What is pain and weakness in human muscle cells are often the result of Build up of what?

Pain and weakness in human muscle cells are often the result of a buildup of lactic acid, which accumulates during intense exercise when oxygen levels are low. This accumulation can lead to muscle fatigue and discomfort. Additionally, the buildup of other metabolic byproducts, such as hydrogen ions, can contribute to the sensation of pain and reduced muscle function. Over time, chronic muscle pain may also be associated with inflammation or damage to muscle fibers.