Bones are a fundamental element of the musculoskeletal system with complex tasks. They need to be lightweight to allow effective locomotion, but also strong enough to resist external forces of often several times body weight. This is possible due to the combination of unique material characteristics and a structure that adjusts to changing requirements. However, bone mass is generally proposed to decrease with age, contributing to an enhanced fracture incidence, which is strongly associated with morbidity, mortality and rising health care costs. The understanding of the bones' adaptation to mechanical forces is vital to preserve good bone health into old age and thus to prevent Osteoporosis the most common skeletal disorder. The objectives of this thesis were to investigate the adaptation of the middle aged and the elderly skeleton to various types of mechanical loading of differing magnitudes, and to evaluate the etiology of the age-related loss of bone mass and strength in the context of strenuous long-term exercise. Altogether 448 participants were involved in the study. The cross-sectional comparisons of bone mass and strength between athletes of differing disciplines and controls showed that differences at the mechanically loaded tibia increased systematically as the discipline specific speed decreased, i.e. greatest differences were found between sprinters and controls amounting to -12% in males and to -20% in females. In the radius no group differences of bone measures were observed, except for sprint cyclists,who had larger bone mass and strength than the controls. Age dependencies considered primarily structural shaft measures of both the radius and the tibia of track and field athletes, whereas fewer correlations were found in either the controls or the cyclists. The correlations appeared to be stronger if the values were larger at young age (40 yrs), i.e. in the tibia of sprint runners. Also, they were stronger and more systematic in females than in males. In co~clusion, mechanical loading was positively associated with bone strength in the middle aged and elderly study participants. The reduction in athletic performance with age may be associated with the observed loss in tibial bone strength in the athletes but not the controls, because maintenance of bone strength 'is dependent on the exposure to mechanical loading in both athletes and non-athletes. The stronger age correlations in the radius compared to the tibia imply a protective effect of exercise against an age related loss in bone mass and strength. Larger athlete vs. control group differences along with stronger age correlations in females as opposed to males suggest a gender specific response to mechanical loading.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:484821 |
| Date | January 2008 |
| Creators | Wilks, Desiree Cristin |
| Contributors | Rittweger, J. : Sargeant, A. : Winwood, K. |
| Publisher | Manchester Metropolitan University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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