What is Your Heart (Rate) Telling You?

What is Your Heart (Rate) Telling You?

While heart rate is often used to prescribe workout intensity, it can also give you valuable insight into the effectiveness of your recovery, hydration, nutrition, and more.

As a coach, I pay attention to my athletes’ heart rate for more than prescribing intensity. I review what heart rate tells us about recovery, fitness progression, general wellness, and the effectiveness of fueling and hydration plans. Understanding what your HR communicates can help you make decisions to adjust your effort as you train and race so that you perform your best, sustainably.  

Heart Rate & Recovery

If you aren’t sure what your baseline resting heart rate is, take some time to track it for a week or two. You’ll need at least seven days of tracking to establish a useful pattern. You can track your HRV (aka, heart rate variability, which looks at the variation in time intervals between heartbeats) as well. Generally speaking, the more variability between heartbeats, the better. To track HRV and resting HR, you can use an app or a wearable device such as the Whoop Strap or Oura ring. A bonus for the Whoop strap and some HRV apps is that they will upload directly into your TrainingPeaks log for easy tracking and pattern assessment. 

When all is right with your body, your heart rate will return to your normal baseline after you recover from a bout of training. On the other hand, if you observe an elevated or decreased resting heart rate for an extended period of time, that could mean that something — usually recovery or general wellness — is off. Exactly what that is could be a variety of things, so you and/or your coach will need to do some sleuthing. 

Likely suspects include the need for additional sleep, fluctuations in stress and hydration, improved workout or recovery fueling, more time between harder and/or longer workouts, or a weakened immune system (or recovery from illness). If you notice your resting heart rate is elevated for more than a day, review this list of likely suspects and see which one fits the bill for you.

If none of the above seem to apply, and the trend continues in a way that impacts how you feel and perform, it’s worth a trip to the doctor. In some cases, long-term disruptions in heart rate can be an early warning sign of nonfunctional overreaching or overtraining. 

Monitoring Heart Rate With Other Metrics

When I analyze an athlete’s training file, I look at all available metrics, which will vary depending on the type of workout and the devices the athlete uses. For example, let’s take a workout file for a run with tempo repeats. 

Let’s say I notice the HR is low relative to the pace compared with previous files. If this is the only information I have, I may infer that the athlete’s fitness is improving because he or she is able to run the same pace at a lower HR cost. That could be a sign of fitness progression, especially if the trend continues and all other metrics are positive. 

However, the athlete has ranked this workout an RPE (rate of perceived exertion) of 8 out of 10, when they typically mark a 6 or a 7 for this type of workout. Additionally, in the comments, the athlete writes: “My legs feel heavy.” Ah! The plot thickens! 

While the athlete still ran at a quick pace for their heart rate, the depressed HR could be a sign of needing more calories. If this is the case, then the athlete needs to replace their glycogen stores to support recovery; otherwise, they will feel the same (or worse) the next day. If this were a longer workout, it is certain the pace would eventually fade. If underfueling were to continue for several days, additional problems including diminished recovery would accumulate such that pacing will eventually be impacted. 

These symptoms may also relate to needing more recovery. If the previous day was a hard or long workout, we now have useful information that more recovery may be necessary. Remember that athletes respond to training differently, so the information heart rate provides is quite useful when combined with the other metrics, especially over time. 

Heart Rate, Pace, and Power

Comparing pace and power to heart rate can give you a sense of how training is progressing. When your HR, pace, and power rise and fall relatively close together, this is called coupling — it’s the sweet spot in training. Decoupling occurs in two scenarios: (1) when your HR rises as pace and/or power either stays the same or drops, or (2) if your HR rises more quickly than pace or power.

I like to see Pa:HR (ratio of pace to heart rate) or Pw:HR (ratio of power to heart rate) at 5% or less in order to be “coupled”. Beyond that is evidence of decoupling, which can be a sign of:

  • needing more fitness for the effort as executed.
  • dehydration, especially when you see a rising HR along with decreasing pace or power.
  • needing more recovery or sleep. In other words, your body is tired, and your HR is “touchy” as a result. This can also happen when your body or mind is under stress. 

Evaluating Your HR

For training and racing purposes, here’s a basic outline of what you should do when you see these metric combinations arise.

If HR stays the same while RPE increases…

Try consuming additional calories. This may or may not come with a decrease in pace or power, but for longer workouts or races, it very likely will if you don’t increase your caloric intake. 

If HR increases while power/pace decreases…

Increase your fluid intake, especially in warmer or humid conditions. Make sure that’s not just water, but also an electrolyte-heavy drink.

If HR or HRV is higher or lower than usual for several days…

You very likely need more recovery. This may also be a response to stress or disrupted sleep patterns. 

Remember that heart rate is sensitive to the energy cost of a given effort. So, on hot or cold days, you may notice that your HR is elevated or depressed in comparison to power or pace. As such, you should train in varied conditions so that you understand how much of this cost your body can reasonably pay for. This can also help you adapt to temperature and humidity fluctuations, which can prove vitally important come summer racing.   

I hope this provides you with a good foundation to understand how useful your heart rate can be as a training metric. As you can see, this goes well beyond the prescription of workout intensity.

Maria Simone

A USA Triathlon Level 2 endurance and USA Cycling Level 2 certified coach, Maria Simone is the owner and head coach of No Limits Endurance Coaching (www.nolimitsendurance.com). She enjoys long weekends in the pain cave, races with hills, and hard runs through meandering single track trails with her husband and two dogs. Maria takes a holistic approach to training that considers physical ability, mental strength, and life-work-training balance. Maria works with endurance athletes of all levels, with the common thread of helping her athletes pursue and achieve their big dreams. She blogs about her personal experiences in training and racing at www.runningalife.com