McArdle's disease (McAd)

Last edited 02/2020 and last reviewed 08/2021

McArdle's disease (McAd) was first described in 1951 by Brian McArdle, and named after him. Synonyms are myophosphorylase insufficiency and glycogen storage disease type V.

McAd is a type of glycogen storage disease that only affects muscle.

Muscle biopsy is diagnostic.

Symptoms of McAd are muscle pain in everyday activities and sport, exercise intolerance, premature fatigue, myalgia, cramps, and myoglobinuria (1,2)

• in most of the patients, resting a few minutes relieves these symptoms (1)

Notes:

• there is evidence to suggest that regular moderate aerobic physical activity provides benefit to McAd patients (3,4)
  • physical activity reduces symptoms in this disorder by increasing effort tolerance, functional self-independence, and quality of life
  • patients with McAd are often able to continue exercising for a longer period as a result of the “second-wind phenomenon,” due to a marked increase in muscle oxidative capacity (3,4)
    • undertaking regular moderate physical activity may be beneficial in reducing the time needed to access this second-wind phenomenon, perhaps due to metabolic adaptations (4)

Further web resources:

• Association for Glycogen Storage Disease (UK) www.agsd.org.uk

Reference:

1. Bartram C et al. McArdle's disease-muscle glycogen phosphorylase deficiency. Biochim Biophys Acta 1995; 1272: 1–13
2. Bollig G et al. McArdle's disease and anaesthesia: Case reports. Review of potential problems and association with malignant hyperthermia. Acta Anaesthesiologica Scandinavica 2005;49 (8): 1077-1083.
3. Haller RG, Vissing J. Spontaneous “second wind” and glucoseinduced second wind in McArdle’s disease. Arch Neurol 2002; 59:1395–140
4. Ollivier K et al.Exercise tolerance and daily life in McArdle's disease.Muscle Nerve 2005; 31: 637–641.
5. Braakhekke JP et al. The second wind phenomenon in McArdle's disease.Brain 1986;109(6):1087-1101
6. S. Tsujino et al. NEJM 1993; 329(4): 241-5.