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Long Distance Running/Cardio


I am a 17 year old male long distance runner and weightlifter... i Usually run anywhere between 25-60 miles per week depending on what season were in.. but i have a question: IM confused about the whole use muscle for energy thing... I know it s good to do cardio in the morning right to burn fat?

does running acutally allow your body to be in catabolism mode and start eating muscle instead of fat or is it after a certain time you ran say an hour...if i ran 4 miles would i lose fat or muscle? thats kinda what im asking...


There is no set "distance" where catabolism kicks in. A lot has to do with your level of training, nutrition, etc. So many factors go into that.

Generally for longer distances events free aminos make up about 5% of the energy usage.

The main aspect of "catabolism" that occurs from running is just atrophy of type II fibers. The whole idea is your body shoots to survive. If it has to run long distances it wants to be small and light. Type IIa fibers and Type IIx, specifically Type IIx are very high in potential for hypertrophy. There is no need to have a huge muscle to run, it is just unneccesary weight.

I'll keep it short, let me know if any of that helped

But definitely pick one or the other.... Long Distance Weight Lifter just doesn't sound right.


By one or the other I mean, I hope you aren't trying to be competitive in both


Very true. But you can be a long distance runner who lifts weights. There are too many benefits to ignore strength training in my opinion, even for endurance athletes.


i guess that helped my perspective onthe subject some...and by no means am i a competitive weight lifter... IM only trying to gain about 5-8 pounds of lean muscle mass and wondering how everything works as you tried to explain. Let me get this straight though and correct me if im wrong:
long slow distance runnign burns fact correct and when there is no more fat to burn up the body sets into catabolism? and short higher intense runs burn carbs?


Mmmm... Longer, slower running uses a greater percentage of fat as enegery to fuel the activity. Faster running uses a greater perfentage of carbs or glycogen. Slower running does not necesarily mean more fat is burned. You will lose more fat with high intensity running if it creates a greater caloric defiict. Fat stores will be tapped into at the end of the day if you're in a caloric deficit. There's also the afterburn and metabolism revving effects of hard running that is similar to lifting though not as great.

Both types of running can cause muscle loss if you're not adequately fueled. Most long distance runners should not be worrying about fat loss or high-intensity v. low intensity for that purpose. Train for performance and your body will sort itself and and be what it needs to be. Lift for performance as well, as being strong will help you particularly at the end of races and on hilly courses.

Eat good to fuel your body. You may find it hard to gain muscle when putting in a lot of miles. This is ok. Not too much more you can do if eating right and lifting. You can add muscle in the off-season when your mileage is lower.


In short, when you're training for an endurance sport, as triguy said, the fast twitch muscle fibers will convert to slow twitch, but this also depends on distance. Take this for example:

You run 7 miles a day at 7 min pace and you've been doing this for about 2 years now, your body is adapted. To increase aerobic capacity, you either need to increase your mileage of daily runs or increase the speed at which you're running your daily runs. Either scenario will exhaust fast twitch fibers that were never exhausted before, turning them into slow twitch fibers basically.

If you think you're burning muscle, this only happens in extreme cases where your glycogen stores are completely depleted and you have very little fat for energy. Any decrease in weight or muscle you see is a result of the fast twitch converting to slow twitch basically. This is an oversimplification, but I hope it helps.