Background: Current recommendations state that all subjects should engage in at least 30 min of moderate intensity physical activity assuming an extra energy expenditure (EE) of 836kJ.
Aims: To determine the EE of walking at different intensities, to check whether the EE of walking could be estimated by intensity codes and to determine the time necessary to expend 836 kJ while walking.
Methods: Resting and walking EE in a treadmill (67/0; 93.8/0; and 93.8 m min(-1)/2.5% slope) were measured by indirect calorimetry in 58 healthy college-aged women. Walking EE was compared (paired Student t-tests) with estimated EE using the physical activity ratio values from FAO/WHO/UNU and the MET codes published in the Compendium of Physical Activities.
Results: Average EE increased from 12.1 (1.9) to 18.6 (2.9) kJ min(-1) or 3.5 (0.5) to 5.4 (0.7) kJ min(-1) multiples of measured MET. Walking EE at the two first intensities could be correctly estimated by the MET codes but according to age-dependent classification walking could only be considered moderate at the highest intensity. For the extra amount of 836 kJ these women would have to walk for at least 46 min at the highest intensity.
Conclusions: EE of walking at ground level can be accurately estimated by MET codes but it is necessary to walk much longer than 30 min to reach the recommended level of EE for good health in college-aged Brazilian women.