When humans workout for a long period of time, the body's muscles may become sore. What process occurred in the muscle cells that made them sore?

When muscles are required to work harder than they're used to or in a different way, it's believed to cause microscopic damage to the muscle fibres, resulting in muscle soreness or stiffness. DOMS is often mistakenly believed to be caused by a build up of lactic acid, but lactic acid isn't involved in this process.

Explanation:

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.