I have a question. I've just started jogging a few weeks ago, and wanted to know if long term running would cause leg muscles to bulk up alot.... sounds like a silly question, right?

i am not a runner, but can honestly say that running alone will not bulk up your thighs. it is the same with cycling as people think that will really bulk your legs up. these athletes do alot of weight training on their legs, hence bulk.

have a look at marathon runners. they are the most spindly people i have ever seen and they run for hours on end.

i think if anything you will find your calves become more defined, but you shouldn't gain any mass on your legs really.

just my opinon

I agree with Daisy Boo...I used to wonder about the same thing...but then look at all of the female runners! You might get more defining with long distance running, but probably not bulkiness.

I've been running for a little while and my legs have SLIMMED down...most definitely NOT bulked.

My calves have become very defined (noticed it quite clearly while trying jeans on at lunchtime today...stood on my tip toes and you could see every single muscle the whole length of my leg...it was awesome! Makes everything so worth it!)

I also noticed that I gained tone and defintion quite rapidly once I did start running (before that I was walking - very very fast lol). Within at least two weeks I could see some change and now about 6 weeks on its obvious.

Stick with it...its definitely great fun!

Running will no bulken your legs up - lifting will. When you run, it's cardiovascular, that's the main workout, if anything, it will bulk up your heart. Techincally, it builds your long twitch muscles. This is what's necessary for endurance excercise, such as running. Short twitch is what you build when you lift heavy weights with low reps. Difference between sprinting and marathoning. OK, so this is a very simplistic explanantion, but the answer is no. You will build strength in your legs to get you through the run, but you will NOT bulk up like a crazy German (no offense to you German's out there!)

Thanks for the answers! I really appreciate it! I"m trying anything right now because I am seriously lacking motivation, and need a good kick in the butt. Walking wasn't doing anything for me anymore, in terms of excitement, and found my pace getting sluggish, because of bordem.

I had the same question when I started running....but I have been doing it for a couple of months and my legs have slimmed down and I have a nice muscle showing in my calves....but its a toned looking muscle not a bulky one...

I started running about 4 years ago, and I run about 15 miles/week. I think how your legs turn out depends a lot on your genes...I have a pretty muscular build overall and have what my trainer calls "runners legs" -- very muscular things and calves. I wouldn't trade them for all the skinny little legs in the world! Keep running...it helped me lose almost 50 pounds!