DPT-402.5- Exercise Prescription: Special Considerations – Osteoporosis

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Osteoporosis is a disease characterised by low bone mass and deterioration of bone tissue leading to enhanced bone fragility and a subsequent increase in the risk of fracture.  Osteoporosis occurs in both males and females but is more common in females. 

There are many misconceptions about osteoporosis, for example that it is “an old woman’s disease”. In fact, bone loss in women can begin as early as 25 years old (International Osteoporosis Federation – IOF, 2004). Worldwide, the lifetime risk for a woman to have an osteoporotic fracture is 30-40%. In men the risk is about 13% (Melton, 1992). 

Research by the National Osteoporosis Society (2003) produced the following statistics:

  • osteoporosis afflicts an estimated one-third of women aged 60 to 70, and two-thirds of women aged 80 or older; approximately 200 million women worldwide suffer from osteoporosis (IOF, 2004)
  • 1 in 3 women and at least 1 in 12 men in the UK will develop osteoporosis over the age of 50 (Melton, 1992) 
  • an estimated 3 million people in the UK suffer from osteoporosis (NOS, 2003) 
  • each year the number of people in the UK with osteoporosis seen by doctors  include over:
    • 70,000 hip fractures (Dolan, 1998)
    • 50,000 wrist fractures (O’Neill, 2000)
    • 120,000 spinal fractures (Reeve, 2002)
  • osteoporosis costs the NHS and government approximately £1.7 billion each year (Torgerson, 2001)

Despite this, osteoporosis was not precisely defined as a disease until 1994. The World Health Organisation (WHO) has since identified osteoporosis as a priority health issue along with other major non-communicable diseases, second only to CHD.

Pathophysiology

Bones are made of a thick outer shell of compact bone and a strong inner mesh filled with collagen, this is called cancellous bone.  This inner mesh looks like honeycomb and osteoporosis will occur when the holes within the cancellous bone become larger, making it fragile and prone to fractures.

Bone development is dependent upon the presence of hormones.  In women this is the female hormone, oestrogen, and in men it is the male hormone, testosterone.  These hormones influence the formation of bone by promoting the activity of bone building cells called osteoblasts.  The body replaces around 10% of its bone a year as long as osteoblasts are active (Dalgleish and Dollery, 2001). However, if osteoclast cells, which destroy or break down old bone, are more active than osteoblasts bone mass will start to decrease. 

Women start losing bone earlier in life and may experience a 3 to 5 year acceleration of bone loss after menopause (Bloomfield, 1997). This is directly attributable to the effects of oestrogen withdrawal, which is temporarily imposed on the on-going age-related loss. It should also be noted that women have a lower peak bone mass in young adulthood so are subject to a lower ‘starting point’ in terms of bone density.  

To keep laying down bone, individuals need the relevant hormones (oestrogen or testosterone), plus the minerals calcium, magnesium and phosphorus and vitamin D.  Any factor which affects the production of the relevant hormone or the intake of the relevant nutrients will be a risk factor for a person to develop osteoporosis.

Key Risk Factors 

  • oestrogen deficiency
  • early menopause (age <45 years) 
  • absence or cessation of menstrual periods (amenorrhoea >1 year) 
  • maternal family history
  • low body mass index (<19 Kg/m2
  • chronic disorders associated with osteoporosis: anorexia nervosa, malabsorption syndromes including chronic liver disease and inflammatory bowel disease, primary hyperparathyroidism, chronic renal failure, hyperthyroidism, prolonged immobilisation, Cushing’s syndrome 
  • female (women are four times more at risk than men) 
  • Asian or Caucasian 
  • poor diet low in minerals and protein 
  • lack of exercise or prolonged periods of immobility
  • smoking 
  • regular and excessive alcohol consumption 
  • advanced age 

Family history is the major risk factor with up to 70% of a person’s risk being genetically based (Compson and Rosen, 1999); the other risk factors are important, but minor in comparison to the genetic basis.

Fracture Sites

Osteoporosis will affect the whole skeleton; however, the most common fractures sites are: 

  • the spine – vertebral fractures are the most common osteoporotic fracture site, with approximately 20-25% of women over the age of 50 having one or more vertebral fractures (Cooper, 1992). 
  • the hip – 1 in 3 women and 1 in 9 men over the age of 80 will have a hip fracture (a break at the head of the femur) as a result of osteoporosis.
      
  • the wrist – this is a common fracture because the automatic reaction when 

falling is to stick your arm out, in order to cushion the fall.

Classification

In seven major countries (France, Germany, Italy, US, UK, Spain and Japan) less than half of women with osteoporosis are diagnosed (IOF, 2004). It is difficult to diagnose because there are few signs that bones are becoming thinner.  Often the first indication that there may be a problem is when a person suffers a fracture. Only a third of people with spinal fractures caused by osteoporosis come to medical attention (Cooper, 1993).

The most common diagnostic tool is a bone mineral density (BMD) test. This is a scan which, depending on the technology, measures bone density in the hip, spine, wrist, heel or hand. DEXA (Dual Energy X-Ray Absorptiometry) – is a special low radiation X-ray capable of detecting quite low percentages of bone loss. DXA scans are the most commonly used method of BMD measurement. They are used to measure spine and hip bone densities.

Normal< 1 standard deviation (SD) below mean
Osteopenia1 – 2.5 SD below mean
Osteoporosis> 2.5 SD below mean
Severe Osteoporosis> 2.5 SD below mean, + 1 or more fragility fractures

Other Symptoms

As the disease progresses and vertebrae begin to collapse, osteoporosis sufferers often lose height, 10-15 cm is not unusual (IOF, 2004). They also develop a “Dowager’s Hump”, the characteristic curvature of the spine that can be seen in so many men, and women of post-menopausal age. 

Exercise Recommendations

There are several strategies for the prevention of osteoporosis:

  • prevention and enhancement of the material and structural properties of bone
  • prevention of falls through balance training
  • overall improvement of lean tissue

Once a woman suffers a first vertebral fracture, there is a five-fold increase in the risk of developing a new fracture within one year (IOF, 2004). Prevention of the first fracture should play a critical part in exercise recommendations.

Regular weight-bearing exercise has been shown to help maintain and build up bone mass. The stronger muscles, better balance and agility to which exercise contributes can also help in fall prevention. The type of exercise should be tailored to the individual’s needs and abilities. People with osteoporosis must take special care when exercising to reduce the risk of fracture due to impact or falls.

Active lifestyles are associated with lower rates of osteoporotic fracture (Bassey, 1994). This is directly attributable to the fact that functional loading through physical activity exerts a positive influence on bone mass in humans (ACSM, 1995). Any long term effect on conservation of bone mass will require at least 9-12 months of effort before change, or lack of change, can be ascertained (Bloomfield, 1997)

Aerobic Exercise Recommendations
Frequency3-5 x/week
Intensity40-70% VO2max RPE 11- 14
Time20-30 minutes per session
Type          aerobic physical activity, weight-bearing

Any mode of aerobic exercise is possible as long as forward flexion is minimised. As swimming and cycling are non-weight-bearing, neither has been shown to be effective in increasing bone mineral density. 

Resistance Training Exercise Recommendations
Frequency2-3 x/week
Intensity2-3 sets of 8-10 repetitions
Time20-40 minutes total, 8-10 exercises
Type          all major muscle groups, especially joints prone to fracture

The goals of resistance training for osteoporotics are:

  • to increase weight-bearing exercises to maintain bone strength
  • to improve balance, co-ordination and flexibility
  • to strengthen muscles, particularly around the high risk fracture sites i.e. wrist, hip and spine (note: strength helps to conserve bone mass and improve dynamic balance [Bloomfield, 1997])
  • to improve posture 

Many clients with vertebral fractures will have weak back extensor muscles, and thus should be prescribed lightweights and be progressed slowly (Bloomfield, 1997).

Flexibility Recommendations
Frequencyminimum of 2-3 x/week
Intensityto a position of mild discomfort
Time10-15 seconds per hold for maintenance10-15 seconds repeated with 6-8 second contractions for development3-4 repetitions for each stretch
Type          all major muscle groups used in the sessions

 

Special exercise precautions:

  • flexion and extension of the spine while vertical may cause compression fractures
  • overtraining in females will exacerbate problems. Women athletes may suffer disruption of their menstrual cycle and thereby become hypoestrogenic. This puts them at increased risk of fracture through loss of bone density despite continuing activity  
  • assure a safe environment, with few obstacles, to reduce the risk of falling

Additional Lifestyle Recommendations

  • oestrogen deficiency is the main cause of osteoporosis; therefore, hormone replacement therapy (HRT) is the most commonly prescribed of all medications.  This medication involves the replacement of oestrogen in the form of a supplement. This helps to maintain this vital hormone which supports bone remodelling and mass. There are some concerns about HRT treatment as the body is naturally trying to close down its reproductive functions and lower its oestrogen levels, whilst the medication keeps them falsely elevated. There are some links with increased risk of breast cancer and endometrial cancer
  • side effects of HRT can include bloating, fluid retention, breast fullness and tenderness, and irregular post-menopausal bleeding (Katz and Sherman, 1998)
  • due to the above cancer risks and side effects the choice of other medications include alendronate and calcitonin which work by inhibiting osteoclast activity, rather than focusing on oestrogen
  • nutrition is also another needed lifestyle change with a particular focus on adequate protein for enzyme, hormonal and bone building activity. Certain minerals are vitally important in the laying down of new bone, namely calcium, phosphorus, and magnesium. Vitamin D is also essential in the formation of bone.

References

American College of Sports Medicine (1995).  ACSM stand on osteoporosis and exercise. Medical Science Sports Exercise. 27, I – vii.

Arthritis Research Campaign (2004). Osteoporosis. http://www.arc.org.uk. 

Bassey, E. J. and Ramsdale, S. J. (1994). Increases in femoral bone density in young women following high impact activity.  Osteoporosis International. 4, 72-75. 

Bloomfield, S. A. (1997). Osteoporosis. In ACSM’s Exercise Management for Persons with Chronic Diseases and Disabilities (J. L. Durstine, ed.). pp. 161-166. Human Kinetics.

Compston, J. E. and Rosen, C. J. (1999). Fast Facts – Osteoporosis.  Health Press.

Cooper, C. (1992). Incidence of clinically diagnosed vertebral fractures: a population-based study in Rochester, Minnesota, 1985-1989. J Bone Miner Res, 7:221-7.

Cooper, C. (1993). Epidemiology and public health impact of osteoporosis. In Baillière’s clinical rheumatology: osteoporosis (D.M. Reid, ed.). pp. 459-477. Baillière Tindall. 

Dalgleish, J. and Dollery, S. (2001). The Health and Fitness Handbook.  Longman.

Dolan, P. (1998). The Cost of Treating Osteoporosis Fractures in the United Kingdom Female Population. Osteoporosis International, 8: 611-617.

International Osteoporosis Federation (2004). Osteoporosis. http://www.osteofound.org.

Melton, L.J. (1992). Perspective: How many women have osteoporosis? J Bone Miner Res, 7:1005-10.

National Osteoporosis Society Online (2003). Osteoporosis. http://www.nos.org.uk

O’Neill, T.W. (2000). Incidence of Colles’ Fracture in the UK. Seventh Bath Conference on Osteoporosis.

Reeve, J. (2002). Incidence of Vertebral Fracture in Europe: Results from the European Prospective Osteoporosis Study. Journal of Bone Mineral Research, Vol 17, No 4.

Torgerson, D. (2001). The Effective Management of Osteoporosis. In UK Key Advances in Clinical Practice (Barlow, D., Francis, R. and A. Miles, eds). Aesculapiuf Medical Press.

Erickson, S M, Sevier, T L, (1997). Osteoporosis in Active Women: Prevention, Diagnosis, and Treatment. The Physician and Sports Medicine.Katz, W A, and Sherman, C, (1988). Osteoporosis. The Physician and Sports Medicine.

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