If you want to run faster , and do so into the later decades of your life, you may need to start moving a little more like a kid again. That’s the case that sprint coach Stuart McMillan, Phoenix-based CEO and coach at Altis who has worked with more than 70 Olympians, makes for one of the simplest and most overlooked tools a runner can include in training. Long used in sprint programs as both a warmup and a gateway to more explosive work, skipping offers a rare combination of coordination and strength benefits that distance runners often miss. “It’s really important to be able to express yourself at multiple different intensities, ranges of motion, and different directions,” McMillan explains. “But we tend to revert back to just one.” For many, that “one” is steady, forward-only easy running.…