Exercises that create both bone and muscle loading, such as impact exercises, have an increased effect on bone metabolism than weight lifting alone (Wendy, Barry & Schwartz (2009). However this is not always the most appropriate option. As one ages, many other factors come in to play such as herniated discs, vertebral fractures, arthritis and various aches and pains meaning that non-impact sports may be more feasible.
When analysing the femoral neck in isolation, it has even been seen that no impact, high intensity resistance training has been more beneficial than impact exercises alone (Howe et al. 2011). However, research (that included 4,320 participants across many randomised controlled trails) than a combination of resistance, impact and aerobic exercises was found to be the most beneficial.
The bone osteogenic response can be triggered via resistance training. This continuous torsion, compression and tensioning of a bone creates local electrical signals that increase the amount of bone mineral density and inhibits bone resorption (Iwamoto, 2013). One study (over a years duration) found that to maintain or improve the mineral density of the femur, exercises of 70-90% one rep max, with 3-4 sets of 8-12 reps must be performed 2-3 times a week (Zehnacker & Bemis-Dougherty, 2007). As well as an improvement in bone density, due to the general benefits of exercise, an improvement in physical function and daily life will also be seen (Wilhelm et al., 2012).
Bone formation exercises usually involve high intensity, short duration and dynamism (Vierra, 2013). When the vigorous muscle contractions - triggered via resistance, speed and high loads – are performed roughly four times a week, type II fibers within the muscles should be activated which are most likely to stimulate bone formation (Turner, 2007).
Many studies have compared strength training against power training. One study - involving concentric and eccentric contractions – found that after two years of training, those that had been submitted to the power training group (involving explosive concentric contractions) maintained lumbar spine bone mineral density, whilst those submitted to the strength training group (involving slow concentric contractions) lost 2.4% lumbar bone mineral density (von Stengel et al., 2007).
Lastly, when considering vertebral fractures, it is also important to assess the muscles. One study by Sinaki et al. (2002) found that there is a significant reduction in vertebral fractures if the back extensor muscle forces are improved. This is also true for those following vertebroplasty surgery (Huntoon, Schmidt & Sinaki, 2008).
Moreira, M.D.F, Oliveria, M.L., Lirani-Galvto, A.P., Marin-Mio, R.V., Santos, R.N., Lazarett-Castro, M. 2014. Physical exercise and osteoporosis: effects of different types of exercises on bone and physical function of postmenopausal women. Arquivos Brasileiros de Endocrinologia & Metabologia. 58(5). [viewed 23 October 2017]. Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0004-27302014000500514#B12
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