osteoarthritis

You may be at the peak of your sporting powers right now, having conditioned your body to be the ultimate machine for your sport, but what will happen to that machine as the miles clock up? Will that highly conditioned physique break down later in life because of too much sport-induced wear and tear? And is there anything that you can do now to prevent potential decline in physical function caused by your sports participation?

A great deal of research has been carried out into the effect of sport participation on the incidence of osteoarthritis and long-term muscle damage in later life. There is also a growing body of research considering the impact of cardiovascular (endurance) training on heart health. These and other sporting ‘legacies’ are the focus of this article.

Let’s take osteoarthritis first: this is a degenerative condition of the joints, which can become swollen and painfully inflamed. The ‘itis’ bit implies pain, without which the condition is known as osteoarthrosis.

The condition affects the joint cartilage – a smooth substance covering bone endings that allows bones to glide over each other with minimal friction and also cushions force as it is transmitted through the joints. In fact, cartilage serves a very similar function to the oil in your car engine, the big difference being that it cannot be topped up when lost.

Degeneration of cartilage occurs as a result of ageing and – more relevant to this article – injury and overuse. The condition is diagnosed by Xray, where cartilage appears as a black space between bones and the joint space is significantly narrowed.

Osteoarthritis is very difficult to treat, and management therefore focuses on relieving pain and preventing deformation of the affected joint. In extreme cases there is no option but to fuse a joint together.

There has been considerable research into the link between contact sports, like football and rugby, and osteoarthritis around the knee, hip and ankle during and after playing careers. For example, Turner and associates investigated the long-term impact of football on the ‘health related quality of life’ of former professional footballers in the UK with a survey of 284 former players⁽¹⁾.

Respondents were asked to report on medical treatments, osteoarthritis diagnosis, other morbidity, disability status, and work-related disability since ending their football careers. The researchers found that medical treatment for football-related injuries was a common feature, as was osteoarthritis, particularly of the knee. And players consistently reported a reduced health related quality of life when suffering from this condition.

This exploratory study suggests that playing professional football can impact on the health of footballers in later life and that osteoarthritis is a key problem. Further research by Drawer et al came up with very similar findings with a study of English professional footballers⁽²⁾.

Demands of the game

The development of knee osteoarthritis in footballers obviously reflects the demands of the game; with constant twisting and turning, the heavy volume of playing and training and the ever-present risk of contact injuries, it is no wonder that knees becomes vulnerable to osteoarthritis.

Moving onto a more brutal sport, Meir and his team looked at the incidence of later life health problems, including ostoarthritis, in retired Australian rugby league players who had suffered injuries during their playing careers⁽³⁾. Twenty eight players who had competed in the professional Australian Rugby League competition responded to a survey in which they were asked to recall all injuries that had stopped them playing for five or more consecutive games.

The researchers found a strong link between incidence of injury and a variety of detrimental effects persisting into retirement, including job limitations, reduced earning potential and increased personal medical costs. Their preliminary investigation suggests that retired professional rugby league players may suffer at least one long-term consequence of injuries sustained during their playing career.

Osteoarthritis of the knee poses a significant risk to serious football and rugby players. However, there are a number of ways to reduce this risk, although the first, in particular, depends more on luck than judgement:

• Injury avoidance. Moretz focused on American football in a study of the incidence of knee osteoarthritis in 23 Grid-Iron participants, 20 years after high school competition, compared with eleven age-matched controls⁽⁴⁾. The good news was that no statistically significant increase in osteoarthritis was found in the players who had not sustained an injury, although there was a significantly increased incidence in those who had sustained a knee injury;
• Choice of sport. Clearly, players of non-contact sport would seem to be less vulnerable to potentially debilitating conditions in later life. However, it could still be argued that, given the intensity of current training and competition requirements, athletes from all major sports risk putting their future joint health on the line. Schmidt and associates, considered the incidence of arthritic conditions in former elite javelin throwers and high jumpers – both exposed to considerable strain on the knees and hips - 10 years after ceasing competition⁽⁵⁾.

Javelin throwers and high jumpers

The team found that the hips of 22 of 33 (67%) javelin throwers showed signs of osteoarthritic deterioration, compared with only 7 of 38 (18%) controls, while 15 of 44 (34%) high jumpers suffered from the same deterioration, compared with 6 of 44 (14%) controls. However, the researchers found that the decline in hip health of the retired athletes had no direct effect on daily living. As far as runners are concerned, research indicates that those who maintain reasonable mileages (around 60 miles per week) are not likely to suffer from osteoarthritis, although elite distance runners may be at risk;

• Improved conditioning methods. It is beyond the scope of this article to go into great detail about methods that can be used to enhance joint stability and potentially reduce the incidence of degenerative conditions like osteoarthritis. Suffice it to say that modern coaching theory is all about shoring up a competitor’s body to make it as sport-efficient as possible, as well as getting maximum playing ability from it. The modern approach of ‘pre-conditioning’ for training was described in last month’s issue (PP 206, December 2004);
• Supplementation. Again, it is not possible to go into great detail on this subject, but there is a growing body of research indicating that glucosamine sulphate and chondroitin sulphate can improve joint health and reduce further deterioration and the symptoms of osteoarthritis.

One clinical study, although not specifically concerned with sports’ participants, makes for very positive reading. Reginster and team looked at the long-term effects of glucosamine sulphate supplementation on knee osteoarthritis over three years in a study of 212 patients with a mean age of 66⁽⁶⁾. Half the participants took 1,500mg of oral glucosamine sulphate daily and the other half a placebo. X-rays were used to measure joint space and pain, while the researchers also assessed joint function, stiffness and use of painkillers. They found that, while those on the active supplements suffered no further narrowing of the knee joint cartilage, those on placebo experienced a further narrowing of 0.5mm. The glucosamine group also benefited from a significant reduction in pain and improved joint function.

Glucosamine is used in the manufacture of very large molecules found in joint cartilage, called proteoglycans. These molecules are able to hold onto water rather like a sponge, so providing cushioning for joints. (For a more detailed consideration of the benefits of glucosamine sulphate and chondroitin sulphate, see PP 192, January 2004).

Soft tissue injury is an almost inevitable consequence of regular, serious training and competition, but will this damage to ligaments, tendons and muscles create long-lasting problems in later life? There is some research that suggests long-term sports training can have lasting negative effects.

In terms of muscle damage, by far the greatest causal factor is eccentric muscular contractions. These occur when a muscle is put on stretch when it contracts, a good example being the action of the quadriceps during downhill running. In terms of distance running, it is argued that there is a limit to the number of years a runner can ‘put the miles in’ before his or her muscles (and, to a lesser extent, tendons) are irreparably damaged, primarily by eccentric action. The suggested limit is 20 years, irrespective of when a running career starts.

Debilitating effects in runners

The prime debilitating effect is manifested as a loss of springiness in the running stride. Running physiologist Tim Noakes believes that the ability of endurance muscles to continuously contract and spring back is significantly compromised by prolonged exposure to runs of over 21k⁽⁷⁾. These distances require longer recoveries, which runners often do not take, and they almost inevitably lead to muscle soreness, irrespective of age.

Noakes therefore advocates that runners in search of a sustained quality running career, which minimises future eccentric muscular damage, should at a very early stage in their careers decide on their running distances, take ‘optimum’ recoveries and carefully plan their races.

To avoid damage from overtraining, he recommends that if you start a run with sore legs and they do not ‘loosen up’ after a few miles, you should stop and take a few days off training. If, when you run again, your legs are still not recovered, you should take further rest. If your legs are permanently sore, you are probably in an overtrained state, from which it may take months to recover fully. (Sleeping difficulties, increased resting heart rate and mood swings can also be signs of overtraining.)

Eight good races

The number of marathons and ultra-distance races performed by an athlete can also have a significant impact on muscle health. It is said that the number of ‘good’ races a marathon athlete has in him or her, irrespective of ability and age, is eight. Over-competing at these distances can accelerate muscular damage.

Mention was made earlier of other soft tissue problems caused by long-term sports involvement. One of the main areas to suffer in runners (of all distances) and participants in many other sports is the achilles tendon, which connects the calf muscle to the ankle.

Achilles problems are rife in runners over 40, often cutting short training and even ending careers. Rather like the muscles damaged by repeated eccentric contractions, these tendons also seem to have a limited optimum life span (See PP Special Report on Achilles Tendinitis). Although not normally a serious threat to future life mobility, damaged achilles tendons can affect future fitness and sports participation.

As with osteoarthritis, it seems highly likely that soft tissue damage will result from long-term sports involvement, but if athletes train sensibly and adhere to the advice given above (and elsewhere in PP) such problems can be minimised.

What of that most vital organ in the body, the heart? Will long-term cardiovascular training lead to heart problems in later life? There is mounting evidence that intense CV exercise can damage the heart, but before considering this in detail, it must be emphasised that the benefits of long-term CV exercise far outweigh the relatively minor risks, as outlined below.

The main potential risk is of damage to the left ventricle (the chamber of the heart that pumps oxygenated blood around the body) resulting from participation in ultra-endurance events. Konig and his team investigated this risk in a study of 11 highly trained male professional road cyclists, putting in around 34,000k per year⁽⁸⁾. The team assessed the cyclists after one stage of a five-day professional cycling race, with a careful cardiac examination, including echocardiography and stress ECG.

They found nothing to worry about and concluded that strenuous endurance exercise in professional road cyclists does not result in structural myocardial damage.

Noakes found a seemingly more worrying scenario when he discovered left ventricular damage in ultra-distance runners (specifically participants in the Comrades Marathon⁽⁹⁾. However, he found that the damage healed itself rapidly during recovery, without lasting structural damage. Research by George et al drew similar conclusions after studying Ironman and Half- Ironman triathlon participants ⁽¹⁰⁾.

Other heart conditions

What of other heart conditions? Heavy and prolonged endurance training builds the heart into a great machine capable of pumping huge amounts of blood around the body with greatly reduced effort. Could this growth (hypertrophy) of the heart create potential problems?

Missault et al compared cardiac anatomy and function in 26 professional road cyclists with those of 21 matched controls⁽¹¹⁾. They found that heart hypertrophy in the cyclists led to an increase in the internal dimension of the left ventricle and an even larger increase in the thickness of the ventricular walls. However, diastolic filling (when the heart fills up with blood between beats) was similar in the athletes and controls, and the researchers concluded that professional road cycling could be regarded as safe from the cardiac point of view.

A number of studies have looked at the hearts of endurance-trained athletes after their serious competitive training days have ceased. Pelliccia and colleagues focused specifically on left ventricular enlargement in elite endurance athletes, studying them first in their twenties and then 1-13 years later⁽¹¹⁾. The researchers found that left ventricular dimensions did not completely return to pre-training levels, with reduction or cessation of exercise. And they concluded that: ‘left ventricular atrophy… may have future long-term clinical implications in some individuals (and that this) cannot be excluded with certainty’.

The ‘this’ being referred to is the (admittedly unlikely) possibility of an athlete with a heart enlarged by long-term endurance activity being misdiagnosed as suffering from a genetic condition known as hypertrophic cardiomyopathy, that can cause sudden death.

So it appears that a commitment to serious endurance training in youth should not cause heart problems in later life. And indeed all ‘retired’ athletes, whether endurace or powerbased, should seriously consider continuing CV exercise at a moderate level for the rest of their lives, since its contribution to reducing deaths from coronary heart disease – and the incidence of numerous other diseases – is indisputable.

The oft-quoted study of Harvard Alumni drew the following key conclusions about the value of CV exercise⁽¹²⁾:

• Expending 8,400kJ (approx 2000 calories) during ‘active leisure time’ through ‘vigorous’ activity reduced the risk of developing all forms of CHD by 20%;
• The same level of effort reduced the risk of a first heart attack by 39%;
• This effort could increase life expectancy by 2.5 years in those exercising regularly after age 35 and by 1.5 years in those taking up exercise after age 50.

This should make very palatable reading for former athletes, as you can see that you do not have to take up a masters’ sport and train seriously to derive the health benefits of life-long exercise. Four 40-minute moderately paced rowing sessions or 60-minute fast walking sessions per week would suffice.

Moving on to a less obvious potential negative consequence of sports involvement, research indicates that endurance athletes have a higher risk of suffering from kidney stones than their non-exercising peers. It’s argued that repeated bouts of dehydration, as may occur during endurance exercise, can create the right conditions in the kidney for the development of stones. The best way to prevent this is obviously by remaining optimally hydrated before, during and after training or competition.

Risk of kidney stones

Kidney stones are created when certain substances in urine – including calcium and uric acid – crystallize and form a ‘stone’. These tend to form in the centre of the kidney, where urine collects before flowing into the ureter, the tube that leads to the bladder. Small stones are able to pass out of the body in the urine and often go completely unnoticed. It is the larger stones that pose problems, as they irritate and stretch the ureter as they move towards the bladder, causing great pain and blocking the flow of urine.

The overall message, then, is that creating a highly-tuned sporting body in youth can have a negative impact on health in later life. Much will depend, though, on the particular sport played, the frequency of injury, the effectiveness of conditioning and the adequacy of recovery.

John Shepherd

References

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