After reading abut Lucy, fast forward from about 2 million years ago when our ancestors first started running, to around 3,000 years ago. It is the story of one of the most amazing feats that humans could perform with a greatly enlarged brain and a body made for endurance exercise, the colonization of the South Pacific including its most remote islands.
Human beings had long left East Africa and populated the entire world with few spots still left untouched by human feet. Taking off from what is today Taiwan around 3,000 BC, they used catamaran-like canoes to first reach the Philippines, then the Melanesian Islands to finally reach one of the most remote places on earth, Easter Island (or Rapa Nui as it is know in the local language) at around 900 AD.
Easter Island (famous for its impressive statues and the rapid decline of their civilization described in Jared Diamond’s popular book Collapse) is so remote that the nearest town with a population over 500 is on the Island of Mangareva 2,600km away, the place from which the original colonizers most likely have taken off.
This task, sailing without any modern navigation tools on small, human powered vessels across 2,600km on the open sea was so heroic that many people in modern days still doubted that it was possible at all.
All doubts were erased once a group from the Polynesian Voyaging Society (a group of enthusiasts who want to keep the art and science of traditional Polynesian voyaging and the spirit of exploration based out of Hawaii founded in the 1970s) successfully repeated the task using original equipment (double-hulled voyaging canoe) and navigation techniques (basically navigating without instruments following the sun and stars and observing ocean-swells) and completed the journey in 19 days in 1999.
This remote place, Rapa Nui, also is the origin of a story that helps our understanding of a healthy life in general and exercise in particular and has even been likened to the discovery of the mysterious fountain of youth. It is the story of a most essential biological mechanism of cell growth and proliferation which we will come back to in the following installments of this series of articles.
If aging is the loss of dynamic homeostatic capacity (i.e., your reduced ability to deal with changes in the environment) can you attach a number to it to know where you stand?
Fortunately, you can and it is called heart rate variability or HRV. Heart rate variability has two great advantages (1) it is a highly integrated and meaningful measure and (2) it is super-easy to measure (at least today).
Before going into why it is meaningful and how to measure it, here is a very brief introduction into what it measures.
What is heart rate variability?
Heart rate variability is a measure of the variation in time between your heartbeats. Your heart is not a drum machine and does not keep a constant timing. Indeed, more differences between heartbeats (i.e., a higher HRV) are in general beneficial and a measure of good health. There are many ways of expressing your HRV but the most common is a statistical measure called the rMSSD (root mean square of the successive differences) which you will most often find displayed on consumer applications. When explaining what it actually measures you most often hear that it reflects the balance between your sympathetic nervous system (speeding up) and your parasympathetic nervous system (slowing down). While its sound attractively ying-yangy and is kind of true, I advise to either (1) ignore trying to understand it physiologically and instead focus on what it means below or (2) actually go a bit deeper and discover that it actually is a bit more complicated and of a higher order of integration that goes beyond heartbeats alone.
Why is HRV meaningful?
Clinically, HRV scores are used in cardiology and other medical disciplines as a risk stratification tool. Poor HRV score is an early predictor of poor outcome in coronary artery disease, cardiomyopathy, arterial hypertension, sudden death, chronic obstructive pulmonary disease, renal failure, heart failure, diabetes, stroke, Alzheimer’s disease, leukemia, obstructive sleep apnea, epilepsy, headache and others. This is consistent with the view that HRV measures how well you deal with disruptions and your ability to return to homeostasis.
Equally important, HRV scores decline with age also consistent with our definition of aging as reduced dynamic, homeostatic capacity.
Also, HRV scores have been used as proxies for positive training adaptations and most prominently as tools for load and recovery management. Simply spoken, you are ready to hit it hard again once your HRV has returned to your base level and better athletes recover faster.
So how do you measure HRV?
It is as simple as downloading an application on your phone and holding your finger on top of the camera for a short period of time (some apps are free, some are not).
What you will discover when starting to measure HRV is that it varies quite a bit an so it should. Therefore, it is important to establish a baseline by measuring under similar conditions (e.g., sitting or lying down) at the same time of the day (e.g., right after getting up and before reading your email) as both stress and circadian rhythm affect HRV scores.
How do you improve your HRV score?
And now the fun starts as you can experiment with all the things effecting both your base score as well as your HRV recovery after exercise. If you have been reading any of the other articles in this series, you will not be surprised that you should optimize successful aging (which will then improve HRV) and we already know how to do this in general: exercise, keeping insulin low (fasting/reducing carbohydrates/increasing muscle mass) and sleeping properly/reducing chronic stress. Please remember to only compare yourself to yourself over time and not to others. You do not win a prize for having the highest HRV in the universe but for keeping or even better improving yours over time.
So let’s play with individual interventions (here are some that I have tested):
How honest am I with my easy sessions? Are they really easy enough so that I recover my HRV base within 30-60 minutes?
How come walking is so effective in improving base HRV even if it is below even Zone 1 levels of exertion?
How honest am I about acute and chronic stressors such as alcohol – does dry January help in improving base HRV?
Surprise again (not): when they analyzed the genes down-regulated in space that are likely to be responsible for the anti-aging effect, they found the insulin equivalent in worms as well as others involved in dietary-restriction signalling.
There are basically three views on aging relevant to an athlete thinking about mitigating its deleterious effects:
The Statistical View
The Cell & Molecular Biology View
The Systems View
Ghirlandaio, Domenico – An Old Man and His Grandson
The Statistical View
The statistical view on aging is based on a definition that – simple as it sounds – actually helps in making sense of many of the things we experience everyday. In its essence, aging is viewed as an increasing probability of dying with time passing. That’s trivial you might shout but then again it is not well understood by the general public. Most of us in January 2021 are still subject to some form of Coronavirus-related lock downs and you will have heard the rationale for it over and over again. COVID-19 is particularly dangerous to the old whom we must protect as the fatality rate increases exponentially with age. Well, indeed it does as does the fatality rate of everything else that you can possibly die off from other respiratory viruses such an influenza to all of the diseases of civilization 2.0 from diabetes to cancer. If your overall risk of dying increases exponentially so should the reasons for dying (at least on average).
Of course this definition does not help us in understanding why this curious statistical pattern should be true.
The Biological View
And in comes biology. Current biological thinking on aging is best summarized with two seemingly contradictory points that you have to contemporaneously hold in your head
Aging is an expression of a pretty complicated interplay of many components
It is pretty simple (at least in animal models) to find single interventions to make you live longer
The Hallmarks of Aging
Let’s start with the complicated: inspired from ideas in cancer biology, Guido Kroemer and colleagues have published a very influential review in 2013 that defines the biological hallmarks of aging of which there are nine in total:
The first type are those are called primary hallmarks and are thought to be the underlying causes of something going wrong. These are (1) genomic instability (i.e., your DNA getting damaged by the environment but also by the byproducts of your own metabolism), (2) telomere attrition (i.e., the protective ends of your chromosome getting shorter with every cell division), (3) epigenetic alterations (i.e., damage to all the stuff that makes sure your DNA can properly replicate) and (4) loss of proteostasis (i.e. the inability to keep your proteins that do the work properly folded)
As a result of the first type, the organism reacts with a second type called antagonistic hallmarks which first try to defeat the damage. The first and very important one is (5) altered nutrient sensing. In its very simplest form, the cell has a nutrient sensing system that is very similar for all animals and even yeast across evolution. It sees if there is enough food out there. If there is, it can afford to divide and grow and if there is not it rather protects what it has and waits for better times but both need to cycle and be in balance. The same is true for (6) altered mitochondrial function. Mitochondria produce reactive oxygen species as a result of stress which are a signal to up the cell’s defense but again too much is bad as it overwhelms the defense capabilities. And last but not least you have (7) cellular senescence or programmed cell death. If cells go bad and are beyond repair, they are made to die but too many dying cells of course are a problem all by itself.
The third category finally are called integrative hallmarks because they lead to what you see (the phenotype) as a result of all that happened previously. They are (8) stem cell exhaustion and (9) altered cellular communication. Stem cell loss leads to trivial results such as hair loss but also more serious results such as reduced repair of muscle and bone while altered cellular communication is most prominently on display in the gradual loss of the competence of the immune system to accurately detect and destroy foreign invaders.
The Interventions – How to live longer
You might agree with me that that was rather complicated and often a bit hand-wavy especially when it comes to the „proper balance“ of the mechanisms of defense or antagonistic hallmarks. Why then do we think it is simple overall? Well, it is quite easy to make animals live longer – and while experiments in humans are a bit more ethically challenging, observational results point in the same direction as the results from animal studies.
Give them anti-aging drugs that primarily affect the nutrient-sensing pathways (metformin and rapamycin)
Restrict their calorie intake (fasting for humans)
Mutate single genes that are (mostly) involved in the same pathways of nutrient sensing – easier for worms that humans
Make them exercise – easier for humans than worms
In my view, exercise is special as it speaks directly to maintaining the cycling and balance between competing systems that only appear to be antagonistic but really are synergistic in nature. Yes, a long run activates many of the same pathways that signal nutrient scarcity but then again, a strength-session activates the competing and insulin-dependent growth pathway for hypertrophy and many sessions will do both at the same time (if in different places).
The Systems View
So how do we have to think about what aging actually does from a system performance point of view.
Humans are complex systems. Complex systems are characterized by many individual components that are connected with each other and give rise to patterns to which they themselves react. An example is cars and traffic. Cars generate traffic but also react to it individually.
Humans are a complex system that maintains homeostasis or a relatively stable internal state (e.g., body temperature) despite changes in the environment (e.g., the weather). Aging can then be defined as a decrease in the dynamic capacity to return the body to its homeostatic state. If you are a masters athlete reading this, you can probably remember your younger self and how much easier it was back then to get away with a lack of sleep or a likely much junkier diet that you adhere to today. Equally, one of the differences between training masters athletes and younger athletes is that masters need a lot more recovery time (or time to return to homeostasis).
There are two important implications to this view of aging:
First, you need to keep challenging the system to keep its own defense mechanisms up. In my view, this is why it is so important to include strength training and high intensity units (with adequate recovery) into your routine. The system is only as good as the ability to deal with external challenges to homeostasis so challenge it. Almost any acute challenge is good the same way that all danger comes from chronic exposure to disruptions of homeostasis (stress, inflammation, lack of exercise, nutrient abundance, …)
Secondly, a complex system can break down at a thousand points and often in surprising ways which are caused by small changes to initial conditions. Here is a example from 2006 and the electrical power grid:
„Germany’s biggest power supplier said on Nov. 15 that human error was to blame for the electricity cut that plunged parts of Western Europe into darkness on November 4. E.ON said the switching-off of an electricity line over the Ems River in western Germany to allow a cruise ship to pass through, coupled with the outage of a second transmission line, „set off the domino effect which led to the temporary disconnection of the European inter-connected power grid.“
Industry News, Nov 15, 2006
If you know your weak spots, do not ignore them but pay particular attention to safeguarding the function of the entire system. If we are honest, we can probably identify some of our potential break-points simply by looking at family history.
In one of my next posts, I will discuss how to read-out the state of your system (other than getting to know and listening to your body) and its dynamic homeostatic capacity.
Moderner Fünfkampf - mehr als ein Sport 