©Journal of Sports Science and Medicine (2006) CSSI, 108-113
Combat Sports Special Issue
THE IMPORTANCE OF ISOMETRIC MAXIMUM STRENGTH IN
Michael R. McGuigan 1??, Jason B. Winchester 2 and Travis Erickson 3
1 School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
2 Department of Kinesiology, Louisiana State University, Baton Rouge, LA, USA
3 Department of Exercise and Sport Science, University of Wisconsin-La Crosse, La Crosse, WI, USA
Published (online): 01 July 2006
Previous research has demonstrated the importance of isometric maximal strength (PF) and rate of force
development (RFD) in a variety of athletic populations including track cyclists and track and field
athletes. Among coaches and sports scientists there is a lack of agreement regarding how much strength
is required for optimal performance in most sports. The purpose of this study was to examine
relationships between measures of PF, RFD and one repetition maximum (1RM) strength with other
variables that might contribute to successful performance in collegiate wrestlers. Eight men (M = 20.0,
SD = 0.4 years; Height M = 1.68, SD = 0.13 m; Mass M = 78.0, SD = 4.2 kg) who were Division III
college wrestlers participated in this study. They were tested for PF using the isometric mid thigh pull
exercise. Explosive strength was measured as RFD from the isometric force-time curve. The 1RM for the
squat, bench press and power clean exercises were determined as a measure of dynamic strength.
Vertical jump height was measured to determine explosive muscular power. The wrestlers also ranked
themselves and the coaches of the team also provided a ranking of the athletes. Correlations between the
variables were calculated using the Pearson product moment method. Results indicated strong
correlations between measures of PF and 1RM (r = 0.73 – 0.97). The correlations were very strong
between the power clean 1RM and PF (r = 0.97) and squat 1RM and PF (r = 0.96). There were no other
significant correlations with other variables apart from a strong correlation between RFD and coaches
ranking (r = 0.62). Findings suggest that isometric mid thigh pull test does correlate well with 1RM
testing in college wrestlers. RFD does not appear to be as important in college wrestlers. The isometric
mid thigh pull provides a quick and efficient method for assessing isometric strength in athletes. This
measure also provides a strong indication of dynamic performance in this population. The lack of strong
correlations with other performance variables may be a result of the unique metabolic demands of
KEY WORDS: Isometric strength, wrestling, power.
Wrestling is a high intensity sport which requires
strength and power of both the upper and lower body
as well as relying heavily on isometric force for the
various wrestling techniques (Callan et al., 2000;
Kraemer et al., 2001; Utter et al., 1998). Two
different forms of wrestling are contested at the
Olympic Games. In Greco-Roman competition,
wrestlers use only their arms and upper bodies. In
freestyle competition, wrestlers also use their legs
and may hold opponents above or below the waist.
Isometric strength in college wrestlers
As a combative sport, both forms of wrestling place
unique metabolic stresses on the body (Kraemer et
al., 2004; Nemet et al., 2004; Utter et al., 1998). For
example the blood lactic acid concentrations in
response to a wrestling match can be over 19
mmol.l-1 (Kraemer et al., 2001). Therefore, the sport
of wrestling is one of the most demanding sports
from a metabolic perspective and it is a sport where
the requirement of absolute strength and power is
critical (Kraemer, 2002; Utter et al., 2002).
Previous research has demonstrated the
importance of isometric maximal strength (PF) and
rate of force development (RFD) in a variety of
athletic populations including track cyclists (Stone et
al., 2004), track and field athletes (Stone et al.,
2003b) and weightlifters (Stone et al., 2005). A
number of studies have investigated the strength and
power characteristics of different types and skill
levels of wrestlers (Hakkinen et al., 1984; Silva et
al., 1981; Utter et al., 1998, 2002). However there
has been limited emphasis placed on relating these
force measurements to
performance. Among coaches and sports scientists
there is a lack of agreement regarding how much
strength is required for optimal performance in most
sports (Stone et al., 2002). However, available data
do suggest that the importance of maximum
isometric strength is underestimated in a variety of
athletic populations (Stone et al., 2003a; 2003b;
The purpose of this investigation was to
examine the relationships between measures of PF,
RFD and one repetition maximum (1RM) strength
with other variables that might contribute to
successful performance in collegiate wrestlers.
Eight men were recruited from the University of
Wisconsin-La Crosse (NCAA Division III) wrestling
team and served as subjects in this investigation.
Subject characteristics were as follows (mean ± SD):
Age 20.0 ± 0.4 years; Height 1.68 ± 0.13 m; Mass
78.0 ± 4.2 kg. All the subjects were lower ranked,
underclassmen members of the team following the
same training programme which involved 4
resistance training sessions each week and
approximately 2-3 hours of wrestling each week.
The wrestlers were currently out of season when
they were tested and were following an off-season
conditioning programme, meaning wrestlers were
not regulating their bodyweight at the time of
testing. Participants were informed of the potential
risks and gave their written informed consent to
participate prior to beginning the study. The
actual indices of
University’s Institutional Review Board for use of
human participants approved this study.
The following testing battery was administered to
the wrestlers over a two day period. All athletes
were familiarized with the tests prior to completing
the testing sessions.
Isometric strength assessment
Isometric strength assessment involved testing PF
using the isometric mid-thigh pull exercise (Haff et
al., 1997; Stone et al., 2003b). The mid-thigh pull
was executed on an isometric rack placed over a
Quattro Force plate (Kistler Instrumente AG,
Winterthur, Switzerland) which was sampled at a
rate of 500 Hz. Participants were instructed to pull
on the immovable bar as quickly as possible and
were required to maintain effort for 5 seconds. It has
been suggested that instructions stated as “hard and
fast” produce optimal results for recording maximal
force and RFD (Bemben et al., 1990; Haff et al.,
1997; Sahaly et al., 2001). Participants performed 3
5 sec trials and were allowed 2 min of rest between
sets. The highest value of the three trials was used
for later analysis. The bar height was adjusted at 2
cm increments so that the knee angle was 130
degrees (straight leg = 180 degrees). Force-time
curves were analysed during the mid thigh pull. The
variables that were analysed included isometric RFD
and isometric PF. The test-retest reliabilities
(intraclass correlation, ICC) of these tests were r ≥
Dynamic strength assessment
The 1RM for the back squat, bench press and power
clean exercises were determined as a measure of
dynamic strength. In the case of the back squat and
bench press, multiple warm-up trials were given
prior to actual 1RM testing as previously validated
by Wilson et al. (1993). These consisted of 10
repetitions at 30% followed by 2 min rest, 7
repetitions at 50% followed by 2 min rest, 4
repetitions at 70% followed by 3 min rest, 1
repetition at 90% followed by 3 min rest (% are
given of participant estimated 1RM obtained
through use of an Eppley chart). From the last
warm-up set, loading was increased through
participant feedback on level of repetition intensity
so that 1RM was achieved within 3 trials. Four
minutes of rest was given between each 1RM effort.
The squat exercise required the participants to rest
the bar on their trapezius and the squat was
performed to the parallel position, which was
defined as when the greater trochanter of the femur
was lowered to the same level as the knee. The
participant then lifted the weight until their knees
McGuigan et al.
were fully extended. Bench press testing was
performed in the standard supine position. The
participant lowered the bar to mid-chest, and then
pressed the weight until the elbows were fully
extended. No bouncing of the weight was
permitted. The reliability of this method of 1RM
testing in our laboratory is high (ICC = 0.98).
The testing method for the power clean
exercise was slightly different due to the nature of
the activity as compared to the back squat and bench
press. As in the case of the other exercises,
participants were given multiple warm-up trials prior
to 1RM testing (% are given of participant estimated
1RM), 2 sets of 5 repetitions at 60% with each
followed by a 2 min rest, 3 repetitions at 80%
followed by a 3 min rest, 1 repetition at 90%
followed by a 4 minute rest. From the last warm-up
set, loading was increased through participant
feedback on level of repetition intensity so that 1RM
was achieved within 3 trials. Four minutes of rest
was given between each 1RM effort. An acceptable
lift was determined by the athlete being able to catch
and hold the bar in a steady position for 5 seconds.
Participants were familiar with the testing procedure
because of its similarity to the testing they are
exposed to as part of their sport.
Vertical jump height was measured to give an
indication of explosive muscular power (Canavan
and Vescovi, 2004). Each participant performed
three trials with the highest jump height used in the
data analysis. The following procedures were
followed for each trial: 1) the participant was
instructed to remain motionless for 2 seconds before
performing the jump trial; 2 the participants were
instructed to place their hands on their hips and to
self-select their depth for a countermovement jump
upon being given a verbal signal; 3) upon conclusion
of one repetition, the participant was instructed to
stand motionless for 2 seconds. Data collection for
the trial was then terminated. Trials were repeated if
individuals did not land onto the force platform from
the vertical jump. Two minutes of rest-time was
allowed between each trial throughout the testing
session. Jump height was calculated using flight
time and the standard Bosco equations.
The wrestlers ranked themselves and the coaches of
the team also provided a ranking of the athletes.
Both the participants and coaches were asked to
Table 1. Descriptive statistics for physiological test results (n = 8). Data are means (±SD).
(kg) (kg) (kg)
85 (15) 129 (23) 105(19)
provide a ranking on a 0 – 100 scale based on their
actual wrestling performance in the most recent
competitive season. Both participants and coaches
were instructed to base their ranking entirely on
performance and not on potential or work ethic.
Taylor et al. (1987) found a strong correlation
between an athletes self perception and their
performance in a variety of sporting events including
basketball, tennis, and track and field events. In
addition, the use of coach ranking as a predictor of
in-game athletic performance was validated by
Marey et al. (1991) who discovered a strong (0.74)
correlation between performance in coaches ranking
of collegiate volleyball athletes.
Correlations between the variables were calculated
using the Pearson product moment correlation
coefficient. Hopkins (2004) and Cohen (1988) have
ranked the meaningfulness of correlations as r =
trivial (0.0), small (0.1), moderate (0.3), strong (0.5),
very strong (0.7), nearly perfect (0.9), and perfect
(1.0). The criterion for statistical significance of the
correlations was set at P ≤ 0.05.
The average results for the testing variables are
shown in Table 1. There were very strong significant
correlations between measures of PF and 1RM (r =
0.73 – 0.97) (p ≤ 0.05). The correlations were nearly
perfect between the power clean 1RM and PF (r =
0.97) and squat 1RM and PF (r = 0.96). There were
no other significant correlations with other variables
apart from a strong correlation between RFD and
coaches ranking (r = 0.62).
Previous research has demonstrated the critical role
of isometric strength to performance across a range
of different sports (Stone et al., 2003b; 2004; 2005).
The results of this study indicate that in collegiate
wrestlers the isometric mid thigh pull test does
correlate well with 1RM testing. However, RFD was
shown to be not as critical in these athletes. These
results suggest that isometric testing provides a good
indication of an athlete’s dynamic performance
during 1RM testing, for both the back squat and
power clean exercises.
A wrestling match consists of a series of
dynamic movements of the legs, hips and back and
Squat Bench Press PF
45 (4) 2645 (465) 32063 (18834)
Isometric strength in college wrestlers
also involves isometric grasping for position
maintenance. Research by Kraemer et al. (Stone et
al., 2002) has shown that these patterns of muscular
force appear sensitive to the accumulated effects of
fatigue ie. muscle damage or acid-base balance.
Lower body power has previously been shown to be
important for freestyle wrestling (Callan et al.,
2000). One study by Silva et al. (1981) showed no
differences in isometric grip strength between
successful and less successful wrestlers competing
for a junior world games team. The values obtained
for PF in the present study were lower than values
that were found for Division I wrestlers (Utter et al.,
1998) (2645N vs. 2950N). This previous research
indicates that greater strength is advantageous for
successful wrestlers. One additional factor that needs
to be considered along with the metabolic demands
of this sport is the weight class restrictions. It is clear
that this combative sport is a unique event and a
number of different physiological characteristics
contribute to successful performance.
We did not find a strong relationship between
RFD and measures of strength and performance in
this study. However, RFD may be an important
performance variable to study within wrestlers
because explosive exercises tend to enhance the
ability to generate high RFD (Aagaard et al., 2002;
Kyrolainen et al., 2005; McBride et al., 2002). In
one study Hakkinen et al. (1984) evaluated the
neuromuscular, anaerobic, and aerobic performance
characteristics of elite Finnish wrestlers. In this
small sample (n = 3) the athletes were found to have
high peak RFD’s although this was not correlated
with performance. Interestingly, the values obtained
in the present investigation for peak RFD (32 063
N·s−1) were similar to values obtained for the Finnish
wrestlers (31 065 N·s−1) and higher than those
achieved by Division I collegiate wrestlers (17 815
N·s−1) (Utter et al., 1998). This provides further
evidence that RFD may not be as important as
maximum strength for this population.
The vertical jump test is a simple and reliable
test that can provide useful information about the
power and performance of athletes (Canavan and
Vescovi, 2004). However, it should be noted that the
values obtained for these Division III collegiate
athletes were considerably lower than values found
in more elite performers (Callan et al., 2000). For
example, the 1997 U.S. freestyle wrestling world
team averaged 60 cm (Callan et al., 2000) whereas
the athletes in this investigation averaged only 45
cm, a finding that should not be surprising given the
lower level of these athletes and the relative
importance of power to performance.
The major limitation of the present study is the
small number of participants who were tested. In
addition, other physical characteristics such as body
composition were not tested. Aerobic capacity has
also been shown to be quite high in elite wrestlers
(Callan et al., 2000) and this may have provided
interesting information about the training level of
these participants. However, it has been suggested
that aerobic capacity is not a major determinant of
success in elite wrestlers (Yoon, 2002). Measures of
muscular endurance may have also provided useful
information regarding these participants. Another
limitation is that the in-season performance on the
wrestlers could not be determined as the testing was
conducted in the off-season.
Maximum strength appears to be a major
factor influencing performance in a variety of
different sports (Stone et al., 2004). It has been
previously been shown that absolute strength and
power are an important component of wrestling
(Kraemer et al., 2001; 2004). It seems conceivable
that given the nature of wrestling where competitors
are often placed in situations where strength is
competing against strength, the ability to exert
maximum muscular force is more important in
wrestling than the ability to exert force in an
explosive manner. Previous work has demonstrated
that isometric strength is attenuated with a wrestling
match and over the course of a tournament (Kraemer
et al., 2001). Specific isometric actions that will
enhance hand grip strength in addition to upper body
isometric strength would potentially be a important
part of an elite wrestlers training program (Kraemer
et al., 2004; Rezasoltani et al., 2005).
The sport of wrestling is a unique combative sport
that places high metabolic demands on the body.
Wrestling is a sport that requires high levels of both
strength and power. The isometric mid thigh pull test
does correlate well with 1RM testing, both in the
back squat and power clean, in college wrestlers.
RFD does not appear to be as important in college
wrestlers. The isometric mid thigh pull provides a
quick and efficient method for assessing isometric
strength in athletes. Given that isometric strength
may potentially differentiate between successful and
less successful athletes (Stone et al., 2002), this test
can provide important information in the strength
diagnosis of wrestlers. This measure also provides a
strong indication of dynamic performance in this
population. The lack of strong correlations with
other performance variables may be a result of the
unique metabolic demands of wrestling.
McGuigan et al.
The authors would like to that the members of the
University of Wisconsin-La Crosse wrestling team
for their cooperation and assistance with the study.
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• In Division III collegiate wrestlers the isometric
mid thigh pull test correlates well with 1RM
• Rate of Force Development does not appear to
be as important in college wrestlers.
• The lack of strong correlations with other
performance variables may be a result of the
unique metabolic demands of wrestling.
of dynamic athletic
Michael R. MCGUIGAN
Lecturer in the School of Exercise, Biomedical and
Health Sciences at Edith Cowan University.
Physiological responses to resistance training and
Jason B. WINCHESTER
Doctoral Student at Louisiana State University.
Strength, power and speed production, muscle
physiology, and resistance training.
Travis M. ERICKSON
Lecturer in Exercise and Sport Science Department, at
the University of Wisconsin- La Crosse.
Strength and Conditioning.
?? Michael R. McGuigan
School of Exercise, Biomedical and Health Sciences,
Edith Cowan University, Joondalup, WA, Australia