Assessing physical activity of women of childbearing age. Ongoing work to develop and evaluate simple methods

Simple methods were developed and evaluated to assess total energy expenditure in 24 healthy, Swedish women planning pregnancy. Total energy expenditure was measured by the doubly-labeled water method (reference method) and three simple methods: heart rate recording, movement registration by an accelerometer, and a questionnaire. Mean total energy expenditure obtained by the four methods varied between 2,530 kcal per 24 hours (10,570 kJ/24 hours) and 2,730 kcal per 24 hours (11,420 kJ/24 hours). No significant difference between the results obtained by the different methods was found. The mean difference between the simple method and the reference method was for the questionnaire 204 +/- 508 kcal per 24 hours (853 +/- 2,124 kJ/24 hours), for the heart rate recorder 58 +/- 338 kcal per 24 hours (241 +/- 1,416 kJ/24 hours) and for the accelerometer 6 +/- 325 kcal per 24 hours (25 +/- 1,360 kJ/24 hours). The heart rate recorder and the questionnaire overestimated high and underestimated low energy expenditures. The accelerometer and the heart rate recorder were able to assess mean total energy expenditure of groups. No systematic bias was found when the accelerometer was used.