Absolute and relative energy costs of walking in a Brazilian adult probability sample.

Background: Walking is commonly recommended for enhancing energy expenditure (EE), a basic principle in weight management, and cardiorespiratory fitness. However, walking EE varies with characteristics of a given population, especially by sex and age.

Purpose: The study's purpose was to measure EE of walking as influenced by physical and physiological characteristics of a sample of adults (≥ 20 yr) living in Niterói, Rio de Janeiro, Brazil.

Methods: Walking EE and HR were measured during a submaximal multistage treadmill test. The test stages lasted for 3 min each and started at a speed of 1.11 m·s(-1) and a grade of 0%. In the second stage, the grade was maintained at 0%, but the speed was increased to 1.56 m·s(-1) and maintained at this speed but with grade raised by 2.5% at each stage until 10% at stage 6. We measured resting oxygen consumption (MET m) before the test with the participants sitting quietly.

Results: MET m (mL O2·kg(-1)·min(-1), mean ± SE) was lower both in women (2.85 ± 0.03) and in men (2.97 ± 0.04) by almost 19% and 15%, respectively, compared with the conventionally estimated MET (METe) of 3.5 mL O2·kg(-1)·min(-1). Walking EE for any given speed and grade had an absolute intensity, expressed as multiples of MET m or MET e, that was practically equal between sexes and age groups, but it incurred higher individual physiological demand or relative intensity for women and older adults.

Conclusions: Resting EE reflected by using METe is overestimated in the adult population of Niterói. Prescription of activities to counteract the existing worldwide obesity epidemic should be ideally based on individual physiological information, especially among women and older individuals.