Home Fitness Muscular Endurance and Strength Evaluation of Possible Anthropometric Advantage in Sit-Up Test – United States Sports Academy Sports Journal

Evaluation of Possible Anthropometric Advantage in Sit-Up Test – United States Sports Academy Sports Journal

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Authors: David Peterson, Meighan Middleton, Sharon and Christman

Corresponding Author:
David D. Peterson, EdD, CSCS*D
Cedarville University
251 N. Main St.
Cedarville, OH 45314
ddpeterson@cedarville.edu
(937) 766-7761

Dr. Peterson is an associate professor of kinesiology at
Cedarville University (CU) and currently serves as the Director of the
Multi-Age Physical Education (MAPE) program at CU.

Evaluation
of Possible Anthropometric Advantage in Sit-Up Test

ABSTRACT

The U.S. Navy currently employs sit-ups as part of its
semi-annual physical fitness in order to assess the abdominal muscular
endurance of service-members.  However,
there is speculation that sit-up performance may be associated with
anthropometric proportions thereby affording certain service-members with a
biomechanical advantage.  To test this
theory, anthropometric measurements were taken at various sites (i.e., humerus,
torso, femur, and tibia) across a convenience sample of 69 participants (37
male / 32 female), to include student, active duty, and retired military personnel
from the United States Naval Academy. 
Humerus length (r = .297), tibia length (r = .385) and sex (r = .314)
were all found to be moderately correlated with sit-up performance.  These findings, coupled with well-documented
concerns of the sit-ups in terms of safety and relevance in the literature,
make a compelling argument for the identification and implementation of other
potential field tests to assess abdominal muscular endurance

Keywords: military physical fitness test, sit up test, anthropometric measurements

INTRODUCTION

As a result of a
presidential mandate, the U.S. Navy developed and implemented its first
physical fitness test in 1980 (6).  The
test included sit-ups, flexed-arm hang (females only), push-ups, pull-ups
(optional push-up alternative for males), 1.5-mile run/walk, and a 3-min
run-in-place (optional run/walk alternative). 
Although the Navy Physical Readiness Test (PRT) has undergone several
changes since its initiation, the U.S. Navy continues to employ sit-ups (curl-ups)
as part of its semi-annual physical fitness test.

Sit-ups were added to
the PRT to assess muscular endurance and specifically chosen due to a potential
link between regular sit-up training and low-back pain prevention as documented
in some of the available literature at the time (6).  Since its implementation, however, the safety
and operational relevance of the sit-up has been called into question.  For example, rarely do service-members
perform repetitive spinal flexion as part of any specific job task (14).  In fact, service-members more often use their
trunk musculature for stabilization in order to lift, push, pull, and
carry.  Additionally, current research
now shows that performing high volume sit-up training may actually lead to
low-back pain and injury instead of preventing them (1, 3, 4, 10, 11, 12,
14). 

Another possible concern
with the sit-up is the possibility for an unfair biomechanical advantage.  For example, some service-members seem to be
able to complete the required range of motion of the sit-up (i.e., lift the
upper torso until the elbows contact the thighs) with modest effort, while for
others it is far more difficult. 
Specifically, some service-members are able to touch their elbows to their
thighs while keeping their low backs in contact with the ground.  Conversely, other service-members must lift
their entire torso several inches off the ground in order for their elbows to
make contact with their thighs.  This
disparity in execution led the authors to suspect that certain anthropometric
dimensions of an individual may offer a biomechanical advantage or disadvantage
thereby influencing the level of ease or difficulty in performing maximum
sit-ups.  It is possible that this
biomechanical advantage may be a result of differences in limb length (i.e.,
humerus, femur, and tibia) and torso length.

Although concerns
associated with the sit-up in terms of safety and operational relevance are
well documented in the literature (14), the impact of certain anthropometric
variables (e.g., weight, height, and limb length) on performance appear to be
less well known.  Vanderburgh (16)
reported that current physical fitness tests employed by the U.S. military tend
to be biased against larger service-members (regardless of body composition)
and instead favor lighter service-members. 
Kranick (8) reported limb circumference, height and weight as
determining factors on maximal muscle strength in college-aged (i.e., 20-28
years old) males (n = 7); although similar findings were not reported in college-aged
females.  As a result, Kranick (8)
concluded that maximal strength is not influenced by an individual’s height or
limb length, but rather their build.  Radu
et al. (15) reported a correlation between anthropometric dimensions and
physical fitness characteristics in college students (n = 67; 44 male / 23
female).  Specifically, Radu et al. (15)
found a moderately positive correlation between abdominal strength and sitting
height-to-height ratio (SHR) in males (r = 0.352); although similar findings
were not reported in females.  Luz et al.
(9) reported a relationship between body size and motor fitness especially in 8
year old girls (n = 74) when performing a variety of physical tasks (i.e., 2-kg
medicine ball throw, hand grip strength, sit-ups, standing long jump,
sit-and-reach, 25-m dash, 10 x 5-m shuttle run, 20-m endurance shuttle
run).  Specifically, Luz et al. (9) found
moderately negative correlations between sitting height-to-stature ratio and
fitness (r  = -0.77) and stature and
fitness (r = -0.56).  Esco et al.
(5)  reported that there are a number of
anthropometric variables (e.g., skinfolds, weight, height, body mass index
(BMI), waist and hip circumferences, and waist/hip ratio (WHR)) that are
predictive of sit-up performance in adults (n = 100; 40 male / 60 female). 

Unfortunately, as
depicted above, current research has yet to show a clear connection between
certain anthropometric measurements and performance on various physical fitness
tests. This lack of consensus provided additional rationale and justification
for the current study.  If a clear
connection between an individual’s anthropometrics and performance could be
found, it could influence which physical fitness tests should be used as well
as how they are to be administered and graded.

The purpose of this study was to evaluate the impact of
limb and torso length on sit-up performance in active duty personnel, recently
retired from active duty personnel and students from the United States Naval
Academy (USNA).  The authors hypothesized
that individuals with longer limbs have a certain biomechanical advantage and
thus will have higher maximum sit-up scores than individuals with shorter
limbs.

METHODS

Participants were
recruited from students, active duty, and recently retired military personnel
from the United States Naval Academy.  Of
the 69 participants, 32 were female and 37 were male.  The mean age of females tested was 24 and the
mean age of males tested was 27.   Height
and weight were measured on each participant. 
Statistical analysis was conducted via IBM SPSS Statistics 23.  Descriptive data for each participant is
provided in Table 1.

Prior to participation
in maximum sit-ups in two minutes, participants were measured at four sites:
humerus, torso, femur, and tibia. 
Humerus measurements were collected from the acromion to lateral
epicondyle (Figure 1).  Torso
measurements were collected on the posterior side of the body, alongside the
back by palpation of the spinous process of the C7 vertebra to midline between
iliac crests (Figure 1).  Femur
measurements were collected from the greater trochanter to the lateral
epicondyle (Figure 2).  Tibia
measurements were collected from the medial condyle to the medial malleolus
(Figure 2).  Participants were then asked
to perform the sit-up portion of the Navy PRT, completing maximum sit-ups in
two minutes.  Formal testing procedures
were taken and read verbatim from the Navy’s Physical Readiness Test (PRT)
procedures guide (13).

Figure 1
Figure 2

Testing ended at the
completion of two minutes, or sooner if the participant stopped, lowered legs,
lifted feet off the floor, lifted buttocks off the floor, or failed to keep
arms folded across the chest and or lowered arms.  Measurements and sit-up scores were recorded
and compared using various statistical analyses to evaluate relationship
between the certain anthropometric measurements and sit-up performance.

RESULTS

The authors hypothesized a relationship between torso and limb lengths with sit-up performance.  As shown in Table 2, there was a moderate positive correlation between humerus (r = .297; p = .013) and tibia (r = .385; p = .001) length and sit-up performance; however the small positive correlations between torso (r = .191; p = .115) and femur lengths (r = .088; p = .470) and sit-up performance were not statistically significant.  Correlational analysis also showed a moderate positive relationship between height and sit-up performance (r = .306; p = .011).  However, because the positive correlation between torso and femur length and sit-up performance was small and statistically insignificant, the correlation between height and sit-up performance is likely attributed to the inclusion and influence of the tibia length.

Table 2

Because the results
supported the authors’ hypothesis that humerus and tibia length could improve
sit-up performance, the authors wanted to determine the practical degree to
which performance was improved.  In other
words, how many more sit-ups could a long-limbed person complete in 2 minutes.  The results of this analysis can be found in
Table 3.  By dividing limb length at its
mean (humerus at 38 cm and tibia at 41 cm), the authors found that a
longer-limbed person could perform between 15 and 20 more sit-ups in 2 minutes.  

Table 3

As was to
be expected, the authors also found a significant difference in humerus and
tibia lengths between males and females. 
As shown in Table 4, there was a statistically significant difference in
both humerus (p = .000) and tibia (p = .000) lengths between males and females,
which was consistent with the significant difference (p = .009) in their sit-up
performance of about 15 sit-ups.

Table 4

DISCUSSION

Based on personal
experience of observing hundreds of naval officers complete their physical
fitness test, the authors hypothesized that an individual’s anthropometric
measurements would have a positive correlation with sit-up performance, and the
results of this study supported that hypothesis.  One explanation for how limb length
influences sit-up performance is illustrated in Figure 3.  Two male subjects who participated
in the study were identified as having very different sit-up performance (i.e.,
subject A = 65 sit-ups; subject B = 113 sit-ups).  These subjects’ humerus, torso, femur and
tibia lengths were then entered into Adobe Illustrator for visual comparison.  This illustration makes it clear how limb
length changes the distance the elbows have to travel in order to make contact
with the thighs.  It is very possible
that a shorter distance allows for less fatigue and thus better sit-up
performance.  

Figure 3

The authors believe there is good internal and
external validity to this study.  Because
all participants were either active duty, recently retired from active duty, or
students in a military service academy, they were familiar with the testing
criteria and had experience performing sit-ups. 
Furthermore, all subjects were given the same instructions before
performing their sit-ups, thus providing strong inter-rater reliability.  Finally, there was equal distribution of male
(n = 37) and female participates (n = 32), providing a representative sample of
those serving in military service academies and the armed forces.

However, there was one limitation to this study the authors identified
regarding the lack of standardization in the distance between the participant’s
heels and buttocks.  Per the Navy’s PRT
instruction, participants are to position their heels about 10 inches from the
buttocks (13).  Although the official PRT
testing criteria was read aloud prior to the test, subjects were allowed to
adjust their body position thereby changing the distance (increasing or
decreasing) between their heels and buttocks. 
This was done to afford participants the ability to employ the same body
position they use during official semi-annual PRT testing. 

 By allowing
participants to adjust their body position, some participants opted to employ a
distance greater than 10 inches from heels and buttocks while others employed a
shorter distance.  It is unknown whether
the disparity in distance from the heels and buttocks would have altered the
angle of the knee and hip enough to change the distance their elbow had to
travel to make contact with the thigh. 
As mentioned previously, the authors speculate that a shorter elbow to
thigh distance decreases the level of difficulty in performing maximum sit-ups
whereas a greater distance increases the level of difficulty.  To address this limitation, the authors
recommend that additional testing be conducted where the distance between the
heels and buttocks either be controlled between participants, or measured for
each participant so that it can be statistically taken into account.

CONCLUSIONS

Although the authors
hypothesized that all anthropometric measurements (i.e., torso, femur, tibia,
and humerus) would be significantly correlated to sit-up performance, the
results showed that only the humerus and tibia lengths were significantly
correlated.  This is likely due to the
humerus’ effect on the elbow to thigh distance and the tibia’s effect on changing
the height and angle of the knee.  In
both cases, these measurements help to determine the distance the elbow has to
travel in order to make contact with the thigh. 
Additionally, the results also showed that sex was also correlated to
sit-up performance, which makes sense since the females in the study measured
shorter tibia lengths on average than the males (Table 3).

Collectively, the
results show a potential for a slight biomechanical advantage in maximum sit-up
performance for certain individuals. 
This, coupled with well-documented concerns regarding the safety and
lack of operational relevance of sit-ups in the literature, make a compelling
argument for identifying and implementing alternative field tests for assessing
abdominal muscular endurance.  Tests like
the standard front plank, side bridge and/or the flexor endurance test show
promise in effectively evaluating abdominal muscular endurance without
possessing many of the concerns and limitations currently associated with
sit-ups (7, 11, 14).  Even so, additional
research would be needed in order to determine appropriate age- and
gender-specific performance standards for these tests if the intent is to
outright replace sit-ups in many of the current physical fitness tests used by
the military, public education and/or health and fitness industry.

APPLICATIONS IN SPORT

Even though the sit-up
test is a common field test used in the military, public education, and health
and fitness industry, the implications for performance among these various
entities are vastly different.  For example,
failing the sit-up portion of the PRT in the U.S. Navy can have severe
ramifications in terms of promotion and retention.  Failing the sit-up test repeatedly at
military service academies such as USNA, can also result in expulsion as well
as profound financial consequences in terms of recoupment.  Additionally, a USNA Midshipman’s overall PRT
score is factored into the physical education grade, aptitude grade and overall
order of merit.  For all Midshipmen,
order of merit is their primary factor in service assignment, which ultimately
places them into their respective military career track following graduation
and commissioning as officers in either the U.S. Navy or Marine Corps.

Additionally, the
results of this study suggest that using age-adjusted standards alone for the
sit-up may not be enough to ensure fairness and impartiality.  For example, height and sex, in addition to
age, also appear to be significant factors that influence maximum sit-up
performance.  With that in mind, the
authors recommend that the U.S. military and service academies consider
revising current sit-up standards to take into account these other
physiological differences.  For example,
through the development and implementation of gender-specific performance
standards for the sit-ups, just as there are for the push-ups and 1.5-mile
run.  These recommendations are both
warranted and necessary when considering the aforementioned ramifications
associated with service-member performance on semi-annual physical fitness
tests in terms of career promotion and retention.

ACKNOWLEDGMENTS

The authors would like to acknowledge the contributions from the following individuals from the United States Naval Academy:  Mr. Dan Riner for his assistance with the initial statistical analysis as well as MIDNs Alexandra Heller, Angelique Starks, and Amar Viswanathan for their role and assistance in data collection.  Additionally, the authors would like to express appreciation to the following individuals from Cedarville University:  Mrs. Kristi Coe for her role in the literature review process and manuscript formatting as well as Mr. Jared Pyles, Miki Veness, and Jinho Jung for their assistance in creating figures 1-3.  Finally, the authors would like to thank Dr. Brian Schilling from the University of Nevada, Las Vegas for his review and recommendations.

REFERENCES

  1. Akuthota, V., Ferreiro, A., Moore, T., & Fredericson, M. (2008). Core stability exercise principles. Current Sports Medicine Reports, 7(1), 39-44.
  2. Bogin, B., & Varela-Silva, M. I. (2010). Leg length, body proportion, and health: A review with a note on beauty. International Journal of Environmental Research and Public Health, 7(3), 1047-1075.
  3. Childs, J. D., Teyhen, D. S., Casey, P. R., McCoy-Singh, K. A., Feldtmann, A. W., Wright, A. C., Dugan, J. L., Wu, S. S., & George, S. Z. (2010). Effects of traditional sit-up training versus core stabilization exercises on short-term musculoskeletal injuries in US army soldiers: A Cluster Randomized Trial. Physical Therapy, 90(10), 1404-1412.
  4. Contreras, B., & Schoenfeld, B. (2003). To crunch or not to crunch: An evidence-based examination of spinal flexion exercises, their potential risks, and their applicability to program design. Strength and Conditioning Journal, 33, 8-18.
  5. Esco, M. R., Olson, M. S., Williford, H. (2008). Relationship of push-ups and sit-ups tests to selected anthropometric variables and performance results: A multiple regression study. Journal of Strength and Conditioning Research, 22(6), 1862-1868.
  6. Hodgdon, J. A. (2011).  A history of the US navy physical readiness program from 1976 to 1999 (Technical Document No. 99-6F). San Diego, CA: Naval Health Research Center.
  7. Juker, D., McGill, S., Krope, P., & Steffen, T. (1998) Quantitative intramuscular myoelectric activity of lumbar portions of psoas and the abdominal wall during a wide variety of tasks. Medicine & Science in Sports & Exercise, 30(2), 301-310.
  8. Kranick, M. (2016). The effect of limb length or total body height on maximal muscle strength. A Journal of Undergraduate Research, 9, 44-54.
  9. Luz, L., Coelho-Sliva, M. J., Duarte, J. P., Valente-dos-Santos, J., Machado-Rodrigues, A., Seabra, A., Carmo, B., Vaeyens, R., Philippaerts, R. M., Cumming, S. P., & Malina, R. M. (2018). Multivariate relationships among morphology, fitness and motor coordination in prepubertal girls. Journal of Sports Science and Medicine, 17, 197-204.
  10. McGill, S. (2010). Core training: Evidence translating to better performance and injury prevention. Strength and Conditioning Journal, 32, 33-46.
  11. McGill, S. (2007). Low back disorders (3rd ed.). Champaign, IL: Human Kinetics.
  12. McGill, S., Belore, M., Crosby, I., & Russell, C. (2010). Clinical tools to quantify torso flexion endurance: Normative data from student and firefighter populations. International Journal of Occupational Safety and Ergonomics, 9,55-61.
  13. Navy Physical Readiness Program. (2016). Guide 5: Physical Readiness Test. Retrieved from https://www.public.navy.mil/bupers-npc/support/21st_Century_Sailor/physical/Documents/Guide%205-%20Physical%20Readiness%20Test%20%202016.pdf.
  14. Peterson, D. D. (2013). Proposed performance standards for the plank for inclusion consideration into the navy’s physical readiness test. Strength and Conditioning Journal, 35(5), 22-26.
  15. Radu, L. E., Hazar, F., & Puni, A. R. (2014). Anthropometric and physical fitness characteristics of university students. Social and Behavioral Sciences, 149, 798-802.
  16. Vanderburgh, P. M. (2008). Occupational relevance and body mass bias in military physical fitness tests. Medicine and Science in Sports and Exercise, 40(8), 1538-1545.
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