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The effect of exercise and physical activity on physical fall risks

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Bird, ML (2012) The effect of exercise and physical activity on physical fall risks. PhD thesis, University of Tasmania.

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Abstract

For older adults, accidental falling produces significant morbidity and mortality,being responsible for personal costs as well as cost to the community at large. The
propensity to fall is dependent on a combination of factors that include intrinsic characteristics of each individual as well as environmental influences. Many intrinsic physical fall risk factors are modulated by changes in physical activity levels or exercise interventions. These physical performance fall risk factors include muscle strength, flexibility and balance. The studies that comprise this thesis examine several interventions designed to impact physical fall risk factors, as well as measuring natural seasonal changes in strength, balance and activity in communitydwelling older adults.
The first study (Study I) investigated the benefits on balance of participating in a 16-week community-based resistance and flexibility program in an observer-blinded
randomised crossover trial. Static and dynamic balance and lower limb strength were measured. Significant improvements in sway velocity, as well as Timed Up
and Go, Ten Times Sit-to Stand and Step Test were observed with both interventions
(all P<0.019), with no significant differences between the two groups. Resistance
training also resulted in significant increases in strength (P<0.001), that were not
evident in the flexibility intervention.
A subsequent study (Study II) examined the longer term effects of this multicomponent
exercise program (Study I) on balance, mobility and exercise behavior 12
months after completion. Differences between those participants who continued to exercise and those who discontinued were investigated. Significant improvements
from baseline in Ten Times Sit-to-Stand (P<0.001), Timed Up and Go (P=0.001),
and sway velocity (P<0.001) remained at follow up in the exercise intervention
group, with a control group remaining unchanged. Participants from the intervention
who continued exercising had significantly greater improvements in strength
immediately after the intervention, compared to those who discontinued (P=0.004).
Benefits to balance and mobility persisted one year after participation in the multicomponent
exercise program, due in part to some continuing participation in
resistance training.
The third study (Study III) evaluated the effects of a Pilates intervention on balance
and function in 32 participants in a randomised crossover study design lasting 16
weeks. Static and dynamic balance measures (medio-lateral sway range, Four
Square Step Test, Timed Up and Go) and leg strength were recorded. There were no
significant differences between Pilates and control groups for any of the measured
variables (P>0.05), despite static and dynamic balance significantly improving over
the duration of the study and from pre- to post-Pilates (P<0.05), and no significant
changes occurring during the control phase. The absence of differences between
conditions may be a result of our small sample size or the crossover study design,
indicating that Pilates may produce neuromuscular adaptations of unknown duration.
Studies IV and V investigated seasonal variation in lower limb strength and balance
respectively in a longitudinal repeated-measures study design concurrently with
serum vitamin D and physical activity. Fall incidence, cause and any adverse
outcomes were recorded using a monthly prospective fall calendar. Mixed-methods Poisson regression was used to determine associations between the data. Eightyeight
community-dwelling older adults were evaluated five times over a one-year
period.
Significant variation in vitamin D (±15%), physical activity (±13%), ankle
dorsiflexion strength (±8%) and hours spent outside (±20%) (all P<0.001) was
demonstrated over the year, with maximum levels of each measure occurring in
January (mid-summer). Quadriceps strength did not change over time (±2%;
P=0.53). Incidence of falls (P=0.01) and injurious falls (P=0.02) were lower in
spring than in any other season. Postural sway did not vary over the year. Small but
statistically significant (P<0.001) changes in dynamic balance (4%) were observed
over the year. Reduced mean ankle strength was associated with increased incidence
of falling (P=0.047). Increased ankle strength in summer may be influenced by
increased levels of activity over summer months, especially time spent outside.
Reduced ankle dorsiflexor strength in winter may predispose older people to
increased risk of tripping related falls at this time of year.
The engagement of older-adults in exercise programs and increased levels of
physical activity (especially outdoors) have important consequences for addressing
age-related decline in aspects of physical functioning related to fall risks. The
studies described in this thesis have added to the type of exercise programs that have
achieved positive outcomes with randomised-designed studies. This gives older
people and health practitioners greater options for exercise, which can be important
for uptake and sustained engagement in exercise programs. Additionally the
seasonal variation in dynamic balance and ankle dorsiflexion strength are novel findings that practitioners and policy makers need to consider in making
recommendations regarding outdoor activity and sunlight exposure for older adults.

Item Type: Thesis (PhD)
Keywords: older, prevention, "accidental falls", exercise, "physical activity, balance, strength, flexibility, Pilates
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Date Deposited: 15 Sep 2012 00:32
Last Modified: 11 Mar 2016 05:53
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