Background: This study was to investigate energy expenditure in physical activities and blood heart rate and lactate concentration during submaximal exercise.
Methods: We measured energy expenditure of 92 participants consisting of 27 twenties age-group (23.22±0.75 years old) and 65 sixties age-group (67.05±4.81 years old) wearing an accelerometer for 10 days. We also measured submaximal work using 20 cm bench stepping exercise test consisting of 4 minutes test with 2 minutes rest between each stage. Stepping frequency was 20, 25, and 30 cycles/min corresponding to 4, 5, and 6 METs. We also measured lactate concentration and heart rate, RPE at rest and after each exercise stage.
Results: Energy expenditure for young and old age-groups was 310.70±78.58 kcal and 160.29± 63.59 kcal, respectively. There was a significant difference in energy expenditure per body weight for a day between two groups (5.33±1.35 kcal/kg for young age-group, 2.71±1.07 kcal for old age-group). There was also significant difference on step number between two groups (10866.44±2263.43 steps, 6265.11±2164.48 steps). Total energy expenditure for young and old age-groups was 1981.22±146.02 kcal, and 1574.88±151.82 kcal, respectively.
Conclusion: Our conclusion is that energy expenditure at least over 5 kcal/kg is mandatory for daily exercise. Everybody should walk at least 10,000 steps for a day with duration of minimum 30 minutes and at least five times a week for maintaining one's health. Moderate intensity-exercise and physical activity would be desired to prevent life style disease.

Keywords: Health behavior, Physical fitness, Energy metabolism