The Natural Zones of Training

(Short note. I’ve decided not to cut 27 chapters out of the Fitness Intuition book, as I announced last Friday. In fact, I’ve added a chapter, an intro called “Where Do I Get Off?”

I was thinking the book needed to be toned down in order to reach a wider audience. But I realize I was mistaken. The audience is there — it’s (a) people who’ve begun to suspect that there’s more to training than the mechanics of the body; (b) people who are interested in the emotional and spiritual aspects of running but have only a vague idea how they work; and (c) people on a spiritual path who want to connect that part of their life to their running.

If you purchased the book between February 1 and 25, I’ll be happy to email you a PDF of the longer version. Just send me an email using the link at the bottom of the Book page – sorry, I can’t give you the link here because it uses special spam-preventing Javascript code.)


In his book, Education for Life, J. Donald Walters describes the six-year phases of a child’s development.

In Fitness Intuition, I talk about the relevance of those phases for runners. I won’t repeat that information here; suffice it to say I think it’s marvelous how nature arranged our development in such an orderly way.

Training has its own orderliness.

Heart rate has a wonderfully clear correlation with good runs. Starting a run at the wrong heart has serious consequences. Go out too fast and heart rate soars — it feels uncomfortable, and it’s likely you’ll run out of gas sooner than if you let your body warm up gradually.

There are lots of books on running that talk about heart rate. Not surprisingly, they tend to refer to the same heart “zones,” although they interpret them differently. Some authors claim the best easy aerobic training zone is 65% to 75% of MHR; others say it’s 60% to 70%. Where do they get these figures? Are they plucked out of the air? I don’t think so.

When I first read Education for Life, I decided it would be interesting to find out if different cultures had recognized the same six-year stages of a child’s growth. I went to the library and checked out some books on the history of education, and, sure enough, I found that in ancient Athens, Rome, and Europe in the Middle Ages, Renaissance, Enlightenment, Industrial Revolution, and modern times, the school years were divided into roughly the same six-year phases.

These phases weren’t plucked out of the air. They’re based on he natural changes that occur in childhood. From birth to age six, for example, children are engaged in learning about their bodies and senses. Education at that age needs to use physical methods: block letters and numbers, and other “play learning” tools. Similarly, in the “feeling years” from six to 12, stories, music, dance, and theater become the most effective instruments to teach academic subjects.

It’s the same for training. The training “zones” are based on changes that occur naturally at various heart rates.

What are the natural training zones?

At 65% of maximum heart rate, the heart does an interesting thing. A complex measure of heart coordination, called “heart rate variability” (HRV), suddenly gets faster at about 65% MHR.

It’s a bit hard to understand HRV. Simply put, it’s how often the heart changes speed in a given interval of time. Researchers at Heartmath Institute have discovered that HRV is deeply affected by positive and negative feelings. Happy, expansive feelings make the heart change speeds smoothly – the HRV output curve looks smooth and harmonious. Negative feelings such as anger and fear make the heart shift gears erratically – the HRV output curve looks jagged and disharmonious.

At 65% of MHR, the heart suddenly starts to change speeds faster. In other words, during a given five-second interval, above 65% MHR the heart suddenly begins to make lots more speed-changes than it does at a slower pace.

My theory about the natural 65% boundary is that it’s approximately the maximum speed at which the body prefers to warm up. Interestingly, several high-end Polar heart monitors use the sudden change in HRV at 65% to estimate a runner’s maximum heart rate, and establish the runner’s “warmup zone.”

When I spend sufficient time warming up at about 65% to 67% of MHR, I nearly always find that my body can run hard more easily, later on. Especially if I work during the warmup to cultivate harmonious, positive feelings. When I tentatively speed up and see how it feels, my heart is more likely to tell me “Yeah, I’m in the groove. I’m beating harmoniously. I can start changing speeds faster without grinding my gears – piece of cake!” When that happens, going faster feels like I’m slipping effortlessly into a higher gear.

This isn’t scientific, obviously – except that I’ve confirmed it in thousands of miles of running. I may not have the lab reports to back it up, but I’ve proved to my satisfaction that it works.

Two other people, Philip Maffetone, author of Training for Endurance, and John L. Parker, Jr., author of Heart Monitor Training for the Compleat Idiot, have conducted similar “unscientific” studies of two interesting heart-rate zones above the 65% warmup figure.

(Forgive me, I’m aware I’ve mentioned Maffetone ad nauseam here, but his training truly is fascinating, because it’s been so successful. As I’ve noted endlessly, “Maff” was the coach of six-time Hawaiian Ironman Triathlon winner Mark Allen.)

Maffetone’s recommended training pace during a slow aerobic buildup phase before the racing season is based on heart rate. He calls it the “180-Minus” pace. I won’t discuss it here. Suffice it to say that, for most runners, it works out to somewhere around 70% of MHR.

Runners who spend several months doing all their training at that pace find that their running speed at the same heart rate gradually gets faster. When they enter the short (5-8 weeks) speedwork phase, they find that they can go faster than if they hadn’t carried out the long aerobic buildup. Thus, when Mark Allen began doing several months of Maff-paced base running, he found that his heart rate fell 15-20 beats per minute during long bike rides, compared to previous seasons.

John L. Parker, Jr. talks about a different aerobic training pace. Parker advises runners to train aerobically and do regular speedwork year-round. For their aerobic training, he tells them to run no faster than 70% of MHR, calculated by the Karvonen formula: maximum heart rate minus resting heart rate, divided by 2, plus resting heart rate.

I once asked Parker how he came up with the 70% formula. His answer was vague — he seemed almost to be dodging the question. I was impatient, because I wanted precise, scientific answers — I wanted studies, research, test results, and numbers. But I no longer feel that way, because I now understand that Parker was justified in saying, “This is the way it is. Just do it.”

In the early seventies, Parker was a member of the Florida Track Club, where he trained with Olympians Frank Shorter, Jeff Galloway, and Jack Bacheler. I suspect that, like Shorter, Parker trusts his body’s feedback, rather than worry about abstract formulas. The 70% figure comes from Parker’s experience and that of hundreds of runners who’ve had success with his method.

Reason, logic, and scientific studies begin to take a backseat, once you’ve had the experience of running in the “harmony zone,” where your own inner feeling tells you clearly and convincingly: “This is right.”

Those feelings, in my experience, come at several distinct heart rates. During the warmup, they appear when I run at 65% to 67% of MHR.

During a transition phase to my fitness-improving endurance training pace, they come at about 70% to 75% of MHR.

And during the actual endurance training phase, the feelings of “rightness” come at about 70% of MHR calculated by the Karvonen formula, which for me, works out to roughly 78-79% of maximum heart rate.

In fact, I find during long runs that once I’m warmed up, if I stay at the 70% Karvonen pace, I feel great, but if I wander above 80%, I immediately feel that something is subtly “off.” I don’t even have to check the heart monitor. I’ll feel that slightly disturbed feeling, and when I glance at the monitor, sure enough, I’m at 81% of MHR or higher.

When I slow and my heart rate falls under 80%, I feel fine again. But if I persist in running faster than 80%, I’m never able to run as far. It feels as if I’m borrowing resources from the next run – like I’m doing a “slow race.”

Dave Cameron had the same experience:

I’m 44; but have been running for 29 years. My max HR has fallen by 20 beats or so since I was a freshman in college; but the percentage ratio has stayed the same. The main difference is that the warmup to get there takes longer now. And, of course, 78% of max used to be 8:00 min/mi pace 15 years ago, and now it’s 9:00 min/mi pace (on average)….

Anyway, I’ve upped my mileage — if I run 12 miles tomorrow, I’ll have four straight weeks of 80 mpw. Something I don’t think I’ve ever done. Ninety percent of the runs are at or below 80% of MHR. Usually, I can intuitively tell when I get over that…. Experience has told me that if I spend even two minutes at 81% of MHR I may as well be running 90% of MHR. It takes me back for a few days. (The other 10% of my training is planned speedwork.)

There’s another heart rate zone that I experience routinely. It’s rarefied territory, and I’m unable to go there during every run. I’m talking about running much faster than 80% of MHR. I find I can do that for only a few brief spurts twice a week, no more than 2-3 one-minute bursts during a run at up to 90% MHR. If I do more, it steals energy from the weekend long run.

About once a month I can enter that exotic territory during the long run for several miles. I look forward to those runs – they’re a special celebration. They’re a reward for training with discipline in the preceding month.

During those special runs, I’m able to run at 90% MHR or faster very comfortably – but only if I practice strict pace discipline during the warmup and training phases, running no faster than 65% to 67% and 75% to 79% MHR respectively.

Are these the body’s natural training zones? I’d love to hear from other runners who believe so, or don’t. To email me, follow this link to the Book page and use the link at the bottom of the page. Thanks. (I can’t reproduce the link here because it uses spam-prevention Javascript code.)

Training is a pyramid. We can do a ton of running in the warmup zone, less in the endurance-training zone, and very little in the exotic zone above 80%.

Which training system is best? Parker’s, Maffetone’s, Arthur Lydiard’s, or Bill Bowerman’s? Who knows? Some runners thrive on a year-round blend of aerobic running and speedwork (Frank Shorter being one good example). Others thrive on periodized training per Maffetone and Lydiard.

I believe what counts is the proportion. Doing lots of slow running bys me those enjoyable weekday speed bursts and the monthly long and speedy session.

I recently watched a DVD of legendary cellist Mstislav Rostropovich playing the Bach Cello Suites. It’s amazingly wonderful. I came home very tired and turned it on and just let it permeate me. My brain was too fried to think about it mentally, and I absorbed the music with my heart. I felt that Bach’s music was tapping the joy of a spiritual world and blessing our home.

In his introductory remarks, Rostropovich explains how Bach would allow the musical line (often in the Suites, there are no melodies) to drop lower in order, as Rostropovich puts it, “to gather energy.” The, he ascends and explores ethereal realms until the energy runs out and he needs to collect energy again.

Training is the same way: it’s about proportion and pyramids and wonderful exploration. Like Bach’s music, honoring its wonderful precision opens doors to inner blessings.

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