How quickly can you lose you ability to run?

September 29, 2007 9:07 AM

Am I losing muscle?

Because of my very hectic schedule, I haven't been able to go to the gym for the last 5 weeks. Previously, for a couple of years, I'd been doing cardio 6 days a week (running 3-4.5 miles/day on the treadmill). I've lost a couple of lbs. in the last week and I'm wondering if this might be muscle. Since I'm not exercising but eating healthfully, I wouldn't have expected to have lost 2.5 lbs in one week. Could this be muscle and how quickly am I going to lose my ability to run 4.5 miles? If I don't work out for several months, how quickly will I be able to build back up?

posted by rglass to health (9 comments total)

I meant--your ability to run. Thanks!
posted by rglass at 9:07 AM on September 29, 2007

Yes, you're probably losing muscle. Welcome to being a carnivore. Evolution has noticed that muscle is expensive and our bodies aggressively cannibalize unused muscle mass. As for retraining, my personal experience has been retraining is about twice as fast. The body seems to remember what it needs to do to accommodate strenuous activity.
posted by TeatimeGrommit at 9:43 AM on September 29, 2007

(explanation for carnivore comment): Herbivores might munch grass for two weeks and then suddenly need to run very fast, and so their bodies are slower to lose unused muscle. Carnivores exercise every day.
posted by TeatimeGrommit at 9:46 AM on September 29, 2007

A trainer I used to have said that you lose fitness twice as fast as you gain. So if you skip a week, it'll take two weeks to get back to where you were.

However, that's demonstrably incorrect. (I think he was trying to scare us.) When I was 25 I started running semi-regularly, and couldn't even complete a mile. Now that I'm 35, even if I don't run for 6 months, I can always go out and run my basic 4 mile loop. (But there are other factors involved, such as "knowing how to run" now, knowing how to pace myself, having the confidence and mental endurance, and I'm always doing *some* form of activity semi-regularly, etc.) Of course, after 6 months I do lose about 2 minutes per mile. :)

But, to further my anecdotal info, I just started running for the first time this year at the beginning of September, and I've already worked back up from a 12 minute mile to a 10 minute mile. For regular training runs I never did run faster than 9-10 min/mile.

Other than that, the idea that this past week you've suddenly lost 2.5 lbs of muscle doesn't make sense to me. I'd think that over the past 5 weeks if you've lost any muscle mass, it would have been gradual. You're probably just less hydrated, or missed a snack or two recently, or have walked up more stairs than you realize, etc. My personal weight fluctuates several pounds per day. A couple pounds here or there wouldn't be something I'd register.

But yes, you will lose muscle if you don't keep at building it.
posted by iguanapolitico at 12:20 PM on September 29, 2007

I don't think you're losing muscle mass. If you've been running that same distance every day, you hadn't been gaining that much muscle mass in the first place; you gain muscle mass from increasing resistance, i.e. working with heavier and heavier weight. Your routine looks designed to maintain stamina and muscle endurance in your legs, and muscle endurance is really a different thing than muscle mass. Look at marathon runners: they have very little muscle mass in the first place, so if they stopped training it would be hard for them to lose that "mass" no matter how out of shape they got.

I don't think it will take long to bounce back from a five-week hiatus.
posted by creasy boy at 12:42 PM on September 29, 2007

I agree with TeatimeGrommit: there's muscle loss, but when you start retraining your body has a kind of 'muscle memory' that kicks in and puts things right, re: mass, etc. I've been working out for over 25 years and a month off from the gym (with controlled eating) will result in overall muscle loss. It's sort of astounding how fast that happens. But like creasy boy says, it won't take that long to regain after a short five-weak break. Good luck.
posted by zenpop at 1:03 PM on September 29, 2007

I think the rule of thumb for poundage when lifting weights is it will take you the length of your break to get back up to where you were before. If you take a month off, expect to spend a month pulling back to where you were before you slacked off.
posted by charlesv at 2:06 PM on September 29, 2007

Yes, you are probably losing muscle some mass. Anecdotally, I lose 5 or so pounds each year after cycling season comes to a close. It usually takes a while though to drop. Whether or not you can recover and get back into shape quickly depends on a number of things:

1. VO2 max
2. Lactate threshold
3. Relative proportion of slow twitch to fast twitch fibers in your muscles
4. Age
5. Muscle memory
6. Diet
7. Running Efficiency and form

So, basically most things are genetic, but some things are in your control. The more healthy you eat and the more experienced you become, the easier it will be to get back after a period of inactivity. The rest is up to the gods.

However, when you do start training again, it helps to train below your lactate threshold, at a pace about 60% of your max HR (rough estimate). Gradually build your distance by 10% per week until you feel that you can reach your 5 mile goal without over exerting your cardio system to the point that your muscles start producing excess lactate. The most important thing is that you don't want to push it when you start again. You're muscles may be fine, but your lungs and heart need time.

Yes, it is frustrating. It takes me about 2 months to get used to being relatively sedentary, after the season is over. And the months of February-March are always painful getting back in shape after a long winter. But so it goes. It's fun and I love the transformation that happens from March-August.
posted by |n$eCur3 at 4:01 PM on September 29, 2007

You are probably not losing muscle mass. Running on the treadmill builds very little muscle especially if you're doing it as moderate intensity steady state work (instead of say intervals). You probably did lose a couple pounds of water as your muscles have released their stored glycogen now that they aren't being exercised.
4.5 miles isn't very far. You can regain the ability to do that pretty fast. But your speed will suffer quite a bit.
posted by ch1x0r at 5:20 PM on September 29, 2007