Swim slightly downhill
Only with a downhill aquatic line can you rotate your hips quickly
Our goal is to create light, fast-moving hips
Swim freestyle (and backstroke) slightly downhill, that is, press your head and chest deeper into the water, so your hips will be higher, so you can rotate your hips faster. A downward aquatic line to the front, just a little, improves your balance; it shifts your balance point forward and the farther you shift your balance point forward, the better you'll swim. With an uphill aquatic line, all you can do is push water with your arms. With a downhill aquatic line (a ½ degree is enough) the dynamics of swimming change, you can spin your torso past the catch.
Put a little tension in your lower stomach so your aquatic line is straight.
With a downhill aquatic line you will have less resistance, a firmer, more effective catch, and fast hip rotation.