13 A 13 year old boy fatigues easily and complains of cramping pain with exercise 'all over' after only a few laps around the track in his high school physical education class. One day, the coach makes him continue much longer, and he develops myoglobinuria. If he rests briefly, he can continue for a few more laps. He has normal range of motion and agility. At rest, or with activities of daily living, he experiences no myalgias.
Physical examination reveals no evidence for muscle wasting.
MENU Question 15 A 9 year old girl gets tired easily but is still able to perform nomal daily activities. Through young adulthood, she continues to exhibit mild generalized muscle weakness. Reflexes are normal. She has no myalgias. A deltoid biopsy shows muscle fibers with numerous rod-shaped intracytoplasmic inclusions.