A procedure was introduced for determining the thickness of the articular cartilage of the patella. The results revealed that the cratilage was thicker at the site of contact between the patella and the femur than in other parts. CT and X-ray images were used to investigate movement of the patella from full extension to full flexion of the knee joint. As the flexion increased, the patella prorated, i, e., the site of contact with the epicondyle and condyle of the femur shifted from the lateral to the medial facet of the articular face, as deduced from the decrease in the bicondylo-patellar angle. Vertically, the patella moved from the epicondyle to the condyle level, but the distance between the apex of the patella and the tuberosity of the tibia remained almost unchanged. Serial slices (5 mm thick) of a plaster replica of the patella cut at right angles to the central ridge showed a change in the angle between the two facets of the articular face from the proximal to the distal side. The same results were obtained with CT slices. These findings suggest that adequate pressure stimulates development of the cartilage and that CT is a good method for studying movement of the patella.

The systolic time intervals (STI's) and the diastolic time (DT) as functions of the RR interval during exercise were proved to be described by cubic regression equations that converge to the origin of the coordinates. Using the equations, we compared I) the systolic time and DT of trained and untrained men, and II) examined the relations between parameters of STI's. I) Forty healthy male subjects aged 19-22 years old were divided into three groups, i, e., 8 long distance runners (group LD), 16 men with relatively high fitness (group A) and 16 men with relatively low fitness (group B) . They performed submaximal exercise test using a cycle ergometer for measuring the time of electromechanical systole (QS₂) and DT. After test, maximal exercise test was conducted to determine the maximal heart rate (HRmax) in each subject. Means±SD of the minimum QS₂ and the minimum DT of the 40 subjects predicted from the regression equations at the HRmax were 209.7±12.5 and 108.2±15.6 ms, their ratio being about 2: 1. The QS₂ was significantly shorter, whereas DT was longer in the group LD than in the groups A and B at the HR of more than 120 bpm. II) Ten healthy male subjects aged 19-22 years old performed submaximal exercise to clarify the relations between any two of QS₂, the left ventricular ejection time (LVET) and the preejection period (PEP) at the same HR: there were positive and negative significant correlations between QS₂ and LVET, and between LVET and PEP, respectively, at the HR of more than 100 bpm. These results reveal that, when the HR is increased in exercise, the left ventricular systolic time (QS₂) is shortened while the diastolic time is lengthened for the subjects trained as long distance runners. The shortening of the systolic time is mainly caused by shortening of LVET. The changes in the systolic and diastolic times suggest that contractility of cardiac muscle is enhanced during exercise of above moderate intensity after an extensive period of the aerobic training.