Abstract:
The desire to age well is a common goal among the human population. How to do so is
therefore, a popular question. One theory of ageing involves the accumulation of damage to
mitochondrial protein and the subsequent loss of function the damage causes. Increasing the
rate of mitochondrial protein synthesis, a variable that declines with advancing age, is one way
to improve quality of life in the twilight years. A review of literature lead to a multi-level
approach, with measurements of protein synthesis made at the whole body, muscle, and
molecular levels. An acute bout of aerobic exercise, followed by feeding, two factors which
have a positive effect on the rate of mitochondrial protein synthesis, was used. Adaptations to
a period of exercise training are mediated by the accumulation of proteins due to each acute
exercise bout, and so an acute intervention was postulated to be indicative of changes expected
over the long term. A stable isotope infusion combined with sampling of breath, blood, and
muscle was used to determine the rate of whole body protein synthesis in 12 older adults.
Intracellular signalling for mitochondrial and whole body protein synthesis was examined using
RT-quantitative PCR and Western blotting in eleven young adults. The rate of post-exercise
whole body protein synthesis was 19% greater over the first four hours of post-exercise
recovery, in subjects receiving a protein-plus-carbohydrate drink immediately after a bout of
cycling than in those receiving a carbohydrate-only drink (p = 0.001). The same trend was
revealed in signalling for whole body protein synthesis and the abundance of cytochrome c, a
mitochondrial protein, although these results were not statistically significant (p = 0.2). In
contrast there was a strong, albeit also statistically insignificant, tendency for signalling for
mitochondrial protein synthesis to be higher in the skeletal muscle of subjects receiving a
carbohydrate-only drink after a bout of cycling (p = 0.06). The exercise and feeding
intervention described in this thesis may provide a means to enhance the rate of mitochondrial
protein synthesis in older individuals and, in so doing, improve the quality of their old age.