Heart Rate training zone systems take for granted that a fairly high level of sustained aerobic effort is comfortable or consistently sustainable for most people, which of course it’s not. Most runners just take for granted that it’s normal and never consider that what they consider “easy” or “recovery” is in fact still too hard.
One of the reasons a runner’s aerobic development improves more quickly than their neuromuscular development is because running itself is very demanding. On both fronts you’re being pushed very hard. However, your aerobic and hormonal capacities bounce back much more quickly than your muscles, bones and joints.
Still, it’s incredibly stressful on your body chemistry to go that hard that often, and the fatigue can snowball too quickly for you to be able to handle a high volume of that kind of aerobic training.
In my cross training, I find I need to go pretty hard to get to Zone 1 in most heart rate training zone systems… somewhat too hard for the purposes of whatever cross training I’m doing. The level of effort require would leave me rather tired and possibly sore. This supposed recovery exercise ends up not helping me recover much at all.
It’s not that most runners are just stronger. They just spend all their lives in this perpetual fatigue, physical and adrenal. The long term effects on their health are taken for granted as aging or wear and tear, when in actuality it’s probably preventable… without compromising your fitness or development.
My most recent heart rate zones of choice were a standard 50/60/70/80/90/100 split based on the Karvonen Formula, which uses heart rate reserve. This is a function of your resting and max heart rates, and the zones are proportioned against those rates. Zone 1 for example would be 50-60% of the gap between your resting and max heart rate (your “heart rate reserve (HRR)”), zone 2 60-70% of the HRR, etc.
With a max HR of around 184 beats per minute, this sets my minimum training heart rate around 120 (depending on what my resting heart rate is at that time), with zone 1 peaking at about 130-135. This is about where most heart rate zone systems would put zone 1, and is considered a “recovery” heart rate.
On the spin bike, even at a brisk but easy effort, my heart rate is around 105-110. On the ARC Trainer I can get to 125-130, but only with a more moderate effort. On the rowing machine, a concerted effort typically gets me to about 110-120.
However, when running, I rarely can cruise at a heart rate below 130, no matter how slow and easy I run. I basically have to stop and walk/run to average a zone 1 heart rate. This is not a product of lacking fitness: Even at my peak condition and training in Chicago, it took the right combination of circumstances for me to average 125-130 at an easy effort.
All of this is to say that maybe our view of heart rate zones and “recovery zones” is a bit warped and could use an adjustment.
This is especially true in our coronavirus circumstances, where if we go to the gym (and in many cases train outside) we need to wear a mask while while exercising. We can’t huff and puff at full volume and expect max results if a mask is filtering much of the air taken in or expelled. I’ve talked before about this being a long term training benefit, but in the present it makes the effort required for aerobic training a bit too much.
Bear in mind as well that, to maintain the typical intensity for a full volume of training, you have to consume a lot of carbohydrates, which can cause a variety of inflammatory health problems if consumed in the large amounts that most endurance athletes tend to require.
One of the reasons low-carb diets tend not to work well for endurance athletes is because they train at an intensity where they need a lot of glycogen, and that can only come from and be replenished from a carbohydrate rich diet.
Could it be possible to scale back carb consumption to a more (shall I say) human level, rely more on slower fat burning, and still be able to train, perform, and develop at a high level.
I say yes, and I say the key to doing so is combining (now-)traditional 80/20 training principles with a revised approach to heart rate zones.