Form Fixers

A “perfect” running style doesn't exist, but there *are* expert-approved ways to tweak your stride at any speed so each step is efficient, powerful, and injury-free. Time to lace up....

- Caitlin Carlson

Is that you, spring? There's no happier feeling than hitting the pavement or trail once again sans earmuffs and wool socks. And when you take off into the new, hopeful season, consider this training shake-up: Even the average runner (hi!) should be working both sprints and endurance runs into their routine for payoffs.

If you're a marathoner trying to PR, speed work will make you faster. (Plus, studies show that sprints can reduce body fat, if changing body composition is a focus for you.) Prefer fast and furious? Know that longer-distance cardio is powerful for overall wellness too. Furthermore, training for a marathon, even at low intensity, reduced vascular age (essentially, the health of your arteries-key for heart health) in people by four years, one study found.

We know-shaking up your run routine can be uncomfortable. In fact, genetics partially dictates why you may favor one training style over another, given that you're born with a particular muscle fiber composition that predisposes you to be better at, say, distance versus short bursts of speed. Long-distance runners rely on thin, small slow-twitch muscle fibers that are more resistant to fatigue, says Yukiko Matsuzaki, DPT, a physical therapist at Hospital for Special Surgery. This allows endurance athletes to perform longer. Sprinters have more of a fast-twitch type, which helps them do high-intensity exercise for short periods.

While you can't grow more of the fiber types you lack, you can strengthen and develop both kinds, says Annick Lamar, a New York Road Runners coach and runner training and education lead. “I recommend two days a week of endurance running to optimize the aerobic benefit that slower miles give you, and one day a week of sprinting to build muscle and power."