Painful muscles are a familiar sensation following unaccustomed exercise. While this phenomenon is well documented in adults, research on delayed-onset muscle soreness and exercise-induced muscle damage (EIMD) in children is limited. It is well documented that a prior bout of eccentric exercise attenuates symptoms of exercise-induced muscle damage following a second bout of damaging exercise. This is co mmonly known as the repeated bout effect. However, there is no research on the repeated bout effect in children. This thesis comprises of four studies on the symptoms of exercise-induced muscle damage in boys and men.