Reality check: What science has to say about the latest fitness fads


What may or may not be someone’s great workout idea works for enough people that it develops a following. If that following grows large enough, it becomes the latest fad.

But eventually scientists step in to help separate the good from the bad and the downright ugly. From kettlebells and CrossFit to barefoot running and battle ropes, scientists have been poking and prodding their way through the latest hype. Here’s what they’re learning:

CrossFit controversies continue

With its emphasis on functional fitness and high-intensity training, it’s no secret that CrossFit has become the workout of choice for many in the military. Although created nearly two decades ago by gymnast and longtime coach Greg Glassman, little research has been done to measure its effectiveness.

Military health leaders have raised concerns over CrossFit and other “extreme conditioning programs,” such as Insanity and P90X, citing rising injury rates, “particularly for novice participants, resulting in lost duty time, medical treatment and extensive rehabilitation,” according to a late 2011 whitepaper by by top military fitness experts and the American College of Sports Medicine.

Until recently, one of the only studies to follow CrossFitters came out of the Army Command and Staff College at Fort Leavenworth, Kan., led by three majors who tracked 14 troops through an eight-week CrossFit program.

“Every athlete experienced an increase in their work capacity, measured in terms of power output, with an average increase of 20%,” wrote the study authors in 2010. “While those athletes that were least fit at the beginning of the study saw the largest net gains in work capacity, even the most-fit athletes in the study experienced significant gains.

“The results of our study indicate that above-average athletes’ overall work capacity increased 14.38%. One of our most fit athletes, with considerable CrossFit experience, saw a gain of 28.32% in overall work capacity.”

New research out of Ohio State University published this year in the Journal of Strength and Conditioning Research found that CrossFit “significantly improves VO2max and body composition in subjects of both genders across all levels of fitness.” Following a 10-week program, body fat percentages among 43 men and women of varying fitness levels dropped by about 4 percent, while VO2max, or oxygen consumption, improved by more than 12 percent.

But the study also fueled criticism of CrossFit by reporting that nine subjects — or 16 percent of those who started — dropped out of the study because of injuries or overuse issues. The injury rate “may call into question the risk-benefit ratio for such extreme training programs,” they said.

Glassman’s CrossFit Journal was quick to fire back, casting doubt on whether participants were truly injured.

“I did all the data collection for the study, and I know every person who didn’t retest. It was easy to figure out they weren’t injured,” the journal quotes CrossFit’s own study coordinator Chelsea Rankin as saying. “This data is inaccurate. Those individuals were not injured, and that wasn’t the reason they didn’t test out.”

OSU kinesiology professor Dr. Steven T. Devor says he and other researchers stand by the study.

“We love CrossFit. It’s a great training method,” Devor told OFFduty. “However, as with any high intensity power training — including CrossFit — your likelihood of having an overuse injury is greater. It is the nature of the intensity.”

Barefoot running battles on

The fight between heel strikers and mid-sole runners continues this marathon season.

Barefoot-style running — either with minimalist shoes or without any footwear at all — caught fire with Christopher McDougal’s 2010 best-seller “Born to Run” and a Harvard study around the same time. Both suggested that runners who landed more to the midsection and balls of their feet could run faster, longer and with fewer injuries than heel-striking runners in modern shoes.

Critics, however, worried that the minimalist trend was making runners less efficient and more prone to injury, especially those transitioning too quickly from traditional shoes.

Now a University of Massachusetts study has tiptoed slightly in favor of heel strikers.

Published in the Journal of Applied Physiology, researchers studied groups of runners who were either regular heel strikers or habitual forefoot runners.

Measuring oxygen consumption and carbohydrate burn as the two groups ran, researchers found no difference in running economy. When trained to switch to the other style of running and measured again, the newly converted heel strikers gained a slight edge.

“Our findings do not support previous recommendations that habitual rearfoot runners should switch to a forefoot pattern to gain a performance advantage,” wrote the researchers. “Rather, it may be beneficial for some habitual forefoot runners to adopt the rearfoot pattern.”

Performing the alternative footstrike resulted in new forefoot runners needing “significantly greater” levels of oxygen than the rearfoot group.

Meanwhile, the jury is still out on whether barefoot-style running prevents injury. A Tufts University Medical Center review of the of the most recent studies on the topic in August concluded that “barefoot running is not a substantiated preventative running measure to reduce injury rates in runners.” More research was needed.

Boost your pushup count with battle ropes

Fifteen-minute bouts of battle rope drills three times a week can raise your maximum pushup count by an average of 24 percent within four weeks.

Researchers at the University of the Windsor, Canada, put 15 men and 15 women, all about 22 years old and already in moderately good shape, through a monthlong battle rope training program.

Subjects also saw gains in situps, with an average 7 percent improvement, though gains were found mostly among women.

You’ve probably seen battle ropes on “The Biggest Loser” or at the CrossFit gym. Think the same motion you use to unsnag the vacuum cleaner cord caught on the couch leg, just with a much bigger cord. In this study, men used a 50-foot-long, 11/2-inch-thick rope weighing 25 pounds. Women used a 40-foot rope that weighed 20 pounds.

Each workout consisted of a series of 30-second, high-intensity exercise periods, followed by 60-second recovery periods, for a total of 10 work-rest rounds. The exercises alternated between the “double whip” method, with both arms moving together, and the “alternating whip,” with each arm taking turns snapping out the long waves.

Researchers suggested men might see better gains in situps using a heavier rope.

Lead researcher Colin McAuslan said to avoid training plateaus, start with shorter, thinner ropes, but keep shifting to longer, heavier ropes as you improve. Reducing rest intervals and increasing exercise times should boost results.

Meanwhile, a study from the University of Minnesota Duluth suggests that battle rope drills also significantly boost metabolic burn, concluding that “an acute 10-minute bout of rope training is a vigorous-intensity workout, resulting in high heart rates and energy expenditure.”

Kettlebells are the bomb

Basically a cannonball with a handle, kettlebells have blown up in popularity in recent years. But are the results just as explosive?

The American Council on Exercise says yes after sponsoring a study by University of Wisconsin-La Crosse’s Department of Exercise and Sport Science

in which researchers found that subjects prescribed kettlebell workouts made predictable gains in strength but also showed significant increases in aerobic capacity and dynamic balance while dramatically improving core strength.

“When most people think of resistance training, they don’t think of being able to increase aerobic capacity,” says Dr. John Porcari, head of the school’s Department of Exercise and Sport Science. “Yet we saw a 13.8 percent increase in aerobic capacity.”

The study followed 30 “healthy, relatively fit” male and female volunteers ages 19 to 25 over an eight-week training program. All took a battery of tests, and then 18 were put into a group that did an hourlong kettlebell workout twice a week while the rest did more traditional workouts.

Researchers saw no significant changes in body composition in either group, but in the kettlebell group, core strength improved by 70 percent.

Jon Anderson is a staff writer for OFFduty. Contact him at jona@militarytimes.com.

1 Comment


about 1 year ago

The article on CrossFit was interesting to say the least. A study done by CrossFitters to show the benefits of CrossFit is flawed out of the gates. Because any group of individuals given a program to improve, then retested after the program built to improve them show improvement, it is the flawed nature of the study to be biased towards showing improvement. The control group in this study (not mentioned in the article, and a group of ACSC students are not "scientists" to say the least) was laughable as well. The fact remains that any program built for improvement in any area will result in improvement when a retest is completed. I've read this and multiple studies on CrossFit in the past and have been part of the program myself. Does it work? Absolutely. Is it the only way? No, and there was no mention that because CrossFit workouts substantially evaluate on work capacity (or the power formula of Work / Time) they fail to take into account incorrect production of force methods (e.g., using bad form to decrease time, thus resulting in higher risk of injury). This has been part and parcel the argument against CrossFit - the pronounced emphasis on improving time at the detriment of proper form and safety. It is not the intensity of the training that causes injury, it the ill-defined and subjective use of "intense" by the CrossFit community, which is often synonymous with "dangerous" by those from both the medical and strength and conditioning fields. Statistics continually show weightlifting as one of the safest physical activities. But most with a weightlifting background can tell you that improper form will lead to injury, instead CrossFit prides itself for pushing beyond what is safe for the sake of time.


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