[in Japanese]

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Since 1990 the authors have measured energy consumption and cardiac tasks during free level walking of 17 preoperative patients with osteoarthritic (OA) hip and 5 normal subjects by studying gait characteristics (cadence and walking velocity), oxygen (O₂) consumption, O₂ consumption rate, O₂ cost, METS (metabolic equivalent units), double products (systolic blood pressure×heart rate) both at rest and at free level walking and physiological cost index (PCI). The subjects were made up of 11 patients with acetabuloplastic surgery (7 with unilateral involvement, mean age of 30.6; and 4 with bilateral involvement, mean age of 33.3) and 6 patients with joint replacement surgery, mean age of 62.5. The gait characteristics, cadence and walking velocity of the patients with OA hip were lower than that of normal subjects.
There were no differences in O₂ consumption rate and METS between the patients and normal subjects. But the patients showed higher O₂ cost and lower walking efficiency than normal. The O₂ consumption rate in the patients was highly correlated with their walking velocity. The double products at walking showed about two times higher than that of rest in the patients who had bilateral involvement and joint replacement surgery.

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The muscle strength of the quadriceps femoris muscle plays an important role in walking in children with spina bifida who have paralyses in lower limb. This study was designed to assess their quadriceps strength and to explore a prediction method of ambulatory status with such factors as muscle strength, neurologic level of lesion and motor development in early childhood. The maximum voluntary strength in isometric knee extension was measured from 61 patients and 92 normal children by strain gauge attached at a distal portion of leg. The patients were classified into five groups according to their current ambulatory status: 1) CA1 whose members were able to walk outdoors without cane, 2) CA2 with cane, 3) HA consisted of patients who walk only indoors with cane, 4) NFA walking for whose patients was a therapy session, and 5) NF whose patients were wheel-chair bound. An index, Z-score associated with the maximum strength and independent of differences in length of leg and body weight among subjects was introduced for determining relationship between muscle strength and ambulatory status. The Z-score represents a deviation from normal development of muscle strength. A cross-sectional and longitudinal study of the Z-score showed that deterioration in development of quadriceps strength of the patients began from 8 years old corresponding to body weight of approximate 25kg. The neurologic level, age of onset of walking and intelligence quotient were closely related to the Z-score. The discriminant function analysis clarified that these four factors were quite useful for assessing and predicting their ambulatory ability.

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The purpose of this study was to assess the effects of bed rest for 2 to 3 weeks on the musculoskeletal and cardiovascular systems. Subjects were seven female patients between the ages of 54 and 65 years with unilateral coxarthrosis deformans who were admitted for the total hip replacement. Biographical and physical data on each subject were considered to be the same. The changes before and after bed rest were measured as follows:
1) The maximum isometric muscle strength on flexion and extension of the uninvolved knee joint and the left elbow joint,
2) The thickness of the uninvolved quadriceps femoris and the left biceps brachii muscle using the ultrasound technique,
3) The responses to ergometric exercise in blood pressure, heart rate and oxygen consumption.
The maximum muscle strength loss after bed rest was greater in the leg muscles than in the arm muscles, and the decrease of knee extensors was greater than that of knee flexors in the leg muscles. The reduction of muscle thickness demonstrated in the rectus femoris was most pronounced in the quadriceps group. In the cardiovascular responses to ergometric exercise, there were significant increases in heart rate and oxygen consumption after bed rest.

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