GUY LEAHY, MED, CSCS,*D
A RESEARCH UPDATE ON EXTREME
CONDITIONING PROGRAMS: WHERE ARE WE NOW
WITH CROSSFIT?
The views expressed in this article are those of the author, and do
not necessarily reflect the official position or policy of the Air Force,
the Department of Defense, or the U.S. Government.
Extreme conditioning programs (ECPs), such as CrossFit/P90X/
Insanity, continue to be popular training programs (5,8,14). Such
ECPs are very popular with tactical populations, and the interest
in ECPs has now even filtered into employee fitness programs for
large corporations. Despite the popularity of ECPs, these programs
remain controversial (3,15). Concerns have been expressed
regarding the safety and efficacy of ECPs, and isolated case
reports of ECP-related injuries continue to fuel the controversy
(7,10). It has been very difficult to sort out fact from fiction
regarding ECPs because until very recently there was an almost
total lack of published research that critically examined these
programs. Within the past two years, however, some examples of
ECP research have been published in peer-reviewed journals, or
presented at national conferences through organizations such as
the National Strength and Conditioning Association (NSCA) and
the American College of Sports Medicine (ACSM). Though many of
these reports are preliminary, we are at last beginning to acquire
some evidence-based findings that will assist in evaluating the
safety and efficacy of ECPs.
INITIAL STUDY
The first full paper on ECPs was not published until November of
2013 (17). This study utilized 43 subjects (23 men and 20 women)
with wide variations in fitness and body composition. The 10-week
study used several different training protocols characteristic of
ECPs (e.g., Olympic lifts, kettlebells, push-ups/pull-ups, ring work,
and bodyweight exercises). All training sessions were supervised
by a Fellow of the American College of Sports Medicine (FACSM)
and an ACSM Registered Clinical Exercise Physiologist (RCEP).
Of the 11 subjects who dropped out of the training program,
nine (16%) of them cited overuse/injury as the reason for not
completing the study. Maximal aerobic capacity (VO2max) was
measured as part of a maximal graded exercise treadmill test
(Bruce Protocol), while body fat percentage was estimated using
air displacement plethysmography. Compared to pre-test values,
the remaining study subjects significantly improved VO2max (both
absolute and relative) and body composition after the 10 weeks
(17).
Though interesting, the study contains design flaws that limit the
value of interpretation. There was neither a control group nor an
alternative intervention group, and the subjects’ diets were not
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