In contrast, when joints are immobilized or persons are bedridden the effects on the neuromuscular and skeletal systems are detrimental. Within 24 hours of immobilization muscle start to atrophy, strength decreases, nerve impulses slow and the circulatory and metabolic systems decrease activity. Local bone mineral density will decrease and collagen and connective tissue will become stiff and disorganized. Cardiorespiratory conditioning decreases significantly with prolonged bedrest.