What's the future of fitness? According to an international survey of exercise professionals, high intensity interval training (HIIT) will be the strongest trend in 2018, outpacing wearable technologies, which held the number 1 position in 2017. Group training, body weight training, and strength training are also on the list of top 10 trends expected to be strong this year, while interest in Exercise is Medicine and exercise and weight loss is expected to drop off.

The ratings are part of an annual review conducted by Health and Fitness Journal, published by the American College of Sports Medicine. Now in its 12th year, this year's survey included responses from 4,133 exercise professionals from around the world. "Medical professionals"—the category that includes physical therapists (PTs) and physical therapist assistants (PTAs) as well as physicians, nurses, and occupational therapists—made up 4% of the responses.

The survey asks respondents to make a distinction between trends—changes in behavior over a period of time—from "fads," which tend be enthusiastically embraced for short periods of time. Consequently, the lists don't typically change dramatically from year to year. Still, the 2018 list includes some interesting differences from previous years. Here's a quick rundown of the top 10 trends for 2018:

1.  HIIT (2017 position: #3)
2.  Group training (2017 position: #6)
3.  Wearable technology (2017 position: #1)
4.  Body weight training (2017 position: #2)
5.  Strength training (2017 position: #5)
6.  Educated, certified, and experienced fitness professionals (2017 position: #4)
7.  Yoga (2017 position: #8)
8.  Personal training (2017 position: #9)
9.  Fitness programs for older adults (2017 position: NA)
10. Functional fitness (2017 position: #12)

Rounding out the top 20 were, in order: exercise and weight loss, Exercise is Medicine, group personal training, outdoor activities, flexibility and mobility rollers, licensure for fitness professionals, circuit training, wellness coaching, core training, and sport-specific training.

Falling off the top 20 list for 2018 were worksite health promotion (#16 in 2017), smartphone exercise apps (#17 in 2017), and outcome measures (#18 in 2017). The biggest decrease was for exercise programs for children and weight loss, a trend that appeared in the top 5 lists every year from 2009 to 2013, but began to drop off in 2014. It's now ranked at #32.

The report lists licensure for fitness professionals, core training, and sport-specific training as possible "emerging trends," but warns that "future surveys will either confirm these as new trends or they will fall short of making a sustaining impact on the health fitness industry and drop out of the survey "—a fate that has befallen indoor cycling, Pilates, and dance cardio.

Far from being an exercise in crystal-ball-gazing, the survey has some very practical applications, according to ACSM.

"The benefits [of the annual survey] to commercial health clubs…are for the establishment (or maybe the justification of) potential new markets…" the report states. "Community-based programs…can use these results to justify an investment in their own markets by providing expanded programs serving families and children. Corporate wellness programs and medical fitness centers may find these results useful through an increased service to their members and to their patients."