Training & Nutrition - muscle mass question

I don't even know how to search for this one (what terms to use, etc...), so forgive me if it has been addressed before.

I have read in body building magazines, etc... that if you work out too much, your body will consume muscle, and you will loose mass (they said this negative affect of aerobic exercise starts at the 20-30 min mark). I look at marathoners (thin as bean posts) and watched the tour (same thing). Is there risk to loosing miscle mass if you spend time on a bike? Right now, I make a 7 mile (~25-35 min depending on wind) one way commute, but also enjoy longer rides too; however, I don't want to loose muscle mass (I just want to loose weight).

Has anyone else heard/read about this? Any thoughts?

BTW, I cannot find the link to that anymore, but I have found this to be a pretty good fitness site:
http://www.hussman.org/fitness/

The guys in the marathon's are in there because they're good at it and one of the reason's they are is they don't have a bunch of muscle mass to carry around. The guys in the tour look skinny because they starve themselves so they have less weight to get over the mountains. Both sports are endurance events and not much muscle mass (except for sprinting) is required so the most serious and successful participants don't have much.

Of course, even in the top pro ranks there have been exceptions to this. Davis Phinney (one of only three Americans ever to win multiple stages of the tour and the winningest cyclist in U.S. history) is no 98 pound weakling.

You can cycle all you want and it will only help your muscle mass. If you starve yourself you can lose muscle mass but probably not before your body fat goes below 10% or so. Just do resistance training three times a week along with your cycling and you'll look and feel fine. The most important muscle you have is your heart and there is no better exercise for it than cycling.

The only time you would be in danger of consuming muscle would be if all your fat reserves were depleted *and* you were not eating sufficient calories otherwise. It's not accurate to look at those athletes at the top of their respective professions as a gauge of what you will 'morph' into if you train hard-- they are genetically predisposed to look that way (marathoners being ectomorphic, for example).

Dave

I don't even know how to search for this one (what terms to use, etc...), so forgive me if it has been addressed before.

I have read in body building magazines, etc... that if you work out too much, your body will consume muscle, and you will loose mass (they said this negative affect of aerobic exercise starts at the 20-30 min mark). I look at marathoners (thin as bean posts) and watched the tour (same thing). Is there risk to loosing miscle mass if you spend time on a bike? Right now, I make a 7 mile (~25-35 min depending on wind) one way commute, but also enjoy longer rides too; however, I don't want to loose muscle mass (I just want to loose weight).

Has anyone else heard/read about this? Any thoughts?

BTW, I cannot find the link to that anymore, but I have found this to be a pretty good fitness site:
http://www.hussman.org/fitness/

I've thought about this, and one observation I've made is that most pro road riders seem have the same size legs for pretty much their whole careers; their legs don't get thinner and thinner, year after year, unless they go on some huge diet like (i think) Bjarne Riis shortly before winning the tour. So, despite doing all that aerobic work, and 16,000 miles a year (near enough), they still maintain their size.

Even chunky guys like Djamolodine Abdujaparov maintained his chunky legs despite doing all those miles.

So, it seems to me more of a question of genetics.

I've heard that your body will consume its muscle mass if your daily calorie deficit is too high. The maximum deficit varies from person to person, but is usually between 500 and 1000 calories. So if you eat 2000 cals a day and burn 2500, you will lose fat, but if you eat 2000 and burn 3500, there is a danger of your body canibalising its muscle mass, even if it has plenty of fat reserves left. This is because the body tries to hang onto its precious fat reserves in a "famine" situation (apparently).

I don't know how widely accepted/disputed that is. But if it's true, the lesson is just don't try to lose too much weight too fast.

Thanks for the information!

I've heard that your body will consume its muscle mass if your daily calorie deficit is too high. The maximum deficit varies from person to person, but is usually between 500 and 1000 calories. So if you eat 2000 cals a day and burn 2500, you will lose fat, but if you eat 2000 and burn 3500, there is a danger of your body canibalising its muscle mass, even if it has plenty of fat reserves left. This is because the body tries to hang onto its precious fat reserves in a "famine" situation (apparently).

I don't know how widely accepted/disputed that is. But if it's true, the lesson is just don't try to lose too much weight too fast.

Bryan, that phenomenon is pretty rare and most of the time is observed only in obese or morbidly obese people who 'yo-yo diet' up and down the scale by crash dieting for brief, intense periods and then go back to their poor eating habits once some weight has come off. I think it's a throwback to our Neanderthal days in which 'feast or famine' meant that fat reserves were precious for long periods of a starvation diet, and thus one's fat reserves were burned more slowly than (or prior to) some muscle mass. A dieter or cycling enthusiast who very suddenly drastically reduced his caloric intake might trigger this effect, but I doubt they'd have the energy to cycle much if thye did.

It would be the rare cycling enthusiast who would encounter this as long as they maintained a pound or so weight loss per week... that seems to be a healthy target of weight loss that will minimize 'catabolic' weight loss.

Dave

No you wont loose mass as long as you are eating right and building mass in addition to biking. Biking brings out the cuts. I completed a 700 mile ride in July and hit the weights hard when I got back. And I continue to ride my bike 25 miles every other day. And I am just getting bigger and more defined. Biking just makes sense for total fitness.
MBD

Right, you will get cut up legs. And burn some fat. Mo visible muscle.

Thanks Dave, I'm glad to know that. There have been a couple of long rides when I've got back exhausted and with zero appetite and have forced myself to eat chocolate to make sure my deficit wasn't too high. (There are probably some nutritionists throwing things at the screen in disgust). Nice to know I won't have to do that again!