks

From the skeletal muscle biopsies RNA and DNA was isolated, DNA was further bi-sulfite converted and DNA-methylation was analyzed using the Illumina HumanMethylation450 BeadChip. The RNA was further used for gene expression analyses by real-time RTqPCR.

measured on treadmill at baseline and after eight weeks, also biopsies from Vastus lateralis were sampled.