Understanding the predisposing factors for older people falling is imperative as falls can lead to considerable medical and societal costs, loss of independence and reduced quality of life. In particular, it is important to understand more about the many possible intrinsic and extrinsic reasons why older people sometimes fail to maintain their postural stability and fall. Older people are increasingly being encouraged to maintain or increase their daily physical activity levels. Healthy older adults have been shown to have altered postural stability following high intensity physical activity; however it is not known whether postural stability is compromised during everyday levels of physical activity. If it were, it could expose them to greater risk of falling. The overall aim of this series of investigations was to determine whether postural stability was detrimentally affected immediately after moderate intensity physical activity. Five studies were undertaken. Study 1 was carried out to determine the typical duration of activity periods that occur during the daily lives of community-living older people. In this study, the activity period durations of older people living either at home or in an aged care facility were recorded over a continuous 72 hour period using an activity monitoring device. Study 2 determined the effect of an activity protocol, designed to be representative of routine daily activity of community-living older people, on clinical indicators of fatigue. These indicators included maximal voluntary torque from the knee extensor and hip abductor muscles, subjective feelings of fatigue and temporal and spatial gait variables. The physical activity protocol involved a series of tasks carried out continuously for 14 minutes, self-paced at moderate intensity. Tasks included walking, step-ups, mini-lunges and avoiding obstacles. The final three studies compared postural stability before and immediately after the moderate intensity physical activity protocol. Study 3 recorded centre of pressure (COP) displacement during quiet standing with feet together. Study 4 recorded forces and postural electromyographic (EMG) activity during a rapid forward step-up task. Study 5 recorded postural responses to a lateral waist-pull perturbation large enough to elicit a step response. Studies 2, 3 and 4 compared healthy young adults with healthy older and balance-impaired older adults, whilst the final study compared healthy young and old adults. Community-living older people were found to have a wide range of activity period durations and those living in aged care had significantly shorter activity periods compared to those living independently at home. As a result of the findings, an activity period duration of 14 minutes was considered representative of community-living older people’s physical activity exposure. In Study 2, immediately following the physical activity protocol, young, healthy old and balance-impaired older adults all showed no changes in leg strength. All groups felt generally tired and had sensations of local leg muscle fatigue but only the balance-impaired adults were still reporting feelings of fatigue 20 minutes after the activity ceased. This group were also the only group to show altered gait after the activity. Their cadence was reduced compared with before activity and remained reduced 20 minutes later. In quiet standing, all groups demonstrated larger COP displacement in the mediolateral direction following the physical activity. For the step-up task, all groups showed small improvements immediately following the physical activity. These included reductions in the duration of the weight-shift phase, lateral COP displacement during weight-shift and the stance leg hip abductor muscle onset times. Participants also showed a shift in COP position towards the stance side prior to the step following the physical activity. In the final study, the older participants used a cross-over step in response to the lateral perturbation more frequently after the activity than before. This response is a less optimal response compared with a faster and more stable single outward step. When older and younger participants did perform outward steps following the physical activity, they performed them as well as they did before activity. Small changes to some of the measures of postural stability were found during quiet standing, voluntary stepping and to the responses after a lateral perturbation following moderate intensity physical activity. These changes may have been due to the impact of subjective feelings of tiredness experienced by participants. The increased use of a cross-over step strategy to regain balance after a lateral perturbation among healthy older people may mean that older people are at greater risk of falling after physical activity. However, the findings from this series of studies do not convincingly support a clinically significant detrimental effect on older people’s postural stability immediately following routine daily physical activity. This thesis has begun to investigate the effect of physical activity at daily levels on older people’s postural stability, however further investigations are recommended.
| Identifer | oai:union.ndltd.org:ADTP/254237 |
| Creators | Thorlene Egerton |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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