I'm not an "extreme endurance athlete" but just so people don't hate on this based on one study here is something to look at which addresses in much more detail and with much more studies. I know two older fellas who used to do triatholons and I'm not so sure both couldn't kick my ass.
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.