[Energy expenditure on different physical activities of rural adults in North China]

To test the energy metabolism of healthy adults in rural north China and to obtain the data of energy expenditure on different physical activities, in order to provide the basis for the Dietary Reference Intakes for Chinese people and the prevention and treatment of diseases related to energy and nutrition imbalance.

The energy expenditures on different physical activities of 30 healthy adult men and women were investigated under strictly controlled experimental conditions by using portable cardiopulmonary function determinator k4b2 to examine the oxygen consumption (VO2) and carbon dioxide production (VCO2) during basal metabolic conditions and seven kinds of physical activities (walking, brisk walking, jogging, cycling, stair climbing, and watching TV). The content of 24-hour urine nitrogen was measured by micro Kjeldahl method. Combining with the change of body weight, the energy expenditures on different physical activities of normal adult men and women in north China were obtained.

The average energy expenditure on physical activities (kJ x h(-1) x kg(-1)) were: walking 12.60 +/- 5.54 (11.46 +/- 2.19 for male and 15.47 +/- 6.97 for female), brisk walking 20.79 +/- 10.46 (15.95 +/- 3.59 for male and 25.33 +/- 12.70 for female), jogging 34.78 +/- 16.00 (30.45 +/- 5.07 for male and 38.84 +/- 21.58 for female) cycling 16.47 +/- 3.95 (14.77 +/- 2.57 for male and 18.74 +/- 4.85 for female), going up stairs 23.55 +/- 5.05 (23.61 +/- 3.43 for male and 23.49 +/- 6.41 for female) going down stairs 12.46 +/- 6.30 (10.43 +/- 1.27 for male and 14.49 +/- 8.48 for female) and watching TV 3.85 +/- 1.97 (3.56 +/- 0.86 for male and 4.16 +/- 2.79 for female).

The average energy expenditure on physical activities of males was lower than that of females (P < 0.05), except of going up stairs, which was roughly equal in males and females. The average energy expenditure on various physical activities was different. Walking, watching TV and going downstairs are low-intensity physical activities; brisk walking, cycling and climbing upstairs are medium-intensity physical activities; and jogging is a high-intensity physical activity.