If you ask a runner or coach about heart rate training, you typically get one of two reactions. They either love it and swear that it made them faster, or they don’t rely on it as a valuable metric. Is heart rate training beneficial or not? If so, how do you effectively use it as part of your training?
Who Benefits from Heart Rate Training?
Two types of runners will benefit from most from heart rate training: those who struggle to train in the appropriate zones and novice runners.
For many runners, it is a struggle to run appropriately easy on easy run days. Easy runs constitute a majority of training, whether you are a new runner or an elite runner. Easy runs develop your aerobic fitness and endurance. If you run them too fast, you hinder recovery (and therefore adaptation), risk injury and overtraining, and can’t push as hard on your workout days. Your training all lands in a gray, moderate zone. You may see improvements, but you aren’t maximizing your potential for the work you are doing.
An easy run should feel comfortable enough to carry on a conversation. Easy means truly easy – and significantly slower than race pace. However, many runners will push the pace just a bit past this point, into a moderate zone. You miss out on the full benefits of easy runs, never quite recover from your training load, and are unable to run fast on your hard run days.
If you struggle to slow down for your easy runs, heart rate training will benefit you. Use a heart rate monitor to help you control the intensity of a run and keep your easy runs truly at a low intensity. Using a formula (which you can find below), you will have an exact range of numbers for your target heart rate. By making sure you keep your heart rate within this zone, you will keep your run at the appropriate intensity.
New runners will benefit the most from heart rate training. Learning how to gauge your perceived effort on a run is an acquired skill. Training within a heart rate zone will reinforce how certain runs should feel.
Heart Rate Training for Hard Workouts
Heart rate monitoring can be used on tempo runs, since those are prolonged and continuous efforts. However, there are downsides. Worrying too much about your heart rate can hinder your ability to gauge your perceived effort. If you are using a less accurate heart rate monitor such as a wrist-based monitor (see below), you could end up training too hard – or not hard enough. Heart rate zones for your aerobic threshold, lactate threshsold, VO2max, and other hard workout zones are narrower than your easy pace zone, meaning a margin of error is heart rate reading is more likely to affect your workout.
Heart rate monitoring becomes even more complicated and less practical on interval runs. Your heart rate doesn’t instantaneously jump up when you start running faster. Cardiac lag occurs, meaning that you will be running hard for a good portion of time before your heart rate monitor reflects it. This is especially true for short intervals; your heart rate will not register the appropriate reading for a majority of the interval.
If you are using a heart rate monitor during longer intervals, your heart rate will stabilize during both the hard and recovery intervals. Just know that you will need to give it a few seconds to adjust each time you change your pace.
When Not to Use a Heart Rate Monitor
When is a heart rate monitor not practical or beneficial at all? Race day! You are running at your maximum effort in relation to the distance, so there are no prescribed zones for your heart rate on race day. The feedback of a heart rate monitor will not help you race faster. If anything, it could be information overload.
Calculating Heart Rate Training Zones
Age, your current fitness, resting heart rate, and other individual factors affect your maximum heart rate. However, most equations only factor in age, which leaves a margin of error. Of the age-based equations, the most accurate is 208 – (0.7xage) = MHR. So if you are 30 years old, your MHR is 187 beats per minute (BPM).
Once you know your maximum heart rate, you can determine your target heart rate for different types of workouts.
- Easy runs: 65-75% of MHR (121-140 for our 187 BPM runner)
- Tempo runs: 87-92% (162-171 for 187 BPM runner)
- Intervals: 95-100% (177-187 for 187 BPM runner)
If you are only monitoring your heart rate on easy runs, you may be able to utilize the formula from the Maffetone Low Heart Rate Method. The Maffetone 180 Formula accounts for factors such as years of consistent training, injury, and illness, thus making it more individualized. The number it generates is your aerobic heart rate, which you can use on easy runs.
What Factors Can Affect Heart Rate Training?
If you opt to use heart rate training, you want to be aware of how external factors affect your heart rate on a run. Your heart rate increases not just due to exercise, but due to external stressors. Caffeine consumption, heat and humidity, stress or anxiety, or poor recovery from a previous workout can all increase your heart rate.
Hot weather and humidity can affect your heart rate, since your body works harder to stay cool. Dehydration can also increase your heart rate. However, you can make a counter-argument that you should slow down more in the heat and humidity. The same argument can be made for stress; if you are stressed enough that your heart rate is higher, you should slow down your run to avoid over-reaching.
You may find it beneficial to use an additional metric such as ventilatory rate. Even the most accurate heart rate monitor (more on that below) can have a margin of error. Your ventilatory rate will roughly correspond with your heart rate zones. Easy runs should be comfortable enough to carry on a conversation, tempo runs so that you can speak in short phrases, and intervals hard enough that you can only speak a word or two before gasping.
Types of Heart Rate Monitors
There are two popular types of heart rate monitors: chest straps and wrist-based. Chest straps rely on sensors to measure heartbeat via electrical activity. According to the American College of Cardiology and supported by many research studies, chest strap heart rate monitors are typically more accurate.
Wrist-based heart rate monitors are rising in popularity and included on many GPS watches now. However, wrist-based heart rate monitors are less accurate, with an error margin of anywhere from 1% (2018, Digital Health) to 13.5% (2019, Journal of Sports Sciences), depending on the brand. Wrist-based heart rate monitors utilize a bright LED light. This light is refracted off of blood flow beneath the surface of the skin. The watch then calculates the data through an algorithm to measure heart rate. Factors such as humidity, sweat on your skin, the tightness or looseness of the watch strap, and any built-up grime on the sensor can affect accuracy.
If you are only using your heart rate monitor for easy runs, the margin of error with a wrist-based monitor is not as significant. Doing an easy run slower will only benefit you.
Is Heart Rate Training Right for You?
Personally, I do not use heart rate zones in my training, nor is heart rate training a significant aspect of my coaching philosophy. However, I’ve worked with runners who have benefited from using it on easy runs. Every runner is different. Some will benefit from heart rate training, others will not.
If you have trouble slowing down on your easy runs, you may benefit from heart rate training. Opt for a chest-strap monitor if possible and focus on your breathing and effort as well. As with paces, you do not want to over-rely on data during a run. Any piece of technology will have a margin of error, but your body’s feedback does not lie.
Do you use a heart rate monitor on your runs?