Healthspan and Lifespan

Back to Healthspan, one of my principal obsessions. Lifespan is the total length of a person’s life but  Healthspan is the length of life spent in good health. For my money, healthspan is hugely more important than lifespan. Who wants an extra few years of life if they are spent in very poor state of health – so called “terminal morbidity”? Since “good health” is difficult to define, the definition of Healthspan is similarly difficult to pin down – but basically it is the length of time which a person lives an active and disease free life. The main determinant is the overall state of physical fitness.

“If exercise could be packed into a pill, it would be the single most widely prescribed, and beneficial, medicine in the nation” (Robert N. Butler, 1977). This straightforward statement says it all.

Lifespan

The huge improvements in public health measures and the increasing effectiveness of medical interventions have seen an enormous increase in human longevity over the past century. The average lifespan has increased by about 30 years over the past hundred years. Recently this increase has stalled and even retreated slightly. Maybe the effectiveness of medical treatment has reached it apex?

One of the undesirable effects of saving the lives of patients with heart disease, cancer, diabetes etc is increased morbidity in the elderly population as a whole. This failure of success means that the average healthspan has decreased. A recent calculation set average healthspan  at 66.1 years which is about 15 to 20% of total Lifespan. This means that nearly one fifth of our life is spent in poor health.  The resultant health care costs are enormous In the US they are estimated to be $4 trillion+ per annum.

Healthspan

Health span is not just the absence of major diseases, it means sustaining adequate physical and cognitive function to enjoy our environment and engage in those activities of daily living essential to a good quality of life. This is what public health should be all about. Sadly, however this is usually not the case. Departments of Health and the medical profession are obsessed with ever more sophisticated investigations and complex medical and surgical management of diagnosed disease.

Our politicians only seem to want to pour money into the care of an increasing elderly and increasingly unhealthy population. The idea of prevention seems not to have occurred to our lords and masters. They have not realised that the primary health goal should be extending and improving the health span of our population.

How to increase healthspan

You will not be surprised to hear me say that the cornerstone of good health is physically activity supplemented by a healthy diet (not eating more than we need!)

Maintaining a good degree of physical fitness is key to being able to live a healthy life – and that means taking adequate amounts of exercise. It is inevitable that we become less fit with advancing years and ultimately this can lead to loss of ability to lead a normal life – look after ourselves and live independently. A sedentary lifestyle accelerates the age-related decline of cardiorespiratory fitness (CRF, best measured as the maximum oxygen uptake, V̇O₂max) by as much as three decades. Inactivity also promotes a large number of diseases of later life – recently calculated to include at least 35 conditions.  The public health scientist Steven Blair regarded physical inactivity as this century’s biggest health problem and it is worsening. A good example of this is the increasing prevalence of Type 2 Diabetes (T2DM) which is predicted to affect about one third of the adult population of Western countries by the year 2050.

In keeping with the central role of exercise in extending health span, V̇O₂max is a strong and independent predictor of all-cause mortality.  A high V̇O₂max is the most important factor delaying all-cause mortality and the onset of chronic diseases, in particular cardiovascular, metabolic, and cancer. In lifelong runners/exercisers, disability is postponed by 14-16 years compared with controls. In addition, adults who exercise 3 or more times per week have a 30% lower risk of dementia.

How and why?

Next time I will discuss some of the mechanisms for all of this – and also discuss the relative importance of diet and exercise.