Looking after your bones

The Role of Exercise in the Management of Osteoporosis

The most common definition of osteoporosis was published in the American Journal of Medicine (1991) as “a systemic skeletal disease characterised by low bone density and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility”. In particular, the disease affects trabecular bone, which is a porous bone type forming the spine and articulating joints.

The body continuously recycles bone mass throughout its life, although the rate of recycling peaks during youth and decreases after the age of 30. Here, bone is formed and re-formed through the processing of cells called osteoblasts and osteoclasts. Osteoblasts originate from bone marrow and are responsible for the slow process of laying down new bone through mineralisation.

Conversely, osteoclasts are responsible for the demineralisation of old bone cells, performing the important job of eliminating damaged tissue (broken bones) and dying cells. These processes, however, are age-related such that once peak bone mass (PBM) has been reached at about the age of 30 (Nijweide, 1996) degeneration outstrips mineralisation, and PBM decreases with age.

This ageing effect, linked with other risk factors (Table 1) can lead to an individual developing a fragile bone structure, or Osteopenia (meaning loss of bone mass). Without intervention, this will most probably progress to Osteoporosis. Importantly, this bone density loss is commonly gradual and can occur without any evident symptoms until well advanced. Under such conditions a break can happen easily, or even spontaneously, and this can be the first known symptom of the disease.

Primary Risk Factors Secondary Risk Factors

Female Premature menopause Age Primary or secondary amenorrhoea Slight build Primary or secondary hypogonadism Asian or Caucasian Race Previous fragility fracture Maternal history of hip fracture Low body weight Smoking High Alcohol consumption Prolonged immobilisation Low calcium intake Vitamin D deficiency

Table. 1 Risk factors related to osteoporosis (WHO)

One of the many methods used to determine BMD is Duel Energy X-ray Absorptiometry (DXA). Kanis (1994) addressed this issue (WHO) by developing a quantitative scheme for the definition of stages of osteoporosis based on measurements of bone density. In this test, DXA is applied to both the spine and the hip (although it can be applied throughout the body), and the resulting score is measured against a mean baseline (a 25 - 35 year old pre-menopausal woman) to define a “T-score” which can be used for clinical decisions. The resulting T-score is interpreted as follows:

a) T-score between 0 and -1 standard deviation (SD) from the mean is considered within the normal range.

b) T-score between -1 and -2.5 SD is defined as Osteopenia.

c) T-score below -2.5 SD is defined as Osteoporosis.

National Osteoporosis Society (NOS) states that there are 3 million people with the condition, of whom ~ 50 % are women over the age of fifty and ~ 20%, are men over the age of fifty. With ~230,000 fractures (120,000 spine, 60,000 hip, 50,000 forearm/wrist; ) each year in the UK, and an osteoporotic-related fracture occurring every 3 minutes, it costs the National Health Service around £1.7 billion annually, or £5 million per day, to care for osteoporotic patients.

As a result of its scale and nature, osteoporosis is often described as the “silent crippler” or “silent epidemic”. Indeed, the scale of the ‘epidemic’ is set to grow as the world’s population ages. Bone mass is lost in all people as they age, however, postmenopausal women have a greater increase in bone loss due to the lack of oestrogen . This lack of oestrogen is seen to stimulate cytogenesis and this in turn, increases osteoclast genesis.

The WHO reported that more than half of the developing world’s women aged over sixty and two thirds of all 45 – 59 years olds will suffer from osteoporosis. In addition to the severe individual discomfort and immobility to millions of people, it is important to recognise that secondary complications associated with this disease can be life threatening to older people. In the UK there is a 20 % chance of mortality within a year of an osteoporosis-related hip fracture (Riggs and others, 1995). Thus, the projected increase in the elderly population will result in loss of life (perhaps on a very large scale) and will have to be addressed by governments and health agencies. This will further stress health services financially, resulting in diversion of expenditure from elsewhere. For example, the lifetime risk of a hip fracture in the UK is 40 % and each fracture results on average in a 30-day period of hospitalisation, comparable in both cases to heart disease.

Prevention is essential to not only quality of life, but to maintain the health and independence in the elderly. Therefore, it is critical that we understand and investigate all avenues for reducing this disease, identifying treatment that is (i) effective, (ii) widely available and (iii) preventative. Importantly, one treatment that may meet all these criteria is exercise, which may play an important role in both the prevention and the management of the disease. Exercise can benefit the body in many ways.

The case for exercise

Whilst there is substantial evidence to support both medication and dietary modifications to assist the direction of osteoporosis, the recent position stand by ACSM on physical activity and bone health signifies a shift in direction to support the important role of exercise. Exercise can benefit the body in many ways. However, combating osteoporosis requires these specific aspects to be addressed:-

Bone Loading

Approximately 70 – 80% of bone mass variability is genetically determined, with a peak bone mass attained by age of thirty (Theinz et al, 1992), exercise during prepubescent and pubescent years is crucial for maximising peak bone mass (Haapasalo 1994, Morris 1997). However, diet and exercise are still able to influence the remaining 20 – 30%.

Wolff’s law states that "Bone accommodates the forces applied to it by altering its amount and distribution of mass" or that bone that is deposited and reabsorbed is dependant upon the stresses placed on it. We understand that exercise or mechanical stress, can increase bone density and conversely, that lack of exercise, or lack of loading to the bone can be detrimental.

In order to observe how mechanical loading can affect bone density, Haapasalo, and others (1996) examined how the humerous bone differed in mass in tennis players. These authors examined the distal radius of the humerous demonstrated that there was an increase in bone density up to 45% in the playing arm compared to the other. By examining the bones belonging to the same person, it was clear that doing an activity, such as hitting a tennis ball, could affect the matter of a certain bone. The study looked at varying levels of fitness, age and in both sexes, and they found that this increase in bone density occurred throughout. To take this a step further, Wolman (1991) then looked at differing sports to see if they had an effect on how bone changed in response to exercise. He compared elite female runners with elite female rowers and although both groups had a high level of fitness, the athletes had higher bone density in the trochanter of the femur compared with the rowers. This starts to indicate types of exercises that are needed so that the BMD occurs in sites that are specifically affected by osteoporosis, namely, the hip, spine, and forearm.

Through work done by Morris (1997), Slemenda (1994) and others, it emerged that jumping, skipping, and running were regarded as the most effective methods in increasing BMD, with changes occurring to the appendicular skeletal sites, and subsequent improvements of up to 15% BMD. Jumping up and down on the spot is sufficient to bring about changes, and there is little or no need to increase heart rate, inducing sweating or to have any cardiovascular training effect.

As people get older, they tend to think that it is better to do lower level of exercise. Indeed, the Department of Health current guidelines are for 30 minutes of low to moderate activity on 5 – 7days per week is regarded as the more modern way of getting our nation fitter, and in terms of helping to reduce obesity, reduce the chances of Type II diabetes and alleviate other conditions, it is highly effective. However, in the quest to increase bone mass Sanaki (1994) indicates that although low impact activity (such as walking) had a positive effect on muscle mass and fitness it did little to alter BMD – despite the programme continuing for over 3 years.

Further evidence on the validity of low impact exercise for osteoporosis came from Dook and others (1997) who looked at BMD of senior Australian Masters swimmers (each with over 20 years exercise training). They discovered that despite long term exercise at a high level, there was little difference in the BMD of these athletes compared to the sedentary control group.

There are also some positive studies to show that it is never too late to start an exercise programme to help BMD. Kapsabelis (2001) investigated the effects of high-strain exercise on postmenopausal women.

His research group were postmenopausal women who were moderately active. They each took part in 60-minute programme of aerobics, bench work and skipping as well as some resistance training, on 3 days per week. The control group did no exercise. After 6 months of continuous work, the results showed an improvement not only in bone mass, but also in total bone density, sub cortical bone mass and lean muscle tissue.

Moreover, studied in China on the effectiveness of more gentle exercise on BMD have shown encouraging results. Qin and others, (2001) reported the effect of Tai Chi on retardation of bone loss. A total of 84 women, aged 47-65 years, were randomly assigned to either practice Tai Chi or not. The subjects in the Tai Chi group practiced the exercise 5 days per week for duration of 45 minutes per session for 12 months. Results showed a significant reduction in bone loss in the exercise group. Of particular interest was the finding that this form of exercise was associated with a low drop-out rate. Compliance with physical activity programs is always a problem, but compared with other exercises, such as brisk walking (average rate of dropout is 45%); the Tai Chi exercise had a drop-out rate of approximately 30%.

Cheng, 2002, investigated the effect of bone loading exercise with HRT. One group did exercise only, one group HRT only, one group exercise and HRT. The exercise involved 12 months progressive training with jumping and bounding exercises for 80 women aged 50-57 who had not had HRT before. Results showed that the exercise intervention contributed to increasing bone maintenance and bone mass. What was interesting, is that bone mass also increased in the group that only took HRT but did no exercise – and it appeared that HRT acted directly onto the bone marrow and created more osteoblast cells.

By bringing the varying elements from these studies together, a picture is emerging that a) exercise has a positive effect on bone density, b) bone loading is site specific, c) women on HRT respond differently to those not on HRT.

Posture and balance

While we appreciate the value and necessity of bone loading as a method of helping to prevent and manage osteoporosis, we must not disregard the importance of posture and balance exercises.

Bone loading, although effective, can take around 9 -12 months of regular exercise before any marked changes can be measured (ACSM 2004). In the mean time, exercises to improve posture and maintain balance can be vital in helping the individual to remain active, to improve quality of life, to help prevent falls and to alleviate the pain caused by osteoporosis.

The classic osteoporotic posture is that of the “dowager hump” or "Kyphosis". A "Kyphotic posture" increases the likelihood of falls in osteoporotic individuals. Poor posture also leads to changes in gait which when linked to loss of proprioception in the muscles due to the natural aging process, causes falls to become more likely. Sanaki also noted that the lower limbs were used more for balance when kyphosis of the spine occurred. Specifically, that the ankle takes more loaded than the hip which is opposite to a normal walking gait. The combination of poor spinal position (and possibly poor vision of the terrain) often leads to fractures of the hip, either through falls directly onto the hip, or heavy stepping to correct misbalance (NHS, 2004). Indeed, the importance of reducing in falls is highlighted in Statement 6 by the Department of Health (2004) as an issue for the management of osteoporosis. Hip fractures lead to substantial disability. Half of the 1.6 million worldwide fractures occur in Europe and North America (Melton LJ II, 1992). In England and Wales, hip fractures occupy one fifth of all orthopaedic beds and 90% of all hospital costs for osteoporotic fractures.

It is therefore important not only to consider how to improve BMD, but also to help people not to fall. This can be done by improving posture and balance. Exercises most suited to improving posture look at re-educating muscles in order to correct alignment. For example, Pilates or resistance machines.

Pilates is based improving range of movement, balance and strength through core work and stretching. Special attention is paid to the contraction of the transverse abdmoninis, to help alleviate the pressure on the vertebral disks and realigned the spinal column; to the lower trapezius to draw the scapular into its correct alignment and not let the back curve forward in kyphosis and finally to work with the pelvic floor to help stabilise the pelvis and improve the tone pelvic floor muscles.

Weakness in the pelvic floor can lead to stress incontinence and prolapse of the internal organs such the bladder, rectum, uterus or prostate. This can often be the main cause for an individual to stop doing the impact exercise necessary for bone loading and its importance should not be underemphasised. As spinal fractures are often undiagnosed, care must be taken not to include forward flexion of the spine which can exacerbate the condition further.

Advice on diet, medication and the correct level of exercise will be vital to the prevention and management of this disease. Management of the disease is critical to alleviate suffering and to bring to an end to further degeneration of the skeleton and prevention is essential to not only quality of life, but to maintain the health and independence as we age gracefully.

I have been increasingly interested in how to improve bone health since doing the Cafe's around the menopause. I have changed the way in which I plan and organise the weekly workouts to include weight bearing, bone loading exercise, alongside the jumping and bounding exercises that prove to be so helpful - and yes, information on pelvic floor to help reduce stress incontinence and ability to jump around without worry!

Get in touch if you want to join the next Café in September 2022 or join the online videos

Join the Café!