Exercise Training Counteracts Compromised Mitochondrial Capacity Induced by Energy Restriction in Prediabetics in a...

The objective of this randomized controlled trial was to examine if exercise training can counteract energy restriction-induced impairment of mitochondrial capacity in skeletal muscle of 55-70-years people with prediabetes and metabolic syndrome. The potential impact of sex was explored. Fifty sedentary men and women with prediabetes and metabolic syndrome (age: 61 ± 6 (±SD) years, BMI: 29.6 ± 4.7 kg·m^-2, body fat content: 37.5% ± 8.2% and VO_2max: 22.3 ± 5.7 mL·min^-1·kg^-1) were randomized to either exercise training and dietary advice (EX-DI) or dietary advice only (DI). Dietary advice aimed to induce weight loss and improve glycemic control. Exercise consisted of 32 ± 2 mixed 30-60 min training sessions with recreational small-sided soccer distributed across 16 weeks. Maximal activity and protein abundance of key regulatory mitochondrial enzymes were determined in m. vastus lateralis pre- and post-intervention. Muscle glycogen content was also determined. Dietary advice only (DI), impaired (p < 0.001) citrate synthase (CS), and 3-hydroxyacyl-CoA dehydrogenase (HAD) maximal activity by 18% ± 43% and 23% ± 19%, respectively. When combined with exercise training, no dietary impairment of CS or HAD maximal activity was detectable. Superoxide dismutase 2 (SOD2) and CS protein expression also declined (p < 0.05) in DI and remained unchanged in EX-DI. In terms of sex differences, a decrease in maximal CS activity in both EX-DI and DI was observed exclusively in men (all p < 0.05). In conclusion, 16 weeks of exercise training counteracts energy restriction-induced impairment in skeletal mitochondrial function in 55- to 70-year-old women and men with prediabetes and metabolic syndrome.