We use a lot of numbers at the gym—reps, sets, pounds, mileage, etc. One you're probably not dialed into on the reg? Your maximum heart rate. Your maximum heart rate calculation (MHR) is super important because it helps you determine the best exercise intensity for whatever workout you're doing. For years, we've used the formula "220 – age" to calculate MHR, then multiplied the MHR by certain percentages to determine the right heart rate "zones" to exercise in:
- 50 to 70 percent (MHR x .5 to .7) for an easy workout
- 70 to 85 percent (MHR x .7 to .85) for a moderate workout
- 85 to 95 percent (MHR x .85 to .95) for an intense workout or interval training
But, like every formula, the 220 – age formula is just an estimate and more recent research is showing it's not a very good one.
The only way to truly know what your maximum heart rate calculation is, is by testing it in a laboratory. Since this isn't practical for most people, we want to give you better tools to help determine your exercise intensity. A combination of the following fitness tips should help you figure out where you are when working out and where you need to be. (P.S. Can Your Life Expectancy Be Determined by a Treadmill?)
1. Talk test your workout routines. This is a super-easy way to figure out your intensity.
- If you can sing, you're working at a very easy level.
- If you can maintain a conversation with a friend, you're generally working at a moderate level. If you can say a sentence or so at a time and maintaining a conversation is more challenging, you're approaching a somewhat hard level.
- If you can only get out a word or two at a time and conversation isn't possible, you're working at a very hard intensity (like if you were doing intervals).
2. Determine rate of perceived exertion (RPE) in workout routines. We use this gauge frequently in Shape. Like the talk test, it's very easy to apply to your workout. While there are a couple of different scales that researchers use, we like the 1–10 scale, where:
- 1 is lying in bed or on the couch. You're not making any effort.
- 3 would be the equivalent of an easy walk.
- 4–6 is moderate effort.
- 7 is hard.
- 8–10 is the equivalent of sprinting for the bus.
You can only sustain a 9–10 for a very short time.
3. Use a heart rate calculator in your workout routines. Keeping in mind that most heart rate formulas have a wide margin of error, one formula that seems to be more accurate, according to Jason R. Karp, an exercise physiologist and running coach in San Diego, is 205.8 – (.685 x age). E.g. If you're 35, your maximum heart rate calculation using this formula would be 182. (Put Your Heart (Monitor) Into Your Workout with classes tailored to your MHR.)
Use a combination of the above methods to determine your exercise intensity and you'll get better, more effective workout each and every time.