Running and squash are somewhat advanced movement patterns that also require some pre-existing musculoskeletal conditioning and skill. Alternatively, weight or resistance training are effective and accessible forms of exercise for maintaining BMD and slowing the rate of BMD loss.
Weight training involves using a resistance to create tension through the muscles, which in turn loads the bones. The research on the optimal amount of weight training required to achieve improvements in BMD is limited, however we can apply what we know about muscle development to develop an effective program to improve both muscle and bone health. A program consisting of 3 weight training sessions per week is sufficient to create positive changes in muscle function, which by extension will aid BMD.
I believe it is imperative to assess your exercise habits and determine if what you are doing is maximising the benefits you could be getting from exercise and also giving you the optimal health outcomes. For example, there are currently 1.2 million people in Australia with osteoporosis with a further 6.2 million with low bone mineral density (BMD). Osteoporosis is a condition which affects the bones causing them to be brittle and fracture more easily. I’m sure we have all heard of this condition before and know someone who has osteoporosis, yet we don’t think it is something that will affect us personally. However, the risk factors for osteoporosis can be directly linked with the habits you develop in your 20s.
Peak BMD is reached in your mid to late 20s and can decrease slightly each year for the rest of your life. The amount of exercise you do is a contributing factor to the BMD peak you reach. That is, if you are physically inactive, your BMD peak may be lower than someone who is very physically active. During your 30s and 40s, BMD can be maintained through exercise, however it can still decrease 1–2% each year. For women, after the age of 45 and post-menopause, BMD can decrease 2–4% per year which again can be slowed through exercise.
Ultimately, our focus must come back onto the exercise you are currently undertaking, to determine whether it is giving you the best chance to maximise your BMD and slow the loss of bone into the future. For example, did you know that swimming provides no benefit to BMD? Whilst swimming can help you improve cardiorespiratory fitness, it does not give you all-round health benefits that can be provided by other forms of exercise that “load” the bones. Table 1 summarises how different forms of exercise impact upon BMD.
Table 1. Different forms of exercise and their effect on bone mineral density.
(Table adapted from Todd & Robinson 2003)
Vigorous aerobic exercise includes activities such as jumping, skipping, and hopping...movements which many leave behind in primary school! Nevertheless, they are important; when performed correctly, these movements impose loads on the bone and it is this loading stress that stimulates the growth and maintenance of BMD.
Based on this information, reflect on the exercise regime that you are currently undertaking. Do you think you are loading your bones sufficiently to reach a higher peak BMD or slow the loss of BMD as you age? Having an individually tailored program designed by an Accredited Exercise Physiologist can help ensure that you are getting the maximum benefits from your training for optimal cardiovascular, muscle, and bone health outcomes.
Written by Rory Scott, Accredited Exercise Physiologist.
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