QUESTION: "So I haven't been going too crazy but [I've been] running on the treadmill about three or four days a week for at least 30 min, I usually go 5 to 6 mph. I took a week off running cause a friend was in town and then I tried to start running outdoors so I went to a track and I couldn't even make it half a mile without stopping. I felt so heavy and weighed down and had stomach cramps and could not go any farther and I have no idea why it felt so impossible! I felt like I was 400 lbs."
I understand that that's not actually in question form, but I'm going to take it anyway.
I learned that my friend had not been running outdoors in quite some time (it's been cold, I totally get it) and that she had been running on a treadmill with the incline set at zero. When we run on a treadmill, we have to use muscles to stabilize our bodies which allow us to continuously run in place. When we run outside, we need to propel our bodies forward. That's why, after four years of being a treadmill queen, I found myself unable to run a half of a mile outside without feeling like I was dying.
There's an easy solution to this - set your treadmill to an incline of 1.0 or 1.5 and this will help mimic the conditions of running outside. I've read some articles claiming to never go above 1.5, but when I'm feeling really baller, I'll set the incline as high as 5.0 and have my way with it.