By Marie-Louise Bird
If you live a long way from the equator, the amount of daylight that you have access to in summer compared to winter varies hugely. For example at 41 degrees (Launceston in Tasmania, Australia; Boston, MA, USA; and Portugal, Europe) the length of daylight varies from just over 9 hours in winter to over 15 in summer and even more dramatic at 53 degrees, with hours of daylight from 7.5 in winter to 17 in summer. It is not surprising that this will have impact on the total amount of physical activity that people perform in the different seasons with less activity in winter (14% at 41 degrees south). This is especially true for the amount of active time spent out-of-doors. The flow-on effect of limited outside activity has several health consequences to consider in winter; both reduced sun exposure for vitamin D production and changes in strength from potential deconditioning. This may also impact winter fall rates in older adults, particularly trip related falls.
Vitamin D levels within the body are important for muscle and bone health outcomes as well as adequate immune function. Recommendations for achieving adequate levels of vitamin D include maximizing safe sun exposure where possible, and opting for supplementation when not. At high latitudes in winter the availability of ultraviolet light for vitamin D production is minimal for 3 months (at 40 degrees south reducing from 36 Mega joules/m2 in summer to 8 Mega joules/m2 in winter). This closed window last even longer at higher latitudes (5 months at 53 degrees north). As well the climate at those latitudes is often not conducive to exposing skin for vitamin D gain!
We have recently identified small changes in ankle strength (reduced by 8% in winter) and dynamic balance (reduced 4% in winter) that may be related to the reduction of outside activity during the winter season. Ankle strength is one important link in the chain of physical fall risk factors for older adults. However, the control of motion around the ankle is equally or more important for maintaining postural balance and prevent falling and requires more than just strength. Postural control also relies on proprioceptive input and central balance mechanisms to maintain good ankle strategy. Walking outside in summer appears to offer challenges to balance and proprioceptive input to assist in balance reaction maintenance. Are there activities that we can recommend people do in winter to maintain ankle strength and balance, and help prevent falls?
It appears that typical falls in summer and falls in winter may be different. Information about inside and outside falls is available for some healthy populations. There are gender differences being found, with more men falling outside than women. The important context of frailty is being explored in Canada, with inside falls being reported to occur in populations that have more markers of physical frailty in terms of slower gait speed and step variation than outside fallers We have found a larger number of outside falls compared to inside falls in summer recently, although other researchers have found weather in winter makes outside falls in winter more common. So perhaps for those able to safely negotiate outside, the adage ‘make hay while the sun shines’ has an important corresponding saying for those who do not work the land ‘walk outside while the sun shines’. Of course there are caveats on this recommendation, with walking programs found to increase falling in people who attempt them who are too frail.
If exercising outside is too difficult because of the weather, we can deliver exercise interventions inside the home. An interesting new area of research is the use of video games to improve activity levels in older adults, and some of these are designed to challenge balance as well. Is this something that older adults may want to do in winter when the weather prevents them going outside? Current recommendations in Australia for exercise to assist in preventing falls indicates that balance activities should be done for 2 hours a week to help reduce falls. These activities should include challenges to balance that move the centre of gravity over the base of support and progressively reduce the base of support. Balance can also be challenged by altering sensory input in terms of surfaces for exercise (softer surfaces are more challenging) or changes to visual input (less visual input increases the challenge). Researchers at Monash University suggest that the level of difficulty should be such that you are challenged but not unsafe. If you use your hands to support you while exercising, it will not challenge your balance or train better balance reactions. So if you want to improve your balance — don’t use your hands.
Following these current guidelines that are based on Cochrane level evidence, it is possible to reduce the risk of falling by up to 38% through targeted exercise programs. Uptake of these appropriate exercises and adherence to fall exercise programs after starting remains disappointingly low, in light of the strong evidence. This is where technology may come into ‘play’ with exer-gaming providing new ways for participants to interact with games and each other, often from the comfort of their own home. The current commercially available sensors allow accurate and immediate feedback for ‘gamers’ and can been used for a variety of exercise goals, not only aerobic, but also to promote stepping and balance reactions. At present no interventional research currently exists to look at seasonal exercise programs to help with the winter reduction in activity (particularly outside activity) that may flow on to impact ankle strength and dynamic balance and winter fall rates. Perhaps activity based videogames may be a new recommended winter pastime for older adults to use with their friends and family.
Dr Marie-Louise Bird is a physiotherapist working at the University of Tasmania, whose area of research includes exercise interventions to improve fall risks in older adults and has recently become increasingly interested in the role of incidental activity to combat sedentary behaviours and motivation for physical activity. She is a committee member for the Australian Gerontology and Geriatrics Group (Tasmanian Branch). She is also a Pilates instructor and mentor for Polestar Pilates Australia. Marie-Louise enjoys mountain biking in Tasmania and Spain. She is the lead author of the paper, ‘Serum [25(OH)D] status, ankle strength and activity show seasonal variation in older adults: relevance for winter falls in higher latitudes’, which appears in Age and Ageing.
Age and Ageing is an international journal publishing refereed original articles and commissioned reviews on geriatric medicine and gerontology. Its range includes research on ageing and clinical, epidemiological, and psychological aspects of later life.
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Image credit: Feet bones anatomy with toes lateral view. By janulla, via iStockPhoto.