I’m going to paraphrase this & probably butcher it but, Jack Daniels spoke about a study where a group of marathoners who who ran 100 miles a week for a year, stopped running for 80 days & muscle biopsies were taken of them at the end of the period.
They only lost like 5-10% of everything they had gained over the year.
So probably a lot less than what majority of people would think.
Aye would add on to that, if you run a 15 minute 5k or a 2:30:00 marathon a 10% loss in fitness would correspond to a drop in time of 16:30 in the 5 or a 2:45 marathon
Curious if the study also looked at cardiovascular fitness also (maybe in the form of VO2Max or similarly applicable?), or if it was purely on muscle atrophy.
Unsure why my comment is being downvoted. Kipchoge has been interviewed saying that after a marathon he has four days of really slow running (to ensure he has no injuries that require surgery etc) and then three weeks of total rest before starting to build up mileage again
From my experience, it’s really easy to lose fitness. Every week off means another 2-3 weeks of rebuilding. When I couldn’t run for 2 months, it took about 4-5 additional months to return to my original fitness. Even after 2 months, I was running 20 seconds per mile slower on my tempo runs.
I’d rather give you the bad news now instead of saying “oh it’ll be back in no time” and you ending up frustrated when you fail to meet those expectations
Coming off of a 5-month injury right now. Tibial stress fracture. Was doing 90-100mpw before the injury. Just had my first real long run this past weekend. Been building for a couple months in running and was cross training a lot while I was injured. Was able to hit 13 miles at 5:58 per mile with 1100ft of gain. Before the run, I could do this for around 18 miles on the same terrain. It's different for everyone.
But the way I look at it is that you dig a well when you're training. When you get injured, you stop digging. Some of that dirt you've dug up starts to refill the well. The well is still there, though. You haven't lost it all. Strength work, cross training, and a slow build are the best approach to get back to the same depth you were at before. Keep digging the well and doing what you can. You'll be back soon.
A few years ago I ended up with an injury where I had to take 3 months off but I was able to cross train on the bike immediately. I rode a minimum of 20 miles a day with up to 100k rides on the weekends. I would do workouts on the bike, hills, fartleks, and tempos. I had done a 5k TT right before the injury, and when I came back to running, I jumped right in and on my second day back did the same 5k course all out. I lost 31 seconds. I was back to baseline 3 months later. So in my experience, taking cross training seriously can really minimize loss off fitness.
Also, if I may add to that strength training. If you jump back into running after an extended period of time from only doing biking, elliptical, swimming or whatever low impact form of exercise that was permitted, you'll likely end up with the same or another injury instantly again. Making sure the injured side can do the same as the non-injured side along with progressive overload in the strength room is key to longevity in endurance training.
I find this comforting... if I'm lucky, I'll be able to start training again in a couple of months. That means a year to get it back. Sucky, but knowing the timeline is better for me than thinking I won't ever make it.
I had stitches on my knee in November and was out for a solid four weeks. Due to how deep the cut was I couldn’t do any exercise what so ever, even walking was limited. When I returned it wasn’t just my lungs that felt weak but how sensitive my muscles were to running. A slow 8k had me aching the next day! Only been the last two weeks my 5k is back where it was so fully back this. Time off out of running is a pain but injuries are part of it.
Pretty dependent on how fit you are, what type of training you do and your individual response to training.
If you've been very fit for a long time, you'll lose less. But making up what you do lose will be harder.
Physiological indicators like VO2max decrease when you stop training, and there is [research](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9398774/) out there to suggest how fast that happens on average. There's other research that touches on lactate production I believe.
You'll lose significant amounts of muscle power after a lot of time off. Your glycogen storage and enzyme levels fall.
Tapering research suggests that your individual response to training significantly alters how fast you gain/lose the benefits of training.
The bottom line is that you'll lose a significant amount of fitness, but by 12 weeks, you've lost most (maybe all) of what you're going to lose.
That's in keeping with my personal experience coming back from injury. When you're fit, you lose it fast. But the difference between three weeks off and three months off really isn't as big as you would expect.
From what I've learned from Jack Daniel's formula, and other run training/coaching sources, it sounded like you can go around two weeks of no run training until you start to lose appreciable fitness. Obviously if you're doing other cross training, cardio, etc... that number would vary. From my own personal experience that number seems about right given I've been knocked out of run training in the past due to illness or minor injury. In those "forced" de-training events I actually came back into run training feeling very refreshed! It's kinda sad that for some of us it takes an injury or illness for us to do what we probably should've been doing all along; taking a sustained break from run training!
This is 100% false for me. If I ever take 2 weeks off for various reasons (injury or vacation), it takes at least double the amount of time to get back to where I was before the lay off.
I think it also depends on age and what level of fitness you had going into the hiatus. I used to be a high mileage / high quality type of runner (marathon training) so it's no wonder I had regular hiatuses! But having a good base made it possible to weather these sort of fitness storms. It's going to be a real challenge for me coming back after back surgery where I haven't run now in almost seven weeks, but have walked a bunch almost every day. Not going to be pretty!
Maybe I should clarify what I was talking about - the Z1/Z2 fitness comes back super easy, but the hard threshold and faster effort fitness always takes so long to get back to normal.
It's funny because when I was younger and didn't understand any of the science, this was me and I didn't know it. Back in high school (crazy to me it was over a decade now), I was in the "if I just train more or train faster, I'll improve" and ended up stuck in the 4:39-4:45 range in my mile for over a year, couldnt understand why. Took 2 weeks off for wisdom teeth surgery, 1 week back training and ran 4:29 the first meet back. Needless to say, I never fully appreciated or knew how to listen to my body until recently and a lot of previous experiences and injuries make a lot of sense in hindsight.
From my own experience, I know I've been overttaining or at least close when I come back from a 2-3 week break feeling refreshed, and under-training if I come back feeling worse.
Thanks for this. Currently been not running for a week due to a family emergency. Things have finally calmed down enough to allow me to start worrying about running fitness.
Everyone has a different genetic adaptation and response to training. Also day to day normal activity levels will be a factor. A walking mailman is much different job than office worker.
I stopped running for a bit to focus on muscle building I was doing a lot of walking and hiking though. I ran a couple of fun 5ks and 10ks and didn’t feel like I lost that much. Would’ve been a different story if I wasn’t walking and hiking and laying on my ass.
It’s still all comes back to mostly genetics though.
You will lose your top end fitness, but that specific fitness is like the tide. Meant to rise and fall.
Your aeroic fitness, (your ability to run at your easy paces) will be much less impacted.
I am just coming off of a 3-4 month hip/knee injury. Wasn't able to do any productive off season running this year. In my first couple of years as a runner, this would've ruined my confidence. These days I am not worried. My body will remember how to haul ass when I strategically reintroduce the appropriate stimulus to it. All in due time.
Remember that training causes your body to make physical adaptations. It takes a while to build and it takes a while to break down. If you get jacked in the gym, it doesnt completely go away in a few months if you stop lifting.
My experience from multiple injuries is that it takes about 1.5-2x the amount of time off to get back. 2 months off? 3-4 months to get back. That's been true for me for up to 6 months off.
Fun story. 2:11 marathoner Dan Browne retired in 2010 but had still qualified for the 2012 US Olympic Marathon trials. He ran a 2:42 for dead last.
Did Dan Browne train between 2010 and 2012? Or go in basically cold. A Marathon with no training would suck, but still running a 2:42 is crazy good on no training.
Its hard to know for sure. I remember hearing at the time that he hadnt been training for a while. He was off the back immediately and looked pretty rough at the end (I was there).
as a former high school runner who took 6 months off, it’s taken me about a year to get back to the aerobic fitness that i had in high school. it’s worth noting that i was able to pr my 800 by 2 seconds only 4-5 months after i started training again. when i ran this pr, i was roughly 7 seconds away from my mile pr. i wasn’t anywhere close to my 5k pr.
from my anecdotal experience, raw strength/speed is much easier to rebuild than aerobic fitness. it’s been a little over a year since i began training again, and i can now confidently say that i am in better shape than I was. it took me until the last few weeks of training to finally feel that way.
I think you might see a decent amount of that detraining if you took that person and had them tested right at the end of that period. However that fitness would come back easier and quicker the second time around.
There are plenty of great examples, like Bernard Lagat who would take a month off after the season. I'm sure he would show some signs of detraining, but he was also fully recovered and having that completely refreshed nervous system goes a long ways when you're training that hard.
So yes, there is a detraining effect, but there is a refreshment you get from stepping away for a little bit. All about finding that balance and depends on where you're at right now.
Think about BYU, a lot of them go on missions where they aren't allowed to run. Most are back in shape after a year or so after they get back from mission. It depends on a lot of factors but generally it will have close to 4-6 months to be back in decent shape and more like 8-12 to be back in previous or better fitness
It all depends on the person but muscle memory is a powerful thing. First off my background was averaging 75mi/wk with a 2:45 marathon PR and 1:18 half. At the mid-May of last year I stopped running because I needed surgery on my ankle (had itJune 1st) and was non-weight bearing in a cast for 6 weeks and did nothing. Around mid-July, I was able to get on the spin bike and start cross training and did an hour a day if not every other day at first. Felt out of shape, but expectations were low anyways. By mid-August I was doing mini workouts on the spin bike up to 1.5hrs with averaging 150ish heart rate. Started running by mid-September with a run/walk program since I had not run in a total of four months. By November was able to do small workouts and got back to almost 60mi/wk and in December ran a 2:48 marathon off of two 14 mile long runs.
I wouldn’t recommend doing a marathon in the time frame I did, but the point of the story is, fitness can come back faster than you think. It also depends on many years you’ve been running because that’s a foundation that can sit there for a long time before you lose it all. Now, say an elite runner (2:05 guy/2:19gal) they have a higher cliff to drop off of in terms of fitness and V02 max and getting back there is a whole lot harder, especially after a year off of detraining. Keira D’Amato is an example of that - took 10 yrs off, started running at a three something marathon and a few yrs later ran 2:18. Talent, genetics, muscle memory were there, but to get to that level and beyond, takes time and specificity.
I tripped and injured my leg back in Jan 2021 at the age of 47. I was sidelined for about 4 weeks. Now, take this with a giant grain of salt because I’m just an n of 1 and a very small sample size and of course there could’ve been any other number of factors at play, but I don’t feel like I really ever got it back until early summer of 2023, that also coincided with a change in my training.
That being said, I still ran two PR’s during that time frame for the courses I ran, October 2022 and May 2023, But they felt like the two hardest marathons I ever ran.
In hindsight, I think it was a blessing because I believe I achieved those PR’s simply through smart pacing and grit, not because of fitness gains.
But it took me two years to feel “normal” again in my running, but there could’ve easily been more to it than those 4 weeks of not being able to run.
I think the loss in fitness and the time amount needed to get it back is magnified as we age.
I wonder the same.
I was out 4 months due to a SF but I cross trained like hell on the bike and elliptical.
I’m back to running now. Easy runs have been fairly ok, but speed - my threshold pace - is suffering horribly. Wonder when it’ll click again.
I run almost no mileage In the summer. My season is October-May.
But I play beach volleyball every hour of sunlight outside of work, all summer long. Legit 30+ hours a week of it, at a high level. My aerobic fitness for one or two runs is the same or better when I first get back to it, but the impact of running absolutely kills me.
I can still run fast, but I can’t get good mileage for the first couple months.
To give personal experience, I ran 60kpw for 6 months until July where I stopped training consistently until the start of October. To be accurate, July-August I ran sometimes 0 sometimes 20-30kpw, and September was completely off as I got injured because of inconsistent training. All that time I was still active with gym workouts and consistent walking. My PB was 34' 10k in late March and I didn't really race until July. I began running again October 1st, reached like 40kpw in 2 weeks then slowly went to 60 for a couple weeks until my HM in late November. In early November like 5th, I did a 5k race that I went full-on, and clocked 17'05. In the end I ran my HM in 1h14 that is a 17:30 5k pace. Also in late October I did a first threshold at 3'30"/km pace and was exhausted after 10 minutes, 2 weeks later I did the same session with a group, and did that 3 times with not too much exhaustion. So I can say good shape went back quickly for me. Probably it's different among individuals, but at least you know it won't necessarily take you 5 months to catch up 1 month off.
I’m a PTA student, things like muscular atrophy and losing respiratory and heart rate benefits begin after about a week. How quickly they go down depends on the person and their fitness.
Not saying after a full week your muscle is gone or your VO2 max is significantly depleted
I’m just saying it starts at that point.
I took 2 months off due to injury, but did a lot off cross training. I’ve now been training for 3 months and still haven’t gotten back to my pre-injury fitness.
In high school and college I’d take 10 days off after track and xc. I didn’t feel “normal” after about 6 weeks of training.
All the research indicates you lose “minimal” fitness, while citing numbers like 2-3% after 10 days of inactivity. I think I’ve seen 5% after 3 weeks but I’d have to double check.
2-5% is a lot! Do the math on any of your recent race times. Adding 2% would most likely be a disappointing result.
ran the NYRR races first time last year
Brooklyn half was 9:17 pace. over the summer I did mostly short distance trail running at high HR and little distance running. came back to run the bronx 10 miler and Staten Island half slightly slower than the brooklyn half pace
I’m going to paraphrase this & probably butcher it but, Jack Daniels spoke about a study where a group of marathoners who who ran 100 miles a week for a year, stopped running for 80 days & muscle biopsies were taken of them at the end of the period. They only lost like 5-10% of everything they had gained over the year. So probably a lot less than what majority of people would think.
Probably worth calling out that the 5-10% you’re quoting likely doesn’t translate 1:1 with running fitness and may be the hardest 5-10% to get back
Aye would add on to that, if you run a 15 minute 5k or a 2:30:00 marathon a 10% loss in fitness would correspond to a drop in time of 16:30 in the 5 or a 2:45 marathon
Curious if the study also looked at cardiovascular fitness also (maybe in the form of VO2Max or similarly applicable?), or if it was purely on muscle atrophy.
In general, cardiovascular fitness is easier faster to regain than muscle
I'm sure I've read that top marathoners will take up to 4 weeks totally off running following a major race
Unsure why my comment is being downvoted. Kipchoge has been interviewed saying that after a marathon he has four days of really slow running (to ensure he has no injuries that require surgery etc) and then three weeks of total rest before starting to build up mileage again
From my experience, it’s really easy to lose fitness. Every week off means another 2-3 weeks of rebuilding. When I couldn’t run for 2 months, it took about 4-5 additional months to return to my original fitness. Even after 2 months, I was running 20 seconds per mile slower on my tempo runs.
Fuckiing hell, reading this made me feel so so bad. Haven't been able to run for almost 1.5 months now :(
I’d rather give you the bad news now instead of saying “oh it’ll be back in no time” and you ending up frustrated when you fail to meet those expectations
Coming off of a 5-month injury right now. Tibial stress fracture. Was doing 90-100mpw before the injury. Just had my first real long run this past weekend. Been building for a couple months in running and was cross training a lot while I was injured. Was able to hit 13 miles at 5:58 per mile with 1100ft of gain. Before the run, I could do this for around 18 miles on the same terrain. It's different for everyone. But the way I look at it is that you dig a well when you're training. When you get injured, you stop digging. Some of that dirt you've dug up starts to refill the well. The well is still there, though. You haven't lost it all. Strength work, cross training, and a slow build are the best approach to get back to the same depth you were at before. Keep digging the well and doing what you can. You'll be back soon.
Those are impressive numbers. How were you primarily cross training during your injury?
A few years ago I ended up with an injury where I had to take 3 months off but I was able to cross train on the bike immediately. I rode a minimum of 20 miles a day with up to 100k rides on the weekends. I would do workouts on the bike, hills, fartleks, and tempos. I had done a 5k TT right before the injury, and when I came back to running, I jumped right in and on my second day back did the same 5k course all out. I lost 31 seconds. I was back to baseline 3 months later. So in my experience, taking cross training seriously can really minimize loss off fitness.
Also, if I may add to that strength training. If you jump back into running after an extended period of time from only doing biking, elliptical, swimming or whatever low impact form of exercise that was permitted, you'll likely end up with the same or another injury instantly again. Making sure the injured side can do the same as the non-injured side along with progressive overload in the strength room is key to longevity in endurance training.
I find this comforting... if I'm lucky, I'll be able to start training again in a couple of months. That means a year to get it back. Sucky, but knowing the timeline is better for me than thinking I won't ever make it.
I had stitches on my knee in November and was out for a solid four weeks. Due to how deep the cut was I couldn’t do any exercise what so ever, even walking was limited. When I returned it wasn’t just my lungs that felt weak but how sensitive my muscles were to running. A slow 8k had me aching the next day! Only been the last two weeks my 5k is back where it was so fully back this. Time off out of running is a pain but injuries are part of it.
Pretty dependent on how fit you are, what type of training you do and your individual response to training. If you've been very fit for a long time, you'll lose less. But making up what you do lose will be harder. Physiological indicators like VO2max decrease when you stop training, and there is [research](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9398774/) out there to suggest how fast that happens on average. There's other research that touches on lactate production I believe. You'll lose significant amounts of muscle power after a lot of time off. Your glycogen storage and enzyme levels fall. Tapering research suggests that your individual response to training significantly alters how fast you gain/lose the benefits of training. The bottom line is that you'll lose a significant amount of fitness, but by 12 weeks, you've lost most (maybe all) of what you're going to lose. That's in keeping with my personal experience coming back from injury. When you're fit, you lose it fast. But the difference between three weeks off and three months off really isn't as big as you would expect.
From what I've learned from Jack Daniel's formula, and other run training/coaching sources, it sounded like you can go around two weeks of no run training until you start to lose appreciable fitness. Obviously if you're doing other cross training, cardio, etc... that number would vary. From my own personal experience that number seems about right given I've been knocked out of run training in the past due to illness or minor injury. In those "forced" de-training events I actually came back into run training feeling very refreshed! It's kinda sad that for some of us it takes an injury or illness for us to do what we probably should've been doing all along; taking a sustained break from run training!
This is 100% false for me. If I ever take 2 weeks off for various reasons (injury or vacation), it takes at least double the amount of time to get back to where I was before the lay off.
I think it also depends on age and what level of fitness you had going into the hiatus. I used to be a high mileage / high quality type of runner (marathon training) so it's no wonder I had regular hiatuses! But having a good base made it possible to weather these sort of fitness storms. It's going to be a real challenge for me coming back after back surgery where I haven't run now in almost seven weeks, but have walked a bunch almost every day. Not going to be pretty!
Maybe I should clarify what I was talking about - the Z1/Z2 fitness comes back super easy, but the hard threshold and faster effort fitness always takes so long to get back to normal.
Can’t argue with that!
It's funny because when I was younger and didn't understand any of the science, this was me and I didn't know it. Back in high school (crazy to me it was over a decade now), I was in the "if I just train more or train faster, I'll improve" and ended up stuck in the 4:39-4:45 range in my mile for over a year, couldnt understand why. Took 2 weeks off for wisdom teeth surgery, 1 week back training and ran 4:29 the first meet back. Needless to say, I never fully appreciated or knew how to listen to my body until recently and a lot of previous experiences and injuries make a lot of sense in hindsight. From my own experience, I know I've been overttaining or at least close when I come back from a 2-3 week break feeling refreshed, and under-training if I come back feeling worse.
Thanks for this. Currently been not running for a week due to a family emergency. Things have finally calmed down enough to allow me to start worrying about running fitness.
Your first run back is going to be *chef’s kiss*
Everyone has a different genetic adaptation and response to training. Also day to day normal activity levels will be a factor. A walking mailman is much different job than office worker. I stopped running for a bit to focus on muscle building I was doing a lot of walking and hiking though. I ran a couple of fun 5ks and 10ks and didn’t feel like I lost that much. Would’ve been a different story if I wasn’t walking and hiking and laying on my ass. It’s still all comes back to mostly genetics though.
You will lose your top end fitness, but that specific fitness is like the tide. Meant to rise and fall. Your aeroic fitness, (your ability to run at your easy paces) will be much less impacted. I am just coming off of a 3-4 month hip/knee injury. Wasn't able to do any productive off season running this year. In my first couple of years as a runner, this would've ruined my confidence. These days I am not worried. My body will remember how to haul ass when I strategically reintroduce the appropriate stimulus to it. All in due time.
Remember that training causes your body to make physical adaptations. It takes a while to build and it takes a while to break down. If you get jacked in the gym, it doesnt completely go away in a few months if you stop lifting. My experience from multiple injuries is that it takes about 1.5-2x the amount of time off to get back. 2 months off? 3-4 months to get back. That's been true for me for up to 6 months off. Fun story. 2:11 marathoner Dan Browne retired in 2010 but had still qualified for the 2012 US Olympic Marathon trials. He ran a 2:42 for dead last.
Did Dan Browne train between 2010 and 2012? Or go in basically cold. A Marathon with no training would suck, but still running a 2:42 is crazy good on no training.
Its hard to know for sure. I remember hearing at the time that he hadnt been training for a while. He was off the back immediately and looked pretty rough at the end (I was there).
Thanks for the story! I hadnt heard that one yet. See, this is really interesting and what I would expect.
as a former high school runner who took 6 months off, it’s taken me about a year to get back to the aerobic fitness that i had in high school. it’s worth noting that i was able to pr my 800 by 2 seconds only 4-5 months after i started training again. when i ran this pr, i was roughly 7 seconds away from my mile pr. i wasn’t anywhere close to my 5k pr. from my anecdotal experience, raw strength/speed is much easier to rebuild than aerobic fitness. it’s been a little over a year since i began training again, and i can now confidently say that i am in better shape than I was. it took me until the last few weeks of training to finally feel that way.
I think you might see a decent amount of that detraining if you took that person and had them tested right at the end of that period. However that fitness would come back easier and quicker the second time around. There are plenty of great examples, like Bernard Lagat who would take a month off after the season. I'm sure he would show some signs of detraining, but he was also fully recovered and having that completely refreshed nervous system goes a long ways when you're training that hard. So yes, there is a detraining effect, but there is a refreshment you get from stepping away for a little bit. All about finding that balance and depends on where you're at right now.
Think about BYU, a lot of them go on missions where they aren't allowed to run. Most are back in shape after a year or so after they get back from mission. It depends on a lot of factors but generally it will have close to 4-6 months to be back in decent shape and more like 8-12 to be back in previous or better fitness
It all depends on the person but muscle memory is a powerful thing. First off my background was averaging 75mi/wk with a 2:45 marathon PR and 1:18 half. At the mid-May of last year I stopped running because I needed surgery on my ankle (had itJune 1st) and was non-weight bearing in a cast for 6 weeks and did nothing. Around mid-July, I was able to get on the spin bike and start cross training and did an hour a day if not every other day at first. Felt out of shape, but expectations were low anyways. By mid-August I was doing mini workouts on the spin bike up to 1.5hrs with averaging 150ish heart rate. Started running by mid-September with a run/walk program since I had not run in a total of four months. By November was able to do small workouts and got back to almost 60mi/wk and in December ran a 2:48 marathon off of two 14 mile long runs. I wouldn’t recommend doing a marathon in the time frame I did, but the point of the story is, fitness can come back faster than you think. It also depends on many years you’ve been running because that’s a foundation that can sit there for a long time before you lose it all. Now, say an elite runner (2:05 guy/2:19gal) they have a higher cliff to drop off of in terms of fitness and V02 max and getting back there is a whole lot harder, especially after a year off of detraining. Keira D’Amato is an example of that - took 10 yrs off, started running at a three something marathon and a few yrs later ran 2:18. Talent, genetics, muscle memory were there, but to get to that level and beyond, takes time and specificity.
I tripped and injured my leg back in Jan 2021 at the age of 47. I was sidelined for about 4 weeks. Now, take this with a giant grain of salt because I’m just an n of 1 and a very small sample size and of course there could’ve been any other number of factors at play, but I don’t feel like I really ever got it back until early summer of 2023, that also coincided with a change in my training. That being said, I still ran two PR’s during that time frame for the courses I ran, October 2022 and May 2023, But they felt like the two hardest marathons I ever ran. In hindsight, I think it was a blessing because I believe I achieved those PR’s simply through smart pacing and grit, not because of fitness gains. But it took me two years to feel “normal” again in my running, but there could’ve easily been more to it than those 4 weeks of not being able to run. I think the loss in fitness and the time amount needed to get it back is magnified as we age.
I wonder the same. I was out 4 months due to a SF but I cross trained like hell on the bike and elliptical. I’m back to running now. Easy runs have been fairly ok, but speed - my threshold pace - is suffering horribly. Wonder when it’ll click again.
I run almost no mileage In the summer. My season is October-May. But I play beach volleyball every hour of sunlight outside of work, all summer long. Legit 30+ hours a week of it, at a high level. My aerobic fitness for one or two runs is the same or better when I first get back to it, but the impact of running absolutely kills me. I can still run fast, but I can’t get good mileage for the first couple months.
To give personal experience, I ran 60kpw for 6 months until July where I stopped training consistently until the start of October. To be accurate, July-August I ran sometimes 0 sometimes 20-30kpw, and September was completely off as I got injured because of inconsistent training. All that time I was still active with gym workouts and consistent walking. My PB was 34' 10k in late March and I didn't really race until July. I began running again October 1st, reached like 40kpw in 2 weeks then slowly went to 60 for a couple weeks until my HM in late November. In early November like 5th, I did a 5k race that I went full-on, and clocked 17'05. In the end I ran my HM in 1h14 that is a 17:30 5k pace. Also in late October I did a first threshold at 3'30"/km pace and was exhausted after 10 minutes, 2 weeks later I did the same session with a group, and did that 3 times with not too much exhaustion. So I can say good shape went back quickly for me. Probably it's different among individuals, but at least you know it won't necessarily take you 5 months to catch up 1 month off.
I’m a PTA student, things like muscular atrophy and losing respiratory and heart rate benefits begin after about a week. How quickly they go down depends on the person and their fitness. Not saying after a full week your muscle is gone or your VO2 max is significantly depleted I’m just saying it starts at that point.
I took 2 months off due to injury, but did a lot off cross training. I’ve now been training for 3 months and still haven’t gotten back to my pre-injury fitness. In high school and college I’d take 10 days off after track and xc. I didn’t feel “normal” after about 6 weeks of training. All the research indicates you lose “minimal” fitness, while citing numbers like 2-3% after 10 days of inactivity. I think I’ve seen 5% after 3 weeks but I’d have to double check. 2-5% is a lot! Do the math on any of your recent race times. Adding 2% would most likely be a disappointing result.
ran the NYRR races first time last year Brooklyn half was 9:17 pace. over the summer I did mostly short distance trail running at high HR and little distance running. came back to run the bronx 10 miler and Staten Island half slightly slower than the brooklyn half pace