15-17 June 2017.
Walking with McArdle's course,
2-9 August 2017.
AGSD-UK Annual Conference,
28-29 October 2017.
The "Six Second Rule" is as useful for people with McArdle's as the "second wind", although in a very different way. By using it you can help to avoid fixed contractures of the muscle, with their attendant muscle break down (rhabdomyolisis) and protein in the urine (myoglobinuria).
When doing something like lifting heavy objects or sprinting, there is an energy pathway (the phosphagen system) which is instantly available and lasts for about 5 to 10 seconds†. This system relies on ATP (adenosine triphosphate) stored in the muscle and creatine phosphate to provide immediate energy. As that is exhausted people unaffected by McArdle's will start to make use of glycogen stored in the muscle, converting it to glucose for energy. However, in McArdle's the enzyme (myophosphorylase) needed in that process is missing so this energy pathway can't kick in after the initial 5 to 10 seconds. That is when a painful fixed contracture of the muscle will develop which can last for hours or days.
Everyday examples of maximum intensity activities are: opening a new jam jar which is firmly stuck, lifting something heavy; standing on tip toe to get something off a high shelf; rushing up a flight of stairs; and squatting. These are everyday activities which it is best to avoid, but if you have to do them you need to know how to protect yourself.
To avoid damage when doing something of maximum intensity it is a good idea to time six seconds by saying to yourself “One thousand, two thousand...” up to six. If the task is not completed by six, stop or put it down. Take a break, let the muscles recover and try again later.
Research shows that the ATP will recover in about three minutes, and in fact substantially recovers in under a minute. We don't really know what factors affect its recovery, whether it varies from one to person to another, or whether we can do much to improve its speed of recovery. These are all questions for future research. However, we do know that if our muscles are fit (aerobically conditioned) we will be safer.
† Saltin, B. (1973) Metabolic fundamentals in exercise. Med & Sci in Sports, v5, n3, 137-146.
Last reviewed: 28 February 2013
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