This a concept that I recently made a connection on across all disciplines. When foreward motion is the goal, motion in any other direction can rob you of energy and reduce your efficiency.
Free Speed! - Yes, this is one area where you can get FREE SPEED and possibly use less energy and be less susceptible to injury. I have found this to be very true in my training. If I find myself getting tired during my swim many times it is because I have fallen into my old habits and maybe coming up too high to catch a breath causing me to sink down more than I should and repeating the process. Once I realize this, even out my breathing and stroke and stop bobbing up and down, I am instantly faster while exerting less energy. Same has held true for the run. My old running form had a lot of bounce in my step with my head bouncing up and down with each stride. It has taken a good year to really even things out, but, I can run with very minimal up and down movement of my head and I can run much greater distances without feeling fatigued (Speed is still a work in progress, but, I enjoy running much more these days. There were also additional form corrections that contributed.) Even on the bike, there has been recent research on tire pressure that shows running too high of an air pressure causes you and your bike to be lifted up and down over small bumps robbing you of power, where a lower pressure tire deforms a bit and absorbs the bump allowing more energy to be directed towards forward momentum. Seems that optimal inflation could be around 80-90 psi. Looking forward to lowering my PSI and hitting one of my rougher routes and see how it goes.
Keep things moving forward and enjoy your free speed.