Science/physiology behind Rest Days?

I think the rest days in running has more to do with the stress on joints and tendons more than anything else. Over the years, the guys in our running group who have maintained their age group speed at a national level more than other guys are the ones that kept their running to 5 days per week and cycled, swam or walked on their off days to keep active but not pound. The guys that just continued to run high mileage 6 or 7 days a week are either just jogging now, injured or no longer running. If it is considered a life sport, I would recommend the 5 day approach.

Easy running. The difference is the debate on how mechanical load affects your recovery. Nobody is really worried about the heart and muscles as much as tendons and bone health.

And to some extent it is also a lot easier to go really easy on the bike.

you need to recognize energy systems

aerobic anaerobic gas tank

different tissues take different time to repair

nutritional deficiency mineral can take months or more to bring back

aerobic adaptation is continuous moderate stress like 70 or so minutes per day

anaerobic adaptation is every other day or every three days intense repeats

gas tank is 90 plus min runs without fuel, or with cross training to adapt

taking a 3 day holiday regularly from running shores up a lot of deficits and allows repair

if you are not running a deficit, you actually don't need days off.

i think once you start setting PRs and have a great streak going, take a day to 3 day holiday, and come back with something like a 70 minute steady run and back at it.

then there is the every day adaptation, like 10x150m strides, which tunes specific firing and muscles, with minor anabolic effect.

to keep your speed you want to monitor the catabolism vs anabolic

over the years distance runners adapt to the net pace of their work, which compromises so called fast twitch, and you need hard high intensity work with full recovery to build back up, and up the protein as well, aka body builder style (moderate) to get a quarter pound muscle in exactly the right places.

this is the alchemy of training, and everybody's body is different, and different every year.

after you have a big engine, you need less weeks on aerobic volume, and can get at the threshold and speed quicker, and also fit in small holidays

Yea that's all good advice.

Consistency over time is keyyyyyyyyyy

The Norwegians run below 90% most of the time. So it's very common for them to run higher mileage because the intensity for them is low. Eliud Kipchoge believes in this same training philosophy where he believes volume is the key instead of intensity. So instead of him taking 1 quality rest day you may see him replace it with easy jog or cross train. Some Kenyans also do this same thing where a typical rest day for them is 1 hour easy run and then they go to church. Does this same rule apply for beginning runners? Absolutely not. Having a continuous training week as a beginning runner can cause burnout.

I take my cue from the other animals. I’m more a bear type, like a long rest, not a shark who never takes a break. Part cat too maybe—need more rest than activity. So, yes, I think the rest cycle just completes the life cycle

Haven’t taken a day off in two years. Only really do easy runs and thresholds. Not pure NSA, but similar. Ran PRs from 10k to marathon at age 46 and 47.

I just ran 6 weeks straight without a rest day and I have a few takeaways.

I think that the training load I was doing was easier in one week in isolation, but by the time I got to 6 weeks my cortisol levels were probably decently elevated and it was starting to impair my recovery. In hindsight I probably needed a rest day on the third or fourth week for hormonal reasons. At not point did what I was doing feel difficult mechanically, though I was starting the notice some niggles on the 6th week.

Something that might've effected some of this is that I have been running in Midwest USA heat and humidity as someone who struggles an unusual amount in those conditions, running too late in the day. Without the heat I might've been able to last several weeks longer until I needed a break. Sometimes I would go for an easy run in the heat and, despite being at like 65% of max heart rate and 9:30 pace, it would feel more difficult than the threshold workout I did the preceding day on the treadmill. I think on a decent amount of these runs if I were to have run for another 30-45 minutes I would've suffered the effects of a heat stroke, collapsed on the pavement, gotten run over by a car, and had to be hospitalized and/or given a closed casket funeral. I'm very young so I might've just been able to get away with this for some time until it inevitably caught up to me.

Also, I'm not sure how to determine how often I should take rest days. I'm not sure if one rest day every third week would be able to lower cortisol enough that it doesn't trend upward over several months. I've experienced trying to cram in a rest day every week making me more fatigued, though I was definitely running more than I should have. My take away is that I probably need a rest day every 2-4 weeks, though that might change in the future.

I'm wondering if Sirpoc might be more able to run for two years straight because he has years of experience cycling, versus someone like Hobbs Kessler who takes weekly rest days maybe because he has way years less experience with aerobic exercise. Sirpoc also runs in a relatively temperate climate and probably does a better job at controlling his environment to suit his needs for running than most do.

If you aren't on dope yourself you shouldn't follow the training of doped runners.

Let's put the question this way. When it comes to elite top runners there are both examples of runners running all days in the week and runners take a day off almost every week. Both seem to work very well , so why run every day in the week if it's not necessary to reach your individual peak performance?

Well, runners just running for the joy of it and health don't have to bother of it and can just take a restday or two whenever they feel for it... 🇸🇪🏃‍➡️🏃‍♀️‍➡️🇸🇪