There are a couple of pieces of information that an athlete needs to know before starting a training session: how long or far will the training session be and how hard to push. The answer to the first part can be simple. It’s usually time or distance. The second one, however, is a little more elusive. My preference is to give people a heart rate training zone. In this article I will explain heart rate training and the different ways to arrive at your heart rate training zones including my preferred. Plus I will explain what I feel is the most important zone to train in for triathlon.

For a long time before heart rate monitors, coaches gave athletes some sort of speed at which to train. Other coaches give some sort of perceived effort like “you go all out” or go “easy”. Run coaches and swimmers give a pace per mile or pace per 100 in the pool.  More recently, cycling coaches rely on a power meter and use watts as the target effort. A power meter measures how hard they push the bike pedals. My favorite, which is a method that started in Finland back in the 70’s; is using a heart rate monitor. Coaches that use heart rate as the method for determining workout intensity give the athlete a target heart rate zone where they want the athlete to be for the bulk of the workout.  When the target heart rate zone is low, the objective of the workout would be easy recovery. When the zone is a middle range, the objective would be base work or endurance development, and when the zone is a high one the objective would be more speed and strength development.

The next question is how does a coach establish the heart rate zones? Some coaches use zones based on a percentage of a person’s maximum heart rate. Many probably recall the 220 minus your age to be an approximation of ones max heart rate and then take percentages of the heart rate range to arrive at the zones. Other coaches also take into consideration ones resting heart rate to then determine the low boundary for the zone range as well.  Other coaches get you to go train at maximal effort and then use that as the maximum heart rate and have that be the ceiling of your higher zone. Finally other coaches have their athletes blood tested during exercise to arrive at the Lactate threshold. This threshold then becomes one of the heart rate zone boundaries and other zones a percentage of that. I prefer using the Phil Mafetone method which is based on the 180 minus the chronological age of the athlete, then we take that number and make adjustments based the athlete’s fitness.  The number arrived at under this formula is the maximum aerobic heart rate, MAHR, not to be confused with maximum heart rate. This MAHR number is the defining heart rate line between highly efficient aerobic training and less efficient aerobic training.  

Let’s discuss for a minute aerobic training and aerobic development and its importance in triathlon. When exercising, the energy required for moving the body comes mostly from two main sources: one is muscle and liver glycogen and the other is fatty acids.  Glycogen is limited as we only have 2 hours’ worth of it, and we use more of it when our exercise is intense and our hear rate is high.  Fatty acids, on the other hand, are fairly limitless even for very thin people, and we use it as a source of energy when the training is easy and heart rate is low. For many years before heart rate monitors, coaches told athletes to make sure they could carry a conversation when training as that insured the pace was easy. Training easy over time causes changes in our bodies that make us become better at generating energy from fatty acids. As we get better, we can run faster or create more watts on the bike at a much lower heart rate than before. This is what is called aerobic development or base work.  Many people are afraid to train easy because they feel that training easy will cause them to not be able to race fast. The plan is not to race easy but the base development will build aerobic capacity. This capacity, when sharpened with high intensity training and anaerobic training, will allow an athlete to reach his/her potential.

Building a big base is not new, and it’s not just for triathlons. Arthur Lydiard, a famous coach from New Zealand in the 60’s and 70’s, pioneered the concept. He made his athletes run many miles in order to develop that aerobic fitness. Even Lydiard had a hard time and was criticized as most coaches back then utilized interval  training as the predominate way to train.  However, Lydiard’s athletes were very successful and went on to win Olympic medals in the 5000, 10000, and the marathon. This same method of building aerobic fitness and allowing the body to become aerobically fit is critical for triathlon success. I think it’s the best way to train for the big majority of hours when training for a triathlon where races can take up to 17 hours.

The final piece to discuss is what constitutes aerobic development?  How to maximize it? Where do we draw the line or what heart rate training zone should we choose for aerobic development. That is why I prefer the MAHR under Phil Mafetone’s method. Training under MAHR is very low stress on the body, it does not cause any stress hormones to be released, and recovery from these workouts is generally fast. This is an important training concept to understand. Heart rate is a barometer for many things that are happening in the body.  If you are dehydrated or you are super stressed from lack of sleep, you are indeed stressing the body and your heart rate will be high. Stress in not only training stress, it includes any of life stresses, your body will adapt because of all you do, not just training. Many times what we feel is easy may still be too stressful for good aerobic development. Let the heart rate monitor be your guide.

I started using the heart rate monitor in the 90’s and used it to guide me at the Hawaii Ironman. But I do think my run training was done at too high of a heart rate, and I did not develop a good aerobic run base. As a result, I almost always had a hard time in the marathon during my early Ironman finishes. I did well because I was young and fit but struggled in the marathon. It was not until I did Hawaii in 1996 at age 45 that I had no issues in the marathon. I ran the whole way and my last 6 miles were my fastest. I attribute this to the great aerobic base developed using heart rate training using MAHR as my upper limit for aerobic development.

This method of heart rate training is very challenging. I had to walk many times and eat my pride when I first started. But over time and with persistence my pace improved, my heart rate was low, and I was loving life. That is not too say there is no hard running and high intensity training with a high heart rate. A good triathlon training plan has to have some of this. I visited the pain cave on all three sports many times.

Recently Javier Gomez who is regarded by many as the best triathlete in the circuit today was interviewed and he reveals that for the last two year he has been utilizing the heart rate monitor and his base building is done with a heart rate ceiling of 155. Incidentally that is the aerobic heart rate limit for someone that just recently turn 30 under our methods. Here is a link to the original article in Spanish and my English translation.