Not only does a Run-up (aka an X-step) give more power, it helps your timing and allow your body to become aligned to crush! I compare the X-step to the Karaoke warmup routine that I learned doing track in highschool. Youre upper and lower body are allowed to twist opposite of eachother, and in Disc Golf it creates that winding up sort of motion.
Here are a few tips for those working on or adding an Run-up into their routine:
1. Keep it condensed - If you take too long of steps, you will be counter-intuative and throw off your timing. Give yourself and your steps enough space to where you still feel your feet on the ground and you never feel off balanced.
2. Go Slow - You may have seen the player who's needs 20 feet of space to start their run-up and then they sporatically run through the motions, just to ultimately shank the shot. While you might think that moving fast will increase your power, it may also work against you. Try focusing on building up the speed through your run-up, with 100% going in to your pull through. Going at 100% (or trying to) may cause you to loose all the power as you start to throw.
3. The last step is the most important - In the pictures, 6 is just starting to plant into the optimal throwing position. Imagine what your body looks like if you were to stand still and throw, this is the position in #6. In #7, I am pushing off that back foot and bring my body on top of the front foot, and in #8 my front foot has rotated to allow me to follow through and my back foot follows. The plant foot should be parallel to the front of the tee to have the solid foundation to bring your body through on the correct line.
4. Take Video - The best way to know what you are doing wrong is to take video of yourself and compare it to the throw of someone who you inspire to throw like. It's hard to know by feeling, especially when you are learning something new. Some key things to look at is how large your steps are, what your final plant foot and follow through look like, and then does your upper body move separate from your lower body through the runup? Watch, compare, and then try to incorporate one thing you want to change at a time. Video yourself again, and keep working from there until you've got your run-up down!