Exercise as it relates to Disease/Can strength training preserve bone mineral density in postmenopausal women?

This is a critique of the journal article titled "Strength training preserves the bone mineral density of postmenopausal women without hormone replacement therapy" by Danilo Sales Bocalini, Andrey Jorge Serra, Leonardo dos Santos, Neif Murad and Rozeli Ferreira Levy published in 2009 in the Journal of Aging and Health

What is the background to this research?

Normal bone vs Osteoporotic bone. Image by BruceBlaus

Bone mineral density (BMD) decreases as we age which can lead to a lot of health implications with osteoporosis being one of the most common in postmenopausal women . One in three women agreed fifty years and older will suffer from osteoporosis in their lifetime . The result of this is linked to a decrease in quality of life for many individuals due to fractures in hips, wrists and forearms which can cause them to struggle with walking, lifting, bending over, cooking, cleaning, personal care and cause mobility issues . The loss of bone mineral density and osteoporosis is commonly linked with older women who have a hormone deficiency .

Hormone replacement therapy is commonly prescribed to postmenopausal women to offset bone loss, however, there is evidence to suggest that resistance training on its own can stimulate bone formation and reduce the risk of osteoporosis . Most studies in this area look at a combination of hormone therapy and strength training, however, in the study being reviewed today, we are looking at bone mineral density and strength training without hormone therapy . This is important as not all individuals are willing to undergo hormone therapy.

Where is the research from?

This research was conducted in Sȃo Paulo in Brazil and was published in the Journal of Aging and Health . The primary author in this study was Danilo Sales Bocalini who is from the Federal University of Sȃo Paulo and Heart Institute and Medical School . Danilo has a PhD and specialises in resistance training, physical fitness, blood pressure, physiology, molecular biology and atherosclerosis . He has published around two hundred articles and is currently undergoing more studies in the area of ageing . There were no sponsorship links that may form a bias or conflict of interest to the study .

What kind of research was this?

The research was a randomised control trial (RCT). RCT studies are known as the gold standard in epidemiology study design and are classified as a level two study as it had a small number of participants in the RCT . RCT are designed to be unbiased and have less room for any systemic error that may occur in the research study . It involves splitting up the participants into two groups, one control and one intervention group . In this particular research article, the intervention group were known as the ‘trained’ participants and the control group were known as the ‘untrained’ participants . The trained group performed the tasks/activity required in the study whilst also continuing their normal daily activity routines whereas the untrained group had no form of intervention and continued with their normal daily activity routines . Both groups maintained a normal dietary intake .

There are many other forms of studies and all have their limitations, however, in epidemiology, RCT is the gold standard .

What did the research involve?

Thirty-five women aged fifty-seven to seventy-five years of age were recruited to participate in this study . All women underwent a medical and clinical examination before the study to check that they were the right candidates . The participants followed a twenty-four-week strength program completing three resistive sessions (one-hour in duration each) per week and focused on eccentric muscle action .

There were three major parameters directly tested before and after the twenty-four weeks which looked at:

1. Bone mineral density;
2. Muscular strength;
3. and body composition.

To test the participant's muscular strength, this was completed via a one-rep max (1RM) . To test their bone mineral density, they used a dual-energy x-ray absorptiometry (DEXA) and their body composition was measured via body mass index (BMI) and body fat percentage .

Study Limitations

• A limited number of final participants (final data based on twenty-five participants);
• No prescribed advice or referral post-study for participants to continue with strength/resistance training;
• There was a no follow-up post-study (i.e. 6 months, 1 year or 2 years later) to see how clients may have progressed or regressed depending on whether they did or didn't continue strength training;
• No mention of what type of training the untrained participants were doing for exercise.

Study Strengths

• Thorough clinical examination and questionnaire looking at the medical history of the participant before participating in the study;
• Strict inclusion and exclusion criteria had to be met to be a participant;
• All training sessions were guided by trained fitness instructors and supervised by the researchers;

What were the basic results?

After the 24-week training program, the results showed us that:

• Bone mineral density in the lumbar spine and femoral neck stayed the same for the trained group and decreased significantly in the untrained group (see table 1);
• Muscle strength increased in the trained group and stayed the same for the untrained group;
• BMI and body fat percentage decreased slightly in the trained group and increased slightly in the untrained group.

What conclusions can we take from this research?

Although this study ended up with a small final participant size, the data shows us that there is quite strong evidence that strength training does keep BMD consistent and could be implemented as a form of training to maintain BMD and therefore reducing the risk of osteoporosis. However, it is to be noted that individuals should invest in an exercise professional. Further research can be conducted looking at the biomechanical mechanisms of bone adaptation to strength training. The findings in this paper align well with other studies which suggest that strength training does help maintain and increase bone mineral density

Practical advice

Before a postmenopausal woman participates in exercise including strength training, they should consult a health professional (general practitioner) to discuss if there may be any risks of potential injury from any form of exercise or to get the all-clear to strength train (if necessary). If given the all-clear, I would recommend investing in a coach/personal trainer or exercise physiologist who will be able to program appropriately for you based on your history and capabilities. The health professional will program all exercises and will make sure that they are monitoring you closely and progressing exercises appropriately.

Further information/resources

If you are interested in further information about osteoporosis, how you can incorporate exercise postmenopause and access to more support, please see the links below:

• Health Benefits of Resistance/Strength Training
• Exercising with osteoporosis
• What is osteoporosis
• Why is physical activity important?
• Ways to incorporate more physical activity into your day
• Physical Activity Recommendations for Adults 18-64 years of age
• Exercise tips for postmenopausal women
• Menopause support/more information