Do cool downs matter?

There’s a familiar pattern recommended for most workouts. Start with a period of light activity, as a warm up. Then proceed with your workout. Finally, bring the intensity down in a gradual manner, the cool down. Proponents of this method tout the last stage as facilitating recovery, promoting clearing of metabolites from the muscles and blood (American Heart Association and Mayo Clinic, as examples). But while these recommendations are ubiqutous, I’ve never seen a universal protocol as to how to cool down. How long does a cool down need to be? Should you use heart rate as an indicator? Does this matter for all exercise types, or only aerobic?

I did some research to answer these questions, and even definitions of cool down are mixed. Cool downs, in most studies, follow a protocol of reduced exertion for 5 to 10 minutes or until the heart rate is below 120 bpm. This active, lower intensity period is commonly called Active Recovery. Active Recovery is differentiated from Passive Recovery, which allows a similar reduction in heart rate and intensity, but accomplished it by simply ceasing to exercise.

Research on cool downs is not common; unfortunately where there is conventional wisdom, there is often a lack of research. I did find three pieces of research I wanted to share:

• First, a narrative review of the psycho-physiological and performance effects of cool down. Researchers found that active cool down is ”  largely ineffective with respect to enhancing same-day and next-day(s) sports performance, but some beneficial effects on next-day(s) performance have been reported.” Researchers also found that active recovery can also interfere with muscle glycogen re-synthesis.
• Next up, a study on heart rate recovery following dynamic exercise. Researchers found that as compared with passive cool down, an active recovery period lead to a lower heart rate after exercise. Researchers concluded that this lower heart rate was the result of improved vagal tone. This research was conducted on just 6 athletes; I’d note that the effect was just within the margin of error and the study has not been replicated (based on my search).
• Finally, here’s some research looking at markers of physiological recovery following exercise with different recovery methods. The specific subjects in the study are recreational athletes, and as such, it’s specifically of interest to me. Researchers investigated recovery strategies including active recovery, passive recovery, cold-therapy, and massage. No strategy was more effective than passive recovery, and active recovery was even somewhat disadvantageous. Researchers did find that cold therapy and massage did lead athletes to report subjective improvement in recovery.

There’s not a ton of research on cool downs, and what research has been done has not been conclusive in support of the practice. For athletes, I would recommend a brief cool down if it adds value to your workouts. If you don’t have time one day, don’t feel like you’re cheating yourself if you skip your cool down. There’s not a clear physiological benefit to the practice, but in most cases there is little downside.

As always, if you have comments or questions, please comment below. And as noted yesterday, talk to your doctor before starting any exercise routine.