Primary care

Patterns of physical activity and ultrasound attenuation by heel bone among Norfolk cohort of European Prospective Investigation of Cancer (EPIC Norfolk): population based study

Rupert W Jakes, PhD student, ^a Kay-Tee Khaw, professor of clinical gerontology, ^a Nicholas E Day, Medical Research Council professor of epidemiology, ^b Sheila Bingham, deputy director, ^d Ailsa Welch, research nutritionist, ^b Suzy Oakes, study coordinator, ^b Robert Luben, research associate, ^b Nicola Dalzell, research assistant, ^c Jonathan Reeve, Medical Research Council team leader, ^c Nicholas J Wareham, Medical Research Council clinician scientist fellow. ^a

^a Department of Public Health and Primary Care, University of Cambridge, Institute of Public Health, Cambridge CB2 2SR, ^b Department of Public Health and Primary Care, University of Cambridge, Strangeways Research Laboratory, Cambridge CB1 8RN, ^c Department of Medicine, University of Cambridge, Strangeways Research Laboratory, ^d Dunn Human Nutrition Unit, Cambridge CB2 2XY

Correspondence to: N J Wareham njw1004{at}medschl.cam.ac.uk

Objectives: To study associations between patterns of physical activity and ultrasound attenuation by the heel bone in men and women.
Design: Cross sectional, population based study.
Setting: Norfolk.
Participants: 2296 men and 2914 women aged 45-74 registered with general practices participating in European Prospective Investigation into Cancer (EPIC Norfolk).
Results: Self reported time spent in high impact physical activity was strongly and positively associated with ultrasound attenuation by the heel bone, independently of age, weight, and other confounding factors. Men who reported participating in 2 hours/week of high impact activity had 8.44 dB/MHz (95% confidence interval 4.49 to 12.40) or 9.5%, higher ultrasound attenuation than men who reported no activity of this type. In women, the difference in ultrasound attenuation between those reporting any high impact activity and those reporting none was 2.41 dB/MHz (0.45 to 4.37) or 3.4% higher. In women this effect was similar in size to that of an age difference of four years. Moderate impact activity had no effect. However, climbing stairs was strongly independently associated with ultrasound attenuation in women (0.64 dB/MHz (0.19 to 1.09) for each additional five flights of stairs). There was a significant negative association in women between time spent watching television or video and heel bone ultrasound attenuation, which decreased by 0.08 dB/MHz (0.02 to 0.14) for each additional hour of viewing a week.
Conclusions: High impact physical activity is independently associated with ultrasound attenuation by the heel bone in men and women. As low ultrasound attenuation has been shown to predict increased risk of hip fracture, interventions to promote participation in high impact activities may help preserve bone density and reduce the risk of fracture. However, in older people such interventions may be inappropriate as they could increase the likelihood of falls.