Associations between muscle soreness, damage, and fatigue.

Eccentric exercise results in muscle soreness, structural damage, prolonged losses in strength and range of motion, and neuromuscular dysfunction. Greater and longer lasting fatigue occurs after eccentric compared with concentric and isometric exercise. Higher forces are achieved during eccentric contractions with less ATP usage and greater increases in temperature. Although mechanisms involved in the damage and repair process are not well understood, active strain during eccentric contractions is suggested to cause the initial damage which increases over 2-3 days, followed by regeneration.