The American sports scientists Steven Devor and Michael Smith are being taken to court. In November 2013 they published a study on the effects of 10 weeks of CrossFit training – and the owner of the gym where the study was done is not happy with it.
CrossFit makes you fitter
After a quick flip through Smith and Devor’s study you might wonder why a court case is necessary [scribd.com]. At first sight it’s pure advertising for CrossFit.
The researchers followed a group of 23 men and 20 women who did CrossFit training almost every day. The subjects became slimmer, more muscled and fitter. The first figure below shows the men’s progression, the second that of the women. By the way, all the subjects were also on a paleo diet.
It’s interesting that CrossFit was effective for all participants. Those who started off in terrible condition became fitter, but participants who were already fit also became fitter. Overweight participants lost weight, as did participants who already had a healthy body fat percentage.
The reason that the owner of the CrossFit gym took the researchers to court is one short sentence in the study about participants who dropped out.
“Of the 11 subjects who dropped out of the training program, 2 cited time concerns with the remaining 9 subjects (16% of total recruited subjects) citing overuse or injury for failing to complete the program and finish follow-up testing”, the researchers write.
This comment touched a raw nerve in the CrossFit movement. CrossFitters are already at loggerheads with sports scientists who say that CrossFit is too demanding for most people who do this form of fitness training. The training programmes include too many exercises that are quite difficult to perform, and the short amount of time devoted to each exercise means that CrossFit workouts don’t give participants enough time to prepare their body for the at-failure type exertion that CrossFit promotes. [Curr Sports Med Rep. 2011 Nov-Dec;10(6):383-9.]
In the last few years there have been several reports in the American media about accidents and injuries from people doing CrossFit training, and CrossFit is not happy with this negative publicity either. It seems that Devor and Smith’s study in the Journal of Strength and Conditioning Research is the last straw for CrossFit.
“To our knowledge, no research on the aerobic benefits of high-intensity power training [this is how the researchers describe CrossFit training] has been conducted”, the researchers write. “High-intensity power training focuses on high intensity resistance training using multiple joint exercises, with little to no focus on traditional aerobic activities. Despite this, our results show that this type of training also provides aerobic and body composition benefits.”
“Based on the results presented here, individuals of all fitness levels and either gender can realize body composition and aerobic benefits from high-intensity power training. Given that our subjects were following a Paleolithic diet, we cannot relate all of the observed weight loss to high-intensity power training. However, high-intensity power training and Paleolithic diet in combination could be used to promote positive changes in body composition.”
Crossfit-based high-intensity power training improves maximal aerobic fitness and body composition.
The purpose of this study was to examine the effects of a crossfit-based high-intensity power training (HIPT) program on aerobic fitness and body composition. Healthy subjects of both genders (23 men, 20 women) spanning all levels of aerobic fitness and body composition completed 10 weeks of HIPT consisting of lifts such as the squat, deadlift, clean, snatch, and overhead press performed as quickly as possible. Additionally, this crossfit-based HIPT program included skill work for the improvement of traditional Olympic lifts and selected gymnastic exercises. Body fat percentage was estimated using whole-body plethysmography, and maximal aerobic capacity (VO2max) was measured by analyzing expired gasses during a Bruce protocol maximal graded treadmill test. These variables were measured again after 10 weeks of training and compared for significant changes using a paired t-test. Results showed significant (p < 0.05) improvements of VO2max in men (43.10 ± 1.40 to 48.96 ± 1.42 ml · kg · min) and women (35.98 ± 1.60 to 40.22 ± 1.62 ml · kg · min) and decreased body fat percentage in men (22.2 ± 1.3 to 18.0 ± 1.3) and women (26.6 ± 2.0 to 23.2 ± 2.0). These improvements were significant across all levels of initial fitness. Significant correlations between absolute oxygen consumption and oxygen consumption relative to body weight was found in both men (r = 0.83, p < 0.001) and women (r = 0.94, p < 0.001), indicating that HIPT improved VO2max scaled to body weight independent of changes to body composition. Our data show that HIPT significantly improves VO2max and body composition in subjects of both genders across all levels of fitness.
PMID: 23439334 [PubMed - in process]