Aerobic dance (AD) is a form of fitness exercise whose program is constructed by a combination of various joint movements. Therefore the exercise is expected to give enough stimulus to not only the cardiorespiratory but also the musculoskeletal system. The purpose of this study was to evaluate the activity level of the leg muscles among the major 22 AD leg movements, or steps (13 low-impact steps and high-impact steps), by electromyography (EMG) analysis. The subjects were two trained AD instructors, who were asked to perform individual steps at a pitch of 144 bpm. EMG data were recorded from the iliopsoas, gluteus maximus, vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius muscles on the right side by means of surface electrodes. The half-wave of the raw EMG was rectified and integrated over periods of 20 s during the exercise. From the raw EMG data it was observed that the pattern and amplitude of the electrical discharge of each muscle varied in response to the difference in step motion. The integrated EMGs of the iliopsoas, biceps femoris, and gastrocnemius tented to show higher values for high-impact steps in comparison with low-impact steps, but that of the tibialis anterior showed a contrary trend. The mean value and stan-dard deviation of iEMG of each muscle for the 22 steps was calculated for the same subjects, and the muscle activity level was classified into 5 degrees. Making use of this evaluation table, it may be possible to construct an AD program that can activate the leg muscles impartially.

The aim of this study was to investigate the differences between male and female in the activity level of trunk and lower limb muscles during basic daily physical actions. Six young adult male and six female subjects performed 14 daily life actions, i. e. postural maintenance and change, and body weight transfer actions. The surface EMG of six muscles of the trunk and the lower limb was recorded using a portable electromyography apparatus. Maximal EMG response (EMG_max) during isometric maximal voluntary contraction for each muscle was used to normalize the EMG signal. In the performed actions, the average activity level of each muscle corresponded to 20% EMG_max or less in male and 30% EMG_max or less in female subjects, though there were some actions which exceeded 40% EMG_max in the soleus muscle. As a result of 3-way ANOVA, significant effects for each of the 3 factors (action, muscle and sex) for muscular activity level were recognized and there were significant interactions among each pair of factors. The mean activity level of leg muscles in actions which support and transfer body weight was significantly higher in females than males. In the case of identical actions, the total time taken to reach a high muscular activity level was longer in females than males. From these results, it can be assumed that the load on the lower limb muscles is larger for females than males in the case of supporting and transferring body weight in daily life.

Near infrared spectroscopy has been used to determine the chemical composition of food stuffs, i, e., the protein, fat, and moisture content. Recently in the U. S. A, this technique was applied to the estimation of human body composition, and a portable instrument was developed. This study was designed to determine the prediction equation of body fat for Japanese people. 69 men and 52 women, aged 18 to 58 years, covering a wide range of percent fat levels, physiques, physical activity levels, had body fat estimated by hydrostatic weighing (HW), skinfold thicknesses (SF) and near infrared spectroscopy. Near infrared interactance spectra were measured on the anterior midline of the biceps halfway (between the anticubital fossa and acromion), the spectral data from which gave best correlation with HW and SF compared the other sites, using the wavelength of 947 nm. The spectral values and percent fat values obtained from HW about 1/2 of subjects were used to develop a prediction equation. This equation was then used to predict % body fat of the other 1/2 subjects. The correlation coefficient between % body fat as predicted by the near infrared method and as predicted by the HW technique was 0.88 (p<0.001, SEE=3.2) . This correlation value was similar to the value between % body fat as predicted by HW and as predicted by SF. In the American data, the correlation coefficients were higher when the other variables were added ; height, weight, age, but in the Japanese they did not almost change even when the other variables were added. There was not a difference between the spectra of right and left arm values. In the results, the prediction equation of % body fat for the Japanese population was determined as follows:
% body fat =54.14-29.47× (the spectral data at 947 nm) [r=0.88, p<0.001, SEE=3.2] (for right arm) .

The present study aimed to investigate the level of muscular activities such as postural mainte nance and change, and body weight transfer during daily physical activities, through electromyogram (EMG) recordings. In each of 27 prescribed movements, EMGs of a total of 8 muscles located in the upper arms, trunk and lower limbs were recorded in 12 young adult men and women using a port-able surface electromyograph apparatus. The percentage of integrated EMG per time (mEMG) to that during isometric maximum voluntary contraction (MVC) was calculated as an index by assessing the muscular activity level in each of the prescribed movements. In most of the prescribed movements, the muscular activity level of every muscle corresponded to about 20-30% of MVC, and tended to be higher in women than men. However, some actions induced an activity level of 40% and more of MVC in the soleus muscle. The activity levels of the lower limb muscles in going up and down stairs and a slope at a fast speed, and jogging were higher compared to other prescribed movements. Thus, the results indicate that body weight transfer actions in daily life raise the activities of the lower limb muscles to a level sufficient for maintaining and increasing their function.

We aimed to elucidate the impact of the conducting state in exercise programs and the degree of improvement in sit-to-stand power index (STS-PI) on the continuation of Chokin exercise by participants one year from the completion of the intervention period. Subjects participated in a 12-week Chokin exercise class for the elderly, which consisted of 10 body mass-based exercises. As variables indicating exercise conditions, the number of exercise days weekly and the total number of sets performed during the intervention period were adopted. STS-PI was calculated using the time required to perform 10-times-repeated sit-to-stand task, and its relative change (%∆STS-PI) was used to represent the degree of improvement in physical function. Among 52 men and 129 women who responded to the inquiry about the continuation of Chokin exercise one year from the completion of the intervention period, 32 men and 93 women confirmed continuation of the exercise program. Logistic regression analysis showed that %∆STS-PI for men, as well as %∆STS-PI and the number of exercise days weekly for women, were factors associated with the decision of subjects to continue the Chokin exercise. These results indicate that the degree of improvement in STS-PI associated with the Chokin exercise class is a factor for continuing the exercise program one year from the completion of the intervention period, at least in elderly men and women. Furthermore, high exercise frequency during the intervention period may be associated with the decision to continue Chokin exercise after the completion of the intervention among women.

To create a safe and effective aerobic dance exercise (ADE) program, the intensity, and difficulty level of each step, and muscle activation during the program must be considered. This study evaluated the muscle activity levels of the lower extremities when major ADE movements were repeated at a fixed speed. The subjects were seven females 21-22 years old who were familiar with the ADE movements. Eleven low impact steps and nine high impact steps representative of the ADE movements were selected, and while the movements were performed, the surface electromyograms (EMG) of six muscles in the lower extremities were measured using a telemeter electromyograph. The EMG data for 10 cycles of each step were full wave rectified and integrated. Then, the average value per unit time was calculated, and normalized (%EMGmax) by the EMG integral value during isometric maximum voluntary contraction (EMGmax). The EMGmax was measured for each of the six muscles to evaluate the muscle activity level, and determine which muscles were activated at higher or lower levels in response to the specific steps. The highest levels of total muscle activity detected in the six muscles were for: double hop, jumping jack, and pendulum. The results of this study may help create ADE programs that consider the differences in muscle activation in the lower extremities.