whole_FoleyStellaJane2009_thesis.pdf (11.1 MB)
Physical activity and musculoskeletal health
thesisposted on 2023-05-26, 20:54 authored by Foley, SJ
Population ageing is unprecedented and enduring. By 2050, the proportion of those aged over 65 would have increased from 13% to 26%. As the population ages, the prevalence of chronic diseases that disproportionately affect the elderly will markedly increase. Osteoarthritis and osteoporosis, including resulting fractures are two such diseases. Physical activity (PA) is an important risk factor for both of these diseases but many questions remain unanswered. This thesis examines how PA and exercise interacts with features of falls, osteoarthritis and osteoporosis. In a population based sample of 50-80 year olds (n=850) followed over 2.6 years, self reported functional ability and pain, and to a lesser extent stiffness (but not radiographic osteoarthritis) have modest but independent associations with physiological predictors of falls risk suggesting it is symptoms not radiographic changes that increase falls risk. In addition, ambulatory activity is positively associated with hip bone density in both sexes which appears most important in those aged over 65 years. However, the associations for spine bone density are both weaker and inconsistent. In a convenience sample of 26-61 year olds (n=325) followed over two years, we found knee cartilage volume and tibial plateau area are dynamic structures that can respond to physical stimuli. Greater muscle strength and endurance fitness, especially in women, protects against cartilage loss, but also results in a maladaptive enlargement of subchondral bone in both sexes, suggesting PA may have both good and bad effects on the knee. 1,434 children, aged 7-15 years, were measured in 1985 and approximately 20 years later. We found childhood fitness levels, particularly in females and in the early pubertal years, predicts adult bone mass, while BMI predicts bone mass in males only. These results suggest that increased skeletal loading in childhood leads to an increase in peak bone mass independent of current loading. In 183 children examined at age 8 and 16, bone mass measured by dual x-ray absorptiometry (DXA) is a good predictor of upper limb fracture risk during puberty. DXA measures track moderately to strongly from childhood to adolescence. Tracking is independent of linear growth and sex indicating bone mineralisation and growth are under largely separate mechanistic control. Body composition is the main predictor of altered tracking but environmental factors, such as having been breastfed, sports participation, fitness and inhaled corticosteroid use also appear important. In conclusion, this series of related studies shed considerable insight onto the role that PA and exercise play in preventing osteoarthritis and osteoporosis. In particular, childhood appears the most opportune time to prevent osteoporosis but later life is also important while for osteoarthritis, results remain less certain for structural change.
Rights statementCopyright 2009 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Chapter 4 is the equivalent of a post-ptrint of an acticle published as: Foley S, Lord SR, Srikanth V, Cooley H, Jones G, 2006, Falls risk is associated with pain and dysfunction but not radiographic osteoarthritis in older adults: Tasmanian Older Adult Cohort study, Osteoarthritis Cartilage, 14(6):533-9 with the DOI: 10.1016/j.joca.2005.12.007 Chapter 5 is a non-final version of an acticle published as: Foley S, Ding C, Cicuttini F, Jones G 2007 Physical activity and knee structural change: a longitudinal study using MRI. Med Sci Sports Exerc 39(3):426-34 found at 10.1249/mss.0b013e31802d97c6 Chapter 7 appears to be in part the equivalent of the accepted version of the following article: Flynn, J., Foley, S. and Jones, G. (2007), Can BMD Assessed by DXA at Age 8 Predict Fracture Risk in Boys and Girls During Puberty?: An Eight-Year Prospective Study. J Bone Miner Res, 22: 1463‚Äö-1467, which has been published in final form at 10.1359/jbmr.070509 Chapter 8 appears to be the equivalent of a pre-print of Foley S., Quinn S., Jones G., 2009, Tracking of bone mass from childhood to adolescence and factors that predict deviation from tracking, Bone, 44(5), 752-7 Chapter 9 appears to be the equivalent of a post-print article finally published as: Foley, S., Flynn, J., Jones, G. (2009), Pedometer determined ambulatory activity and bone mass: a population-based longitudinal study in older adults, Osteoporosis International, 21, (11), 1809-1816. he final publication is available at Springer via http://dx.doi.org/10.1007/s00198-009-1137-1