A 42-year-old white woman contracted poliomyelitis in 1955 at the age of 13 years. The initial paralysis involved the muscles of the lower trunk and the lower extremities, The upper trunk and upper extremities were not involved. The patient underwent physical therapy that according to the patient, involved "painful' stretching and strengthening exercises conducted three times a week by a physical therapist and on alternating days by a family member. The patient completed her rehabilitation program two years after the onset of poliomyelitis and was able to ambulate independently without the use of assistive devices. Results of a manual muscle test conducted after the completion of her initial two year rehabilitation program revealed a muscle strength grade of normal in t right leg, but Fair plus in the left quadriceps femoris and lower abdominal muscles, Good plus in the lett ankle dorsiflexor and hip flexor muscles, and Fair minus in the hip abductor muscles (Table). The patient subsequentl reported difficulty ascending and descending stairs and standing from a low seated position. At the age of 3 years, the patient began to notice increased muscular weakness in the left leg that caused her to drag her leg during the swing phase of gait. She also recalled being awakened during the night with "muscle cramps in her legs after a day of excessive walking. The muscular weakness and fatigue progressively worsened until she began falling outdoors a year later. Preexercise manual muscle test results revealed a muscle strength grade of Poor minus in the left quadriceps femoris muscles and Fair in the left ankle dorsifiexor, hip flexor, and hip abductor muscles (Table). A progressive resistive exercise strengthening program performed three times a week on alternating days was prescribed by her physician. Three months later at discharge from the program, she was able to ambulate safely with a straight cane, Manual muscle test results after the three months of physical therapy showed improved muscle strength in the left quadriceps femoris to agrade of Fair and in the ankle dorsiflexors t a grade of Fair plus. Hip flexor and hip abductor muscle strength improved to a grade of Good (Table). Despite these improvements in muscle strength, the patient reported that she had not regained her former level of endurance in ambulation. She independently continued the muscle stretching and strengthening exercises with leg weights at home, At 40 years of age, the patient was unable to ambulate out of doors the distance to her job even with the aid of a straight cane. A pair of Lofstrand crutches was prescribed by her former physical therap No formal gai training in the proper use of the crutches was provided. The patient independently used a three point gait pattern with the bilateral use of Lofstrand crutches. At the age of 42 years, the patient reported a feeling generalized fatigue and muscle weakness. She began falling indoors and, thus, became fearful of ambulating She was referred for physical therapy with the diagnosis of post-polio syndrome. The patient participated three times a week in a home physical therapy program that included therapeutic exercises, postural exercises, a