Back in 1998, while I was pouring over my latest issue of Owen Anderson’s Running Research News, I came across a really interesting study on recovery that fundamentally changed the way I did some workouts for years to come.

What is the 36-Hour Recovery Rule?

Researchers at both McMaster University (Ontario) and Washington University (St. Louis) had six healthy young guys do some strenuous bicep curls with only one arm and then used an isotope tracer to compare protein synthesis between the exercised arm (which was recovering) and the unexercised arm (serving as baseline).  For the first 24 hours, recovery was well underway.  By 36 hours, recovery was pretty much done.

Of course, getting as fit as possible means incorporating as many hard (appropriate) workouts in the shortest time period while allowing for adequate recovery.  Too much recovery is just wasted time and potential loss of fitness.  An early morning workout, followed by an early evening workout the next day allows for the optimal 36-hour recovery window.  Then, an evening workout followed by a day off and an early morning workout on the third day also leverages the optimal 36-hour window.  This new 36-hour rule seemed so much more efficient than the standard 48 hour rule that most of us follow (i.e. hard day / easy day plan)

Since it was 1998, I was a lot younger and even more foolish.  So I developed a hard training plan that would fully capitalize on the 36 hour rule.  My plan had me doing tempo runs on Monday morning, followed by speed work on Tuesday night.  Then, I’d take Wednesday off.  Thursday morning was a long run and Friday evening it was right back to doing a tempo run.  Let’s just say that this schedule didn’t work out so well.  What went wrong and how do I now use the 36-hour rule?

The Limitations of the 36-Hour Recovery Rule for Multisport Athletes

When I first thought about where things had gone wrong, I thought that the problem was my age (I was 34 years old at the time) versus the youthfulness of the study participants (who were likely in their late teens or early 20’s).  Over time, I began to appreciate that the study…

1. involved measuring only muscle repair (i.e. protein synthesis)…
2. from a purely strength building exercise.

Recovering from the damage of multisport training involves a lot more than just protein synthesis, in large measure because our sport involves a lot more than just building strength.  For instance, energy systems need to be replenished.  This means more than just gulping down a bunch of calories immediately after a hard run to kickstart glycogen replenishment.  Also, fatigue in our sport is system-wide and not just confined to looking at protein synthesis in one limb.  Lastly, I think that a lot of recovery is mental; long hard workouts are mentally taxing and it can take some time before we really have the mental reserves to dig into an effort like that again.

How Can the 36-Hour Rule Affect Multisport Training?

While the 36-hour recovery rule certainly has some limitations and can’t be used constantly by even the youngest of multisport athletes, it has some definitely application for all multisport athletes.

1. Treat 36 Hours as the Absolute Minimum Recovery.  Use the rule to prevent yourself from doing too much instead of using it to set your expectations.  In other words, if you have just done a hard workout, remember that you need at least 36 hours if you want to be fully recovered for your next hard effort; don’t just come back 36 hours later and expect to be able to hammer out another tough one.
2. The 36-Hour Recovery Rule Generally Works Better with Short Intense Stuff.  You’ve probably experienced the gut-wrenching feeling of doing high intensity interval training (HIIT) like Tabata workouts.  This involves workouts like a 15-30 second all-out sprint, followed by a recovery of equally short duration, and repeated over and over again (pretty much until you puke– and then some).  As disgustingly hard as they are, the body also recovers much faster from these workouts than from doing a hard tempo effort, which in turn has a much shorter recovery time than a long hard run.  So if you are trying to cram as many hard workouts into a week as possible, you may be able to get away with doing a Tabata workout followed by another hard workout only 36 hours later.  I would further emphasize the word “may” in the previous sentence– so much has to do with your overall stress, baseline fatigue, recovery speed, age, etc.  If you do find that you can get away with 36 hours after your Tabata workout, just don’t expect the same amazing recovery speed on your tempo or long efforts.  If you find yourself recovering from everything in just 36 hours, either (1) you’re not going hard enough or (2) you have been taking some performance enhancing drug (PED) on the WADA list (in the latter case, please drop your name off in the comment section so you can be drug tested at your next event).

If you’d like to dig into the research backing up the 36-hour rule, you can check out an article in which Owen talks about the same study and offers insights into recovery nutrition.