The first thing I would try is to slow down. The 1% incline makes it equivalent to running outside, so the faster speed is just that - faster speed. The other thing I would look at is running tense. I know I tend to run less relaxed with the constraints of running on the treadmill - i.e., I have to concentrate on staying on the belt, a little bit at least.  Also check your form and footplant. Make sure you're running with your normal stride and planting your foot under your body, not out in front of your body.

Len

IGottaRun,

I know exactly how you feel...When I started running again this year back in May I strictly ran on my treadmill until just last month when I finally started taking my long runs outside, so I didn't have to stare at my walls and be on the treadmill for over an hour!! But, now that I have been outside, I find it so much more difficult to run on the TM!! I feel so confined, like I can't stretch out enough, or relax enough, and my runs are no longer even remotely enjoyable on the TM!! I have also noticed that my form and way I land are completely different then when I run outside!! If this is true for you I can see why you are having these pains in your muscles!! When I run on my TM, I always use at least a 2% incline, anything lower for me makes me feel like I'm going downhill, which is maybe contributing to your knee pain...I too, have a small child that keeps me from running outside during the week, so the TM it is for now, but weekends when my bigger kids aren't in school, I am so outside to run. My legs and entire body feel so much better outside!! Last Saturday I ran 10 miles outside, and felt great, then this week when I ran 4 miles on my TM it felt like it would never end, and I felt confined and my sides were cramped up the whole time. I hope it gets better for you...I guess maybe I would suggest, try upping the incline to 2%. Good luck!!!

KEEP ON RUNNING!!;)

Carey

Do you have good shoes for running?  When you run on roads, the impact is generally greater.  If your shoes don't have adequate impact absorption and arch support, they could be the cause.

It seems to me that you should be able to run as much as you wish on roads. 

Have you ever had a gait analysis done in a running specialty store?  I've been impressed with the care and knowledge of the staffs at Fleet Feet and Roadrunner Sports shops.

Have you thought about your stride length?  You're not over-striding, are you?  (your front foot should hit the ground under or slightly behind your knee)

Are you by any chance running on "crowned" roads? Often asphalt roads slope downwards at the edges to drain away water when it rains. If you run for long periods on the same side of the road, you're effectively running with one short leg and one long leg, which can lead to injuries. If that applies to you, switching direction (from one side of the road to the other) periodically should help.

I had the crowned road problem myself so can vouch for that  being a real issue.  I had terrible pain in my groin (right where the top of the thigh meets the torso) and could barely walk without limping.  I refused to give in and stop running so I really tried to pay attention to what I was doing and read these posts like crazy searching for tips.  After a few weeks, I bought new running shoes, got extra arch support (cost a fortune but VERY worth it) and started running directly down the middle of the street (I run in the neighborhood in the very early am with almost no traffic so I can do that fairly safely with lots of reflective wear) and after about a week of doing this my pain was gone.

OMG!!!!  My knees do the exact same thing!   I was fitted for running shoes and it helped some.   I still have more issues on the TM than outside.

Good Luck!