Post - exercise protein supplementation in muscular dystrophy 1 Protein - carbohydrate supplements improve muscle protein balance in 1 muscular dystrophy patients after endurance exercise : a placebo 2 controlled crossover study 3

26 In healthy individuals post-exercise protein supplementation increases muscle protein anabolism. 27 In patients with muscular dystrophies, aerobic exercise improves muscle function, but the effect of 28 exercise on muscle protein balance is unknown. 29 Therefore, we investigated 1) muscle protein balance before, during, and after exercise and 2) the 30 effect of post-exercise protein-carbohydrate supplementation on muscle protein balance in 31 patients with muscular dystrophies. 32 In 17 patients (7 women and 10 men, age 33 ± 11 years (18–52), BMI: 22 ± 3 kg/m (16–26)) and 8 33 healthy matched controls (3 women and 5 men, age 33 ± 13 years (19–54), BMI: 23 ± 3 kg/m 34 (19–27)), muscle protein synthesis, breakdown, and fractional synthesis rates (FSR) were 35 measured across the leg using tracer dilution methodology on two occasions; with and without 36 oral post-exercise protein-carbohydrate supplementation. 37 In patients, muscle protein breakdown increased in the recovery period (11 ± 1 μmol 38 phenylalanine/min) versus rest (8 ± 1 μmol phenylalanine/min, P = 0.02) enhancing net muscle 39 protein loss. In contrast, post-exercise protein-carbohyddrate supplementation reduced protein 40 breakdown, abolished net muscle protein loss and increased the muscle FSR in patients (0.04 to 41 0.06 % per hour, P = 0.03). 42 In conclusion, post-exercise protein-carbohydrate supplementation reduces skeletal mixed muscle 43 protein breakdown, enhances FSR, resulting in a reduced net muscle loss in patients with muscular 44 dystrophies. The findings suggest that post-exercise protein-carbohydrate supplementation could 45 be an important add-on to exercise training therapy in muscular dystrophies, and long-term 46 studies of post-exercise protein-carbohydrate supplementation are warranted in these conditions. 47 Post-exercise protein supplementation in muscular dystrophy 3