Gender differences and reliability of selected physical performance tests in young women and men

Abstract

Although push-ups and sit-ups are among the most commonly used body-weight exercises to improve and assess strength and fitness, there is a lack of reproducible test protocols in the scientific literature. The aim of this study was to evaluate the test–retest reliability of sit-ups and push-ups and to determine performance differences in muscular endurance (maximal number of repetitions) and power (timed, maximal number of repetitions in 30 s) in young women and men. Thirty-eight women and 25 men, 18–35 years of age, participated in the study. Thirteen women participants performed two test sessions of each test using a test–retest design. A high reliability was noted for both the sit-up and the push-ups tests (intraclass correlation values ranged from 0.92 to 0.95). There were no significant differences between the men and the women in the mean number of sit-ups (42 and 41 repetitions respectively for endurance and 16 and 14 repetitions respectively for power), whereas the men performed significantly more push-ups than the women (39 and 17 repetitions respectively for endurance and 29 and 13 repetitions respectively for power). In conclusion, sit-ups and push-ups are tests with high reliability, which are easy to perform and may therefore be recommended for clinical use to evaluate muscular endurance and power in young men and women. Moreover, the fact that men performed twice as many push-ups as women indicates that, when designing training programme for women, attention should be turned towards strengthening exercises of the upper body.

Full text

ORIGINAL ARTICLE
Gender differences and reliability of selected physical performance
tests in young women and men
SOFIA RYMAN AUGUSTSSON
1,2
, ELLEN BERSA
˚S
1
, ELIN MAGNUSSON THOMAS
1,2
,
MARGARETA SAHLBERG
3
, JESPER AUGUSTSSON
2
& ULLA SVANTESSON
1,2
1
Institute of Neuroscience and Physiology/Physiotherapy,
2
Institute of Clinical Sciences, Department of Orthopaedics,
3
Institute
of Clinical Sciences, Department of Pediatrics, Sahlgrenska Academy at Go
¨teborg University, Go
¨teborg, Sweden
Abstract
Although push-ups and sit-ups are among the most commonly used body-weight exercises to improve and assess strength
and fitness, there is a lack of reproducible test protocols in the scientific literature. The aim of this study was to evaluate the
testretest reliability of sit-ups and push-ups and to determine performance differences in muscular endurance (maximal
number of repetitions) and power (timed, maximal number of repetitions in 30 s) in young women and men. Thirty-eight
women and 25 men, 1835 years of age, participated in the study. Thirteen women participants performed two test sessions
of each test using a testretest design. A high reliability was noted for both the sit-up and the push-ups tests (intraclass
correlation values ranged from 0.92 to 0.95). There were no significant differences between the men and the women in the
mean number of sit-ups (42 and 41 repetitions respectively for endurance and 16 and 14 repetitions respectively for power),
whereas the men performed significantly more push-ups than the women (39 and 17 repetitions respectively for endurance
and 29 and 13 repetitions respectively for power). In conclusion, sit-ups and push-ups are tests with high reliability, which
are easy to perform and may therefore be recommended for clinical use to evaluate muscular endurance and power in young
men and women. Moreover, the fact that men performed twice as many push-ups as women indicates that, when designing
training programme for women, attention should be turned towards strengthening exercises of the upper body.
Key words: Endurance, functional test, power, push-ups, reliability, sit-ups
Introduction
When it comes to physical training and exercise,
push-ups and sit-ups are among the most frequently
used body-weight exercises to increase strength and
fitness. They are thought to be convenient and easily
learned, require no equipment and are adaptable to
different fitness levels. In sports, sit-ups and push-
ups are used to improve both muscular power and
muscular endurance. They are also used to evaluate
the effect of training, the eventual risk for injury and
to predict and specify talent (1,2). Moreover, sit-ups
and push-ups are used clinically as tests and
exercises in rehabilitation to increase upper-body
strength and to evaluate the effect of treatment
(1,3,4). Physically demanding professions, such as
fire fighters, military and police, also use sit-ups and
push-ups as work-assessment tools (5), for example,
when recruiting new personal, to evaluate physical
performance, to measure the effect of training and
the risk of injury (611). Additionally, sit-ups and
push-ups are used to evaluate both muscular en-
durance as in maximal number and power as in
timed tests (11,12). Taken together, functional tests
such as push-ups and sit-ups are common practice in
the evaluation of different aspects of physical per-
formance, which is an important target of physical
therapy practise (7,13). However, although sit-ups
and push-ups are frequently used, the evidence of
reliability for these tests is limited.
Several physical fitness test batteries that includes
either the push-up or the sit-ups tests, e.g. the
Eurofit test battery (14), the American College of
Sports Medicine’s (ACSM) guidelines for exercising
(15) and the Canadian Physical Activity, Fitness &
Correspondence: Sofia Ryman Augustsson, Lundberg Laborator y for Orthopaedic Research, Department of Or thopaedics, Sahlgrenska University Hospital,
S-413 45 Go
¨teborg, Sweden. E-mail:sofia.augustsson@orthop.gu.se
Advances in Physiotherapy. 2009; 11: 6470
(Received 28 August 2007; accepted 30 January 2008)
ISSN 1403-8196 print/ISSN 1651-1948 online #2009 Informa UK Ltd.
DOI: 10.1080/14038190801999679
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Lifestyle Approach Protocol (CPAFLA) (16) have
been developed and used globally through the years.
When it comes to the Eurofit test battery, research
has been limited to children and the reliability of
Eurofit’s tests when applied to other sample popu-
lations is limited. One study has been performed on
university students to provide testretest reliability
of the Eurofit test battery (17). However, no test
retest for push-ups and for the maximal number of
sit-ups was performed. Furthermore, protocols for
the sit-ups and push-ups tests in the above men-
tioned physical fitness test batteries are different
from each other, making comparisons difficult. In
the Eurofit test battery, for example, the sit-ups are
measured in 30 s (14), whereas sit-ups are done for
1 min in the ACSM protocol (15). The push-ups
and the sit-ups tests in the protocol by the CPAFLA
on the other hand are performed with no time limits
(16). Also, as opposed to the CPAFLA protocol, in
the ACSM push-ups test, women do not perform
push-ups on their hands and feet. Instead, the
women perform a modified push-up on their hands
and knees (15). Thus, using the ACSM push-ups
test, it is not possible to compare men and women
in terms of physical fitness. Furthermore, according
to the Canadian Society for Exercise Physiology
(CSEP), the reliability is assured, but only if the
person administering the tests adheres to the
measurement procedures and tolerances specified
in the CPAFLA and trained by the CSEP (16).
Consequently, the tests might not be reliable if
the tests are supervised by someone other than a
CSEP instructor. Although both the CPAFLA and
the ACSM guarantee the reliability of their test
manuals, no peer-reviewed testretest reliability
study published in a scientific journal has been
performed. Taken together, the reliability of sit-ups
and push-ups is not well established considering
their global use.
It is commonly accepted that there are physiolo-
gical variations between men and women. When the
general population is investigated, men appear to
have an advantage over women in terms of muscular
endurance and strength (8,18). It has previously
been observed that abdominal muscle strength for
women is 7580% compared with men’s, and that
women’s upper-body strength is 55% of men’s
(19,20). These differences in muscle physiology
have been reported to contribute to the differences
seen in gender distribution of sports injuries as well
as work-related injuries (2123). It might therefore
be of importance to investigate strength and mus-
cular endurance in women and men in order to
optimize preventive actions and rehabilitation pro-
grammes. The gender differences reported in earlier
studies have generally been measured using isoki-
netic dynamometers, whereas studies that examine
differences between men and women with regard to
more functional tests such as push-ups and sit-ups
are limited (19,20). Furthermore, on one hand, an
association between decreased physical activity level
and decreased physical performance in young adults
and adolescents has been reported in recent years
(24,25), which supports a continued need for
monitoring physical performance in this population.
On the other hand, in recent years physical fitness
systems and activities have emerged, making people
more physically active (e.g. the Les Mills
TM
Group
Fitness System) (26). Programmes such as Body
Pump
TM
, which is a barbell class workout, have
become popular among women in particular (26). It
is possible that these recent forms of resistance
training that specifically target young women could
contribute to a change in gender differences when it
comes to strength and fitness. Therefore, because of
changes in physical activity patterns among young
women and men it is important to continually
examine gender differences.
The aim of this study was to evaluate the reliability
of the functional tests sit-ups and push-ups, and to
determine performance differences between genders
in young women and men.
Materials and methods
Subjects
University students, from both practical (28/63) and
theoretical programmes (35/63), were asked to
participate in the study. Twenty-five men and 38
women between 18 and 35 years of age participated
in the study. Subjects with illness or injury of the
musculoskeletal system during the past 2 months,
which were thought possibly to affect the test results,
were excluded. Elite athletes (individuals training/
competing at a high level) were also excluded. The
participants’ age, height, weight and physical activity
level were documented, as shown in Table I. The
study was approved by the Ethics Committee at
Go
¨teborg University, Sweden, and written informed
consent was given by each participant.
Table I. Subject characteristics (n63).
Men (n25) Women (n38)
Age 23 (93) 23 (92)
Height (cm) 181 (97) 168 (96)
Weight (kg) 77 (910) 62 (96)
Physical activity level 5 (18) 5 (18)
Mean and standard deviation are given except for physical activity
level where median and range is reported.
Gender differences and reliability of selected physical performance tests 65
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Assessment instruments and procedure
Two different tests, sit-ups and push-ups, were used
to assess the participants’ physical performance.
The sit-ups test was a modification of the Eurofit
test battery manual and the push-ups test a mod-
ification of the American College of Sports Medi-
cine’s (ACSM) guidelines for exercising, tests and
prescription (14,15). Each test session was standar-
dized and began with a warm-up, which consisted of
5 min of ergometer cycling at 100 W of resistance,
and 20 submaximal standing push-ups against a
wall. The sit-ups and push-ups tests were performed
in the same order for all participants. The partici-
pants were given 4 min rest between the different
tests to maximize recovery and to avoid fatigue (20).
Each participant estimated his/her level of physical
activity over the past month using a scale from 1 to
8, where 1 represented no exercise and 8 repre-
sented competitive training six to seven times a
week. The physical activity scale was constructed by
the authors (SA, EB) and has not been tested for
reliability or validity. Thirteen women performed
the tests on two separate occasions within 1 week to
evaluate the reliability of the push-up and sit-ups
tests.
Sit-ups
Starting position. The participant was sitting on the
floor with the knees in 908of flexion and the feet
placed 10 cm apart on the floor. The hands were
clasped behind the neck and the elbows placed
against the knees. The test examiner knelt in front
of the participant, pushing the participant’s feet
lightly against the mat. The sit-ups were performed
on a rubber mat and the participants wore shoes
during the test (Figure 1a).
Procedure. The participants lowered their upper
body until the scapula came in contact with the
mat. The participant’s head was not permitted to
touch the mat (Figure 1b). The participant then
reversed the motion by curling back up to the
starting position. For muscular endurance, the
participant performed as many repetitions as possi-
ble using maximum speed throughout the test. The
test was stopped if two consecutive repetitions were
unsuccessful or if the participant was unable to
continue. An unsuccessful repetition was regarded as
one that deviated from the standard procedure. The
maximum number of sit-ups was documented to
evaluate muscular endurance. To investigate power,
30-s timed sit-ups were also documented.
Push-ups
Starting position. The participant was in a prone
position on toes and hands. The hands were placed
shoulder-width apart with the fingers pointing for-
ward. The elbows were held in full extension and the
feet were placed 10 cm apart. The push-ups were
performed on a rubber mat and the participants
wore shoes during the test (Figure 1c).
Procedure. In a continuous motion, the torso was
lowered by bending the elbow joints to 908of flexion
(Figure 1d). Keeping the midsection tight and the
head held in neutral position, the participant there-
after pressed him/herself back up to full elbow
extension. For muscular endurance, the participant
performed as many repetitions as possible using
maximum speed throughout the test. The test was
stopped if two consecutive repetitions were unsuc-
cessful or if the participant was unable to continue.
An unsuccessful repetition was regarded as one,
which deviated from the standard procedure. The
maximum number of push-ups was documented to
evaluate muscular endurance. To investigate power,
30-s timed push-ups were also documented.
Statistical method
Independent-samples t-tests were used to compare
men and women with regard to the number of sit-
ups and push-ups. The meaningfulness of the group
differences was determined by calculating eta-
squared (h
2
). Intraclass correlation coefficient
(ICC
2,2
) was used for analyses of the testretest
reliability and 95% confidence intervals (CI) were
calculated. Differences between the number of
repetitions of sit-ups and push-ups performed at
testretest were computed using paired-samples t-
tests. The level of significance was set at pB0.05.
Results
Testretest for sit-ups
The ICC
2,2
value for the maximal number of sit-ups
was 0.92 with a 95% CI of 0.730.98. The ICC
2,2
value of 30-s timed sit-ups was 0.93 with a 95% CI
of 0.770.98. The mean number (9SD) of maximal
sit-ups for the 13 participants was 48 (925) on
the first occasion and 53 (938) on the second
occasion, with no significant difference between test
and retest (p0.295). The mean number of 30-s
timed sit-ups for the 13 participants was 14
(94) on the first occasion and 13 (93) on the
second occasion, with no significant difference
between test and retest (p0.085).
66 S. Ryman Augustsson et al.
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Testretest for push-ups
The ICC
2,2
value for push-ups was 0.95 with a 95%
CI of 0.850.99. The ICC
2,2
value of the 30-s timed
push-ups was 0.93 with a 95% CI of 0.620.96. The
number of push-ups for the 13 participants was 17
(99) on the first occasion and 19 (910) on the
second occasion, with no significant (p0.131)
difference between test and retest. The mean num-
ber of the 30-s timed push-ups for the 13 partici-
pants was 14 (97) on the first occasion and 15 (96)
on the second occasion, with no significant (p
0.222) difference between test and retest.
Gender comparison for sit-ups
The mean number of sit-ups was 42 (917) for men
and 41 (923) for women. There were no significant
differences between the number of sit-ups per-
formed by the men and women (p0.898; h
2

0.0002) (Figure 2). The mean number of 30-s timed
sit-ups was 16 (93) for men and 14 (94) for
women, with no significant difference between men
and women (p0.110; h
2
0.038) (Figure 3).
Gender comparison for push-ups
The mean number of push-ups for men was 39 (9
13) and for women 17 (910), with a significant
difference between men and women (pB0.001;
h
2
0.504) (Figure 2). The mean number of 30-s
timed push-ups was 30 (98) for men and 13 (96)
for women (pB0.001; h
2
0.615) (Figure 3).
Discussion
The main observation in this study was that both the
tests of maximal number as well as the 30-s timed
push-ups and sit-ups showed high testretest relia-
bility (ICC
2,2
values above 0.90 for all tests). An
ICC value below 0.40 has been described as ‘‘poor’’,
and from 0.40 to 0.75 as ‘‘fair’’ to ‘‘good’’ and above
0.75 has been described as ‘‘excellent’’ (27). ICC
values of 0.92 or above were noted in this study,
which indicates that excellent reliability was at-
tained. There is a lack of studies investigating the
testretest reliability of sit-ups and push-ups in
young women and men. Previous studies that have
examined the testretest of sit-ups and push-ups are
either timed or modified from normal position
(17,28). These differences in study design make
the comparison with other studies difficult to make
when it comes to the testretest reliability. However,
the 30-s sit-ups test in our study can be compared
with the 30-s sit-ups test in the study by Tsiglis et al.
(17), who reported excellent reliability (ICC value of
0.83) in young women and men. Similarly to the
Figure 1. Positions of the tests: (a) starting position and (b) finish of the sit-ups, (c) starting position and (d) finish of the push-ups.
Gender differences and reliability of selected physical performance tests 67
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results of our study, Suni et al. (28) reported
excellent (ICC value of 0.88) testretest reliability
for a modified push-ups test on middle-aged men
and women. Hence, the result in our study supports
previous studies that both sit-ups and push-ups are
reliable tests. Furthermore, the results of our study
suggest that the tests are highly reliable for both
muscular endurance and power testing in young
adults who are physically active on average twice per
week.
In our study, we measured the maximal number of
push-ups (with a mean numbers of 39 and 17
respectively for men and women) and sit-ups (with
a mean numbers 42 and 41 repetitions respectively
for men and women) as well as 30-s timed push-ups
(with a mean numbers 30 and 13 respectively for
men and women) and sit-ups (with a mean numbers
16 and 14 respectively for men and women). There
was a significant difference between men and women
in the push-ups test, but no differences were found
in the sit-ups test, regardless if whether the tests were
timed or maximally performed. The result indicates
that younger women’s muscular strength in the
upper body is less then younger men’s, and that
women
men
120
100
80
60
40
20
0
60
25
16
52 push-ups max number
situps max number
Figure 2. Box plot showing median and quartile distances for the number of sit-ups and push-ups in men (n25) and women (n38). Y-
axis represents the number of repetitions. The central horizontal line within each box is the median 50th percentiles. Open circles represent
individual outliers of 90th percentiles, and asterisks denote ‘‘far-out’’ outliers. The presence of extreme values did not influence the results.
womenmen
40
30
20
10
0
48
41
6
51
push-ups 30 sec timed
situps 30 sec timed
Figure 3. Box plot showing median and quartile distances for the number of 30-s timed sit-ups and push-ups in men (n25) and women
(n38). Y-axis represents the number of repetitions. The central horizontal line within each box is the median 50th percentiles. Open
circles represent individual outliers of 90th percentiles. The presence of extreme values did not influence the results.
68 S. Ryman Augustsson et al.
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the women’s abdominal strength is similar to the
men’s, regardless of which methods are being used
(timed or maximally performed). Hence, these
findings suggest that both sit-ups and push-ups can
be used to test muscular power as in a timed test, but
also for muscular endurance as in the maximal
number of repetitions. Differences between men
and women in terms of muscular endurance and
strength have been reported in earlier studies
(8,11,18). It has been noted that women’s upper-
body strength averages 55% of men’s and that the
lower-body strength averages 72% of men’s (20).
However, gender differences can partly be explained
by total body weight and fat-free mass, and when
comparing strength expressed relative to body-
weight or fat-free mass, the differences become
smaller (20). Considering push-ups represent a
training exercise in which strength is expressed
relative to bodyweight, one would assume that
gender differences in performance would be rela-
tively small. In our study, however, the men per-
formed more than twice as many push-ups as the
women, which is in agreement with previous ob-
servations (8,11,29). Women’s upper-body muscular
endurance averages no more than 44% of men’s in
the present study. Since one of the key risk factors
for work-related injuries, as well as training injuries,
appears to be inadequate physical fitness (8,12), it
might be of importance to study fitness status in the
general population. The results of the present study
(that men are twice as strong as women in the upper
body when it comes to both local muscular endur-
ance and power) suggests that upper-body training
in women may be important to prevent work- and
sports-related injuries. Interestingly, there were on
the other hand no differences between genders
regarding sit-ups performance. This result is in
contrast with earlier studies in which it has been
estimated that abdominal muscle strength in young
women is approximately 7080% compared with
young men (12,18,19). One explanation for the fact
that women performed as many sit-ups as men in
our study could be that the women performed
physical activities involving the abdominal muscles
as much or even to a greater extent than the men. We
have noted that until a few years ago women’s
physical conditional programmes (aerobics and re-
sistance training) frequently contained sit-ups,
whereas exercises for the upper body such as push-
ups were less common. It is therefore possible that
the lack of upper-body training resulted in poorer
performance for women than for men when exam-
ining upper-body strength and endurance in the
present study. When it comes to abdominal strength,
the gender difference was non-existent, perhaps
because of a more similar training regimen among
women and men. However, we only investigated the
amount of physical activity and not the form of
physical activity, which would have been interesting
to know. Furthermore, the sample size in the present
study is modest, which could be a limitation of the
study, although it is not significantly smaller than
other studies of similar nature (2,3032). As a
general principle, a larger sample size will give a
more reliable estimate of the change in measurement
error.
However, the values present in our study could be
used as an indication that young women tend to be
relatively strong in the abdominal area and in fact
equally strong compared with young men, but
unfortunately young women do not even have half
the strength and endurance in the upper body
compared with young men. It is well known that
gender differences in strength and endurance can be
reduced when women perform strength and endur-
ance training and that the greatest improvements
have been seen in local muscular endurance (8). As
mentioned in the introduction section, recent forms
of strength and conditioning programmes that target
women in particular are continuously developed,
which might lead to changes in gender differences.
However, in our study, we do not have the results to
support this theory and the gap in upper-body
strength between men and women still is rather
large.
There are several variants of both the sit-up and
push-up exercises proposed in the literature, which
makes comparisons between studies difficult to
make. We chose to standardize the sit-ups test, as a
modification of the Eurofit test battery (14), and the
push-ups test, as a modification of the ACSM’s
guidelines (15) and according to the normal position
(33), to attain a high-quality standardization.
It is not certain that the subjects in the present
study are fully representative of the normal popula-
tion; men and women aged 1835 years. The values
obtained may be slightly overestimated because the
participants were partly recruited from health-re-
lated education programmes. It is also likely that
participants who are enrolled in this type of study
may have a greater interest in physical activity and
are perhaps more enthusiastic in testing their max-
imum capacity compared with less physically active
persons. Another limitation is that the tests used in
the present study are only applicable for young and
relatively fit women and men. However, the values
can be applied to young men and women aged 1835
and who are physically active on average twice per
week.
In conclusion, sit-ups and push-ups are tests with
high testretest reliability. They are easy to perform
and, furthermore, require no special equipment and
Gender differences and reliability of selected physical performance tests 69
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may therefore be recommended for clinical use. The
results of a discriminate analysis indicated that
women do not differ from men in the mean number
of sit-ups. Also, the fact that men performed twice as
many push-ups as women indicates that, when
designing training programmes for women, attention
should be turned towards strengthening exercises of
the upper body.
Acknowledgements
This study was supported by a grant from Swedish
National Centre for Research in Sports and a grant
from the Adlerbert assistance fund.
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