The Effects of Eccentric Resistance Exercise on the Physical and Physiological Profile of the High Functioning Older Adult
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The population is ageing in nearly every country in the world and New Zealand is no exception. In New Zealand, 14% of the total population is currently 65 years and older, compared to 12% in 2002 (Statistics NZ, 2012). The number of older adults has doubled since 1980 and this number is expected to double again by 2036 (Statistics NZ, 2012). However, populations of disabled and diseased older adults are of major social and economic concern. Preventative efforts against the devastating yet predictable effects of ageing are likely to translate into significant reductions in this societal and economic burden (Goldman et al., 2013). Structured resistance exercise is increasingly acknowledged as a potent treatment of many of these effects that are commonly associated with ageing. Thus, the primary focus of this PhD was to conduct a series of cohesive investigations in order to answer the research question, What is the relative efficacy of eccentric-only resistance exercise and the more practically applicable eccentrically-biased resistance exercise when compared the more conventionally prescribed traditional resistance exercise with regards to changes in the physical and physiological profile of healthy, high functioning, resistance trained older adults? This PhD thesis is constructed into several parts to organize the flow of investigation. The conclusion from our narrative literature review provides evidence in support of eccentric exercise for several outcomes of interest to older, healthy adults. Outcomes such as increased muscular strength and improved functional capacity are expected to occur following eccentric exercise. In addition, major muscular soreness that typically accompanies eccentric muscle actions can be avoided in this older population. Taken together, eccentric exercise proves to be at least as effective as other heavy training modalities as well as to be found safe to perform. Our acute crossover study describes novel physiological data not previously described for healthy, resistance trained older adults during eccentric resistance training. Thus, the exercise variables for the safe use of eccentric resistance exercise and the resulting physical and physiological outcomes from this acute study laid the groundwork for our subsequent chronic study. Consequent outcomes from our eight week intervention show no statistical differences between eccentric training modalities when compared to the more conventionally prescribed, traditional resistance exercise (when relative load is equated) for a number of outcomes including maximal muscular strength, functional capacity, body composition and metabolic biomarkers. Finally, outcomes from our follow-up qualitative study show that any modality of heavy resistance training is subjectively well tolerated and thoroughly enjoyed by healthy, older adults. This thesis contributes to the World Health Organization’s policy framework surrounding and supporting the action of a relatively new concept of ‘active ageing.’ The implications and applications of this research will not only improve outcomes of interest to individual older adults themselves, but also lighten the societal and economic burden that typically accompanies sedentary ageing.