This Workout Is More Likely To Cause Knee & Ankle Injuries, New Study Finds

High-intensity interval training (HIIT) is to fitness what collagen is to nutrition. That's to say, it's super freakin' trendy. And for good reason—this form of exercise, which consists of alternating short bursts of high-intensity activity with short periods of rest, has been associated with loads of health benefits from increasing endurance to boosting fat burn and basal metabolic rate. Most recently, it was found to be more effective at reducing belly fat than moderate-intensity exercise.

But before diving full-tilt into this fitness trend, there's something you need to know: HIIT could be significantly upping your risk of injury.

A new study in the Journal of Sports Medicine and Physical Fitness found that, while HIIT was great for boosting fitness and building lean muscle mass, it was associated with increased injury—particularly knee and ankle sprains and strains and rotator cuff tears.

To reach this conclusion, researchers analyzed data from the National Electronic Injury Surveillance System from 2007 to 2016 and found over 3 million injuries resulting from equipment (barbells, kettlebells, boxes) and specific exercises (burpees, lunges, pushups) that are common in HIIT programs. They found a steady increase in the number of these injuries each year, corresponding with an increased interest in HIIT (measured by Google searches).

So, why exactly is HIIT particularly risky from an injury standpoint? "These workouts are marketed as 'one size fits all.' However, many athletes, especially amateurs, do not have the flexibility, mobility, core strength, and muscles to perform these exercises," said study co-author Joseph Ippolito, M.D., in a news release. "There is strong evidence that these types of injuries—specifically from repetitive overload at the knee—can lead to osteoarthritis."

With HIIT, poor form, improper workout recovery, and muscle overuse are likely what's driving these injuries. That's not to say HIIT should be avoided altogether, but this research does emphasize the importance of switching up your workout routine, improving flexibility through stretching, and building strength and balance with less intense workouts before you jump into a grueling HIIT routine.