Of all the performance metrics runners can track these days, heart rate max may seem a little hum-drum, but that's definitely not the case. Knowing that one number can help you train smarter, make your workouts more effective and help guide you through your best performance on race day. But to do that, you can't just rely on "220-Age" or some other one-size-fits-all formula. You'll need a realistic estimate of your unique maximum heart rate, so here's a field test to help you find it.
What You'll Need
First, make sure you're fit enough to exercise at or near maximal effort for a sustained period of time. If you have any type of medical condition or are working through an injury, you'll have to get clearance from a doctor before undertaking the field test. Make sure you let them know your effort level will be very high.
As far as gear goes, you'll need a heart rate monitor. Although wrist-based technology has come a long way, it's not quite as accurate as chest straps yet. So, if all you have is wrist-based HR, you might want to repeat the field test one or two times over the course of two weeks to be sure the results are accurate.
The other thing you'll need is a way to track your pace. A GPS watch is ideal since it can display your pace in real-time, but it's also possible to do the test with a simple stop watch on a track.
The Field Test
Once you have your gear together, head out to a relatively flat route and follow this protocol:
- Warm up easy for 10 minutes.
- Run one mile at tempo pace or approximately your 10K race pace. If you've never done a 10K, the effort should feel "comfortably hard."
- Once your tempo mile is done, increase your pace by 20 seconds per mile every minute until you can no longer increase your pace. If you're running on a 400-meter track with a stop watch, you should reduce the time it takes you to complete each half lap by 2 seconds until you can no longer increase your pace.
- Just before you start to slow down, look at the number on your HR monitor. This will give you a good estimate of your unique maximum heart rate.
Using HR Max to Train Better
Once you have your number, you can use it to plan your training runs. Although the exact training protocol will differ greatly depending on your level of fitness and the distance of your goal race, here are a few universal guidelines:
1. Follow the 80 Under 70 Rule. Even if you're only training for a 5K, you'll want to run about 80 percent of your weekly miles at an easy pace that never goes above 70 percent of your heart rate max. The ideal range is between 65 and 70 percent of maximum, so take the number from your field test and multiply it by 0.65 and 0.70, and that will give you your easy-run range. For example, if your HR Max is 185, that means for most of your training runs your heart rate should stay between 120 and 130 BPM. This may seem "too slow," but elite runners and their coaches know it's the best way to build fitness without getting injured. Be like the elites and slow down!
2. Run Harder on Hard Days. Just as most runners run too fast on easy runs, they also run too slow on their hard runs. While tempo runs are often described as a "comfortably hard" effort, many runners tend to focus on the "comfortably" part rather than the "hard" part. To really get the physiological benefits of speed work, you need to push yourself a fair bit outside of your comfort zone.
Depending on the goals of your hard workout, your training heart rate zone will vary. For tempo or acidosis threshold runs, for example, you want to maintain a steady effort somewhere between 80 and 95 percent of maximum (the fitter you are, the higher your heart rate can go before acidosis outpaces your body's ability to clear it away). If your goal is to work on fast turnover and pure speed, then you should expect to see your heart rate exceed 95 percent of maximum at the end of your intervals. The same is true of hill repeats where building leg strength and anaerobic power are the goals.
3. Stop Doing Intervals Wrong. While it's important to push yourself to maximal effort levels during a speed interval or hill repeat, it is equally important that you let yourself recover fully between each one. The whole point of these workouts is to repeat a maximal or near-maximal effort, so if you aren't fully recovering between, you won't be able to push yourself as hard or do as many repeats as you otherwise would—and that's a missed training opportunity.
A good guideline for sprints and hills is to warmup easy for 10 minutes, then go very hard for 20 to 30 seconds so your heart rate reaches 90 to 95 percent max at the end, followed by a very easy recovery effort for as long as it takes to get back down to 65 percent max. Repeat for the desired number of intervals or minutes. As the workout progresses, expect your working heart rate to go higher and higher, maybe even hitting 100 percent while your recovery intervals take longer and longer. That's exactly what you want to do to maximize the physiological benefits of those workouts.
Once you've established your unique heart rate maximum, you can put it to use in every training run, which will pay off big during your next race!
READ THIS NEXT: Training Zones Explained
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