Do you go for a run and finish questioning if your heart rate is too high or too low, what that means and how you can train better? We're here to help.
Understanding Heart Rate
Our heart beats multiple times every minute to pump blood around our body, carrying oxygen to give our cells energy to function. When we run, we need more oxygen to power our muscles and as a result our heart has to beat faster.
As we get fitter, our body becomes more efficient at this process, so we can do the equivalent load/pace with a lower heart rate (or we can do more with the same heart rate).
Over time as we get fitter, we might find that running at the same 'easy pace' after 10 weeks of training sees a drop in our average heart rate. Additionally, when we're pushing the pace we can run faster, but at a lower heart rate.
Training to heart rate is more complex than training to pace, but it can be a useful measure if used correctly.
Cons on Training to Heart Rate
Inaccuracy
Firstly, most wrist-based HR data is inaccurate. Whilst it can be a good indicator of your resting HR, it is also affected by weather, sweat or even how tight your watch is. We would suggest only relying on your HR data if training from a chest-based or arm-based HR monitor.
Lagging data
Heart rate is a secondary data point – it responds to what your body is doing rather than driving the effort itself. Your HR changes due to many factors, not just the act of running.
If you want to raise your heart rate, you can’t simply will it higher; you need to increase your effort and then wait for your HR to catch up. Likewise, when you stop or slow down, your heart rate may take a while to come back down. This delay makes HR a “lagging” metric.
Because of this, it’s often easier and more accurate to use pace as your primary measure of effort. If you’d like, you can still monitor your heart rate at the prescribed pace and aim to keep it within a similar range when terrain or elevation changes.
Individuality
Finally, HR data has huge individual variation. There are a huge number of factors which affect how fast your heart beats when you exercise, including genetic factors.
As a result if you notice your heart rate is higher than a friend who you may be running with, don't panic and don't compare! We would suggest being aware of your heart rate and noticing if something is out of the ordinary, but only comparing it to your own usual rate.
This also applies to our HR zones, which can be used to guide effort in training. You could have two people who are the same age, same gender and have the same 5k PB, but one person might have a higher easy run HR zone than the other.
Heart Rate Zones
To train with heart rate, start by identifying your heart rate zones. The most accurate way to do this is through a VO2 Max test, but we don't all have access to this so here are two other options.
The most simple, but least accurate, way is to estimate your max heart rate is 220 - your age. For example, a 40 year old would have a max heart of 220 - 40 = 180bpm. A better way to find your max HR is to do a field test. You should only a field test if you are healthy, uninjured and used to raising your heart rate to maximal levels.
A field test should be done whilst wearing an heart rate monitor and a medical professional should always be consulted first. An example of how to perform a field test is to:
Warm up for 15-20 minutes
Find an area you can run along with no obstacles, preferably a hill that will take at least 2 minutes to run to the top of at a maximum pace. Run up the hill for 2 minutes at a steady but challenging pace that you estimate you could hold for 20-30 minutes.
Run up the hill at a pace you think you could hold for 3km or 1.9 miles. Watch your heart rate. The maximum value of this effort should be about 10 beats fewer than your maximum heart rate value.
Run up the hill at a maximum effort for 45 seconds to a minute. You should achieve your maximum heart rate.
Cool down for at least 15 minutes.
Once you know your maximum heart rate, you can calculate your heart rate zones. There are many differing opinions of exactly what percentage of your maximum heart rate each zone should be, but generally speaking there are 5 HR zones which are as follows:
Zone | Description | % of max HR | Duration you should be able to hold this HR for |
Zone 1 | Very Easy | 50-60 | 6+ hours |
Zone 2 | Easy | 60-70 | 1-3 hours |
Zone 3 | Moderate | 70-80 | 40-90 minutes |
Zone 4 | Hard | 80-90 | 6-40 minutes |
Zone 5 | Very Hard | 90-100 | Less than 5 minutes |
When thinking about training with heart rate, you can think about what type of runs match with which heart rate zones.
Generally speaking:
Easy runs should be in Zones 1 and 2.
Tempo and Interval runs should average out to be Zone 3 or Zone 4, however you may spend some time in Zone 5 during intervals.
Most races will be run in Zone 3-5 depending on their length.
You can use this as a guide, particularly when doing easy runs to ensure that you are not pushing yourself too hard.
Factors that can push your hear rate higher include:
Heat and humidity
Hills, elevation and challenging terrain
Stress and fatigue
Caffeine
So, if you are doing your easy run on a hot day or on a hilly route, your heart rate will be higher than it would usually be on a flat, cool route. If you're training to heart rate and aiming to stay in Zone 2, you might need to slow down or walk up any particularly steep sections.
Ultimately, an elevated heart rate simply means your body is working harder. So, if you're running in the heat or on hills, it helps to know what your heart rate normally is during a flat, cool easy run or interval session. Then, aim to run at a pace that keeps your heart rate close to that usual range. This helps you maintain the same effort level, even when conditions make the run feel tougher.
Pros on Training to Heart Rate
Stressed out about pacing
If you are on holiday and it is hot, up in the mountains at high altitude, or in a hilly area and you can't find somewhere flat to do session, then training to pace can be quite stressful.
When the conditions are not optimal and you know hitting the pace will be tough (or impossible!), then training to HR is a great to way to get in the work and know you are training at the right effort.
Control the effort
You've got a dream pace you want to hit for your upcoming race in 12 weeks and you are determined to hit that in training, but in reality, your fitness isn't there yet. Do you hammer it anyway and push to your max to get there? Or do you ease it back to work in the right zone and trust that over the next 12 weeks you'll get there?
The latter is the right answer! If we push too hard too often in training, then this increases our chance of injury. By using HR, you can be confident that you are working in the right zone, not getting carried away and track your fitness over time by seeing your pace improve for the same HR.
Good indicator of illness
This only applies if you track your resting HR over time too, but if you know your HR zones and typical trends, then changes (usually an increase!) in HR is an indicator that you are under the weather. This is beneficial for tailoring your training to ensure you are not pushing through when you should be resting!
How Should I Understand My Own Data?
When it comes to understanding your own heart rate data, there are some general patterns you should expect to see:
As you get fitter, your resting heart rate will go down. Your resting heart rate is the lowest amount of blood your body needs to pump while you are relaxed and not exercising.
The average resting heart rate is between 60 and 100 beats per minute, however many runners will have significantly lower heart rates than this as their body has become so much more efficient at delivering oxygen to cells.
As a result, overtime you should see your heart rate lower when running the same paces.
Your heart rate should go up when training harder, for example when training in the heat, running uphill or running on trails rather than tarmac.
When your heart rate is higher than usual, it may indicate that you are overtraining or ill. If any of these are the case, it is best to take a few extra days of rest.
The Takeaway
Our view is that HR is useful but we recommend primarily running to pace and using HR data as a secondary measure. Pace gives us the confidence we need for race day and the more we get used to running at a certain pace, the more conditioned our body is to that pace come race day.
However, HR is great to check you are working in the right zone and not overdoing it, and to track your health over time. Remember that wrist-based tracking lacks complete accuracy too. Happy training!