Article

Age-related declines in physical activity are commonly observed in
human and animal populations, but their physiologic bases are not fully
understood. The authors hypothesize that a lack of available energy contributes
to low levels of activity in older persons. DESIGN: Cross-sectional analyses of
relationships between physical activity level and energy availability were
performed in 602 community-dwelling volunteers aged 45-91 yrs from the Baltimore
Longitudinal Study of Aging. Energy expenditure was measured at rest and during a
maximal 400-m walk for calculation of "available energy." Overall and vigorous
physical activity levels were assessed using standardized questionnaires. General
linear regression models were used to assess the relationships between available
energy and general and vigorous physical activity, and stratified analyses were
used to analyze the possible differential association between available energy
and physical activity across high and low (peak sustained walking oxygen
consumption per unit time, <18.3 ml of oxygen per kilogram per minute) levels of
aerobic fitness. RESULTS: Low available energy was associated with low levels of
total physical activity (beta = 64.678, P = 0.015) and vigorous activity (beta =
9.123, P < 0.0001). The direct relationship between available energy and physical
activity was particularly strong in persons categorized as having low aerobic
fitness between available energy and physical activity with both total (beta =
119.783, P = 0.022) and vigorous activity (beta = 10.246, P = 0.015) and was
independent of body composition and age. CONCLUSIONS: The findings from this
study support the hypothesis that available energy promotes the maintenance of
physical activity in older persons. The findings also run counter to the
perception that age-related declines in physical activity are primarily
societally or behaviorally driven.

Langue : ANGLAIS