A preliminary study on estimation of energy expenditure at different locations of acceleration sensor during submaximal exercise

The purpose of this study is, for estimating energy expenditure with triaxial accelerometers during exercise, to compare determination coefficients of equations of the estimated regression according to several locations of the accelerometers on the body and then to present an estimation model on the location where there is the least restriction on physical activities. A small portable device that is able to obtain acceleration data during exercise was developed. It was attached on the back, wrist, knee and ankle of the body and then submaximal exercise was conducted on treadmills with the Bruce protocol. For the experimentation, seventeen males of twenties and thirties in good health (27.23plusmn2.18) participated and wore the equipment to analyze respiratory gas, so that the values of acceleration and energy expenditure from the respiratory gas analyzer could be obtained at the same time. The energy expenditure values from the outputs of the respiratory gas equipment were set as a base value, and the accelerations and the physical features of the participants (age, weight, height and BMI) as variables, to check each correlation, and for each of the four locations of the accelerometers on the body, regression analysis was carried out. The results of the experiment are as follows: the correlation between the acceleration and the energy expenditure was the highest on the knee and the lowest on the wrist; but, the determination coefficients (R²) of the regression equations using the continued hours of exercise, weight and acceleration values did not show significant difference among the locations on the body, as the highest R²=0.873 on the back and the lowest R²=0.852 on the wrist. This study has shown two possibilities. First, it is possible to predict energy expenditure using accelerometer sensor without respiration gas analyzer in laboratory situation. Second, these findings can be applied to application about predicting conveniently- - energy expenditure during outdoor activities using accelerometer on watch or shoes.