Objective: To investigate the energy expenditure at physical activities of young and middle-aged adults in southern China.
Methods: 64 healthy young and middle-aged adults living on light physical activity intensity were recruited by questionnaire and physical examination. A Cosmed k4b2 portable metabolic unit was used to measure the oxygen consumption (Vo2) and carbon dioxide production (Vco2) at a status of basic metabolism and during seven physical activities, including slow walking, brisk walking, walking upstairs, walking downstairs, watching TV, jogging and bicycling. The urinary nitrogen excreted in 24 hours was detected by a standard Kjeldahl method. Energy expenditure at physical activities was calculated by Weir equation.
Results: The energy expenditure (kJ x h(-1) x kg(-1)) at physical activities were 14.77 +/- 2.47 for slow walking, 22.18 +/- 3.68 for brisk walking, 41.34 +/- 7.32 for jogging, 18.41 +/- 3.89 for bicycling, 26.11 +/- 4.18 for walking upstairs, 13.68 +/- 2.89 for walking downstairs and 5.06 +/- 1.09 for watching TV. The energy expenditure of males at physical activities was higher than those of females (P < 0.05).
Conclusion: There is a significant difference among energy expenditures at different physical activities; watching TV is a physical activity in light intensity; slow walking, brisk walking, walking upstairs, walking downstairs and bicycling are physical activities in moderate intensity, and jogging is a vigorous physical activity.