A worldwide survey conducted by the American College of Sports Medicine (ACSM) predicted that the most popular workout of 2014 will be High-Intensity Interval Training (H.I.I.T.).This type of exercise wasn’t even on the top 20 list of workouts in last year’s survey, but it’s #1 this year.

H.I.I.T may not be for everyone. H.I.I.T. workouts include short, timed intervals of intense workouts followed by short rests to recover. The routines exercises include body weight training, Olympic lifting, plyometrics (jump training), and sprints. This type of training has become so popular because the workouts are very effective at changing the body into a more-fit one. They only take about 30 minutes to perform, which also make them a time saver.

A Montreal Heart Institute study found that volunteers placed  higher on cognition tests and had a higher brain oxygen level after doing just two HIIT workouts a week for four months. An additional study at Colorado State University discovered that due to a boost in people’s metabolic rate, they can burn 200 more calories in the next 24 hours from only 150 seconds of completing an intense workout.

Yet despite its high demand, it isn’t for everyone. Joshua Kozak, founder of HASfit, said, “High intensity workouts are extremely effective in a short period of time, but they can come with a higher risk of injury.”

“Traditionally, these routines are high impact so if you have any preexisting joint problems, then you’ll want to stick with low impact exercises. H.I.I.T is also best suited for those with a solid fitness base. If you’re just beginning, then this probably isn’t for you.”

This type of workout approach produces what people want the most  — fast results.