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Understanding Injury Risk of High-Intensity Interval Training (HIIT) to Globalize Its Benefits

In This Article

  • The risk of injury in high-intensity interval training (HIIT) is poorly documented and little studied
  • Overall, HIIT-related injury incidence rates are similar to those of weightlifting studies, and less than those reported in American football and soccer studies
  • Cross-training and physical conditioning with a focus on overall functional fitness can help prevent injury

High-intensity interval training (HIIT) is an increasingly popular exercise approach for building strength and cardiovascular endurance for all levels of exercise enthusiasts, from highly competitive professional athletes, to older adults seeking functional fitness and protection against sarcopenia. By alternating timed intervals of dynamic bursts of power and speed with intervals of weightlifting, properly executed HIIT workouts can build strength, tone muscle, increase aerobic capacity and improve heart function.

But with the broader appeal and availability of HIIT, there is concern for increased potential for injury without proper physiology training for coaches. Proper coaching and body alignment are crucial to HIIT success. Orthopedic specialists at Massachusetts General Hospital have been investigating HIIT and its potential injuries.

"With my background as a strength conditioning specialist, I am always trying to bridge the gap between medicine and exercise," says Gregory Waryasz, MD, orthopedic surgeon in the Mass General Foot & Ankle Center and team physician for the New England Revolution. "And in 2013 I started to notice injuries related to exercise activities that I hadn't known about—high-intensity interval training—and I got curious to learn more."

Assessing Form

In addition to specializing in foot and ankle injuries and working with professional athletes as a team medical advisor, Dr. Waryasz trained as an Olympic weightlifter and has been a personal trainer for more than 15 years. He is a certified strength and conditioning specialist through the National Strength and Conditioning Association. This background gave him perspective and insight as he began investigating HIIT training and instruction.

"I went a little deeper into what people were doing during their HIIT workouts and started to really focus and look at how much knowledge instructors had about form," he says. In particular, he was concerned about the training details of HIIT instructors.

"I wanted to know how much they knew, where they learned it and their comfort level with learning more from a rigorous exercise physiology point of view."

Comparing HIIT Injuries

To assess the performance of advanced HIIT practitioners, Dr. Waryasz and colleagues studied advanced athletes at various gyms and compared HIIT injury patterns to those of other sports.

Findings from a descriptive survey show that in a HIIT exercise regimen, characterized by 4.3 workouts per week (lasting just over 1 hour), 74 participants reported 127 HIIT-related injuries, yielding an injury prevalence of 46.5% reported with an estimated incidence of 3.3 per 1,000 hours.

Of the 127 injuries reported, the most commonly injured body parts were:

  • Shoulder, 33.1%
  • Low back, 18.1%
  • Knees, 12.5%
  • Wrists, 10.2%
  • Elbows, 5.5%
  • Rhabdomyolysis, 0.8% (1 case was reported)

Overall, the HIIT-related injury incidence rates were similar to those of weightlifting studies, and less than those reported in American football and soccer studies.

Elements of Success

Injuries related to improper strength training regimen can impede the goal of functional fitness. Dr. Waryasz's research shows that, in general, HIIT workouts are vulnerable to error that may lead to injury when:

  • Musculoskeletal alignment is off, particularly when muscles are under load
  • Explosive, rupture-prone starts are practiced during ramp drills or in gym competitions
  • Weight training regimens rush to increase the amount of weight lifted while ignoring mastering dynamics of movement

"Being in a better athletic position, whatever you do, is the best way to prevent injury," Dr. Waryasz says. "Everyone needs cross-training to be healthy, in whatever forms appeal to them; it could be HIIT, or combining lifting weights with yoga, spinning, walking. But you need strength and movement to be functionally fit."

Functional Fitness

Functional fitness is one of the Mass General Orthopaedics team's priority research areas, due to the aging of the population and prevalence of movement-related injuries as a major factor in declining quality of life. Best-practice strength training regimens have much to contribute to the functional fitness landscape of the general population because building muscle mass, improving balance and maintaining bone integrity are foundations of healthy aging, Dr. Waryasz says.

Weight training forms—from lifting to HIIT—performed correctly can help a person control and enjoy movement free of injury. Playing tennis, resisting falls or the ability to get out of a chair easily are common examples of functional fitness that all improve from coaching informed by rigorous education in anatomy and exercise physiology.

To further research the interplay of medicine and exercise in the pursuit of health, Dr. Waryasz is conducting baseline studies of various HIIT and bodybuilding workout approaches and injury profiles. Future emphasis includes studies related to female fitness competitions and functional fitness across the lifespan.

Learn more about the Foot and Ankle Center at Mass General

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