"
1. Changes in muscle function
.... As
reduced activity leads to less efficient muscles (reduced strength, tone and size), it is more difficult for the muscles to squeeze the blood back to the heart causing blood to pool in the lower part of the legs.
Pooling of blood can cause pain and a feeling of heaviness both during activity and rest."
Reality:
No evidence at all in bed rest studies of pain; some of heaviness but only briefly after longer-term bed rest and this only lasted a few days. There is no evidence that such pooling is happening in CFS patients, or that it is responsible for pain/heaviness.
"When muscles are not used regularly, they become weaker or unfit/deconditioned. One week of rest reduces strength in large muscles by 10%. When these muscles contract during activity, uneven stresses are produced. This
may result in a feeling of weakness and instability/unsteadiness followed by delayed pain and discomfort."
Reality:
Studies have found that after 3 months (13 weeks) of bed rest, fitness declines by only a third, and that's far more resting than is typical for CFS patients in outpatient clinics. There's no evidence that the 'low-normal' levels of fitness in CFS patients could account for such weakness/delayed pain and discomfort.
Claim: "However in all individuals, muscle pain and stiffness are a natural consequence and normal response to the beginning a new exercise programme or when unaccustomed physical activity or exercise is taken."
Reality:
yes, we know that and are familiar with it; PEM is something else altogether.