History of Physical Fitness and Sports Medicine in Japan / 体力科学

Kanehiro Takaki, the founder of The Jikei University School of Medicine suggested that a nutritional factor was important for preventing beri-beri, which was a common disease in the Meiji era in Japan and Southeast Asia. He improved the rations fed to crews of the Imperial Japanese Navy to include wheat and meat. The rations he devised effectively prevented beri-beri. Some 30 years later, vitamin B₁ was discovered, and a deficiency of vitamin B₁ was found to be the cause of beri-beri. Takaki believed that nutrition and exercise were important for keeping our bodies fit. He often gave lectures on how people could keep fit to prevent diseases. Thus, his activities are considered to be the beginning of preventive medicine in Japan. The contributions of Takaki to the physical fitness of the Japanese people have been continued by the graduates of The Jikei University School of Medicine. Some of the graduates became professors of The Jikei University School of Medicine and Tokyo University of Education (now, Tsukuba University). Thus, both universities have the common basis and tradition for research and education in the fields of physical fitness and sports medicine, and have collaborated with each other in these fields. In this article, we provide a brief overview of the history of the development of research regarding physical fitness and sports medicine in Japan. We discuss the contribution of various persons including our graduates, to the health and physical fitness of the Japanese people.

Estimation of Knowledge Level with A-, K- and X-Type Multiple-Choice Questions / 医学教育

With multiple-choice questions presenting one, two, or three of five choices (types A, K or X), the expected probability of a correct answer (P) can be obtained with a five-dimensional equation for the knowledge level (q), which is the probability of discriminating correct and incorrect items. From equations for each question type, we inversely estimated the q value (the estimated knowledge level), replacing P with the raw score rate in the actual examinations for promotion. The distribution and mean value of the raw score rate of type X differed from those for types A and K. However, distributions of estimated q values for the three question types were similar. This method can be used to estimate the actual knowledge level of students without the question type affecting the raw score but cannot be used to estimate incorrect knowledge.

The influence of exercise and nutrition on the bone mineral density in sportswomen / 体力科学

Recently, interest has been forcused on the increasing incidence of bone fracture due to low bone mineral density (BMD) in some sportswomen. Therefore the present study attempted to elucidate important factors associated with an increase or decrease of BMD in sportswomen.<BR>The results obtained were as follows;<BR>(1) Ball games appeared to be the most desirable main sports. Also it appeared necessary to increase lean body mass (weight) by maintaining a higher activity of daily living (ADL) index.<BR>(2) There were no clear nutritional factors that had a beneficial influence for increasing the BMD.<BR>These results suggest that sufficient exercise, at least, is necessary in order to increase BMD.

ANALYSIS OF HOLD STRENGTH, TWISTING HOLD STRENGTH AND TORQUE BY GRIP-TORQUE DYNAMOMETER / 体力科学

We have developed the new dynamometer to measure twist strength of upper limbs that was not investigated sufficiently before. This dynamometer can measure both twisting hold strength and torque at a time. Therefore, it can be applied to motion analysis at demonstrating muscle strength. Both development curve of the age group's average of the average hold strength of left and right hand { (LH⋅HS+RH⋅HS) /2} and the average twisting hold strength of left and right hand { (LF⋅HS+RF⋅HS) /2} showed the peak of development in man's thirties and in woman's twenties-thirties and then marked depreciation gradually with ageing. The average torque of forward twisting of left hand and that of right hand { (LF⋅T+RF⋅T) /2} showed the same tendency in respect of the peak of development too, but woman's curve showed the peak in twenties different from that in man and then didn't mark depreciation remarkably. From the analysis with respect to twisting motion by the subjects of right handedness, we have recognized that the twisting hold strength of right hand by the action of left or right forward twisting (LF·RH·HS, RF·RH·HS) is greater than that of left hand (LF·LH·HS, RF·LH·HS), the torque of forward twisting of left hand (LF·T) is greater than that of right hand (RF·T) and that the hand of back twisting supports the grip-torque dynamometer from the result of EMG. Therefore, we can understand that the stronger torque is generated by the motion of forward twisting of left hand which can support stronger than by that of right hand. But we have recognized too that the average hold strength and the average torque correlate to one another closely. Therefor, we can understand that it requires the stronger hold strength to generate the higher torque.

EFFECTS OF SWIMMING ON CARDIAC FUNCTIONS OF RATS AT GROWING STAGE / 体力科学

Long term physical training is known to cause a change of cardiac functions and this effect is observed at various levels of the heart (from whole heart to subcellular level), although its mechanism is not fully understood. It is reported that cardiac hypertrophy and decreased heart rate can be observed as effects of long term physical training, but change of the catecholamine content in heart tissue induced by training is controversial.<BR>In the present experiment, long schedule of short daily swimming episodes was employed to observe the effect of mild physical training on cardiac functions of rats in the growing stage. We measured body weight, heart weight, heart rate under light anesthesia, variation of R-R-interval of electrocardiogram, and catecholamine contents in cardiac muscle.<BR>1) Wister rats were divided into 2 groups 3 weeks after birth. One group rats was kept sedentary in cages, and the other group was required to free swim in a tank containing water at 30°C. At the beginning of the programme, swimming time was 10 min. Swimming was applied 5 days a week for up to 14 weeks, and swimming time was gradually increased to 30 min.<BR>2) Body weight of rats in the trained group was significantly less than that of the controls, and the heart weight to body weight ratio in the trained rats was significantly higher than in the controls.<BR>3) In the exercised rats, the R-R interval of the ECG was longer than that of the controls, and there was a tendency for the variation of R-R interval in the trained group to be larger than that of the controls.<BR>4) At 10 and 17 weeks, rats from each group were sacrificed after or without a 30 min test swim for measurement of catecholamine content of the ventricular muscle. One time swimming for 30 min increased dopamine content, but did not change norepinephrine content except for the trained group at 10 weeks. There was no significant difference in cardiac catecholamine contents in the rested state of the control and trained groups at 10 and 17 weeks.<BR>5) Results were interpreted as follows: One time swimming for 30 min influences the activity of the autonomic nervous system innervating the heart, and catecholamine metabolism at nerve terminals of the sympathetic nervous system. Long term mild swimming does not cause permanent change of catecholamine contents, and the low heart rate in the trained group cannot be soley explained by the decreased activity of the sympathetic nervous system.