June 2012

Going to extremes: Battling dangers of high intensity exercise

In the moment: Sports medicine

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By Jordana Bieze Foster

The exploding popularity of so-called extreme conditioning programs is now infiltrating the armed forces, prompting military sports medicine experts to take a closer look at the potential risks and benefits of high intensity exercise.

“We’re interested because our warfighters are,” said Col Francis G. O’Connor, MD, MPH, medical director of the Consortium for Health and Military Performance in Bethesda, MD. “Extreme exercise is very hot right now.”

Extreme exercise is also, potentially, very dangerous. Taking exercise intensity to a higher level by definition elevates the risks of a range of injuries that can result from fatigue and overtraining—risks with which military practitioners are already very familiar.

With little in the medical literature to offer guidance, military sports medicine experts convened at a 2010 workshop to create a set of recommendations, which were subsequently published last November in Current Sports Medicine Reports. And in late May, O’Connor and four other experts further discussed and debated the relative merits of extreme conditioning during a symposium at the annual meeting of the American College of Sports Medicine, held in San Francisco.

Hundreds of thousands of private citizens have been drawn in the last few years to high intensity workout programs such as CrossFit, Tough Mudder, and TRX, often attracted by their military-style training techniques. Now members of the actual military are embracing extreme conditioning for reasons that experts are still trying to determine, whether it’s filling a void in existing training, satisfying the competitive soldier’s need to continually push harder, or just a fun change of pace.

“There are a lot of anecdotal reports of soldiers enrolling in training programs outside the military,” said Timothy C. Sell, PhD, PT, an assistant professor in the Department of Sports Medicine and Nutrition at the University of Pittsburgh, who has worked with members of the 101st Airborne Division of the US Army and the Navy SEALs.

Not surprisingly, anecdotal reports of soldiers being injured in conjunction with such programs are also increasing. According to survey data presented by Sell at the ACSM meeting, about one-third of injuries to 101st Airborne soldiers and half of injuries to Navy SEALs during one year occurred during training that was not part of military activity.

The recommendations, which its authors hope will be useful for private citizens as well as members of the military, acknowledge that extreme conditioning may have significant benefits. Previous studies, sum­marized in a February review in the Journal of Sports Conditioning and Research, have documented the effectiveness of conventional resistance exercise for improving load carriage, and it’s possible that raising the intensity would in turn increase the benefit.

But it is also difficult to ignore implications for extreme conditioning in the existing body of research on injury risks related to overtraining and fatigue. As a result, the recommendations call for trainers to introduce extreme conditioning to novices gradually, ensure adequate rest during and between sessions, monitor for signs of overtraining, and discourage the use of caffeine and other stimulants that can mask fatigue.

The recommendations also emphasize that not all soldiers or athletes will have the same fitness levels or physical skills, and suggest that trainers work to adjust conditioning programs based on the needs and abilities of individual participants.

“When you get into group training situations, it’s very difficult to individualize, but not every body has the same level of fitness,” said Michael F. Bergeron, PhD, a professor in the Department of Pediatrics at the University of South Dakota’s Sanford School of Medicine in Sioux Falls, SD, and first author of the recommendations. “One size does not fit all, but when you pull programs off the shelf, there’s not a lot of room for individualization or job specificity.”


Bergeron MF, Nindl BC, Deuster PA, et al. Consortium for Health and Military Performance and American College of Sports Medicine consensus paper on extreme conditioning programs in military personnel. Curr Sports Med Rep 2011;10(6):383-389.

Knapik JJ, Harman EA, Steelman RA, Graham BS. A systematic review of the effects of physical training on load carriage performance. J Strength Cond Res 2012;26(2):585-597.

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