Problems with activity

• Everyday activities can cause problems, e.g.: chewing, brushing teeth, hanging out washing, drying after a shower, standing on tiptoe.

• As the anaerobic metabolic pathway is blocked, people with McArdle disease should avoid intense activity, especially isometric and repetitive actions.

• During more gentle activity, patients need to recognise the signals from the muscles that warn them to slow down or pause for a rest.

• Rushing and sudden activity from a rested state are both likely to lead to muscle cramps.

• ‘Six second rule’ [1] – If a patient has to undertake any activity at maximal effort (e.g. opening a jam jar, running for a bus), they are advised to limit duration to 6 seconds [2]. They can try again after resting for at least 30 seconds.

• ‘Second wind’ [3] – alternative energy pathways (fat, amino acids, glucose from the liver glycogen stores) help to some extent when they start to come into use after about 8 to 10 minutes.

• Patients must learn the techniques for safely achieving ‘second wind’ [3]. It is universal to all patients, but some need help to recognize it.

• Tensing muscles (e.g. due to anger, fear or excitement) greatly increases the risk of injury.

[1] 101 Tips for a Good Life with McArdle Disease. (2013-2022) Wakelin, Andrew. IamGSD. (See page 19.)

[2] Metabolic fundamentals in exercise. Saltin, B. (1973) Med & Sci in Sports, v5, n3, 137-146.

[3] Outcome Measures in McArdle Disease. Quinlivan R, Vissing J (2006 ) 144th ENMC International Workshop, 29 Sept-1 Oct 2006, Naarden, The Netherlands. Neuromuscular Disorders 17: 494-498.