Do Recovery Runs Work?

The magical recovery run, truly a thing of physiological beauty. Lace up and run hard one day, absolutely destroy your muscles, head out again on a short and easy recovery run the next day and things improve — your muscles heal, waste is cleared and the world is a better place to be in. But is this really how things work? Do recovery runs actually help us recover? Let’s explore what the science says and answer that question. 

Before the science stuff though, let’s look at what contemporary culture says a recovery run actually is. 

Wherever we look online, we see pretty much the same thing — do a short, easy run up to 24 hours after a hard session, and it will aid in our body’s recovery. It does this by increasing blood flow, which pumps oxygen-rich blood to our bodies to clear out metabolic waste and aids in muscle repair. It relieves pain and reduces that tight, heavy feeling in our legs. And, it also adds mileage to our week while not introducing additional stress to our bodies. 

Is this how it actually works though? Do recovery runs actually do all of this for us? Let’s investigate. 

Let’s start by actually defining what recovery is.

Interestingly, definitions are all over the map because recovery can mean different things depending on its purpose. Any time we go for a run, we’re damaging muscles, depleting glucose, changing our fluid balance, etc… and all of these things “recover” at very different rates. My thinking is that we have two points, A, where we are post-long run, tempo or interval session, and B, where we were before. So, a definition should take us from A to B. Here’s my working definition: 

“Recovery is the process by which the body restores physiological function or capacity that has been temporarily reduced or disrupted by exercise.”

How’d I do? Kinda sounds like I have a PhD after my name, right?

So, the question is: does a recovery run help restore that physiological function or capacity that has been disrupted by our harder training runs? Does it help get us from A to B more quickly. 

Let’s examine the claims of a recovery run one by one. 

Increased blood flow 

Yes, absolutely. Whenever we lace up and head out on a run, blood flow does increase. Keep in mind though that blood flow increases any time we raise our heart rate, whether that’s through exercise or drinking our morning coffee or tea. It’s the body’s way of saying “Wait, something just changed, let’s send some more blood to the body to address it.” And the body seems to be highly intentional when it does this — when heart rate and blood flow increases, there’s good reason for it.

When we start running, whether it’s an interval session, a long run, or a “recovery run”, we’re adding stress to our muscles. We’re putting additional load on them — the muscles are doing a lot of work so they need more oxygen and fuel, more CO₂ and other byproducts need to be cleared, additional heat needs to be dissipated, etc… And this moves us to our next point, immune/inflammatory cells arrive in greater numbers.

Aids in muscle repair

Blood flow increases, but does increased blood flow help muscles repair more quickly? This is where things get a bit murky, and a bit misrepresented. I think the answer is yes but… there’s a “but.” 

At the risk of sounding pedantic, I’ll back up a bit to talk about what’s going on. 

Firstly, any time we turn our feet over a few thousand times, any time we go for a run, we’re putting stress on our muscles, we’re causing damage. True, it’s not in the magnitude of yesterday’s interval run, but new damage is still being incurred. 

And secondly, blood is all about transportation, it doesn’t heal; it supports healing by carrying things to and from the damaged tissue. 

Think of repairing damaged muscles as a worksite. When we run, we’re creating a work order asking for muscles to be repaired — yesterday’s interval run created a work order and workers and supplies have been dispatched to the job site. And now we’re expanding the scope of the work order as we do our “recovery run”, asking for more workers and supplies. So, it’s not that increased blood flow speeds up the repairs on the damage that was created yesterday. It’s more that the increased blood flow is intended to deal with the new damage that’s now occurring, to address the amendment to the existing work order. Again, the body is very intentional in how it acts.

But, remember the first work order that was written as a result of our interval run? Those workers are already on-site, and will remain there as the muscles are being repaired. And, to facilitate this, our bodies have already increased blood flow locally — to the worksite — and will continue to do that largely until the work has been completed. 

Think of a time that you cut a finger. The cut doesn’t heal immediately, and doing a “recovery cut” won’t speed things up. But, the body has and will continue to increase blood flow to the area of the cut until it’s healed. Same thing happens in our muscles. 

So, saying that a recovery run speeds up healing? I’m not seeing the evidence that supports that. Rather, it seems to be a case that we’re adding more work to a process that’s already underway. So does increased blood flow aid in muscle repair? Yes, but not in the way that recovery run proponents represent. 

Clearing out Metabolic Waste

When mentioning that recovery runs help clear out waste, lactate is the waste product that’s almost always mentioned. There are a few problems with this. First, lactate isn’t metabolic waste. Second, lactate doesn’t hang around for 24 hours post-run to be cleared out, even if you wanted to clear it out. 

It’s true that lactate used to be considered metabolic waste, but that was only until the 1970s when UC Berkeley professor George Brooks started to suggest that lactate actually played a fairly important role in our body’s energy production. Fun fact that’s actually relevant: Brooks worked with a team and created the sports drink Cytomax, which included lactate as part of its blend to get energy to muscles as fast as possible.

So lactate as a waste product? Seems to be old-school thinking that was well on its way out by the time cell phones became popular. But just for fun, let’s look at how long it stays in the system post-run. 

When we begin a run, and I’m talking about just the first few steps here, the body senses that it’s going to need more energy, so it starts producing it (referred to as adenosine triphosphate, or ATP by the cool kids in science ATP by the cool kids in science). Part of this process also involves making lactate, which can also be used to produce more ATP as needed. As is often the case though, the body can produce more lactate than it’ll actually need so yes, there can be a buildup of lactate.  

So, we can have all of this lactate floating around in our blood. What happens to it? We use it or we convert it to glucose and store it. In either case, it’s typically gone within an hour. In other words, by the time you lace up for that recovery run, in part to clear out this “metabolic waste” that has been produced on our run, it’s long gone. 

Makes Our Legs Feel Better

Well, yes, a recovery run absolutely can make our legs feel better after a hard run the previous day. And I’m not even going to bother hunting down a scientific study for this because I’m not refuting it and it’s been experienced by so many runners, myself included. Keep in mind though, that this is merely an experiential effect; it says nothing about whether or not our legs have actually experienced any physiological recovery. And this makes it either its weakest, or its strongest point. Let me explain. 

The Recovery Run, its Original Intentions

It’s hard to pin down exactly when the phrase, “recovery run” was first used, but the earliest uses that I can see come from workout plans like those detailed in the Daniels’ Running Formula. 

Jack Daniels uses a “recovery run” as an interval workout of sorts. He’ll have you run hard for a given distance, and then take a slow jog, at a point called a Recovery Station in between intervals. The intent was to give your system a break in between intervals to allow your heart rate to come down and for your legs to regain some of their strength before going hard again. And this is a technique that many still use today except we call them things like an interval session with recovery jogs. So that part about making your legs feel better as part of a recovery run? That was a huge component of the workout. 

New Zealand running coach, Arthur Lydiard used the concept of a recovery run in the 1960s, but it was a bit different than what Daniels did. His athletes put in a lot of miles, and I mean a lot. Adding an easy run after a long or hard run was a tactic that he used quite a bit. The intention wasn’t to stimulate healing though — it was used as a way to help runners continue to build and maintain their aerobic base while keeping the stress on their bodies relatively low. In Lydiard’s words, “Do all of the easy jogging you can, along with the hard running.”

And the way that Daniels and Lydiard treated recovery runs? I think that’s how they should appropriately be viewed. 

I think that my issue with a recovery run isn’t necessarily the run itself; it’s more with how we’ve morphed its meaning into something that doesn’t have any scientific basis. There’s zero evidence that I’ve seen that suggests that they promote healing, and there are at least two huge issues with their claimed ability to clear out that metabolic waste product, lactate. 

I also think that calling them recovery runs can lead to some pretty negative results. And I’m thinking of a new runner who’s just run their first 10k and has heard that a slow run the next day will help fix what’s broken. I’d say that’s bad advice. So I think we have a branding problem with the name. 

Can they be a valuable part of a running plan? Absolutely. Personally, I’ll do an easy run the day after an interval workout; it feels good and my body can handle it. The day after a long run though, I’ll almost always have an off-day. That’s just me though — your mileage may vary. 

And with that, I’ll get off my soapbox. 

Keep moving.

Sources & Further Reading

• A Systematic Review on the Effectiveness of Active Recovery Interventions on Athletic Performance
  – An analysis of how low-intensity active recovery impacts subsequent performance and physiological markers in trained athletes. (via PubMed)
• Effectiveness of Recovery Strategies After Training and Competition in Endurance Athletes
  – An umbrella review evaluating real-world recovery protocols and their actual measurable outcomes on endurance performance. (via PubMed Central)
• Physical therapy interventions for the treatment of delayed onset muscle soreness (DOMS)
  – A systematic review comparing physical interventions against perceived leg tightness and objective muscle recovery. (via ScienceDirect)
• Q&A with Arthur Lydiard
  – Archival insights into Coach Arthur Lydiard’s original methodology on easy mileage and building aerobic foundations. (via International Running Academy)
• What is a recovery run?
  – A breakdown of modern training advice and popular claims surrounding post-workout easy runs. (via Styrkr)
• The lactate shuttle during exercise and recovery
  – George Brooks’ landmark research outlining how lactate acts as an active fuel source during and after exercise rather than a metabolic waste product. (via PubMed)