Exercise as it relates to Disease/Resistance training and osteoporosis in postmenopausal women

This article is an analysis on the study "Resistance training over two years increases bone mass in calcium-replete postmenopausal women" conducted by Deborah Kerr, Timothy Ackland, Barbara Maslen, Alan Morton and Richard Prince (2009).

What is the background to this research?

Osteoporosis is one of the most under-diagnosed conditions because it has no clear symptoms and is often not diagnosed until a fracture occurs, with around 10% of Australians aged 50 or over having been diagnosed, according to the Australian Bureau of Statistics.Osteoporosis is a condition that causes bones to become thin, weak and fragile which in turn lead to a higher risk of fractures. After menopause, women are more at risk of developing osteoporosis as oestrogen levels in the body drop and with that they experience increased bone loss. Early postmenopause is a critical time for loss of muscular strength and bone mass in women. There may be a relationship between these two phenomena as age-related losses in muscle strength precede losses in bone

Understanding the adaptation of bone to resistance exercise is critical for prevention and whilst it has been shown in previous studies that weight-bearing exercises have a positive effect on bone mass, it has been suggested that strength training may have more favourable effects in maintaining or increasing bone mass .

Where is the research from?

All of the researchers came from different professional areas such as the School of Public Health, Department of Human Movement and Department of medicine but all of them were based in Perth, Western Australia. Deborah Kerr is an associate professor at Curtin University and has a PhD in Exercise and Bone Health, the critical area in this study done. Professor Ackland from the University of Western Australia has research interests in the mechanics of human movement with themes spanning musculoskeletal rehabilitation and physical ergonomics. Mr Alan Morton is also a professor at UWA and has done previous papers on bone mass in young women with Richard Prince, another researcher in in this study.

What kind of research was this?

Recruitment for this study was done through media articles with a telephone screening being done shortly after to narrow it down to 163 eligible participants which then became 126. Being a randomised controlled trial it reduced the selection bias. The group of 126 females were divided into 3 groups.

• Intervention groups: There were two intervention groups for this study, aerobic and strength based.
• Control group: The control group is used to design an experiment in which the group does not participate in so that the natural changes can be monitored and compared against the rest.

Randomised controlled trials are the most rigorous way of determining whether a cause-effect relation exists between treatment and outcome and for assessing the cost effectiveness of a treatment.

What did the research involve?

The research looked at the differences between resistance training and aerobic in 126 postmenopausal women. All subjects were given 600mg calcium supplementation every day.

Exercise intervention

Both intervention groups were subject to the same nine exercises but the resistance group had their load progressively increased at an individually tailored increment. The aerobic group had a minimal load and their load remain the same for the duration of the study. The nine exercises that were chosen because they caused either compression or tensile stress at the scanned sites and they were wrist curl, reverse curl, biceps curl, triceps pushdown, hip flexion, hip extension, latissimus dorsi pull down, and calf raise.

What were the basic results?

The change in BMD for the hip, lumbar spine and whole body sites expressed as percent change per year

	Resistance Group	Aerobic Group	Control Group
Whole Body	-0.62 +- 1.38	-0.79 +- 1.73	-0.71 +- 1.69
Lumbar Spine	-0.65 +- 2.12	-0.32 +- 1.85	-0.01 +- 1.98
Total Hip	0.57 +- 1.76	-0.65 +- 1.81	-0.57 +- 1.97
Neck of Femur	1.04 +- 2.81	0.03 +- 2.22	0.11 +- 2.60

The results presented are accurate to the data presented from the study. A significant increase in BMD was noted at the neck of the femur for the resistance group while most of the other results showed a decline in the BMD. The data collected showed similar results in a previous study where they had a similar exercise protocol. In the current study, the effect on the forearm site was different to that of the previous study. The lack of effect observed at the spine suggests that insufficient loading occurred with the strength training intervention.

What conclusions can we take from this research?

The authors concluded saying that a progressive strength training program designed to promote maximum strength gains effectively increases bone density over two years especially at the important neck of femur and intertrochanter. A positive effect of calcium supplementation cannot be excluded. A previous study, the effects of calcium supplementation (milk powder or tablets) and exercise on bone density in postmenopausal women by Prince. R, showed the placebo group lost bone at all the hip sites whereas the calcium supplemented group did not.

Practical Advice

• Resistance training is important for retaining BMD.
• Strength training must not replace cardiovascular fitness, a balance of both is needed.
• Calcium supplementation prevents loss of bone at the hip.
• Consistent supervision for high risk of low trauma fracture.

Further Information/ Resources

• Australian Institute of Health and Welfare: Osteoporosis Snapshot - https://www.aihw.gov.au/reports/chronic-musculoskeletal-conditions/osteoporosis/contents/what-is-osteoporosis
• Osteoporosis Australia - https://www.osteoporosis.org.au
• Is high impact or low impact exercise better for osteoporosis prevention? - Musculoskeletal responses to high- and low intensity resistance training in early postmenopausal women
• Preventing osteoporosis: International Osteoporosis Foundation - https://www.iofbonehealth.org/preventing-osteoporosis