Research proves it: the human body is designed for strenuous, long-haul adventure. Recent studies have even suggested that endurance running actually shaped the evolution of the human body. According to Harvard paleoanthropologist Daniel Lieberman, an author of many such studies and The Story of the Human Body, human beings "are fundamentally adapted to get exercise." But the gym is not enough. "There's nothing like the real thing," says Adam Chase, president of the All American Trail Running Association. The outdoors is simply more demanding. "When you're out on the trail, you have to dance through the rocks and routes." That translates into automatic interval training, which strengthens your heart by forcing it to learn to adapt to just about anything. Here's your guide to getting your heart in shape – and having fun while you're at it.
Humans are built to jog; our ancestors are thought to have hunted this way across dozens of miles at a time. Cool spring temps also mean more oxygenated blood for your muscles.
Quads, hamstrings, glutes, and calves all work to keep you moving, but as your distances increase, running demands more of your core to keep you upright and stable.
Amp It Up
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Scott Berlinger's clients run at a comfortable pace for 10 minutes and then at a faster, but sustainable, pace for two and a half minutes. Repeat this drill four times. As you get stronger, try cutting some of the slow periods to five minutes. When you're ready to truly test your mettle, begin decreasing the length of the slow periods as your workout progresses; you'll be pushing yourself hard when you could use the longer rest.