The Masters Athlete Series: Matters of the Heart

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?

Fun Bonus Episode

Flying into space improves your HRV and the effect is likely to be anti-aging for humans and proven to be life-extending for worms (C. elegans).

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.

The Masters Athlete Series: Walk, Don’t (Always) Run

Today, I have a radical suggestion for the average Joe Masters (if not the highly trained and young, elite athlete) — and face it, that certainly means me and probably a lot of you: every once in a while, go for a brisk walk instead of a long run.

Very careful readers of my blog already know of my high regard for taking a walking break when going on a long run and here are two good arguments:

1. Evolutionary: humans are the best endurance runners in the animal kingdom but when going for a day of persistence hunting with our buddies in the African Savannah 100,000 years ago, we very likely took a walking break every once in a while (if for no other reason than finding the animal again which was taking a break)
2. Biomechanical: endurance running is a repetitive movement that puts a lot of (eccentric) load on our muscles, bones and connective tissue. Taking away the stress even for a short period by walking for less than a minute has the power to prevent a lot of overuse and injury

But now I argue for adding entire walks rather than another run for the average masters athlete (for clarification, I am not talking about the overweight couch potato wanting to slowly ease into exercise again but about you: the active masters athlete training regularly and following a plan).

My key insight (and subsequent changes to my training regimen) came from two scientific papers:

The first insight came from a classic paper by Stephen Seiler, the great scientist and generous popularizer of polarized training. In the paper, the authors describe that if we want to accumulate those many hours to build our aerobic base, the ventilatory threshold I (below which we can carry on an easy conversation) is the break-point for autonomic nervous system disruption. Below it we are fine and recover very fast, but above we do not recover fast independently of how intense the effort above the VT1 is (which supports the key argument for avoiding Zone 2/threshold training as the cost is as high as for HIIT but the pay-off is less).

As masters athlete of course, the limiting factor to our training volume is most likely our ability to recover (not our willingness to do more).

The second key insight for me came from a review on the evolution of humans as endurance runners. In it, there is a nice chart (see below) comparing the energy cost of human running and walking.

The cross-over is at around 9 J/(kg*sec). One milliliter of oxygen yields around 20 J so this equates to around 27 ml 02/(kg*min). If you want to make sure that you train in Zone 1, you should be at around 60% of VO2max. If you train at the brisk walking pace of 27 ml 02/(kg*min) and want to be at 60% of VO2max, your VO2max should therefore not be more than 45 ml o2/(kg*min).

Are you still with me? A V02max of 45 means you run a little more than 2,500m in the 12 minute Cooper test – and I bet that many of the joggers that I see in the woods during my regular runs do not.

For me it served as a nice reminder of how psychologically hard it is to stay in Zone 1 for an entire hour while running when every other runner is an invitation to pass and every hill is one to jack up your heart rate. The litmus test is going home and seeing if your heart rate variability (HRV) score returns to normal within 30 min after your work-out. If you go for a walk instead, you are safe as it is virtually impossible to leave Zone 1 unless you are going steep uphill.

What happened to me as I started to incorporate brisk walks into my training routine?

First, I did not stop running but just added walks on my resistance training and off-days and never felt tired as a result.

Even better, I incorporated a lot more hours in Zone 1 without any overuse injury risk and should not have been (but still was positively) surprised that my base HRV score improved as well. Why not give it a try yourself?

Bonus for Sports History Buffs

… the Finnish runners began their walking training in January or February, depending on the distances they raced. […] The distances walked also depended on the distances the runners would race; marathon runners walked longer distances (15 to 35 km) than did the 1,500m runners (8 to 15 km) and the 5,000- to 10,000 m runners (10 to 20 km). Each group would walk these distances two to four times per week until the end of March.

The Finnish Training Methods of Kohlemainen and Nurmi (page 376, Noakes, Timothy. Lore of running. Human Kinetics, 2003.)