Looking to improve your next race time? Save your money on expensive sneakers and skip that organic protein bar. According to a new study, running faster may be as easy as changing the way your foot hits the ground. Physicists at Southern Methodist University in Dallas analyzed the technique of the world’s best runners and determined that adjusting the force you hit the ground with can improve your race time.

According to a study now published online in the Journal of Experimental Biology, the equation for better race times calculates the total force of the shin, ankle, and foot striking the ground, along with the total force of the rest of the body striking the ground, to determine the ultimate speed of an athlete. In order to calculate the formula for yourself, all you need to know is the time your foot spends on the ground, how much time you are in the air, and how quickly the ankle is moving when you hit the ground, The Huffington Post reported.

“The human body is mechanically complex, but our new study indicates that the pattern of force on the ground can be accurately understood from the motion of just two body parts,” said Kenneth Clark, first author on the study, in a statement.

Although it's no new information that fast people are fast because they’re able to hit the ground harder in relation to how much they weigh, the new formula is able to calculate how fast a runner can run with impressive accuracy.

“This was true to within a millisecond, every single time. And we did it hundreds of times.” said study co-author Laurence Ryan in a statement.

While the formula technically will help any runner improve their time, according to the study, it will be particularly useful for sprinters who already run with a very specific stride to get the most force out of each step. For other types of runners, especially long distance, attempting to hit the ground too hard without the help of a trainer could result in joint injuries down the line, The Huffington Post reported. For this reason, the authors urge you not to try and incorporate the equation into your workout on your own, but rather ask someone (or even a computer program) who can better explain it to you.

However, if you’re just running to keep in shape and lose weight, the equation isn’t as important. Rather, it’s more essential for you to add diversity to your runs, such as hill workouts and intervals, to ensure your body doesn’t get too used to any one workout. In addition, it’s also important for runners to ensure they are getting enough calories into their diet, but not to overdo it. While you need fuel for a run, many overestimate how many calories they actually burn in a workout and end up eating more than they burn.

Source: Clark KP, Ryan LJ, Weyand PG.A general relationship links gait mechanics and running ground reaction forces. Journal of Experimental Biology. 2017