Energetic Assessment of the Nonexercise Activities under Free-Living Conditions

Abstract EN

Nonexercise activities (NAs) are common types of physical activity in daily life and critical component in energy expenditure.

However, energetic assessment of NA, particularly in free-living subjects, is a technical challenge.

In this study, mechanical modeling and portable device were used to evaluate five common types of NA in daily life: sit to stand, lie to sit, bowing while standing, squat, and right leg over left.

A human indirect calorimeter was used to measure the activity energy expenditure of NA.

Mechanical work and mechanical efficiency of NA were calculated for mechanical modeling.

Thirty-two male subjects were recruited for the study (20 subjects for the development of models and 12 subjects for evaluation of models).

The average (mean ± SD) mechanical work of 5 NAs was 2.31 ± 0.50, 2.88 ± 0.57, 1.75 ± 0.55, 3.96 ± 1.25, and 1.25 ± 0.51 J/kg·m, respectively.

The mean mechanical efficiencies of those activities were 22.0 ± 3.3%, 26.5 ± 5.1%, 19.8 ± 3.7%, 24.0 ± 5.5%, and 26.3 ± 5.5%.

The activity energy expenditure estimated by the models was not significantly different from the measurements by the calorimeter ( p > 0.05 ) with accuracies of 102.2 ± 20.7%, 103.7 ± 25.8%, 105.6 ± 14.6%, 101.1 ± 28.0%, and 95.8 ± 20.7%, respectively, for those activities.

These findings suggest that the mechanical models combined with a portable device can provide an alternative method for the energetic analysis of nonexercise activities under free-living condition.