I've been running regularly for a couple of months now, and I haven't yet supplemented it with any other exercise like weights, situps or anything like that, but I noticed last night that my abs are crazy strong now compared to before! I just sort of assumed that running would strengthen my leg muscles, I never thought it would carry over to my abdominal muscles too. BONUS! Anyone else notice this?

Oh yeah running is a great core workout, so abs get a nice toning! i have notcied mine getting stronger and under the fat i can see them more pronounced.

Yes, running has definitely helped tone my abs...I also never would have suspected it would to the extent it has. I knew running was a good overall body workout - but its still a nice surprise

The other surprising one was spinning...DEFINITELY thought spin class would mostly focus on my legs and bum but it's helped define my abs further. *shrugs* go exercise heh

I was just thinking this too. I noticed during my run today that my abs were really tight. Good thing too, because I need all the help in that area I can get!

I can't see my abs yet (still a little too much cushioning around them!) but they are definitely way stronger. I remember when I first started out and I did that move where you lay on your back with your legs straight up in the air and slowly lower them all the way to the ground (keeping them straight). I couldn't actually get all the way down, I would start to shake and then have to drop them the rest of the way. On a whim last night I decided to try the same move and I could do it easily and smoothly and repetitively!!! It was an awesome feeling!

Off road running is even better for them - because it takes more effort to keep your balance it really works your abs as well as your legsl.