Effect of CrossFit on health related physical fitness: A pilot study

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Barfield, JP & Anderson, A. Effect of CrossFit™ on Health-related Physical Fitness: A Pilot
Study. J Sport Human Perf 2014;2(1):23-28.
DOI: 10.12922/jshp.0033.2014
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EFFECT OF CROSSFIT™ ON HEALTH-RELATED
PHYSICAL FITNESS: A PILOT STUDY
Barfield, JP1 & Anderson, A2
1Radford University, Radford, VA 24141
2Tennessee Technological University, Cookeville, TN 38505
.
Keywords: Aerobic fitness, Muscular fitness, Training Adaptations
INTRODUCTION
CrossFit™ is a relatively new training
program that is gaining favor as a non-
traditional resistance training modality (2).
Smith and colleagues (2) published one of the
seminal studies on CrossFit™ and reported
improved aerobic fitness and body
composition among middle-aged adults
following ten weeks of training. However,
this study did not address other components
of health-related physical fitness and because
individuals desire varied benefits from
resistance training, it is imperative to examine
SHORT REPORT OPEN ACCESS
ABSTRACT
PURPOSE: CrossFit™ is a novel training modality but empirical support of its effectiveness is
lacking (1). The purpose of the current study was to: 1) examine the effect of CrossFit™ on health-
related physical fitness, and 2) to compare the effects of CrossFit™ against matched participants in a
traditional training program. METHOD. Pre- and post-assessments of body composition, upper-body
muscular endurance, muscular power, and hamstring flexibility were conducted on 25 male CrossFit™
participants (Age: 22 ± 3 yrs, Weight: 91 ± 14 kg, Waist/Hip Ratio: 0.87 ± 0.06, Moderate Activity
Minutes: 239 ± 191) and 25 male traditional resistance program participants matched on baseline push-
up and vertical jump performance. CrossFit™ participants were also assessed on pre- and post-aerobic
capacity. Percent change was used to examine the effect of CrossFit™ over twelve weeks of training
and ANOVA was used to examine the fitness change differences between groups. RESULTS.
CrossFit™ participants improved aerobic capacity (6%) and muscular endurance (22%) with the mean
change in endurance differing significantly from the traditional training group (p = 0.004).
CONCLUSION. CrossFit™ Basic Instruction Program (BIP) courses may be a viable option to
traditional weightlifting programs in terms of health-related physical fitness improvement and/or
maintenance.

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CrossFit™ adaptations across all areas of
health-related physical fitness.
In an attempt to extend research in this
area, Barfield and colleagues (3) examined
the effect of a functional fitness program on
four components of health-related physical
fitness. Functional fitness training is similar
to CrossFit™ in that it incorporates high-
intensity, short-rest programming. Although
functional training is not the same as
CrossFit™, it does provide evidence on the
potential effectiveness of these training
programs. Barfield et al. (3) reported
improvements in muscular endurance and
muscular power following twelve weeks of
functional training among young adult males.
However, participants matched by training
experience and baseline strength who
participated in a traditional weightlifting
program demonstrated greater muscular
fitness gains across the twelve weeks.
Because functional training in this study was
not lead at a CrossFit™ facility by certified
instructors, caution is warranted in
extrapolating these findings to CrossFit™
training adaptations.
The current pilot study seeks to extend
the previous work in this area by examining
the effect of CrossFit™ on all four health-
related physical fitness components (i.e.,
aerobic fitness, muscular fitness, body
composition, and flexibility). To provide
context for the purported results, the
secondary purpose was to compare effects to
those demonstrated by matched participants
in a traditional resistance training program.
METHODS
Participants
Participants (N = 50) were recruited
from intact college weightlifting courses or
CrossFit™ courses contracted through the
university. To ensure groups were similar at
baseline, participants were matched on
muscular endurance and muscular power (i.e.,
Vertical Jump). Baseline data indicated that
group participants were similar in terms of
age, physical activity level, and body type
(Table 1). IRB approval was obtained prior to
the study and all participants signed inform
consent before participation. There was no
coercion as participants could participate in
the either program without participating in the
research study.
Table 1. Baseline Demographics (M ± SD, N = 50)
CrossFit
Traditional
Demographics
Age (yrs)
22 ± 3
20 ± 2
Height (m)
1.82 ± .05
1.78 ± .04
Weight (kg)
91 ± 14
84 ± 15
Moderate Physical Activity
Minutes*wk-1
239 ± 191
230 ± 200
Vigorous Physical Activity
Minutes*wk-1
131 ± 155
153 ± 216
Matching Variables
Push-Ups
31 ± 13
30 ± 13
Vertical Jump
23 ± 3
22 ± 4

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Instruments
All instruments were selected from the
American College of Sports Medicine’s
(ACSM) health-related physical fitness
assessments (4) with the exception of the
vertical jump (5). Assessments targeted
typical health-related domains and were
selected from tests used in previous work on
the topic (2-3, 6).
Aerobic Fitness.
CrossFit™ instructors administered
the 1.5 mile run. This option was presented
because it can be used to predict VO2 Max.
However, because of the training goals of the
traditional group (i.e., muscular strength),
weightlifting participants did not complete
this test.
Muscular Fitness.
The push-up and the no-step vertical
jump were administered to assess muscular
endurance and muscular power, respectively.
The push-up requires participants to touch
their chin to the mat and the score is the
number of continuous repetitions.
Body Composition.
Wasit:hip ratio was used to assess
body composition. This method was chosen
over body mass index because of the atypical
muscle mass inherent among active, college-
aged males.
Flexibility.
The YMCA sit-and-reach test was
used to assess hamstring flexibility.
Procedures
Testing was conducted during the first
two weeks (baseline) and the final week
(post-test) of the course semester. The lead
researcher trained all program instructors on
testing procedures and the instructors, in turn,
conducted all baseline and post-testing. This
method ensured that all participants were
tested by the same raters and under the same
conditions for both the pre and post
assessments. All participants attended training
sessions at a frequency of twice per week and
completed a minimum of 24 of the 28 training
sessions.
To determine the effects of CrossFitTM
relative to traditional resistance training, it
was imperative to administer distinct
programs to similar groups under similar
conditions. Matching participants on two
performance variables (i.e., muscular
endurance and muscular power) was an
effective means of selecting two training
groups. Although training outside of class
was not prevented, the similar physical
activity levels and training conditions allowed
the training program to be the major
distinction between training groups.
CrossFit™ Training Program.
Participants traveled off-campus to
participate in the contracted CrossFit™
training led by two certified instructors at
their own facility. Classes consisted of 10
students and programming consisted of a non-
linear design emphasizing high-intensity
resistance training with self-selected rest
between repetitions and sets. Each session
started with a 10-minute dynamic warm-up,
followed by 15 minutes of technique
instruction and 10-25 minutes of CrossFit™
training. For a detailed description of
CrossFit™ training sessions, see Smith and
colleagues (2). In general, this training
includes varied gymnastic and multi-joint
exercises (e.g., squats, Olympic lifts)
organized into: a) maximum repetitions to be
completed within a given time period, or b) a
given repetition goal to be completed within
the shortest time possible. As a rule, training
sessions are characterized by high-intensity
exercise with minimal rest.
Traditional Resistance Training Program.

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The traditional resistance training
class was led by one experienced campus
instructor. Classes consisted of 16 students
and programming consisted of a linear
periodized program with appropriate rest
between sets. Each session started with a 10-
minute dynamic warm-up, followed by 10
minutes of resistance warm-up (e.g., full-
body exercises) and 25 minutes of traditional
weightlifting. Training addressed hypertrophy
[3 sets, 8-12 repetition maximum (RM), 45
seconds rest], strength (3-5 sets, 3-6 RM, 90
seconds rest), and power (3-5 sets, 2-3 reps of
low- to moderate-intensity weight, 90 seconds
rest). In general, training included core multi-
joint exercises (e.g., bench press, deadlift,
squat) with supporting multi- and single-joint
lifts. Although frequency of training was
matched between groups, training volume
was not.
Analysis
Percent change was computed to
examine improvement on each dependent
variable in each group. Separate independent
groups ANOVA (p <0.01) were used to
examine fitness change score differences
between groups.
RESULTS
CrossFit™ participants improved
aerobic fitness (6%) and upper body muscular
endurance (22%) but did not demonstrate
improvement in muscular power, body
composition, or flexibility (Table 2). Fitness
changes were greater among CrossFit™
participants on muscular endurance (F = 9.14,
df = 49, p = 0.004) compared to traditional
weightlifting participants. Better waist:hip
changes were noted in the traditional class
(0% vs. -3%).
Table 2. Fitness Changes (M ± SD) across the Semester by Resistance Class Type
CrossFit (N = 25)
Traditional (N = 25)
Aerobic Fitness
Baseline 1.5
41.49 ± 8.00
Post 1.5
43.90 ± 7.32
Percent Change
-6%
Body Composition
Baseline Waist:Hip
0.87 ± 0.06
0.89 ± 0.05
Post Waist:Hip
0.87 ± 0.08
0.86 ± 0.09
Percent Change
0%
-3%
Muscular Fitness
Baseline Push-Ups
31 ± 13
30 ± 13
Post Push-Ups
38 ± 11
30 ± 9
Percent Change
22%
0%
Baseline Vertical Jump
23 ± 3
22 ± 4
Post Vertical Jump
23 ± 3
22 ± 3
Percent Change
0%
0%
Flexibility
Baseline Sit-and-Reach
4.5 ± 3.0
2.5 ± 3.0
Post Sit-and-Reach
4.5 ± 2.5
2.5 ± 3.0
Percent Change
0%
0%

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DISCUSSION
The purpose of the current study was to
examine the effect of CrossFit™ on health-
related physical fitness. The secondary
purpose was to compare the effects of
CrossFit™ against matched participants in a
traditional resistance training program.
Findings from the current study support
aerobic and muscular endurance benefits from
CrossFit™ training. Similar, if not greater,
improvement on health-related physical
fitness variables occurred following
CrossFit™ training compared to traditional
resistance training. The results from this pilot
study support the use of CrossFit™ as an
alternative resistance training modality.
Findings from the current study are
consistent with the aerobic benefit of
CrossFit™ reported by Smith and colleagues
(2). These authors reported a 13.6%
improvement in VO2 Max among young adult
men following ten weeks of CrossFit™
training. It is worth noting that although our
participants demonstrated a similar pattern
(i.e., improved aerobic fitness), the current
findings were not as substantial despite the
younger sample (6% vs. 14% improvement).
This difference is likely explained by the
lower training frequency, as current
participants were limited to two sessions per
week.
CrossFit™ training has a high aerobic
stimulus due to minimal rest periods;
therefore, the improvement in aerobic fitness
among CrossFit™ participants was not
surprising (Table 2). Current findings are
consistent with the work of Astorino and
colleagues (6), who reported a 6% increase in
VO2 Max among young men who completed 6
sessions of high intensity training (4-6
Wingate tests per session). Although Asotrino
et al. (6) did not examine CrossFit™
participants, the consistent high intensity
exercises were an appropriate comparison to
the current training program.
Current findings conflict with a prior
study on functional fitness training. Barfield
and colleagues (3) reported a 7.5%
improvement in upper body muscular
endurance following functional training and
even greater improvement (18%) among
traditional weightlifting participants. Current
findings support a much greater training
adaptation for muscular endurance among
CrossFit™ participants (22%). Our results
clearly indicate how training setting and
instructor affect adaptations within high-
intensity training programs. We incorporated
a similar sample, training intensity, training
frequency, and training mode as
aforementioned study (3). The primary
distinctions between the two studies were the
trainers (i.e., certified CrossFitTM in the
current design) and location (i.e., CrossFitTM
facility in the current design).
There are a couple of limitations to the
current study. We chose general health-
related physical fitness variables to ensure
neither group had a training-specific
advantage; however, given the lack of
improvement on several muscular fitness
items (e.g., vertical jump), examination of
training-specific variables is warranted. It is
likely that traditional weightlifting
participants would demonstrate greater grains
on certain muscular fitness variables such as
strength. Also, we did not match training
volume. It is difficult to match volume
between linear (i.e., traditional) and non-
linear (i.e., CrossFit™) programs. A valid
means of matching work output must be
developed if empirical comparisons between
traditional and non-traditional programming
continue.
PRACTICAL APPLICATIONS
CrossFit™ training is a popular
commercial program but empirical research
on its effectiveness is lacking. The current

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study extends the formative work on this
topic and documents chronic adaptations
resulting from this non-traditional training
program. Additionally, the current study
demonstrates similar fitness adaptations
between CrossFit™ and traditional
programming.
REFERENCES
1. Prawdzik C. Doctors: Exercise caution
when introducing CrossFit. Athletic
Business [Internet]. [cited 2014 April 27].
Available from:
http://www.athleticbusiness.com/military/
doctors-exercise-caution-when-
introducing-crossfit.html
2. Smith MM, Sommer AJ, Starkoff BE,
Devor ST. Crossfit-based high-intensity
power training improves maximal aerobic
fitness and body composition.. J Strength
Cond Res 2013;27(11):3159-3172.
PubMed PMID: 23439334. doi:
10.1519/JSC.0b013e318289e59f. [Google
Scholar]
3. Barfield JP, Channell B, Pugh C, Tuck M,
Pendel D. Format of basic instruction
program resistance training classes: Effect
on fitness changes in college students.
The Physical Educator;2011:69-325.
[Google Scholar]
4. American College of Sports Medicine.
ACSM’s Health-related physical fitness
manual. Philadelphia (PA): Lippincott,
Williams, & Wilkins; 2005. [Google
Scholar]
5. Harman E, Garhammer J. Administration,
scoring, and interpretation of selected
tests. In: Baechle T, Earle R, editors.
Essentials of strength training and
conditioning. Champaign (IL: Human
Kinetics; 2008. [Google Scholar]
6. Astorino TA, Allen RP, Roberson DW,
Jurancich M. Effect of high-intensity
interval training on cardiovascular
function, VO2max, and muscular force.
The Journal of Strength & Conditioning
Research 2012;26(1):138-145. PubMed
PMID: 22201691. doi:
10.1519/JSC.0b013e318218dd77.
[Google Scholar]