A guide on what heart rate can tell you about your training & how to choose the best heart rate monitor for you.
What does heart rate tell you?
A heart rate monitor measures how fast your heart is beating as a unit of heart beats per minute. The higher the intensity, the faster your heart will beat until you reach your maximum heart rate. The figure below shows heart rate as a function of running speed during a stepwise fartlek run. From the best fit line we can see that there is a linear relationship between running speed and heart rate.
How to use heart rate in your training
Heart rate can be used to design training zones similar to speed and power training zones. Heart rate training zones can be expressed as either a percent of maximum heart rate or as a percent of lactate threshold heart rate. It is very important to use accurate values for maximum or threshold heart rates, otherwise your training zones will be inaccurate. I do not recommend endurance athletes use the formula of 220 – your age to predict maximum heart rate. This becomes particularly problematic for middle-aged athletes who have a much higher maximum heart rate than this formula predicts due to years of training and enhanced aerobic fitness.
How to get an accurate maximum heart rate value
- In a laboratory setting, an athlete can perform a graded exercise test whereby either the percent gradient or the running speed is continually increased until the athlete reaches their maximal capacity. It can be challenging to reach maximal capacity in these tests particularly for recreational athletes that may not be used to pushing themselves that hard in training or for runners who aren’t used to running on a treadmill.
- In a field setting, most athletes will reach their maximum heart rate during a 5 km or 10 km race. The graph below represents a TrainingPeaks screenshot from an athlete’s 10 km road race. The red tracing represents heart rate, and the green tracing represents running speed. In this instance, the athlete did reach his maximum heart rate during the 10 km race. I first look for any artifact values that are obviously from electrical interference or movement artifact. I then eliminate the first 3 – 5 minutes of the race data as it takes several minutes for heart rate to reach a steady state value. Finally, I follow the remaining tracing searching for the maximum heart rate and will create range that includes 3 beats per minute. In this example, the maximum heart rate was 183 – 186 bpm.
How to get an accurate threshold heart rate value
An entire book could be written on threshold heart rates, power outputs, and speeds. For the sake of brevity, I will discuss what I have found to be the most practical in working with endurance athletes.
- Athletes run or cycle as hard as they can for a duration of 30-minutes. I then take the average heart rate from minutes 10 – 30, and this is a predicted threshold heart rate for each of those disciplines. You can read more about this in this article by Joe Friel, https://www.trainingpeaks.com/learn/articles/joe-friel-s-quick-guide-to-setting-zones/.
If working with a five-zone training model, the table below represents percent maximum and percent lactate threshold heart rates for each training zone. There will be slightly different values depending on the coach or scientist you refer to.
Heart rate is impacted by a number of factors including heat, humidity, stress, hydration levels, and sleep to name a few. I believe one of the most useful ways to use heart rate is to look for instances where heart rate mismatches pace and/or power. For example, if a runner normally has a heart rate value of 140 – 145 bpm when running at 7:30 / mile pace, but one day that runner is displaying heart rate values of 155 bpm at the same pace it would be a flag for concern. Was the temperature significantly warmer? Did the athlete report poor sleep quality, increased stress, or dehydration? It signifies that the athlete and/or coach should investigate further to address the discrepancy.
What heart rate monitor should I use?
If heart rate is an important metric for you and your training or you use heart rate training zones, I recommend that you use a chest strap heart rate monitor. Although wrist-based optical heart rate monitors are convenient, research has shown that chest strap heart rate monitors are more accurate than wrist-based monitors.
In conclusion, I believe that accurate heart rate data is a helpful additional tool to use in monitoring athletes’ training. It should be used in conjunction with other tools such as pace, power, and rating of perceived exertion. No one thing is going to be the magic bullet in someone’s training. Learn to diversify the tools you use in your training, and you will be a more knowledgeable, healthier and faster athlete!