The effects of exercise and creatine supplementation on bone mass, metabolism and body composition

The prevalence of both lifestyle and age related conditions is on the rise, with 10%of the global population obese, and 300,000 hip fractures costing the NHS £2 billion in 2010. This thesis aims to examine two methods of improving body composition and bone health, using exercise and creatine supplementation.The first study (Chapter 5, page 94) of this thesis outlines the test-retest reliabilityof the author conducting dual-energy x-ray absorptiometry (DXA) scans. This study shows that the author has good reliability in conducting DXA scans with coefficients of variation of 2.2, 1.8, & 1.55% for total lumbar spine, neck of femur and total proximal femur BMD, as well as 1.57, 0.77, &0.26% for sub-total fat, lean and total mass. The second study (Chapter 6 page 108) examines the relationship between biochemical markers of bone turnover and BMD measured by DXA, indicating that biochemical markers significantly predict a proportion of the variance in proximal femur BMD (15.6%, F(4-59), p<0.05) but not in the lumbar spine (6.9%, F(4-61), p=0.352). The first intervention study (Chapter 7, page 118) showed that 12 weeks circuit exercise increased lean mass (1.72%), and decreased fat mass (-3.07%), whilst having no effect on bone health compared with non-exercising controls. Creatine supplementation had no effect on body composition or bone health in this study. Finally, the fourth study (Chapter 8, page 136) showed that high-intensity interval training (HIT) reduced lower limb fat mass (-8.02%) and sub-total mass (-1.23%) whilst also showing the potential for improving bone mass with trends for increased total proximal femur BMC (5.79%) and area (4.81%) as well as femoral neck BMD (1.75%). Again creatine supplementation was shown to have no effect on either body composition or bone health.Two main findings of this thesis are, firstly that biochemical markers of boneturnover should be further investigated as measures of bone health as they are significant predictors of BMD, a important predictor of fracture risk. Secondly,whilst creatine supplementation was ineffective at inducing changes in bone massand body composition, HIT has the potential to improve bone health, as well asbeing an effective training method in reducing fat mass.