On compressing morbidity (or How I Learned to Stop Worrying and Live with Ageing)

Yes, I know. I am plagiarising the title of Dr. Strangelove. The point is that I find it one of the best titles of a movie ever.

In my "gerontology" post I had addressed the question of what is happening when athletes get really old (by "really" I mean 80 and beyond). I did argue there that, despite the pessimistic conclusions of some scientists, things do not start really deteriorating before 80 or so.

In this post I am going to revisit the question of the ageing athlete. It somehow complements the two recent posts of mine, "On Ageing" and "On Dying". The motivation for this is a recent article by Lazarus and Harridge on the declining performances of master athletes. Although the article is quite interesting they are off on the wrong foot by using the usual arbitrary, based on time, argument. They show the dependence of the 100 m master world records on age (for men) and conclude, rather arbitrarily, on an accelerated increase around the eighth decade. They could have moved their arrow to the left or the right by a decade and present the same argument.

I have repeatedly argued in this blog that the only reliable arguments are the ones based on the velocity. So what does the velocity dependence on age tell us? The graphic below shows that a rapid decline arrives at around 90 years of age. And, to tell the truth, I am not quite sure that this is not an effect of the population of master athletes the size of which shrinks with age.  

It could be argued that the straight-line fit I present here could have been based on a different set of points, showing a performance dip occuring at earlier or later ages. This is indeed true and this would support the argument that the reports of the performance dip are greatly exaggerated.

The gist of Lazarus and Harridge argument is summarised in the graphic below.

The authors introduce what they call the "set point" theory. It is based on the hypothesis that a given threshold of physical activity is needed in order to age optimally. 

At the set point, physical activity is sufficient and health is optimised. The decrement in physiological function that occurs through the decades is governed by the inherent ageing process. Health is maintained, but at a lower physical activity level. This intertwined relationship between health and the amount of physical activity necessary to counter inactivity applies throughout the "healthspan" and morbidity is compressed. The green shaded area reflects the spread of the set points in the general population. Below the set point the negative and unpredictable effects of inactivity on physiological systems may not be perceived in the early ages, but as age progresses the added decremental effect of the inherent ageing process on an increasingly compromised physiology will result in one or more systems showing clinical disease with extended morbidity. Individuals who engage in exercise above the set point level do also counter the effects of inactivity while they age. Master athletes represent a group that are probably exercising at maximal levels. The decrement in the performance curve as age advances is due to the inherent ageing and should not be perceived as a disease process. However, according to the authors, this over-the-set-point exercise is unlikely to lead to an increase of the lifespan. The main beneficial effect on health is the maximal reduction of morbidity. 

To put it in a nutshell, do exercise if you wish to stay healthy while ageing. And if you are competition-minded do not hesitate to train, even vigorously. The effects can only be positive.