I started doing my cardio on a treadmill, and I'm noticing that I feel it more in my right leg than in my left.

Should I try to manipulate stride length? I tried this a bit, but couldn't tell much difference. I couldn't tell if my left leg had too large a stride or too small a stride.

Any ideas?

Also, what's the benefit to increasing slope as opposed to increasing speed. Is slope working on muscle gains, or is it just a way to make me work harder.

I've been manually adjusting the speed to warm up 3.0 kmph 3 minutes, 6.0 kmph 3 min, 9.0 kmph 3 min, then 3 minutes spurts of 6.5, 9.0, 6.5, 9.0, 7, 9.5, 7, 9.5, 6.5, 3.0, or something like that, using only 1% slope. There should be a way to program this in, but I read the book and couldn't figure it out yet, so I think I'll have to try what they call Program 3 (45 minutes 6-9kmph from 2-4% slope, but I don't know the intervals)

I've used a treadmill since day 1. I notice on some days that it seems like my right leg works harder too, but I think it's mostly in my head. I wouldn't try to manipulate your stride. Just do what comes naturally. As for the incline, you are correct, it is just meant to increase your work load. I started flat, but I only have a 5mph maximum, so a few weeks into it I had to up the incline. I still use the treadmil (did cardio on it this morning, in fact), but the incline is now maxed out at 10%. I can still hit my heart rate goals, but I think I'm gonna have to upgrade in the not-so-far future.

Also been using a tread since day one, and found the incline makes you work harder its given me a longer muscle shape, i used to have thick strong legs and found that the muscles appear to have lengthened, if you know what i mean, im doing 5.5k-12k intervals 5 deg constant incline, for about 35 mins, started at a slower pace and lower incline but am gradually working it up.

My left knee also had a slight twinge when running, it was because my foot was rolling from outside to in, went to get some properly fitted runners and problem solved.

Ooh, longer muscles, sounds great. I'm gonna start right up on working in that incline.

Yeah, I'm due for a new pair of shoes. Mine are about five years old, but they sat in the closet for three of those years. :o

I would always use an incline, even a slight one. I think I read that even the minor incline settings on most treadmills can help burn 10% or more calories in an average workout! That would definitely be worth it