Article

Older adults present with altered movement patterns during stair negotiation
although the extent to which modifications in pattern and speed influence
mechanical efficiency is unknown. This study evaluated mechanical energy
transfers attributed to active force production during stair negotiation in young
and older adults to provide insight into age-related changes in mechanical
efficiency. Secondary analysis on data obtained from 23 young (23.7+/-3.0 years)
and 32 older adults (67.0+/-8.2 years) during self-paced stair ascent and descent
was conducted. Mechanical energy expenditures (MEE) during concentric transfer,
eccentric transfer and no-transfer phases were determined for the ankle, knee and
hip power profiles in the sagittal plane. Mechanical energy compensations (MEC)
were also determined at each joint. During ascent, MEEs were similar for young
and older adults although older adults compensated ankle muscles to a lesser
extent during concentric muscle action. Controlling for cadence eliminated this
difference. During descent, older adults demonstrated lower energy expenditures
at the ankle and hip and similar expenditures at the knee compared to young
adults. Changes in joint MEE in the older group resulted in reduced energy
compensation at the ankle during concentric and eccentric activity and at the
knee during eccentric activity. These age-related differences in mechanical
energy transfers and related adjustments in MEC were not a function of the slower
cadence in older adults and suggest a loss in mechanical efficiency. These
results provide a benchmark against which physical impairments in older adults
may be explored.
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Langue : ANGLAIS