Michio Ikai

Calculation of muscle strength per unit cross-sectional area of human muscle by means of ultrasonic measurement

SummaryBy means of the ultrasonic photography of the cross-section of the acting muscle bundle, together with the measurement of the muscle strength developed by the subject with maximum effort, the strength per unit area of the muscle was calculated in 245 healthy human subjects, including 119 male and 126 female.The result was summarized as the following:1.The ultrasonic method used in this work was possibly admitted as the best way to calculate the cross-sectional area of the muscle.2.The arm strength was fairly proportional to the cross-sectional area of the flexor of the upper arm regardless of age and sex.3.The strength per unit cross-sectional area of flexor of the upper arm was 6.3 kg/cm2 in the average, standard deviation of 0.81 kg/cm2. When cross-sectional area of muscle was measured at extensive position of the forearm the strength per unit area was calculated to be 4.7 kg/cm2 at flexed position of the forearm.4.As to the individual variation, the strength per unit area was distributed in a range from 4 kg/cm2 to 8 kg/cm2.5.The strength per unit cross-sectional area was almost the same in male and female regardless of age. In addition to that, there was not found any significant difference in ordinary and trained adult.

A study on training effect on strength per unit cross-sectional area of muscle by means of ultrasonic measurement

SummaryThe training effect on the human arm flexor was studied by subjecting 5 healthy males. The training was made by isometric maximum contraction, 3 times (10 seconds/bout) a day, every day except Sunday for 100 days. Ultrasonic photography was employed to estimate the cross-sectional area of the muscle.1.The muscle training of 100 days increased the maximum strength by 91.7% and the cross-sectional area of muscle by 23.0%.2.The average values of strength per unit cross-sectional area of muscle increased from 6.3 to 10.0 kg/cm2 after 100th day of training at extended position of arm, from 4.7 to 7.5 kg/cm2 at flexed position of arm.3.The increase of maximum strength was associated with the increase in cross-sectional area and the increase in strength per unit cross-sectional area.

Training effect of muscular endurance by means of voluntary and electrical stimulation

SummaryThe training effect on muscular endurance was studied by voluntary effort as well as electrical stimulation. The results were summarized as the followings:1.The endurance of the muscle was observed to be about 13% of final voluntary contractions higher by electrical stimulation than that by voluntary contractions.2.After the training for 12–13 weeks, the muscular endurance was increased by about 130% in voluntary muscle contractions. The number of contractions due to electric stimuli, given after complete exhaustion in voluntary contraction, was practically the same in the beginning and in the end of one experiment.

Maximum oxygen uptake of Japanese related to sex and age.

ABSTRACTAerobic work capacity (maximum oxygen uptake) of indigenous populations in various countries has been determined by using treadmill walking and bicycle ergometry (1–7, 9–12, 14–23). The maximum oxygen uptake during treadmill work was consistently higher (7–15%) than during bicycle work. Sinc

Strenuous Exercise Electrocardiogram of Top Class Swimmers in Mexico City

The effect of strenuous exercise (60 knee bends in 1min.) on the electrocardiogram was studied in 8 top class swimmers in Mexico City (altitude 2, 240M.). The electrocardiographic changes during the 3 week Mexico training were compared with the responses in Tokyo.(1) Heart rate immediately after the exercise increased markedly on the second day in Mexico, and declined gradually. Heart rate before and immediately after the exercise remained at higher level during Mexico training than in Tokyo.(2) Average amplitudes of P waves before and after the exercise in lead II were taller during Mexico training than in control study in Tokyo, the most prominent P waves after the exercise being observed on the second day in Mexico. P pulmonale at rest was observed in 2 cases. Right axis deviation of P waves was observed in 3 cases. These changes in heart rate and P waves returned to the control value after coming back to Tokyo.(3) Amplitude of T waves in lead II decreased immediately after the exercise throughout the study. Decreased amplitude of T waves before and after the exercise was remarkable after 12 days of Mexico training.(4) The junctional depression of ST segment after the exercise was remarkable in the first week of Mexico training, and disappeared gradually in the following week.(5) Relative QT duration was increased 2 and 5min. after the exercise. Relative QT duration increased during the Mexico training both before and after the exercise.These electrocardiographic changes during Mexico training and anginal chest pain experienced during and after the race indicated the need for the careful health examination of the athletes.