RELATIVE EFFECTS OF RESISTANCE TRAINING, BODY WEIGHT, AND SPINE DEGENERATION IN LUMBAR BONE DENSITY

Abstract

562 Several studies have shown that weight lifters have higher bone densities (BD). On the other hand, heavy lifting is one of the main suspected risk factors for disc degeneration, which includes sclerosis and osteophyte formation, both increasing BD measurement values without increasing bone strength. High body weight, often present in weight lifters, also contributes to higher BD. The goal of this study was to investigate the relative roles of resistance training and other determinants of lumbar vertebral BD. The subjects consisted of 117 former elite athletes including weight lifters, soccer players, endurance runners and shooters (mean age was 59 and range 45-68 years). Data on lifetime physical loading consisted of work, leisure and all sport activities from the age of 12 years, as collected through an extensive structured interview. Areal bone densities were measured at the L3 vertebra in lateral position using dual energy X-ray absorptiometry. Vertebral degeneration was evaluated from MR images obtained using a 1.5 tesla devise with surface coil. The stepwise multivariate model explained 24% of the total variance of BD. Age, although not significant, was included as an effect modifier and accounted for 1% of the variation. Other factors in the model were "lifetime mean" body weight, explaining 9%, disc height narrowing, adding 10%, and lifetime resistance training hours contributed 3% to the total variability explained in BD measurements. Recent weightlifting over the prior 12 months did not have contribute to the model. In conclusion, the role of lifetime resistance training in vertebral BD is significant, however, greater variability in BD among former top athletes was explained by higher body weight and spine degeneration, both of which are more common among weight lifters. Much of the increased BD in weight lifters that has been attributed to resistance training is likely due to the covariates of higher body weight and spine degeneration, neither of which are perceived as beneficial to health. Supported by Ministry of Education and Social Insurance Institution.