Aging and physical mobility in group-housed Old World monkeys

Abstract

While indices of physical mobility such as gait speed are significant predictors of future morbidity/ mortality in the elderly, mechanisms of these relationships are not understood. Relevant animal models of aging and physical mobility are needed to study these relationships. The goal of this study was to develop measures of physical mobility including activity levels and gait speed in Old World monkeys which vary with age in adults. Locomotor behaviors of 21 old (x0 20 yoa) and 24 young (x09 yoa) socially housed adult females of three species were recorded using focal sample and ad libitum behavior observation methods. Selfmotivated walking speed was 17% slower in older than younger adults. Likewise, young adults climbed more frequently than older adults. Leaping and jumping were more common, on average, in young adults, but this difference did not reach significance. Overall activity levels did not vary significantly by age, and there were no significant age by species interactions in any of these behaviors. Of all the behaviors evaluated, walking speed measured in a simple and inexpensive manner appeared most sensitive to age and has the added feature of being least affected by differences in housing characteristics. Thus, walking speed may be a useful indicator of decline in physical mobility in nonhuman primate models of aging.

Force-Generation Capacity of Single Vastus Lateralis Muscle Fibers and Physical Function Decline With Age in African Green Vervet Monkeys

“…Interobserver reliability was r ≥ .92. Methods used to assess physical performance have been described in detail (26) and are described briefly later. Physical performance tests do not necessarily correspond to maximal performance recorded in humans.…”

“…Each animal was observed until at least five instances of usual walking speed were recorded. To minimize the potential influence of circadian rhythms, observations were made over the course of several days, prior to morning feeding (06:00-09:00), when the monkeys were most active (26).…”

“…Leaping and jumping were recorded together (leaping/jumping) and defined as no body parts touching a surface (26).…”

“…Recently, we developed and applied a battery of physical performance tests modeled after human interventional studies to various monkey species (26). Identifying relationships between physical function and the functional and biomolecular characteristics of single muscle fibers could provide valuable insights into the mechanistic bases of functional decline with aging.…”

Age-related structural changes in upper extremity muscle tissue in a nonhuman primate model

“…Older vervets demonstrated age-related deteriorations of the shoulder similar to reports in older adult humans including; degeneration of the glenoid, increased glenoid retroversion, and decreased supraspinatus superficial cross-sectional area.. 31 Similarly, measures of physical performance that incorporate the upper extremity were diminished in older vervets. 7,31,39 However, within this vervet species, age-related changes to the upper extremity musculature have not been evaluated and degenerative rotator cuff tears, a common age-related injury affecting older adult humans, 44 have not been described. 31 …”