If you're not properly recovered then you won't get the benefits of a high-intensity session.

There is no denying the power of properly dosed hard workouts, but determining the correct timing can be tough. Some time-crunched athletes try to maximize the intensity of every workout, while others take the more conservative 80/20 approach, making eight out of every 10 sessions easy and reserving only two for “hard work.” So how can you tell if you’re recovered enough to execute another high-intensity workout?

It’s more important to know if you’re recovered enough to do another hard workout and benefit from it. Because the purpose of a hard workout isn’t surviving the workout, it’s to gain some measurable fitness.

In 2007, a group of Finnish researchers looked at this exact question. Their study showed that when athletes saved their high-intensity workouts for when their Heart Rate Variability (HRV, a measure of autonomic readiness) was higher than average, they added four times more fitness (VO2max) for exactly the same amount of work, compared to those who didn’t listen to their body and followed a more rigid workout structure.

The practical takeaway here is that monitoring your HRV is a great way to tell when your body is recovered enough and ready to benefit the most from the next hard workout. There are many apps available to help you do this, but if you prefer a lower-tech approach, the following are all indicators of a strong and ready nervous system:

Am I Recovered Enough? Look at These Factors

Sleep
Are you sleeping deeply and well through the night?
Weight
Is your weight in a stable place – not gaining or retaining?
Mood
Are you generally in a good mood and not easily agitated?
Responsive Heart Rate
Is your heart rate responsive during your warm-up or is it slow to come up?
Spring in Your Step
Are you feeling light on your feet? Is your cadence in a normal range or are your legs feeling heavy?

Running through this daily checklist before you commit to a hard session helps minimize injury risk and will ensure you get the most from every hard workout you do.

Alan Couzens is a Boulder-based exercise physiologist with a master’s degree in sports science. He is also coach to professional and top amateur endurance athletes. You can find him on Twitter @alan_couzens and at Alancouzens.com.