The social media climate makes training sound far more complicated than it needs to be.
One of the biggest problems in endurance sport right now is that there is so much training data available, and everyone wants to sound like they’ve discovered a groundbreaking new protocol or hidden training secret.
Training zones are one of the hottest topics online at the moment, and I think athletes need a bit of clarity.
A lot of pro athletes are now promoting “Zone 1 training.” When I used to train very high volume, a fair amount of our training was also done in Zone 1. But context matters.
When training volume gets very high, intensity has to stay low enough that the athlete remains fresh for key sessions. The purpose of some of that training is not necessarily to maximize aerobic adaptation from that individual session — it’s to accumulate volume, improve durability, and keep the body functioning well enough to continue training at a high level.
Most amateur athletes train less than half the volume of elite athletes. Many are also newer to endurance sports and simply don’t yet have the aerobic base where lower zones are especially relevant. For some beginners, even easy jogging can drift into Zone 3 heart rate territory.
Building an aerobic base takes time. One of the best ways to measure progress is simply to go out and run consistently while observing how pace and heart rate gradually improve over months and years.
For athletes who already have a decent aerobic base and train around 6–10 hours per week, Zone 1 may only really be useful for recovery or active rest sessions.
To get the most out of aerobic training, you generally want to train at an intensity where the heart reaches near maximal stroke volume without creating excessive fatigue. As intensity increases, both heart rate and stroke volume increase up to a point. Somewhere around low-to-mid Zone 2 for most trained athletes, stroke volume reaches its maximum, and after that further increases in intensity mostly raise heart rate rather than the amount of blood pumped per beat.
This is one reason why lower Zone 2 has traditionally been such an effective training intensity:
– strong aerobic stimulus
– high oxygen delivery
– mitochondrial adaptation
– relatively low fatigue cost
For athletes with a good aerobic base, even those training 10–15 hours per week can often benefit from doing most of their volume here without needing to go slower.
Another thing that gets misunderstood is that Zone 2 is actually a fairly large range for well-trained athletes.
For me, Zone 2 for running is currently somewhere around 4:20/km to 5:00/km. There is a massive difference in fatigue, energy expenditure, and muscular stress between doing a long run at 4:50/km versus 4:20/km — even though both technically fall within Zone 2.
The same applies to cycling, where the difference can become even more significant over rides lasting 3+ hours.
Things get even more complicated when you move into multisport and hybrid training.
Heart rate is useful, but pace and power are often more relevant because heart rate can vary day to day at similar effort levels. HR is still valuable — especially when unusually high or low for a given effort — but “Zone 2 heart rate” is not interchangeable across different activities.
That’s why triathlon relies heavily on power for cycling and pace for running and swimming.
Hybrid training complicates things even further because modalities like SkiErg and RowErg create very different muscular demands.
I’ve been running for over three decades, doing triathlon training for almost as long so my body is extremely efficient at running, cycling, and swimming. That efficiency does not automatically transfer to erg machines.
If I run at lower Zone 2 intensity with a heart rate around 130 bpm, that is not remotely the same metabolic or mechanical stress as holding 130 bpm on a SkiErg for an hour. An hour run at that effort might leave me feeling fresh and ready for a hard session the next day. An hour on the SkiErg at the same heart rate would probably leave me wrecked.
For most of my career, we barely talked about training zones at all. Distance runs/rides were simply done at conversational pace, and in both running and triathlon that made up the vast majority of training volume.
Training science has absolutely advanced, and some of the details are useful. But the fundamentals are still the fundamentals.
Unfortunately, social media often turns those details into overhyped trends that end up confusing athletes more than helping them.
Keep your training simple.
