High tech devices that monitor people's waking and sleeping hours are revealing exercise trends, reports Reuters.

Fitness buffs purchased an estimated 84 million tracking devices in 2013, according to figures from analyst group HIS Inc. The gadgets are already delivering valuable data by revealing to fitness experts what the most popular trends are in the industry.

Digital fitness app and website MyFitnessPal said data collected from its 47 million U.S. users shows fitness routines like cycling were popular last year and are likely to continue in 2015.

The San Francisco-based company analyzed the minutes logged on devices for each activity, divided by the daily active users. They compared the findings to 2013.

"The trend list was compiled to identify the workouts we thought would be hot for the year, going into the new one," Rebecca Silliman, a spokeswoman for MyFitnessPal, told Reuters.

One of the most popular trends in 2014 was SoulCycle, a national chain of indoor cycling studios. The studios saw a participation increase of 75 percent and is expected to continue.

High Intensity Interval Training (HIIT), which alternates extreme effort with recovery periods, increased 28 percent and CrossFit, a rigorous, back-to-basics regimen, increased 15 percent. CrossFit mixes aerobic exercise, gymnastics and Olympic weight lifting with an intense cult-like core strength and conditioning program that continues to grow in popularity.

The American College of Sports Medicine has reported similar findings. It predicted that body weight training like CrossFit, bootcamp and HIIT, which uses minimal equipment, will be the top fitness trends of 2015. Among others:

  • Insanity
  • T25 Workout
  • PiYo Workout
  • 7 minute workout
  • P90x

If you want a personal trainer but aren't sure you can afford one, Shape magazine suggests getting together a group of friends and hiring a personal trainer to work with your group. You'll still receive individualized attention without the high cost, plus you'll be more motivated to workout knowing there is a supportive group of pals exercising with you.