Skeletal muscle is not only essential for human movement and performance, but is unfortunately also a common site for acute injuries related to physical activity and sports. The influence of exercise on skeletal muscle represents a wide range all the way from (i) physiological adaptation with regard to metabolism, morphology, and contractile properties, through (ii) physiological development of muscle hypertrophy, to (iii) pathological/physiological responses to heavy unaccustomed exercise with associated delayed onset of muscle soreness, and ending with (iv) muscle injury caused by either strain or contusion (and seldom laceration) trauma. In the present chapter we will focus on the muscle responses to acute stimuli that cause muscle injury of minor or larger magnitude, and the ensuing recovery....