Fat metabolism during exercise in patients with McArdle disease

TY - JOUR

T1 - Fat metabolism during exercise in patients with McArdle disease

AU - Ørngreen, M C

AU - Jeppesen, T D

AU - Andersen, S Tvede

AU - Taivassalo, T

AU - Hauerslev, S

AU - Preisler, N

AU - Haller, R G

AU - Van Hall, Gerrit

AU - Vissing, J

N1 - Keywords: Adaptation, Physiological; Adult; Carbohydrate Metabolism; Exercise; Fatty Acids; Fatty Acids, Nonesterified; Glycogen Storage Disease Type V; Humans; Muscle, Skeletal; Oxidation-Reduction; Palmitates; Young Adult

PY - 2009

Y1 - 2009

N2 - OBJECTIVE: It is known that muscle phosphorylase deficiency restricts carbohydrate utilization, but the implications for muscle fat metabolism have not been studied. We questioned whether patients with McArdle disease can compensate for the blocked muscle glycogen breakdown by enhancing fat oxidation during exercise. METHODS: We studied total fat oxidation by indirect calorimetry and palmitate turnover by stable isotope methodology in 11 patients with McArdle disease and 11 healthy controls. Cycle exercise at a constant workload of 50% to 60% of maximal oxygen uptake capacity was used to evaluate fatty acid oxidation (FAO) in the patients. Healthy controls were exercised at the same absolute workload. RESULTS: We found that palmitate oxidation and disposal, total fat oxidation, and plasma levels of palmitate and total free fatty acids (FFAs) were significantly higher, whereas total carbohydrate oxidation was lower, during exercise in patients with McArdle disease vs healthy controls. We found augmented fat oxidation with the onset of a second wind, but further increases in FFA availability, as exercise continued, did not result in further increases in FAO. CONCLUSION: These results indicate that patients with McArdle disease have exaggerated fat oxidation during prolonged, low-intensity exercise and that increased fat oxidation may be an important mechanism of the spontaneous second wind. The fact that increasing availability of free fatty acids with more prolonged exercise did not increase fatty acid oxidation suggests that blocked glycogenolysis may limit the capacity of fat oxidation to compensate for the energy deficit in McArdle disease.

AB - OBJECTIVE: It is known that muscle phosphorylase deficiency restricts carbohydrate utilization, but the implications for muscle fat metabolism have not been studied. We questioned whether patients with McArdle disease can compensate for the blocked muscle glycogen breakdown by enhancing fat oxidation during exercise. METHODS: We studied total fat oxidation by indirect calorimetry and palmitate turnover by stable isotope methodology in 11 patients with McArdle disease and 11 healthy controls. Cycle exercise at a constant workload of 50% to 60% of maximal oxygen uptake capacity was used to evaluate fatty acid oxidation (FAO) in the patients. Healthy controls were exercised at the same absolute workload. RESULTS: We found that palmitate oxidation and disposal, total fat oxidation, and plasma levels of palmitate and total free fatty acids (FFAs) were significantly higher, whereas total carbohydrate oxidation was lower, during exercise in patients with McArdle disease vs healthy controls. We found augmented fat oxidation with the onset of a second wind, but further increases in FFA availability, as exercise continued, did not result in further increases in FAO. CONCLUSION: These results indicate that patients with McArdle disease have exaggerated fat oxidation during prolonged, low-intensity exercise and that increased fat oxidation may be an important mechanism of the spontaneous second wind. The fact that increasing availability of free fatty acids with more prolonged exercise did not increase fatty acid oxidation suggests that blocked glycogenolysis may limit the capacity of fat oxidation to compensate for the energy deficit in McArdle disease.

U2 - 10.1212/01.wnl.0000343002.74480.e4

DO - 10.1212/01.wnl.0000343002.74480.e4

M3 - Journal article

C2 - 19237700

SN - 0028-3878

VL - 72

SP - 718

EP - 724

JO - Neurology

JF - Neurology

IS - 8

ER -