We explored the extent to which fair knee extensors might be judged to be weaker than the normal knee extensors of healthy young adults. To obtain quantitative data for normal strength of knee extensors, we recorded knee torque in 20 healthy young subjects using an isokinetic dynamometer, and calculated muscle strength equivalent to fair, including the effect of inertial force, using a rigid body model. The results showed that fair torque as a percentage of actual normal torque at 60 degrees per second was 4.8 ± 1.2% (mean ± standard deviation) among the men and 4.6 ± 1.0% among the women. This difference in per cent strength was not statistically significant between men and women.

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A noninvasive kinematic recording technique involving geometric modeling of the knee joint was employed to determine anteroposterior displacements of the knee during walking. The model estimated how much the femoral condyles slid and rolled on the tibial plateau. Movement not due to sliding or rolling was attributed to horizontal translation of the tibia with respect to the femur. Thirty normal adults participated in this study. A three-dimensional analysis system with noninvasive skin markers was employed to collect kinematic data of the femur and tibia during walking. Within-session and between-session reliabilities were high in the tested subjects. Normal subjects had an average of 5.5 mm of maximum anterior displacement of the tibia during stance phase of walking. These results differed neither between left and right knees, nor between men and women. Dynamic instability of the knee during walking can be reasonably measured by the proposed method in normal subjects.

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In this study we investigated the correlation between working capacity and APDL of middle- aged and elderly residents of welfare homes for the intellectually retarded. The subjects were 313 intellectually retarded people over 35 years old. The subjects were chosen from residents of four welfare institutions and job-placement centers for intellectually retarded people in Otaru, Hokkaido. Personal attributes, working capacity, and APDL were investigated in each subject. The items of personal attributes were: gender, chronological age, severity of intellectual impairment, and presence/absence of Down’s syndrome. Working capacity was evaluated according to the 6 items. APDL was evaluated according to the 51 items. For statistical analysis of the working capacity of the subjects, the variables were summarized using principal component analysis and scored. Next, a search was made for the common factors in the 51 items of APDL using the principal component method. Finally, the correlation between working capacity and APDL was investigated by multiple regression analysis, with the obtained composite scores as dependent variables and the scores of APDL factors extracted by principal component analysis as independent variables. The following three factors were selected for the subjects: health management, outdoor movement and social activity. The multiple correlation coefficient using these three factors was R=0.63 (F=55.20, p<0.01). This indicates the necessity, from the viewpoints of prevention of senility, to focus not only on the decrease in working capacity of aging residents with intellectual impairment in welfare institutions but to establish various countermeasures based on the interrelationship between working capacity and APDL.

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We have been studying mainly the changes in collagen fiber solubility with respect to its influence on immobilization of the soleus muscle and Achilles tendon of rats. We decided to investigate also the change of the collagen fiber solubility in the gastrocnemius muscle which, like the soleus muscle, is assumed to influence the range of motion of the ankle joints. The purpose of this study, therefore, was to investigate the effects of a 7-week immobilization on the solubility of the gastrocnemius muscle and soleus muscle collagen fiber of rats. The results were that in a 7-week immobilization period, hydroxyproline concentration in tissue was increased and salt and pepsin soluble collagen was decreased in both the soleus and the gastrocnemius muscles. The results suggest an increase in the collagen concentration in tissue and an increase in the intermolecular cross-link with a stronger molecular structure. As far as the amount of collagen and solubility were concerned, the immobilization had a similar influence on the collagen fiber in both muscles.

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The purpose of this study was to evaluate cardiopulmonary responses during submaximal cycle exercise at various angles of backrest inclination. Ten healthy Japanese men of mean age 25.9 yrs, height 170.6 cm, and body mass 66.1 kg, performed cycle exercises at a constant workload which reached the anaerobic threshold, at 20 degrees, 40 degrees, and 60 degrees of backrest inclination from the vertical plane, but the angle between the seat and back rest was kept at 110 degrees. The results were as follows: 1) Both cardiac output and stroke volume showed a higher value at the resting control state and during exercise as the backrest angle increased. 2) Oxygen consumption, carbon dioxide output, heart rate, gas exchange ratio, and oxygen pulse were not affected by the angle of backrest inclination. 3) Tidal volume at 20 degrees of backrest inclination was higher than at 60 degrees. 4) No significant differences were found in minute ventilation between each backrest angle. These findings suggest that changes in the backrest angle significantly alter cardiopulmonary parameters at rest and during exercise; in particular, an angle difference of 40 degrees may be enough to alter tidal volume, cardiac output and stroke volume, but not the minute ventilation.

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