Dr Feitong Wu1, Dr Michele Callisaya1, Dr Karen Wills1, Dr Laura Laslett1, Professor Graeme Jones1, Professor Tania Winzenberg1
1Menzies Institute For Medical Research, University Of Tasmania, Hobart, Australia
Objectives: Poor balance is a risk factor for falls and fracture in older adults, but little is known about modifiable factors affecting balance in younger women. This study aimed to examine whether lower limb muscle strength (LMS) in young women and changes in LMS are independent predictors of balance in middle-age.
Methods: This was an observational 10-yr follow-up of 470 women aged 25-44 years at baseline who had previously participated in a 2-yr population-based randomised controlled trial of osteoporosis education interventions. Linear regression was used to examine the association between baseline LMS (by dynamometer) and change in LMS over 12 years with balance at 12 years (timed up and go test (TUG), step test (ST), functional reach test (FRT) and lateral reach test (LRT)).
Results: LMS declined by a mean of 17.3 kg over 12 years. After adjustment for potential confounders, baseline and change in LMS were independently beneficially associated with TUG (β=-0.008sec/kg, 95%confidence interval (CI):-0.01 to -0.006 and -0.006sec/kg:-0.009 to -0.003 for baseline and change respectively), FRT (β=0.057cm/kg, 95%CI: 0.030 to 0.084 and 0.071cm/kg: 0.042 to 0.101) and LRT (β=0.030cm/kg, 95%CI: 0.012 to 0.049 and 0.022cm/kg:0.002 to 0.043)12 years later. There was an association between baseline LMS and ST (β=0.044steps/kg, 95%CI: 0.022 to 0.067) but not between change in LMS and ST.
Conclusions: Among young women, greater LMS at baseline and slower decline over time are both associated with better balance in midlife. Analogous to the contributions of peak bone mass and bone loss to fracture risk in older adults, this suggests that both improvement of muscle strength in younger age and prevention of age-related loss of muscle strength could be potentially useful strategies to improve balance and reduce falls in later life.
Prof Winzenberg is a Senior Research Fellow-General Practice at Menzies Institute for Medical Research, University of Tasmaina. She is a member of the Australian and New Zealand Bone and Mineral Society (ANZBMS), the ASBMR and the Australian Association of Academic Primary Care and is a fellow of the RACGP. She is an invited member of the Therapeutics, the Professional Affairs and the Research Committees of the ANZBMS. Her work focuses on chronic disease prevention and management, particularly for musculoskeletal conditions and cardiovascular disease, with a particular interest in aspects of this relevant to primary care.