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Chapter 5 – Discussion
Often decreases in function and motor control are seen as a
consequence of ageing and disease. While multi-factorial in nature,
these declines may reflect changes in morphology, e.g. sarcopenic-
related reductions in muscle cross-sectional area, relative loss of fast-
twitch motor units as well as changes in neuromuscular function related
to changes in motor unit size and firing properties in the agonist and
antagonist muscles (Hess & Woollacott, 2005; Peterson, et al., 2010;
Seguin & Nelson, 2003). Such changes have been correlated with age,
though interestingly some have also been correlated to the decline in
strength (Sosnoff & Newell, 2006). Sosnoff and Newell (2006) compared
force variability and strength in young and older adults and found that
there was significantly greater finger force variability in the older age
group. However when accounting for age in the analysis, a significant
relationship between higher force variability and lower levels of strength
were seen. Though there is a link between strength and function, it can
be complex with a number of factors playing a role in functional
improvement (Shumway-Cook & Woollacott, 2007). A good example of
this is seen in issues of balance in older adults. Factors such as altered
vestibular or proprioceptive system function can have a negative effect
on balance performance as does reduced leg strength (Hess &
Woollacott, 2005). Where there is reduced leg strength, balance
performance can be greatly improved with resistance training (Hess &
Woollacott, 2005). Likewise, with a period of RT increases in dexterity
have been observed (Kornatz, et al., 2005). As such the improvement of
strength observed in this study could be of functional significance to
older adults with ET-related upper limb losses of hand and finger manual
dexterity.
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