Exercise as it relates to Disease/Does resistance training impact bone mineral density in postmenopausal women?
This Wikibooks Page is a critical appraisal of the article ‘Heavy resistance training is safe and improves bone, function, and stature in postmenopausal women with low to very low bone mass: novel early findings from the LIFTMOR trial’ by Watson et al.
What is the background to this research?
Osteoporosis is a disease involving the loss of bone mineral density (BMD), instigating a lack of structural integrity in the body’s framework, increasing the risk of fractures. Common fracture sites of osteoporotic individuals are the hip and lumbar spine (main weight bearing areas). It affects nearly 10% of the world’s population and 30% of women after menopause.
During menopause, the ovaries cease functioning and 17beta-estradiol levels decrease causing accelerated bone loss (~ 2 - 6.5%).Therefore contributing to high incidence rates of osteoporotic postmenopausal women. A risk factor associated with these women is re-fracturing previously affected areas. After experiencing damage, a bone never returns to its original strength - making it more susceptible to re-injury.
To counteract the osteoporotic effects associated with menopause, women are prescribed hormone replacement therapy (HRT) and/or calcium supplementation by their GP’s or specialised doctors. HRT maintains BMD through artificially restoring oestrogen levels, whereas calcium supplementation replenishes calcium stores lost during menopause. However, research is beginning to associate bone strength with regular resistance training in this population.
Where is the research from?
This research was published in the journal ‘Osteoporosis International’ with Watson, Weeks, Weis, Horan, and Beck conducting research from Griffith University, Menzies Health Institute and the Bone Clinic in Queensland, Australia.
The study was led by Beck, B. who is a highly reputable Associate Professor at 'Griffith Health Institute's Centre for Musculoskeletal Research' and Watson who attained his PhD for 'Physiotherapy' following this research.
What kind of research was this?
The research by Watson et al. is a single-blind randomised controlled exercise intervention trial. RCT’s are commonly considered the gold standard for comprehending the dose-response outcomes of exercise and is therefore an appropriate study design for this intervention. It is through these highly specific studies that meta-analyses can be comprised on the overview of a treatment’s effectiveness in a target population.
What did the research involve?
Seventy-two postmenopausal women (>60 years old) with a low BMD at the hip and/or spine sites were randomised into 2 groups with there being a High intensity Progressive Resistance Training (HiPRT) group and a Control group (CON). HiPRT individuals performed 30 minute, supervised workouts twice weekly over 8 months involving high intensity resistance exercises (deadlift, squat, overhead press etc.) with progressions being added after 2 months. Control participants exercised at the same frequency however were un-supervised and home-based performing stretches and low resistance exercises (lunges, calf raises, shrugs etc.) with intensity mildly increasing over time. Only 28 individuals completed the full trial period with participants quitting due to reasons such as medical contraindications (n = 36), being unable to attend sessions (n = 28), currently conducting resistance or impact training (n = 23), and not having Osteopenia or Osteoporosis (n =10).
Post-trial, BMD was recorded at the Femoral Neck (FN) and Lumbar Spine (LS) using a Dual-energy X-ray Absorptiometry (DEXA), which is considered the gold standard for measuring body composition. A hand-held dynamometer and other performance-based tests were performed to analyse changes in strength also.
What were the basic results?
In the HiPRT group significant increases in BMD were present at both the LS (HiPRT = 1.6 ± 0.9 % , CON = -1.7 ± 0.6 %) and FN (HiPRT = 0.3 ± 0.5 %, CON = −2.5 ± 0.8 %) locations in comparison to the CON group. Presenting great evidence for resistance training as a treatment of osteoporosis in postmenopausal women.
However, it continues on to deliver the message ‘HiPRT is safe’ and do not further extrapolate. This is true, although many factors must first be considered for this to be accurate. For example, if a novice began this exercise regime un-supervised, this could potentially be extremely dangerous – increasing the incidence of injury not only in the present but in the future. Therefore, for HiPRT to be deemed as ‘safe’ it must be supervised by an exercise professional (e.g. exercise physiologist) especially in the cognitive stage of the task with progressive overload being utilised correctly throughout.
Another limitation of this research is that they claimed to have 72 participants when only 28 were mentioned in the data. Either they have severely over-exaggerated their group size or data was not collected for each participant and is therefore insignificant.
What conclusions can we take from this research?
Although this research had a small final group size, it shows strong evidence that high intensity resistance training does improve the BMD of post-menopausal women and could be implemented as a form of treatment for Osteoporosis. However, success of the intervention relies heavily on it being instructed by an exercise professional with increases in intensity being introduced periodically in regard to their stage of skill acquisition and physical ability. Further research should also be conducted to understand the specific exercises and load that provide the most significant results regarding Bone Mineral Density (BMD) / Bone strength at the Lumbar Spine and Femoral Neck respectively to reduce the prevalence of Osteoporotic fractures in this high risk target population.
Before postmenopausal women consider performing any high intensity exercise, a local GP or specialist should be approached to reduce the risk of serious injury. As mentioned above, if being introduced into an individual’s routine, correct technique and slow progressions must be utilised. This is safest when supervised by an exercise physiologist (or similar) as they are highly knowledgeable of the potential risk factors associated with exercise and can accurately prescribe protective measures to prevent injury. The combination of resistance and aerobic training should be considered also with research suggesting that both exercise modes can be extremely beneficial for BMD, aerobic capacity as well as anxiety and depression.
- Watson S, Weeks B, Weis L, Horan S, Beck B. Heavy resistance training is safe and improves bone, function, and stature in postmenopausal women with low to very low bone mass: novel early findings from the LIFTMOR trial. Osteoporosis International. 2015;26(12):2889-2894.
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