What is the underlying cause of muscle stiffness?

Muscle stiffness primarily results from excessive muscle fatigue without adequate relaxation. When muscles are subjected to intense physical activity, they can become fatigued, which leads to the accumulation of metabolic byproducts such as lactic acid. This accumulation affects the muscles' ability to relax, resulting in stiffness. This stiffness often manifests in the form of delayed onset muscle soreness (DOMS), which some individuals experience after intense exercise or unfamiliar activity.

While other factors, like hydration levels and overtraining, can influence muscle function and recovery, they do not directly cause muscle stiffness in the same way that muscle fatigue does. Therefore, understanding the importance of muscle recovery and the physiological impacts of intense exercise is crucial in recognizing the primary contributor to muscle stiffness.