16 Feb Fundamentals of Heart Rate Training
Glossary of TLAs
HR: Heart Rate RHR: Resting HR HRMax: Maximum HR BPM: beats per minute
TT: Time Trial OCT: Obstacle Course Training TLA: Three Letter Acronym
Practical Heart Rate Training: how to not be a slave to your HR monitor
Some Background (the Why)
The fact that someone is training implies that they have a goal that they are trying to attain, and the training is designed to help them move towards that goal. Pretty much all athletic training is trying to improve performance. With that in mind, what is the general goal for running training programs? What would improve performance for these athletes?
I imagine it's as basic as this: to run faster.
In order to know if we are making progress, we need to be able to measure performance as training progresses. For runners, pace is the best measure of performance (other than actual race times). If their pace improves, then the training is effective.
With modern GPS watches and phones it is easy for anyone to measure their pace in real time. We seem to be all set, right? So why bother with HR? Why not simply train using pace?
Pace is useful, and is perfect for certain workouts, but it has some significant limitations. Running at a target pace is fine for flat runs with no wind. However, as soon as you have some hills (up or down), technical terrain, or a significant wind, the target pace becomes either too hard or too easy.
We need to find some way to measure how “hard” your body is working, not just how fast you are going. Ideally we'd want to measure how much force you are applying to the ground with each step. This would take into account all those variables such as hills and wind, and it is directly related to your pace. We need a power meter for runners.
Unfortunately running does not lend itself to direct measures of power. Instrumenting shoes with power meters would make them much too bulky and heavy. That is why we have to take another step back and look at what’s going on inside the body. We need to try to find some metabolic thing that we can measure that relates as closely as possible to pace.
*** A company has recently released an accelerometer based power meter for running: stay tuned.***
After much research, and also because it is super-easy to measure in real time, we had decided that HR was a decent measure of workout intensity. Basically, as exercise intensity goes up or down, so does HR, so it's a reasonably good indicator of how hard the body is having to work.
If you try to hold the same pace up a hill, your HR will rapidly climb. Same thing if you are running into a stiff headwind. Conversely, running downhill or with the wind will see your HR decrease if you maintain the same pace. If you maintain a steady HR instead of pace at these times, then you are good to go. This neatly solves the problems we had with just using pace to measure our workouts.
Heart Rate Training Basics (the How)
Most HR Training is based off an athlete’s Maximum HR, although some also incorporate Resting HR. As we will see, neither of these limits are absolutes set in stone: they vary, from person to person as well as from hour to hour within the same person.
Actually measuring HRMax is rarely done outside of high performance athletes or research studies. This is because it is a very stressful measurement that would ideally need to be repeated several times to get a range of HRMax, or to account for a possible training effect. Furthermore it would need to be done for each type of activity of interest. Even furthermore, there is no guarantee that the subject truly reached their maximum possible HR: maybe there was more capacity there, but the pain and effort was so intense that the brain said "shut it down".
**** Future Post: Noake’s Central Governor theory of fatigue ****
Instead of direct measurement, such as what is done for RHR and during exercise, HRMax is almost always estimated using one or more formulae that have been developed. Note the emphasis on "estimated".
The simplest and by far the most common HRMax formula is 220-age.
As an example, a 35 year old would have an estimated HRMax of 220-35=185 bpm. This would be his/her HRMax regardless of gender or training status, so it has been falling out of favour due to its oversimplification and generalization.
Fortunately, several new and research-based formulae have popped up in recent years.
The best one for my money is Tanaka, Monahan, & Seals (2001):
HRmax = 208 − (0.7 × age)
Their meta-analysis (of 351 prior studies involving 492 groups and 18,712 subjects) and laboratory study (of 514 healthy subjects) concluded that, using this equation, HRmax was very strongly correlated to age.
However, even if you use the best formula, the fact remains that maximum heart rates vary significantly between individuals.
“Even within a single elite sports team, such as Olympic rowers in their 20s, maximum heart rates have been reported as varying from 160 to 220. Such a variation would equate to a 60 or 90 year age gap in the linear equations above, and would seem to indicate the extreme variation about these average figures.” - Kolata, Gina (2001-04-24). 'Maximum' Heart Rate Theory Is Challenged. New York Times.
This is the lowest measured HR, which typically occurs when one is asleep. In practice, we measure it when awake. Most of the time RHR refers to the lowest HR measured while lying supine (on your back) first thing in the morning.
Recently, athletes and coaches have started using a standing RHR as the base, especially for activities such as running. Think about it: standing upright means that your heart now needs to generate enough pressure to pump blood from your feet up to itself and then from there up to the top of your head, all against gravity. In most healthy individuals, that's a good 10-15 BPM above the supine RHR.
Since HR response is posture-dependent, it makes sense to me to use a RHR measurement that most closely mimics the body position of the activity (supine or prone for swimming, seated for rowing and cycling, standing for running). In practice though, supine RHR is still pretty much the standard.
This is me playing with my HR monitor in bed, doing a couple of orthostatic tests. You can clearly see that my “resting” HR is significantly higher when I am standing.
Doing orthostatic tests regularly is possibly a good way to monitor for signs of overtraining or other issues. But that's a discussion for another day.
HR Training Zones
Research and experience have shown us that there are certain physiological parameters that seem to determine running performance. The Big 3 are: VO2 Max, Running Efficiency, and Lactate Threshold.
Most people who have done some running or other endurance sport likely have an idea what those all are. Anyways, more research into these indicated that certain workout intensities seemed to be optimal at improving each of the Big 3. Therefore, working at the HRs associated with those intensities formed the basis for the concept of HR Training Zones.
All Training Zones are designed to optimally train one of the physiological determinants of running performance: aerobic capacity, lactate threshold, running efficiency, and neuromuscular (sprint) optimization. The Target HRs or the Training Zones are variations on this. Because of the high variability of HR, I believe it’s more useful to use a substantial range of values (a Zone) as the target rather than a single number or very narrow range.
The classic formula for calculating the various Target HRs is very simple:
Target % x HRMax = Target HR
For example a 35 year old would have an estimated HRMax of:
220 - 35 = 185 BPM
If this person then wanted to train at 75% HRMax, it would be simple math:
0.75 x 185 BPM = 139 BPM
It may be simple, but it becomes progressively less accurate and eventually impossible at lower intensities. Try jogging at 30% HRMax…
For the same 35 year old, let’s say they have a RHR of 60 BPM
30% x 185 BPM= 55 BPM
This is below this person's RHR, and is pretty much impossible. The problem is caused by using 0 BPM as the Minimum HR. That's Walking Dead territory...
A sensible solution to this is the Karvonen formula. It is essentially the same, but uses RHR as the Minimum HR instead of you being dead. Here is the formula:
RHR + [Target% x (HRMax – RHR)]
Using the same person as above, we'd get:
60 + [0.30 x (185 – 60)] = 98 BPM
This number actually makes sense relative to RHR and HRMax.
At higher intensities the differences become smaller, but they remain significant up to the 90% zone, with the Karvonen formula giving consistently higher target HRs than the old formula.
Here is a handy online calculator for both methods: http://www.briancalkins.com/HeartRate.htm
Which HR Training Zones System?
After all of that has been said and done, there remain many interpretations and variations on what the actual ideal HR Training Zones should be. Some advocate for just 3 zones, some for 4 or 5 or 6. Any more that a half dozen starts to become meaningless due to the high variability of HR response, which will start causing the different zones to overlap.
HR Training Zone schemes can range from fairly simple…
To more complex than tax forms.
HR Training Zones at OCT
These are not supervised workouts with a live coach. Add to that the facts that HRMax is just an estimate, and that HR in general is sensitive to many things that have nothing to do with your workout, and we have decided to keep things as simple as possible without compromising effectiveness.
We are working off 3 broad Zones, emphasizing the 3 energy systems: aerobic, aerobic lactic, and anaerobic. It’s important to note that the body is never using just 1 system at a time, but that all 3 are active at all intensities of exercise. However, there are definitely zones of exercise intensity where each of the systems is the predominant source of energy, and that’s what those Zones refer to.
The long, slow, easy runs are Zone 1, emphasizing your aerobic energy system. It’s very important to not do these at a higher intensity, even if it feels very easy.
The TT at the start of each OCT program forms the basis of Zone 2, emphasizing the aerobic lactic energy system. The TT sets your initial threshold pace and HR. These workouts will be some tough work.
The sprints and hill intervals are mostly hitting the anaerobic energy system as well as providing a good neuromuscular stimulus. This means that it helps the nerve-muscle interaction, to get the timing synchronized and get you efficient at higher cadences. These are Zone 3 workouts, and generally don’t use HR monitor due to HR Lag.
Examples of Common Issues with HR Training
“I regularly see HRs higher than my HRMax during training runs.”
The first thing to do is read (or re-read) the manual that came with your monitor and make extra sure you have it positioned and tightened properly. Chest straps work far better when there is water/sweat/gel between the sensors and your skin. Guys with hairy chests may have to shave or use some sort of gel to get good conductance.
If that checks out and you still get higher numbers, then you are one of the many people for whom the HRMax predictive formulae aren’t particularly accurate. If they underestimate your HRMax, then you’d also likely find that the workouts seem easier than they should. In this case, use the highest reliable recorded HR as your new HRMax for your target HRs going forward and see how the workouts feel.
“The slow run is too slow; I need to walk all the hills to keep my HR in the Zone.”
This happens a LOT with people who have not done HR Training and/or have not done any long slow workouts. This is where a good HR monitor can be fantastically useful, as almost everyone wants to go faster for their first few slow runs. DON’T!!
The slow training runs are essential to the running program, and they are very much a case of “more is NOT better.” Going faster will decrease the benefits you gain from this type of training. Stick with it, walk the hills - most of the rest of us do as well.
“This workout is supposed to be hard/easy but it felt easy/hard at the target HR.”
If it consistently seems that the target HRs give you easier workouts than you think they should, then it might be a good idea to try using the Karvonen formula to derive your target HRs. We went over that earlier in this article, including a handy link for calculations. Give that a try and see how it works, since Karvonen will always give you higher target HRs for anything less than 90% intensity.
If the workouts feel very hard, to the point where you may not be able to finish some of the more intense ones, then it’s likely that the formulae over-estimated your HRMax. The first thing to try is to take your 5 km or 10 km Time Trial HR as being 85% of your HRMax
i.e. if your TT HR was 160 then your new HRMax would be 160/0.85 = 188 BPM
If that leaves the workout still too hard, then just brute force it: subtract 10 BPM from your HRMax until the workouts feel about right. What the actual numbers are is not the important thing. They are just markers to let you know when you are training at the proper intensities.
Accuracy and Consistency of HR Monitors
A fair number of common HR Training questions can often be solved by ensuring that you have an accurate HR monitor, and that it is set up properly. That should be your first step in troubleshooting whenever you see what appear to be crazy HRs during training.
Currently, chest straps are better than wrist bands. However, both need to be properly set up in terms of positioning and tightness. The chest straps also need a wet contact with the skin, as it is picking up tiny electrical signals from your heart. Guys, if you have a lot of chest hair, then that may or may not be an issue.
Limitations with Certain Workouts
There are some characteristics of cardiovascular physiology that make it HR Training unsuitable for certain types of workouts. HR Lag and Cardiac Drift are the 2 big ones.
1. HR monitoring is useless for sprint intervals (the anaerobic system) due to HR Lag. Look at these actual workout screenshots from actual OCT members.
You can see that the HR is still rising by the time the work interval is done. The athlete never reaches a steady state during short intervals, so having a target HR is not practical.
2. Many athletes will experience Cardiac Drift on longer runs, even if pace and/or perceived effort stay the same. Here is what it would look like.
You can see that pace remains steady, yet HR starts to climb after a while. This is a classic scenario where you need to override the HR Monitor. Your effort is constant, it doesn't feel any harder, yet your HR is climbing. This is because your HR has decoupled a bit from your exercise intensity, and is increasing for some other reason - usually to manage core temperature. Stick with your pace in this case.
Heart Rate Variability
HR is extremely sensitive to many, many factors that have nothing to do with your training intensity. A few of the common ones are: caffeine, nicotine, sleep status, stress, hydration level, ambient and body temperature. This means that even for the same person doing the same workout, the measured HRs can differ by a fair amount.
So after all this HR-bashing, one might be left with a single, burning question.
With all these limitations and variablity and accuracy issues...should we even bother? Yes, and here’s why...
Heart Rate Monitoring Helps Keep Intensity In Check
Perhaps the most valuable effect that heart rate monitors have had on endurance sports is that they have introduced athletes to the idea that there is an appropriate intensity level for each type of workout. The realization that "more training, harder" is not the optimal way of doing things has been a game changer for many a weekend warrior.
Even if an athlete has accepted that easy workouts are beneficial, the most common error is still pushing too hard in workouts that are intended to be easy or moderate. The use of target heart rate zones is a very effective way to prevent athletes from getting carried away with themselves.
Heart Rate-Pace Relationships Provide Very Useful Information
While heart rate monitoring on its own is admittedly of little value, simultaneous monitoring of heart rate and pace in running is very useful in helping the athlete track changes in fitness, fatigue and performance.
For example, as you gain fitness, your heart rate at any given pace should gradually decrease, and your pace at any given heart rate should gradually improve. Tracking both pace and heart rate allows you to follow these trends as they unfold. This is Running Efficiency, and is a Big Player in running performance.
People love to see objective, hard evidence that they are improving. Never mind how you look and feel, or how your clothes are fitting: people trying to lose weight are all about the numbers on the scale. It’s a similar scenario with runners, who are wanting to know their pace and efficiency numbers as ways to track their progress.
We all know that having a concrete, measurable long term goal, such as breaking 25 minutes for 5 km, is a boost to motivation. The same is true on the smaller scale of individual workouts, where having distance, pace, or HR targets that we can see measured in real-time are a big push to getting it done.
The Bottom Line
HR Training is a decent concept; the benefits outweigh the limitations for most people, especially for non-elite runners. Note that the benefits are real actual pluses, while the limitations are not detrimental minuses, but rather indications that it may not be optimal. It's still a good thing, but likely not the best thing. Optimal training is something that is very much an individual thing and can really only be done 1-on-1.
Your HR monitor is YOUR tool - don’t be a slave to it. Remember that everything about HR training at this point is based on estimates: RHR, HRMax. Furthermore, even the measured HRs are subject to quite a bit of variability that have nothing to do with your workout. Go by how the workout is feeling as well as the HR guidelines.
The important thing is not so much what the numbers actually are, but that they help you know when you are training at the proper intensity for that workout.