Page 122 - Journal of Special Operations Medicine - Fall 2015

Figure 2 Changes in physical fitness in the Columbus, Ohio, What is needed to more effectively evaluate the fitness
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study. (A) Changes in Vo max. (B) Changes in body fat. effects of CrossFit training (and other ECPs) is studies
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(C) Changes in Vo max in participants of various levels of that directly compare these programs to more tradi-
2
pretraining fitness. (D) Changes in body fat in participants tional physical training programs involving aerobic and
of various levels of pretraining body fat.
resistance training. These investigations should control
for the length (weeks), frequency (times per week), and
duration (times per session) of the training sessions. Un-
til these studies emerge, the current data suggest that
improvements in CrossFit in terms of muscular endur-
ance (push-ups, sit-ups), strength, and aerobic capac-
ity appear similar to those seen in traditional training
programs.

Injuries
Because of the high intensity and multijoint movements
involved in ECPs, many have questioned the safety of
these exercise systems. 15,16 Two studies have examined
injuries among participants in ECPs and one of these
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involved a US Army light infantry brigade combat team
Notes: In Figures 1C and 1D, the % at the top of each bar is the % 17
change in Vo max or body fat for the group. Vertical bars are standard (BCT). In the BCT study, selected Soldiers attended a
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errors. Vo max, aerobic fitness. 1-week certification class on the Advanced Tactical Ath-
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lete Conditioning Program (https://sites.google.com/site/
the strength measures were similar to, or perhaps even schofieldatac/services) that incorporated many aspects
lower than, those seen in traditional combined aerobic of ECPs. In addition, some Soldiers received certification
and resistance training programs (either linear and peri- in CrossFit training and/or the Ranger Athlete Warrior
odized). 8–10 We cannot directly compare changes in Fran (RAW) program (http://www.benning.army.mil/tenant/
or Fight-Gone-Bad because no other investigation has 75thRanger/content/PDF/Intro%20Brief.pdf).
examined changes in these tests. It should be noted that
Fran and Fight-Gone-Bad are typical CrossFit routines Certified trainers conducted a hybrid ECP with some
and as such, large improvements might be expected, Soldiers in the BCT, while other Soldiers in the BCT did
since training on a particular task will likely improve not participate in the ECP. Injuries were tracked from
performance on that task. 11 medical records for 6 months before the hybrid ECP pro-
gram and 6 months after the program had begun. Over-
In the Columbus, Ohio, study, observed changes in aer- all injury incidence increased 12% for those reporting
obic fitness were similar to those of other studies us- participation in the ECP and 14% for those who did not
ing high-intensity aerobic training. For example, one report participation. Overuse injuries (those presumably
study had subjects exercise on a cycle ergometer for due to repetitive activity and the microtrauma induced
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6 weeks at about 50% (60 minutes per session), 75% from that activity) increased 16% in the ECP partici-
(40 minutes per session), and 95% (five repeats of 5 pants and 10% in those who did not report participa-
minutes each) of their maximal aerobic fitness level tion. Thus, the change in the overall injury rate was very
(%Vo max). The study found improvements in Vo max similar, although overuse injuries were somewhat higher
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of 10%, 14%, and 20%, respectively. Improvements at in the ECP. A problem with this study was that subjects
the two higher intensities were similar to those seen in self-reported their exercise participation and it was not
the Ohio CrossFit study. However, it should be noted directly observed.
that in the cycle ergometer study, participants trained
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with a cycle ergometer and investigators measured Vo- A more recent civilian study used an online ques-
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max with a cycle ergometer. Participants in the civilian tionnaire to ask participants in Internet-based Cross-
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CrossFit study trained with whole body and multijoint Fit forums about training behaviors and injuries they
exercises, and tested aerobic fitness with a treadmill. Im- had experienced during CrossFit training. On average,
provements in Vo max are specific to the muscle groups respondents (n = 132) had performed CrossFit for 5.3
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that are involved in training 13,14 and it is likely that the hours/week over 19 months. Injuries that prevented
aerobic fitness of other muscle groups (e.g., upper body) participants from working, training, or competing had
were improved with CrossFit training. But this remains been sustained by 74%, with 7% having an injury that
to be determined, since the Ohio CrossFit study did not required surgery. The most common injury locations
specifically evaluate Vo max in other areas of the body. were the shoulder (32%), spine (28%), and arm (20%).
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110 Journal of Special Operations Medicine Volume 15, Edition 3/Fall 2015