Heart Rate, Intensity of Training, Base Building and Why Low-Intensity is King

For all runners, the majority of their training is going to be low intensity. But for more advanced runners who are training for a race, they are going to have more high-intensity training than someone who is building an aerobic base. Any average runner who is not closing in on a race should be focused on building that base. The amount of time spent training is directly correlated with faster race times. The best way to increase training time is by focusing on building a base and growing that capacity to run more. That base is built with low-intensity training.

Training runs can generally be broken up into two categories. Low-intensity and high-intensity. The divide between low-intensity and high intensity can be based on feel or on heart rate. Many runners use heart rate to determine what “zone” they are in. Runners use either a 5 zone system or the less popular 3 zone system.

These “zones” are ranges of the percent of the athlete’s max heart rate. Yeah, that is a mouthful, but the table below makes it easier to understand. Low-intensity training takes place in Zone 1,  Zone 2, and the lower end of Zone 3. Higher Intensity training takes place in the other zones. High-intensity training includes thresholds, intervals, and repeats.  Zone 1 training is easy running. This would be something like a recovery run or a light jog. Zone 2 is where most of the training should take place. This is where the long run and other easy runs should be. Zone 3 would be a long run at marathon pace or higher.

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Calculating Max Heart Rate

The maximum heart rate is the highest beats per minute the athlete’s heart will reach during exercise. This is different for everyone. A quick rule of thumb is to subtract the athlete’s age from 220.

Max Heart Rate = 220-Age

For example, someone who is 30 years old would have an estimated max heart rate of 190. That means their zone 1 training would be 95-114 bpm. The problem with this equation, the Fox method, is that multiple studies have found it to be inaccurate. It gives a decent estimate, but it can easily be off by 10-15 bpm.

The more accurate way of testing it is on the track. Basically trying to get the heart rate as high as possible. I recommend running an 800m sprint and seeing how high the heart rate reaches. Then resting a few minutes and running one again. If the heart rate does not reach any higher then the athlete is done. If the athlete’s heart rate reaches a higher bpm then rest a few minutes and do it again. This is continued until the athlete does not have their heart rate increase from one sprint to the next.

Rough Estimate

Personally, I find heart rate training to be a little too much. It stresses me out. I find myself constantly looking at my watch. For many, they like the accuracy of heart rate training; knowing that they are in the correct zone. For me, I would rather be off by a little and not feel worried about the numbers. But this is all preference. Plus, I spent some time doing heart rate training so I have a good idea of how I should feel during different training runs.

I like having the basis of heart rate training to help understand what is going on in my training. But, when it comes to what zone I am in, I prefer to use rough estimates or “landmarks.” Zone 1 is the recovery zone. This is a very easy jog, barely breathing hard and can hold a conversation with no problem. Zone 2 is a conversational pace but running harder. This is a steady jog and if the pace is picked up the conversation will be harder to hold continuously. Zone 3 is where the more intense long steady-state runs will take place. Zone 4 is a difficult pace. This is where the lactate threshold pace falls into. Breathing heavy and cant talk more than a few words. Zone 5 is running as hard as possible, gasping for air.

For me, Zone 3 tends to be the hardest to judge. I always think of it as in between easy run pace and lactate threshold pace. But that doesn’t really help. It is a pace that is fast but can be held for 60+ minutes.

when I’m really in tune with my training, I find it better to use pace rather than heart rate zone. Using pace allows me to make sure that I am on the right track with my training. If I have a specific goal in mind then I can tell if I have a good shot of hitting it baed on my pace in training runs. This also allows planning of runs in order to hit a specific goal.

Pace and heart rate zone are opposite sides of the same coin. Both get to the same place, but sometimes pace may be less accurate. When running uphill, downhill, or if it is very windy, then pace will be less accurate than zone. For example, if my zone 4 pace is usually 6:50 min/mi, but it is very windy then my zone 4 pace might be 7:20 min/mi for the day.

Zone 2 is Where Most Training Should be

Zone 2 is where the aerobic base is built. This is where the resting heart rate is lowered and muscular vascularity is improved. Since this zone allows us to run longer distances and at a less intense pace, I like to think of it as “getting reps in.” It allows the form to be improved and strengthens connective tissue over time.

Research as well as case studies done on elite runners lead us to believe it may be necessary to build up a large amount of zone 2 training before moving into the higher intensity stuff. It is important to build the base early in a training cycle. When training for a race, that base needs to be there so the higher intensity running can be done closer to the race.

The goal is to increase training volume. Running is improved by running more. But most of the time the higher intensity training cannot be increased so the lower intensity training needs to be increased to increase volume. High-intensity training is more fatiguing and leaves runners more prone to injuries. Since the goal is to increase volume, we can generate more volume and less fatigue with easy runs than with high-intensity training.

If injuries are more likely to happen with high-intensity training, then high-intensity training should be minimalized with respect to the return that we get from it. Meaning, we know there is a benefit of high-intensity training, but as more is added we see less benefit from it. The marginal benefit of high-intensity training is decreasing. There needs to be just enough high-intensity training to get the benefits of it, but not anymore since that will lead to unnecessary injury risk.  Injuries will lead away from increasing volume.

Even if we were able to forget about injury risk and increase high-intensity training (assuming some high-intensity training is in the training plan already) this would make it harder to recover, thus making it hard to increase the volume again.

Where does High-Intensity Training Belong?

In the short term more results may be seen from high-intensity training, but over the long term, building up a lot of zone 2 training seems to be more beneficial. Plateaus also occur quickly with high-intensity training. The focus should be on building an aerobic base. 1-2 sessions per week of high-intensity training is plenty. If you are closing in on a race, or test, then the higher intensity stuff should definitely be incorporated.

Polarization of Training

This is very important for amateur athletes, i.e your average joe runner. The polarization of training intensity is the difference between your training sessions based on intensity. For example, 1 mile repeats and 100m sprints have a much smaller polarization than a 10 mile easy run and 100m sprints.

Studies have shown, including one on the German national rowing team, that polarization is extremely important. It is what makes the difference between the elite and the sub-elite. The elite are able to make their low-intensity training LOW and their high-intensity training HIGH. They are able to turn the intensity down very low for low intesity training and crank it up very high for high-intensity training.

Many casual runners fall into the trap of always running pretty hard. They run their low-intensity runs too hard and their high-intensity runs too easy. They think that the easy runs dont seem challenging so they run them faster. This is a common issue in all areas of athletics with many casual athletes. They think every day should be pedal to the floor, balls to the wall, posting Instagram pictures of their “sweat angel” hard. But then after pushing themselves too hard on all the easy runs and not recovering, they can’t push it hard on the high-intensity runs and they end up running their repeats slightly faster than their easy runs.

Each training run has it specific purpose and it needs to be used for that purpose. I know that it seems beneficial to always be pushing hard but that could be hindering performance.

Takeaways

  • Run your easy runs EASY and your hard runs HARD. 
  • The goal is to increase training volume over time
  • High-intensity training causes quick improvements and plateau quickly
  • Focus on building an aerobic base and use high-intensity closer to race