How quickly do you lose fitness maintaining mileage but without hard sessions?

aquestion wrote:

There's plenty of literature looking at how quickly you lose fitness when you can't run at all through injury or whatever, but what about if you just didn't do any intervals/tempos for a week, 2 weeks etc? If your mileage was the same, but all easy pace what would the effect be?

Reason I ask is with all the bugs and things going around at this time of year sometimes when you're ill you can run, but it has to be at an easy pace. Is it critical to get a session in asap when you're better or should it not be a concern?

If you take the traditional 2 weeks off completely at the end of the season you will rapidly lose both aerobic and anaerobic fitness.

If you go more than 5 day without doing a race or an anaerobic interval workout, you will begin to lose anaerobic fitness. This is why once you start an anaerobic phase you must continue to do something anaerobic every 5 days until your season ends.

As far as aerobic fitness goes, if you continue to do easy distance you will slowly start losing some aerobic fitness. You need to do a tempo or at least close to tempo pace at least once every 7 days or you will continue to slowly lose some aerobic fitness.

I think this depends a lot on the kind of runner you are. Base building gets me in good shape, tempos get me close to race ready for 5k and up. Even 3k. Others need speed work.

aquestion wrote:

There's plenty of literature looking at how quickly you lose fitness when you can't run at all through injury or whatever, but what about if you just didn't do any intervals/tempos for a week, 2 weeks etc? If your mileage was the same, but all easy pace what would the effect be?

Reason I ask is with all the bugs and things going around at this time of year sometimes when you're ill you can run, but it has to be at an easy pace. Is it critical to get a session in asap when you're better or should it not be a concern?

"And some factors, like capillary density—the number of small blood vessels that grow deep into the muscles—did not seem to be affected at all by detraining."

-->80% retention of fitness after 12 weeks of complete inactivity

-->long term gains in fitness are only minimally affected by time away from running

So in essence, your loss of whatever "specific" fitness (speed, thresholds, etc.), is related to the permanence of said "specific" fitness. If you've been doing tempos for months, two weeks off easy distance will probably have minimal impact than if you only had tempos for a few weeks, etc.

Long slow runner wrote:

I think this depends a lot on the kind of runner you are. Base building gets me in good shape, tempos get me close to race ready for 5k and up. Even 3k. Others need speed work.

I ran 15:40 in college off of 70-80 miles per week, mostly in the 6:30-7:30 range, periodized work at tempo, interval, and fast anaerobic speed, and regular weight lifting stretching abs and ice baths.

8 years removed from that PR was last year, when I was doing 50-60 per week including 1-2 workouts per week of either tempo or interval with the rest being 7:30-8:30 pace with my wife. I ran in the mid 16s off of that kind of training.

This year I've done almost exclusively easy mileage (50-60 per week), one workout maybe per month of 8x400 at 5k pace or something like that, and this past weekend I ran 16:47.

Aerobic strength takes a long time to build, but also a long time to lose, and not much to keep it going.

I agree. In hs when I first ran sub 17 I was averaging around 40-50 mpw. took a year off after running in college and was averaging around 10-15 mpw and still could run sub 17. I think It all depends on how well you know your self.

I'm not sure you know how yourself works because that's impossible... Letsrun pls?

A video of Jack Daniels might help clarify somethings...

https://www.youtube.com/watch?v=5TWzC0KA6uo

Thanks for the responses so far. It still looks like a bit of an unknown to me as there are lots of studies of people doing nothing or cross-training, but not sure if the same is the case for just not doing sessions.

I also wonder what the significance would be of incorporating/maintaining strides to preserving full fitness.

When I do my next session it will have been about 10 days since my previous one due to a bug which has forced me to just run easy pace. I've still been doing a decent pace, it's just not been steady or faster running, generally around 6:30-7:00 miling. I'll post with how the session goes when I return as I should have a good idea of whether I've lost anything or not. I can't imagine it will be anything significant, but I would be interested in determining this in the future, so if a week or 2 between sessions on the odd occasion would make any difference...

It's nothing new, but Edward Coyle did a good job revealing the effect of detraining back in 1985.

He proved that the principal loss of fitness during the first 14 days of no-training was due to central capacities decline (heart output, systolic ejection volume). He showed that those central capacities reach a "plateau" after about 14 days.

On the other hand, he proved that there was no real loss of peripherical capacities (arterioveinous difference) in that first 14 days. But, those capacities begin to decline massively after that period.

So, you need to consider that you can maintain central capacities by doing about anything stimulating your cardiovascular system. And you can maintain peripherical capacities by simply running (at various pace ideally).

In other words, the science might show that you will maintain better fitness by doing interval workouts than by doing only a lot of easy miles. This is specially true in a short-term perspective (> 4 weeks).

Know how your body reacts to certain training. Example: I know I run better off higher mileage than lower mileage. I have teammates who are not able to handle high mileage without getting hurt(stress fractures). Or for another example in hs xc I once raced a guy who ran 1:49 in hs and he had won the previous state xc title by sitting and kicking. I generally ran well in races where the pace was fast from the start line so knowing that I am not going to just sit behind him and let him dictate the pace. pretty much these are examples of knowing yourself. Just Look at the 2014 ncaa xc championships compared to the 2015 ncaa xc championships. Patrick Tiernan this year knew he would have a greater chance of success if they jogged the 1st 70% of the race like the previous year.

somuchb8 wrote:

I'm not sure you know how yourself works because that's impossible... Letsrun pls?

Thanks, informative.

Those studies must be partly right.

I've taken a week off, and ran great when I came back.

A fortnight off, and I'll lose probably 20 seconds pace per mile on all runs.

I only do hard work half for 30% of the year. I lose no real fitness, IMO, when not doing hard sessions for an extended period. However, I do race year round.

I'll also add the odd fast mile or tempo run, as a feel like, but nothing really hard like 20x400 or whatever every week like I do in peak season.

So for anyone interested I had one of my best ever sessions after 10 days of easy running only. I did incorporate some strides in my runs which I'm sure made a difference in terms of keeping all the systems working, but it's encouraging that with no proper tempo or interval workout I didn't lose anything.

Obviously everyone is different and I do respond strongly to mileage, but I didn't increase my mileage to compensate for the lack of sessions.

It really depends on the training you were doing before you took the time down but the first three weeks will be negligible in dropoff and since most people overdo their speed sessions there is a very good possibility you will actually improve in the 7-14 day mark.

After that, you should expect to lose around 3% in the next three weeks. (So a 4 minute miler would run just under 4:10 after 6 weeks of no speed.)

A lot depends on age and the current fitness of the individual.

If you are 25 and quit doing speed for 3 weeks, you would hardly lose much at all. But if you are 45 and quit doing speed for 2 weeks, you'd see a pretty significant difference.