Are you in Canada? Click here to proceed to the HK Canada website.

For all other locations, click here to continue to the HK US website.

Human Kinetics Logo

Purchase Digital Products

If you are looking to purchase an eBook, online video, or online courses please press continue

Booktopia Logo

Purchase Print Products

Human Kinetics print books are now distributed by Booktopia Publisher Services throughout Australia/NZ, delivered to you from their NSW warehouse. Please visit Booktopia to order your Human Kinetics print books.

Human Kinetics Logo

Purchase Courses or Access Digital Products

If you are looking to purchase online videos, online courses or to access previously purchased digital products please press continue.

Mare Nostrum Logo

Purchase Print Products or eBooks

Human Kinetics print books and eBooks are now distributed by Mare Nostrum, throughout the UK, Europe, Africa and Middle East, delivered to you from their warehouse. Please visit our new UK website to purchase Human Kinetics printed or eBooks.

Feedback IconFeedback

Why Recovery is Such an Essential Element of High-Intensity Interval Training

High-intensity interval training (HIIT) is among the top fitness trends reported by the American College of Sports Medicine over the past two years. And thanks to the increasing popularity of programs like P90X and CrossFit, HIIT will likely remain at the top of that list for years to come. That's why recognizing the importance of recovery is crucial for people taking up a HIIT program. “Recovery is not a suggestion,” says 30-year fitness veteran Irene Lewis-McCormick, author of The HIIT Advantage: High-Intensity Workouts for Women.


Known for quick, challenging workouts that maximize time and efficiency, HIIT increases metabolism and aerobic capacity, strengthens muscles, and increases weight loss. But as Lewis-McCormick emphasizes, overtraining can be very detrimental. Not only can it lead to injury, but it can also result in burnout and have significant negative long-term effects that interfere with a lifestyle of exercise. “Fitness and performance enhancement require a complex combination of overload and adequate recovery,” she says. “Too much overload and too little recovery will likely result in both physical and psychological signs and symptoms of overtraining.”


Overtraining results from performing exercises that are above and beyond one's tolerance, or beyond the body's ability to recover. Exercising longer and harder without the benefit of recovery will do exactly the opposite of what the training program is designed to do—that is, it will increase the risk and likelihood of injury and decrease performance. Lewis-McCormick points to a number of signs and symptoms that may determine whether someone is overtraining and not giving themselves enough recovery between workouts:


  • Consistent muscle pain and soreness
  • Fatigue that doesn't diminish with sleep
  • Elevated resting heart rate
  • Decline in maximal heart rate
  • Insomnia
  • Irritability
  • Increase in number of colds and sore throats
  • Depression
  • Loss of appetite
  • Increased incidence of injuries
  • Compulsion to exercise
  • Loss of enthusiasm for training or sport
  • Drop in performance


“You can use your resting heart rate for signs of overtraining,” Lewis-McCormick explains. “For three consecutive mornings, document your resting heart rate. It should stay relatively consistent from morning to morning. Try to take it at the same time each morning. Any marked increase from the norm may indicate that you aren't fully recovered. If your resting heart rate begins to rise and you experience other overtraining signs or symptoms, you may be heading into overtraining.”


All successful athletes know that rest and recovery between training sessions are critical for optimal, high-level performance. The body strengthens and repairs itself in the time between workouts, and continual training without the benefit of recovery will weaken even the strongest athlete. Likewise, fitness enthusiasts need to realize that adequate recovery between workouts is mandatory for reaching fitness goals without experiencing burnout and increasing the risk of injury. However, Lewis-McCormick concedes, many still overtrain, feeling guilty when they take a day off. “Rest days are critical to performance,” she stresses. “Practicing both short and long-term recovery, as well as planned recovery using periodization, will result in a better balance between lifestyle and fitness goals.”


As the authoritative guide on high-intensity training, The HIIT Advantage is comprehensive yet accessible, describing how and why HIIT is one of the most effective ways to burn fat and improve performance. It includes 19 complete workouts consisting of a combination of 20-, 30-, and 45-minute sessions, along with exclusive access to the HIIT Advantage video library.