Effects of strength training on muscle lactate release and MM and MCT4 content in healthy and type 2 diabetic humans

Lactate is released from skeletal muscle in proportion to glucose uptake rates, and it leaves the cells via simple diffusion and two monocarboxylate transporter proteins, MCTI and MCT4. In reponse to endurance training MCT1 - and possibly MCT4 - content in muscle increases. The MCTs have not previously been measured in patients with type 2 diabetes (Type 2), and the response to strength training is unknown. Ten Type 2 and seven healthy men (Control) strength-trained one leg (T) 3 times a week for 6 weeks while the other leg remained untrained (UT). Each session lasted no more than 30 min. After strength training, muscle biopsies were obtained and an isoglycaemic, hyperinsulinaemic clamp, combined with arterial and femoral venous catheterization of both legs, was carried out. During hyperinsulinaemia lactate release was always increased in T versus UT legs. MCTI was lower (P < 0.05) and MCT4 similar in Type 2 versus Control. With training, MCT1 content always increased, while MCT4 only increased in Control. Conclusions: MCT1 content in skeletal muscle in Type 2 is lower compared with healthy men. Strength training increases MCT1 content in healthy men and in Type 2, thus normalizing the content in Type 2.