What causes post-exercise soreness in muscles?

Post-exercise soreness in muscles, often referred to as delayed onset muscle soreness (DOMS), is primarily caused by microtrauma to the muscle fibers. When muscles undergo intense physical activity, especially when unfamiliar or eccentric movements are involved, small tears occur in the muscle tissue. This process of microtrauma leads to inflammation and the subsequent sensation of soreness that typically peaks 24 to 72 hours after the workout.

The body responds to this microtrauma by initiating repair processes, which may involve swelling and increased sensitivity in the affected muscles. This response is a natural part of muscle adaptation, ultimately contributing to muscle growth and improved strength over time.

While dehydration, excessive hydration, and imbalances in electrolyte levels can certainly affect overall muscle function and performance, they do not directly cause the specific post-exercise soreness associated with microtrauma. Instead, these factors might lead to cramps or fatigue during exercise but are not the primary reason behind the soreness felt after a workout that results from muscle tear and repair.