Oral conjugated linoleic acid supplementation enhanced glycogen resynthesis in exercised human skeletal muscle

Present study examined the effects of conjugated linoleic acid (CLA) supplementation on glycogen resynthesis in exercised human skeletal muscle. Twelve male participants completed a cross-over trial with CLA (3.8 g/day for 8 week) or placebo supplements by separation of 8 weeks. CLA is a mixture of trans-10 cis-12 and cis-9 trans-11 isomers (50:50). On experiment day, all participants performed 60-min cycling exercise at 75% VO2 max, then consumed a carbohydrate meal immediately after exercise and recovered for 3 h. Biopsied muscle samples from vastus lateralis were obtained immediately (0 h) and 3 h following exercise. Simultaneously, blood and gaseous samples were collected for every 30 min during 3-h recovery. Results showed significantly increased muscle glycogen content with CLA after a single bout of exercise (P < 0.05). Muscle glucose transporter type 4 expression was significantly elevated immediately after exercise, and this elevation was continued until 3 h after exercise in CLA trial. However, P-Akt/Akt ratio was not significantly altered, while glucose tolerance was impaired with CLA. Gaseous exchange data showed no beneficial effect of CLA on fat oxidation, instead lower non-esterified fatty acid and glycerol levels were found at 0 h. Our findings conclude that CLA supplementation can enhance the glycogen resynthesis rate in exercised human skeletal muscle.