Science/physiology behind Rest Days?

dude, think back to when you were a teen. my buddy and i used to meet up after our respective select games, order a pizza, and watch sunday football. that also counts as recovery and energy replenishment.

you're trying to confuse that with adult responsibility. but most people can't break their youth PRs as an adult.

to be blunt, i doubt 40 mins of walking around zaps a kid much. if you're fit to run 6-7 quick miles a day, walking 2 is more like an easy day.

personally i thought easy runs were contradictory nonsense, what you actually want is a pool or a bike, ie, off your legs.

As you can see by the hot air in the comments, no one has any scientific rationale for or against rest days

This is reasonable info & advice on the topic.

I've heard this a lot in argument in favor of rest days and it makes some sense to me, and I've planned my training on account of this, but I think it might be egregiously oversimplified or misapplied. Is my body only able to adapt on days I don't run? Does running, lets say, 4 easy on Sunday have any impact on how I recover from the other 6 runs I've done that week? If so, why? This logic is commonly accepted, but it doesn't really make sense to me.

The mention of Norwegian singles is because part of it is the encouragement to not periodize and maintain as consistent of a load as possible. Also, part of the mythology of Sirpoc is that he trained at a sustainable level every day for 2 years straight. I think running every day is a logical extension of the idea that load should be as consistent as possible, because running every day except one is a massive difference in load within the week and seems very inefficient. I don't think this logic would extend to upending the hard easy principle due to muscle tension.

Months ago, Mo Farah said on a podcast that he would take a rest day every 2 or 3 weeks during his in-season training.

I think it is a myth that elite runners don't ever take a day off, they do, but not every 7 days.

Elite runners, like most professional sports people, also have downtown after a season or an A race. They make take a month off to completely unwind. Sifan Hassan took 4 months off after the Paris Olympics.

It's going to be impossible to control for all the variables that make one approach better than another.

Taking a full rest day can be helpful mentally if the athlete just needs to switch off periodically to avoid burnout. There's also some limited evidence that I found somewhat compelling that even if you have muscle recovery and adaption, it's good for your endocrine system to have periodic total rest days to stabilize cortisol, allow for full glycogen recovery, reset hormonal responses, and catch up on caloric intake. I recall Elise Cranny had a period of time after hard racing and training where she skipped a period and found herself in deep fatigue from RED-S despite not intentionally restricting calories. A rest day here and there can be protective against getting in those sorts of holes because it can help with energy balance and hormonal function.

That said many athletes run 7 days a week and it can also be helpful for certain soft tissue issues, like chronic achilles issues to avoid total rest (say do a 3 mile shakeout instead of a rest day). Probably the overall total load over months is more important than total rest days, but some athletes find planned rest days helpful.

I think you're bringing up legit points for which there is probably no existing answer. To get an actual answer based in science, it seems like the thought process would have to go something like:

1. What are all of the physiological components of recovery: restoration of parasympathetic nervous system function, muscle fiber repair, liver and/or muscle glycogen restoration(?), and ???

2. For each of those components, to what extent does a total rest day produce a different effect from say running at <70% max HR for a few miles?

3. If there are any situations where a total rest day is different than jogging, "different" in what direction? I mean, at least for the nervous system, jogging is likely an improvement in recovery since HRV goes up after low intensity exercise. And maybe we would find out that muscle fibers are repaired more quickly when there is increased blood flow from jogging than when the person just sits around the house.

4. If there are some components of recovery that are sped up by an easy day as opposed to a total rest day, and some that are slowed down by an easy day as opposed to a total rest day, how do those balance out in terms of some sort of total recovery value?

The science behind a rest day? It's to rest and recover. Empirical data outweighs your stupid "scientific" evidence.

Ya, it seems the lower percent of volume done at a fast pace, the less someone gets injured. Someone doing 20 miles faster than easy pace is much more likely to get injured at 60 mpw than 120 mpw. But of course, jumping in mileage greatly increases injury risk, so buildup has to be gradual.

I consider myself a serious hobby jogger. I don't race much but love to train and see my body adapt.

I started back to training after 6 months off a couple years ago. Here was my plan: run hard for 20-40 min, depending on how I felt. Run easy for 40 min/day until I feel like running fast again. Sometimes it would take 2 or 3 days of easy running until I felt like running fast.

Now, two years later, I can run 70 minutes per day without my body breaking down, although I occasionally run for 1 hr 40 min, and only run 40 min very slow the next day.

Just skimmed the thread, but if you're looking for the SCIENCE behind rest days, look into hormonal responses to various types of exercise.

There are plenty of "scientific rationales" in the sense of theories that are informed by science. What we don't have is any science that directly proves that rest days are or are not beneficial. That's true of most training. It's nearly impossible to do realistic, controlled experiments with something as multi-faceted and long-term as endurance training.

To actually address the original question, the choice between a true rest day and an easy day mostly comes down to the athlete's training capacity. Elite distance runners rarely take true rest days, but they can handle so much training that a one-hour easy run doesn't interfere with recovery. Newer runners are likely to need multiple days off per week.

I was able to run a sub 3hr marathon with no training, lol so take that for what its worth. Suckers!!!

I always thought rest days were good because resting was easier than working out.

A list of some of the top athletes that only run six days a week:

Conner Mantz, Clayton Young, Kenneth Rooks, James Corrigan (and the rest of the BYU team), Parker Wolfe, Ethan Strand, Graham Blanks, Nikki Hiltz, Drew Bosley (potentially more NAU/Mike Smith athletes, he likes the rest day), Hobbs Kessler, Cole Hocker, Cooper Teare, Josh Kerr (interesting 2/3 of 1500 podium in Paris), Georgia Bell, Keely Hodgkinson. To name a handful. I’m sure there are plenty more big names I missed. Point is, it’s not unheard of for elites to take a day off.

So basically you are making excuses of why not to keep the load consistent on a daily basis. There is no evidence for consistent load over days and pretty much all the evidence points against it. It is why everyone does hard easy. Consistent load over weeks/months is a lot more defendable.

running every day definitely appeals the low level ocd that some people have. Proving that a super low day causes better super compensation is also going to be very hard to prove. Same thing with proving you can do more load in 7 days versus 6.

What is the NSA? I know the double treshold, but singles approach?

You are correct there aren't any scientific studies that prove restdays are or are not the very best recovery.But the claim that elite distance runners rarely take true rest days is not entirely correct. It varies even among them. Most Kenyan elites take one day off every week, not due to any scientic proof ( that don't excist )) ) , but more due to the religious society where many go to church and take one day off in the weekend to socialice with family and friends. It seems to work very well.....😎