How to use your heart rate as a guide for stress and recovery

You probably have some sense of what fatigue feels like.

You might have felt the symptoms.

Fatigue can feel like:

• “heavy” movement (e.g., feeling physically weighted-down, with a body that feels harder to move. Walking or running might feel like slogging through mud rather than snappy and weightless.)

• difficulty maintaining strong posture and form

• brain fog or slow thinking

• uncertainty and indecisiveness (difficulty making decisions or deciding what to do next)

• slow and delayed movement (rather than quick and snappy movement)

• feeling tired, depressed energy, and or depressed mood

• a vague sensation of feeling “off”, or somehow not quite right

• disrupted sleep

• more intense cravings, especially for refined carbs (sugar and sweets) or high-fat foods

• decreased sex drive

• getting sick often, or illness that lingers

Often, though, it’s not easy to tell if what you’re feeling is a deep and lasting body fatigue, or something else more mental or emotional.

For example, are you fatigued? Or are you simply bored and disinterested in working out today?

How do you know if what you’re feeling is fatigue?

How do you really know if your body would get stronger from taking on more stress, or if you'd be better off with more recovery

For more objective measures, track your heart rate.

Your resting heart rate (RHR) is the rate at which your heart pumps blood to support all your body functions at rest (i.e., while you’re not active or exercising). An elevated resting heart rate is a sign of an overly alert nervous system (specifically, your sympathetic nervous system).

What’s your normal resting heart rate?

To know whether or not your RHR is abnormally high, first you need to know your normal.

Track your morning heart rate every day for 3 weeks, then watch for changes and patterns.

To track your morning heart rate:

• As soon as you wake up in the morning, find your pulse by pressing two fingers down firmly either on your wrist or on your neck at the base of your skull.

• Watching seconds on a clock, count the beats for 1 minute.

• Record that number.

• Ideally, do this at about the same time every morning, before any other activity.

A normal RHR value for an adult is between 60 and 100 beats per minute. Trained athletes will have an RHR closer to 40-50 bpm.

Resting heart rate varies with:

• Age

• Fitness

• Training background (aerobic or strength training)

• Temperature

• Dehydration

• Stress (all kinds: mental, emotional, and physical)

• Smoking and medications

• Genetics

Heart rate is a measure of the body’s response to a particular work output, not of output itself. Max heart rate does not increase with fitness.

All types of stress are cumulative and have similar affects on the body. For example, mental, emotional, and physical stressors will all cause the body and heart to have to work harder to generate the same work output. That harder work will be expressed through an elevated heart rate.

If RHR is elevated by ~5-7 bpm (or ~10%), that’s a sign of increased stress and an elevated sympathetic nervous system.

Watch for elevations that persist for several days compared to your baseline “normal”.

In those times of elevated RHR, the body is less suited for training adaptations.

That means that continuing to add additional stress with challenging workouts won’t provide optimal gains, until the body is more fully recovered. An elevated RHR is a signal that an active recovery day (rather than increased stress) may be more beneficial for your long-term training gains.

When the body is primed to take on more stress (when RHR is low), the body will react positively in the face of increased challenges.

For example, when your body is recovered and primed for workouts, you’ll be able to:

• Be more energized and push harder

• More fully engage your whole muscle system

• Stay within stronger movement patterns to prevent injuries

• Build strength faster

Listen to your heart rate to stay closely tuned-in to your state of recovery. By knowing when your body is ready to take on more stress, you can maximize the gains you get in workouts and minimize the effects of prolonged fatigue.