Serum [25(OH)D] status, ankle strength and activity show seasonal variation in older adults: relevance for winter falls in higher latitudes.

Abstract

BACKGROUND seasonal variation exists in serum [25(OH)D] and physical activity, especially at higher latitudes, and these factors impact lower limb strength. This study investigates seasonal variation in leg strength in a longitudinal repeated measures design concurrently with serum vitamin D and physical activity. METHODS eighty-eight community-dwelling independently mobile older adults (69.2 ± 6.5 years) were evaluated five times over a year, at the end of five consecutive seasons at latitude 41.1°S, recruited in two cohorts. Leg strength, serum [25(OH)D] and physical activity levels were measured. Time spent outside was recorded. Monthly falls diaries recorded falls. Data were analysed to determine annual means and percentage changes. RESULTS significant variation in [25(OH)D] (±15%), physical activity (±13%), ankle dorsiflexion strength (±8%) and hours spent outside (±20%) (all P < 0.001) was demonstrated over the year, with maximums in January and February (mid-summer). Low mean ankle strength was associated with increased incidence of falling (P = 0.047). Quadriceps strength did not change (±2%; P = 0.53). CONCLUSION ankle dorsiflexor strength varied seasonally. Increased ankle strength in summer may be influenced by increased levels of outdoors activity over the summer months. Reduced winter-time dorsiflexor strength may predispose older people to increased risk of tripping-related falls, and warrants investigation in a multi-faceted falls prevention programme.

DOI: 10.1093/ageing/afs067

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@article{Bird2013SerumS, title={Serum [25(OH)D] status, ankle strength and activity show seasonal variation in older adults: relevance for winter falls in higher latitudes.}, author={Marie-Louise Bird and Keith D. Hill and Iain Kilpatrick Robertson and M. J. Ball and Jane K. Pittaway and Andrew Williams}, journal={Age and ageing}, year={2013}, volume={42 2}, pages={181-5} }