Intended for healthcare professionals

longer version

Preventing osteoporosis, falls and fractures among elderly people

Author's reply

Editor—Due to the space limitations of editorials many important aspects of the theme remain without detailed discussion, and this concerns my editorial too. Therefore I am most delighted that the readers want to discuss further this important topic.

Feder et al emphasise that exercise programmes for unselected older people do not prevent falls while those for selected older groups do. I do not know of any comparative study indicating which specific groups of older adults will (and which will not) benefit from a well conducted exercise programme in terms of the prevention of falls, but those randomised controlled trials which have shown an effect have included clearly different age groups, with mean ages of 65 years,(1.1) 77 years,(1.2) and 84 years.(1.3) Thus, at least within reasonable limits, a person's age does not seem to be a strong predictor of success or failure of the programme and I personally believe that the content and quality of the programme and the motivation of the exercise leaders and supervisors are crucial in obtaining good results.

Feder et al point out further that multifaceted intervention programmes are effective in reducing the incidence of falls of older adults. I agree. The strongest evidence for this has come from the studies of Tinetti et al(1.4) and Close et al,(1.5) and in this context it is of interest that in the former study a balance and strengthening exercise programme was an important part of the intervention. Unfortunately, neither of these studies was able to separate the specific fall-reducing effect of each of the modified individual factors, although such analyses are of importance when, for example, the cost effectiveness of the entire programme is studied. Thus these multifactorial interventions in no way excluded regular exercise as one possibility to reduce the risk of falling of an older adult, and within this category it is important to determine the exercise programme that is most effective in preventing falls.

Seeman is worried about the level of evidence concerning the ability of regular exercise to prevent osteoporosis and related fractures. As in the prevention and treatment of any medical condition, the level of evidence varies considerably from method to method and condition to condition, and actually few actions in our modern medical world have been verified by a number of randomised high-quality trials. This does not mean that we should stop trying to obtain better evidence but that at a certain point we have to summarise the current evidence and be brave enough to give current recommendations. And in some conditions such as smoking and lung cancer—or lifelong physical activity and osteoporotic fracture—the Cadillac of the epidemiological studies (the randomised controlled trial) will probably never show up, but still it is important to collect together the evidence otherwise available and act according to its guidelines. We have to remember that absence of final evidence does not mean absence of effect of the studied action.

Keeping in mind this philosophy, it is easy to agree with Seeman that no randomised trial has proved that regular exercise reduces the risk of fracture. Such a trial would need so large a number of subjects and such a long follow up that it is likely that the trial will never be conducted successfully. However, this does not mean that regular exercise is ineffective in preventing fractures related to age.

Concerning the effect of physical activity on areal bone mineral density (BMD), a large number of well controlled cross sectional and longitudinal studies indicate that exercise during growing years is clearly more beneficial than that in adulthood. What is now needed is long term follow up of those who once obtained clear bone gain by exercise in childhood and adolescence. Such follow ups are going on—for example, in our institute. In this context it is also of interest that the relatively small areal BMD increments obtained by exercise in adulthood (1-3%) may have seriously underestimated the true effect of mechanical loading on bone strength, the final parameter of interest. Recent experimental(1.6) and clinical(1.7) interventions give good evidence that mechanical loading can improve bone strength (by reshaping the bone structure) without changing the areal BMD of the same. If these first results can be repeated in later interventions our current, somewhat pessimistic, attitudes on the possibilities of regular exercise to improve an adult person's bone strength must be re-evaluated.

The final answer to whether lifelong physical activity will decrease (or increase) the risk of falls and fractures will probably never be available, but so far the evidence summarised in my editorial speaks strongly for a recommendation that regular physical activity should become an essential part of strategies aiming at controlling the alarming increase in osteoporotic fractures of our older adults.

Pekka Kannus

Chief physician and head

Accident and Trauma Research Centre, UKK Institute, PO Box 30, FIN-33501 Tampere, Finland

Klpeka@uta.fi

  1. McMurdo MET, Mole PA, Paterson CR. Controlled trial of weight bearing exercise in older women in relation to bone density and falls. BMJ 1997;314:569.
  2. Wolf SL, Barnhart HX, Kutner NG, McNeely E, Coogler C, Xu T. Reducing frailty and falls in older persons: an investigation of Tai Chi and computerized balance training. J Am Geriatr Soc 1996;44:489-97.
  3. Campbell AJ, Robertson MC, Gardner MM, Norton RN, Tilyard MW, Buchner DM. Randomised controlled trial of a general practice programme of home based exercise to prevent falls in elderly women. BMJ 1997;315:1065-9.
  4. Tinetti ME, Baker DI, McAvay G, Claus EB, Garrett P, Gottschalk M, et al. A multifactorial intervention to reduce the risk of falling among elderly people living in the community. N Engl J Med 1994;331:821-7.
  5. Close J, Ellis M, Hooper R, Glucksman E, Jackson S, Swift C. Prevention of falls in the elderly trial (PROFET): a randomised controlled trial. Lancet 1999;353:93-7.
  6. Jörvinen TLN, Kannus P, Sievönen H, Jolma P, Heinonen A, Jõrvinen M. Randomized controlled study of effects of sudden impact loading on rat femur. J Bone Miner Res 1998;13:1475-82.
  7. Adami S, Gatti D, Braga V, Bianchini D, Rossini M. Site-specific effects of strength training on bone structure and geometry of ultradistal radius in postmenopausal women. J Bone Miner Res 1999;14:120-4.