Cramps and contractures
Patients should try to avoid incurring cramps that last for more than a minute or two.
Intense or isometric activity for more than about 6 seconds will risk severe cramps or fixed contractures which last for hours or days.
Such contractures can be incurred accidentally or in extremis (e.g. having to run away from danger).
Pain medication will usually be required and medical attention often so.
Muscles recover from fixed contractures but frequently-repeated contractures can accumulate debilitating damage in the long term.
During episodes of fixed contracture or rhabdomyolysis patients are advised to choose pain medications which are not eliminated through the kidneys, as they are stressed due to clearing large amounts of myoglobin.
Pain medication should be avoided in the absence of an episode, as it will obscure the signals from the muscles. These are needed for patients to recognize when to slow down or pause for a rest in order to avoid injury .
If some muscle injury is incurred, pain relief should be taken only once activity has ceased.
Patients who start on opioid medications are at risk of dependency and of developing chronic pain .
 See page 7, reference .
McArdle Disease Medical Overview