If you want to run fast, the saying goes, you've got to run fast.
To stoke speed, most runners do traditional speedwork: aiming for near race pace over distances of 400 meters or more, with recovery periods equal to the length of the repeat (or slightly less). Or you can get fast even faster with super short, super fast efforts, sometimes referred to as high intensity interval training (HIIT).
While HIIT definitions vary, repeats are generally 10 to 60 seconds long, run nearly full out, and are followed by a rest period lasting 1 to 4 times the length of the effort (so you're recovered to do the next repeat at the same speed and with good form). Researchers have found the low volume, high intensity approach of HIIT training can boost your speed and fitness.
More: Interval Training Tips for Runners
"For the athlete who's already doing intervals," says Martin Gibala, Ph.D., a McMaster University researcher, "Upping the intensity with short bursts of speed may provide new benefits."
Your cardiovascular system gets stronger and pushes more oxygen-rich blood through your body. Muscles get better at using that oxygenated blood. Your stride becomes more efficient as coordination between the muscles and nervous system improves. The perks may even extend to reducing your risk for chronic diseases by improving blood sugar control.
Running super fast does increase the risk of injury, however (avoid getting hurt by following these 10 Rules of Injury Prevention).
You need to be strong and flexible and have a solid base of both mileage and speedwork to safely do this training, says Joe McConkey, M.S., an exercise physiologist and coach at the Boston Running Center. You're ready for HIIT workouts if you've been running 4 to 5 times a week for at least four months, regularly doing some runs at paces 60 to 90 seconds per mile faster than easy pace, and completing a weekly long run of at least 50 minutes.
More: How to Create Your Own Interval Workouts
In terms of strength and flexibility, you should be able to hold a squat position for 90 seconds and, while standing, grab and touch your heel to your butt, feeling only a minor stretch in your quad. Start with one HIIT session a week, and build up to no more than two in a 10-day period.
Related: 5 Moves Guaranteed to Make You Faster
On the Track
High-intensity track sessions move the muscles through the full range of motion, improving elasticity and enhancing coordination between your nervous system and muscles. With time, you'll develop a more efficient stride at all your paces, says McConkey.
HIIT It: Begin with two 100-meter accelerations that include 40 meters at top speed, with 2 to 3 minutes of walking or jogging between.
Build to 6 x 150 meters hard, including 80 meters at top speed, with 3 to 4 minutes jogging or walking rest.
Over time, increase the number of repeats to 10, lengthen reps to 300 meters (running nearly the entire distance at top speed), or reduce the rest interval to one minute.