Approved research

Implementing a novel accelerometer-based method to quantify the association between habitual physical activity beneficial to bone and direct measures of bone health in pre and postmenopausal women

Lay summary

Precise measurement of short, sharp bursts of habitual physical activity (PA) is important for prescribing PA to improve bone health. Recently in a laboratory, we established a PA intensity threshold (from raw accelerations recorded by a wrist-worn triaxial accelerometer) that corresponds to a magnitude of activity that benefits bone health. This study aims to apply this intensity threshold to free-living PA data collected from premenopausal and postmenopausal women, in whom bone health was also measured. This cross-sectional study will enable us to quantify the relationship and make recommendations about the dose of activity associated with healthy bones. This research advances the precise, objective accelerometer measurement of PA patterns relevant to bone. This method can then be used in future large prospective studies to classify habitual PA patterns relevant to bone in women and follow-up bone health outcomes (fragility fractures) in later life. This classification method can also be used to accurately evaluate PA interventions and develop evidence-based PA recommendations to prevent, maintain and reduce age-related decline in bone mineral density. This research will help UK Biobank increase understanding of the influence of PA on disease progression and health outcomes in relation to bone. Raw accelerations recorded by triaxial accelerometers over seven days and measures of bone health (ultrasound heel scan) will be analysed in pre and postmenopausal, Caucasian, non-HRT-taking, non-smoking women. Specialist computer algorithms will be used to calculate, for each woman, patterns of activity and time spent above a threshold of acceleration known to benefit bone. Multiple regression analyses will be used to quantify the relationship between activity patterns and bone health and to determine the amount of time associated with bone health independent of age, height, weight, body fat percentage, lean body mass, vitamin D and calcium intake. Three subsets are required comprising 1) premenopausal women aged 40-49; 2) postmenopausal women aged 50-59; 3) postmenopausal women aged 60-69. All cases must be healthy, Caucasian, non-smoking (including no/limited exposure to passive smoking), with no exposure to HRT, corticosteroids or bisphosphonates and must have had their PA objectively measured. Based on the preliminary application (initially for premenopausal women), we expect each subset to comprise at least 1200 cases to meet statistical power but to enhance the stability of our data and generalizability of our findings we will accept up to 3000 in each subset.