Maximal eccentric and concentric strength discrepancies between young men and women for dynamic resistance exercise.

Abstract

Although research has demonstrated that isokinetic eccentric (ECC) strength is 20-60% greater than isokinetic concentric (CON) strength, few data exist comparing these strength differences in standard dynamic resistance exercises. The purpose of the study was to determine the difference in maximal dynamic ECC and CON strength for 6 different resistance exercises in young men and women. Ten healthy young men (mean +/- SE, 25.30 +/- 1.34 years), and 10 healthy young women (mean +/- SE, 23.40 +/- 1.37 years) who were regular exercisers with resistance training experience participated in the study. Two sessions were performed to determine CON and ECC 1 repetitions maximum for latissimus pull-down (LTP), leg press (LP), bench press (BP), leg extension (LE), seated military press (MP), and leg curl (LC) exercises. Maximal ECC and maximal CON strength were determined on weight stack machines modified to isolate ECC and CON contractions using steel bars and pulleys such that only 1 type of contraction was performed. Within 2 weeks, participants returned and completed a retest trial in a counterbalanced fashioned. Test-retest reliability was excellent (r = 0.99) for all resistance exercise trials. Men demonstrated 20-60% greater ECC than CON strength (LTP = 32%, LP = 44%, BP = 40%, LE = 35%, MP = 49%, LC = 27%). Women's strength exceeded the proposed parameters for greater ECC strength in 4 exercises, p < 0.05 (LP = 66%, BP = 146%, MP = 161%, LC = 82%). The ECC/CON assessment could help coaches capitalize on muscle strength differences in young men and women during training to aid in program design and injury prevention and to enhance strength development.

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34
Journal of Strength and Conditioning Research, 2007, 21(1), 34–40
? 2007 National Strength & Conditioning Association
MAXIMAL ECCENTRIC AND CONCENTRIC STRENGTH
DISCREPANCIES BETWEEN YOUNG MEN AND WOMEN
FOR DYNAMIC RESISTANCE EXERCISE
DANIEL B. HOLLANDER,1ROBERT R. KRAEMER,1MARCUS W. KILPATRICK,2ZAID G. RAMADAN,1
GREG V. REEVES,1MICHELLE FRANCOIS,1EDWARD P. HEBERT,1AND JAMES L. TRYNIECKI1
1Department of Kinesiology and Health Studies, Southeastern Louisiana University, Hammond, Louisiana
70402;2School of Physical Education, Wellness, and Sport Studies, University of South Florida, Tampa, Florida,
33620.
ABSTRACT. Hollander, D.B., R.R. Kraemer, M.W. Kilpatrick,
Z.G. Ramadan, G.V. Reeves, M. Francois, E.P. Hebert, and J.L.
Tryniecki. Maximal eccentric and concentric strength discrep-
ancies between young men and women for dynamic resistance
exercise. J. Strength Cond. Res. 21(1):34–40. 2007.—Althoughre-
search has demonstrated that isokinetic eccentric (ECC)
strength is 20–60% greater than isokinetic concentric (CON)
strength, few data exist comparing these strength differences in
standard dynamic resistance exercises. The purpose of the study
was to determine the difference in maximal dynamic ECC and
CON strength for 6 different resistance exercises in young men
and women. Ten healthy young men (mean ? SE, 25.30 ? 1.34
years), and 10 healthy young women (mean ? SE, 23.40 ? 1.37
years) who were regular exercisers with resistance training ex-
perience participated in the study. Two sessions were performed
to determine CON and ECC 1 repetitions maximum for latissi-
mus pull-down (LTP), leg press (LP), bench press (BP), leg ex-
tension (LE), seated military press (MP), and leg curl (LC) ex-
ercises. Maximal ECC and maximal CON strength were deter-
mined on weight stack machines modified to isolate ECC and
CON contractions using steel bars and pulleys such that only 1
type of contraction was performed. Within 2 weeks, participants
returned and completed a retest trial in a counterbalanced fash-
ioned. Test-retest reliability was excellent (r ? 0.99) for all re-
sistance exercise trials. Men demonstrated 20–60% greater ECC
than CON strength (LTP ? 32%, LP ? 44%, BP ? 40%, LE ?
35%, MP ? 49%, LC ? 27%). Women’s strength exceeded the
proposed parameters for greater ECC strength in 4 exercises, p
? 0.05 (LP ? 66%, BP ? 146%, MP ? 161%, LC ? 82%). The
ECC/CON assessment could help coaches capitalize on muscle
strength differences in young men and women during training
to aid in program design and injury prevention and to enhance
strength development.
KEY WORDS. dynamic strength, gender
E
training using concentric (CON) and ECC con-
tractions, with greater ECC loading, produces specific ad-
aptations for a stronger, faster muscle, as indicated by
greater IIx myosin adenosine triphosphatase gene ex-
pression using primarily isokinetic protocols (11, 35, 42).
These findings have been validated through enhanced
performance in Olympic lifters who trained with loads
that were between 10 and 30% above their CON 1 repe-
titions maximum (RMs) across 6 weeks (13). Addition-
INTRODUCTION
ccentric (ECC) resistance training has been
shown to increase muscular strength and pro-
duce muscle hypertrophy (4, 8, 10). Moreover,
it has recently been reported that resistance
ally, in powerlifters, a slower ECC movement was ob-
served in better performances in the bench press and
squat exercises during competitions (28, 32). Thus, pre-
liminary evidence in resistance exercise research sug-
gests that ECC overload can enhance lifting performance.
Despite these findings, implementation of ECC overload
strength training has been lacking in traditional strength
and conditioning program designs. One contributing fac-
tor may be the lack of an established method for deter-
mining dynamic ECC strength. Without a valid, stan-
dardized protocol in place for determining optimal ECC
load during training, potential for injury and ineffective
loading is great. Moreover, if the goals of strength and
conditioning coaches are to help prevent injury and en-
hance athletic performance, then the development of an
optimal 1RM determination to individualized dynamic
ECC training protocol would be beneficial.
With a few exceptions (30, 44), previous ECC strength
studies have employed isokinetic machines (6, 7, 14–19,
31, 40, 45). These studies have demonstrated a range of
greater ECC relative to CON isokinetic strength. It is not
currently known whether these strength differences exist
for dynamic constant external resistance exercises. If
these values can be determined, it is possible that train-
ing loads of ECC and CON portions of resistance training
could be optimized for more rapid training adaptation and
injury prevention.
Additionally, the potential moderating factor of gen-
der remains relatively understudied with regard to dy-
namic resistance exercise. Several studies have attempt-
ed to quantify the relation between isokinetic ECC and
CON strength between men and women; however, no in-
vestigations have been identified that compare maximal
ECC/CON dynamic strength ratios across gender. There
is some evidence that these differences may be affected
by the gender of the participants being examined, with
greater isokinetic ECC/CON torque ratios in women than
in men between the ages of 20 and 93 years. (26, 27).
Griffin et al. (12) further supported gender discrepancies
when comparing ECC and CON strength differences in
elbow and knee joint exercises. Although the use of iso-
kinetic ECC strength data may be very helpful in reha-
bilitation settings, the translation of this research into
functional recommendations for athletes who normally
train on dynamic resistance machines such as weight-
stack equipment, plate-loaded equipment, or free weights
is lacking. Investigators are challenged to explore the

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ECCENTRIC AND CONCENTRIC STRENGTH IN MEN AND WOMEN
35
FIGURE 1.
Lat pulldown.
FIGURE 2.
Leg press.
paradigm of dynamic resistance exercise, as the lack of
control for range of motion, speed of movement, and con-
sistency of levers across equipment manufacturers often
impedes ecologically valid or comparable data. Moreover,
although Kraemer and Ratamess (25) have provided some
guidance with regard to the fundamentals of resistance
training, there are very few data concerning maximal
ECC/CON strength differences for different resistance ex-
ercises. Thus, description of the differences in maximal
strength for different ECC and CON dynamic resistance
exercises could be very applicable to typical exercise pro-
grams for athletes and noninjured exercisers.
Thus, the purpose of the present investigation was to
determine the difference in maximal dynamic ECC and
CON strength for 6 resistance exercises in young men
and women using elements of previously reported proto-
cols for determining maximal CON strength (14, 24, 34).
Because previous studies have demonstrated equivocal
results when comparing isokinetic ECC and CON
strength between samples of men and women (14, 24, 34,
36), it was hypothesized that dynamic ECC/CON strength
ratios using a constant load would be greater in young
women than in young men, but that the strength ratios
would be within previously reported ranges for isokinetic
strength. The isokinetic strength in 654 individuals doc-
umented by Lindle and colleagues supports this hypoth-
esis. Specifically, maximal ECC strength would be rough-
ly 20–60% greater than CON maximal strength in both
young men and young women (20, 24).
METHODS
Experimental Approach to the Problem
We determined CON and ECC strength for 6 convention-
al resistance exercises in 2 counterbalanced and random-
ized trials on separate days. During the trials, either a
CON or an ECC 1RM was established for each subject.
Within 2 weeks, subjects returned and completed a retest
trial to establish reliability. The main outcome measures
were ECC and CON 1RMs and ECC/CON strength ratios.
The ECC/CON strength ratios for young men and women
were contrasted with the previously reported isokinetic
strength ratios (120–160%). In addition, we compared
these values between young men and women.
Subjects
The study was approved by the Southeastern Louisiana
University Institutional Review Board. Ten healthy
young men and 10 healthy young women volunteers par-
ticipated in the study. The subjects were recreational,
noncompetitive exercisers with resistance training expe-
rience for a minimum of 1 year and were between 18 and
30 years of age. A health history questionnaire was ad-
ministered to rule out (a) participation in competitive
bodybuilding or weightlifting for the previous year, (b)
smoking, (c) taking medications that could alter test re-
sults (e.g., anabolic steroids or sympathoadrenal drugs),
(d) history of pituitary, renal, hepatic, cardiovascular, or
metabolic disease, (e) adherence to a reduced-calorie, low-
fat, or ketogenic diet that could affect hormone levels, and
(f) use of commercial ergogenic aids in the past 6 months,
such as creatine monohydrate, androstenedione, dehydro-
epiandrosterone, or ephedra.
The subject sample represented young healthy sub-
jects whose strength data were greater than those of nov-
ice lifters but not quite as high as strength data reported
for collegiate athletes (2, 29, 38, 39). Our sample repre-
sented a median strength sample that was neither hin-
dered by lack of training nor limited by advanced training
such that application of results could be considered for a
greater strength range of individuals.
Concentric and Eccentric Trials
We employed conventional resistance exercise that in-
volved the performance of dynamic, full range-of-motion
contractions against a constant external load. Two sepa-
rate sessions were performed to establish CON and ECC
1RMs for lat pull-down (LTP), leg press (LP), bench press
(BP), leg extension (LE), seated military press (MP), and
leg curl (LC) on weight stack machines (Master Trainer,
Rayne, LA). The exercises selected included multi-joint
and single-joint exercises that have been employed in
many resistance training regimens and have been deter-
mined to be effective in increasing muscular strength and
power (24). Equipment was modified to isolate ECC and
CON contractions using steel bars and pulleys. The trials
began with a 3-set warm-up followed by a counterbal-
anced and randomized trial of determining the CON and

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36HOLLANDER, KRAEMER, KILPATRICK ET AL.
FIGURE 3.
Bench press.
FIGURE 4.
Leg extension.
TABLE 1. Demographic characteristics of the sample.*
Age (y)Height (cm)Weight (kg)
Men (N ? 10)
Women (N ? 10)
* Data are expressed as mean (? SE).
25.30 (1.34)
23.40 (1.37)
177.54 (1.98)
164.34 (3.39)
88.91 (4.42)
66.45 (5.19)
TABLE 2. Concentric (CON) and eccentric (ECC) strength
values for young men and women.*
Exercises
Men
Mean
SE
3.46
5.64
8.77
8.02
12.74
14.73
3.64
4.38
7.40
10.61
1.18
1.36
Women
Mean
SE
2.08
3.48
7.49
11.35
4.00
5.58
2.63
5.43
3.22
3.44
1.43
2.08
LTP CON
LTP ECC
LP CON
LP ECC
BP CON
BP ECC
LE CON
LE ECC
MP CON
MP ECC
LC CON
LC ECC
100.68
132.05
188.64
270.23
148.41
203.18
74.09
99.09
84.55
124.55
35.00
44.09
59.55
76.82
107.05
174.32
30.91
69.09
39.77
61.82
20.23
44.55
13.18
22.27
* Data are values in kg for absolute 1 repetition maximum
ECC and CON strength. LTP ? lat pulldown; LP ? leg press;
BP ? bench press; LE ? leg extension; MP ? military press; LC
? leg curl.
ECC 1RM. Before each subject was tested, two 48-in. (10
lb each) steel pipes were bolted on top of the machine
bench and military press. The steel rods were placed on
the machine before the 1RM to simulate the conditions of
the CON and ECC trials. For the lat pull-down and the
leg extension, a spotting mechanism was designed so that
the subject only performed either ECC or CON move-
ments, while the spotter(s) performed the other half of
the lift (Figures 1–6). The protocol to determine CON or
ECC 1RMs employed elements of previously published
protocols (14, 24, 34).
Briefly, a 2–3 set warm-up was performed with 5–10
repetitions that represented 40–60% of a perceived max-
imal exertion. Each warm-up set was performed in a lin-
ear progression. Subjects were instructed to perform the
next 1–2 sets for 5 repetitions at a weight that was ap-
proximately 80% of perceived 1RM. Following these sets,
subjects were instructed to perform a 1RM for ECC or
CON actions; if the 1RM was not achieved, a lighter
weight was chosen. Rest periods between all sets were 3–
5 minutes. The CON and ECC contractions were per-
formed to a 3-second cadence (14, 34) and failure was de-
termined as inability to maintain the 3-second cadence
throughout the range of motion.
Every effort was made to ensure that speed of move-
ment was maintained throughout the maximal lifting at-
tempt. An external metronome recording of the 3-second
cadence was played during the lift. Based on the warm-
up trials, distance traveled by the weight stack was re-
corded and grommets were placed as external markers on
the machine to designate when the weight had traveled
each third of the full distance. A measuring yardstick was
placed on the machine as well as an arrow on the weight
stack to keep measurements accurate. An observer
watched the range of motion to determine that the weight
passed along each predesignated range throughout the 3
seconds so that adherence to the 3-second cadence at the
specified range of motion was maintained. This was to

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ECCENTRIC AND CONCENTRIC STRENGTH IN MEN AND WOMEN
37
FIGURE 5.
Military press.
FIGURE 6.
Leg curl.
TABLE 3. ECC/CON strength ratios and effect sizes (ES).*
LTP LPBPLE MP LC
Men
Women
ES
1.45 (5.09)
1.57 (5.20)
0.52
1.46 (2.76)
1.71 (6.98)
1.06
1.40 (4.58)
2.40 (0.16)
2.68
1.38 (4.42)
1.57 (4.23)
0.97
1.51 (5.09)
2.87 (0.36)
1.18
1.30 (3.63)
1.83 (0.12)
1.33
* All strength ratios are reported in mean (? SE) increments. LTP ? lat pulldown; LP ? leg press; BP ? bench press; LE ? leg
extension; MP ? military press; LC ? leg curl.
ensure that neither gravity nor inconsistent effort ham-
pered results. The 3-second cadence selection was an im-
portant aspect of this study because recommendations for
ECC and CON exercise have traditionally used an isoki-
netic protocol. Two recent studies have demonstrated a
comparable cadence of 3 seconds for determining CON
and ECC differences for isokinetic contractions (14, 34).
Kraemer and Ratamess (25) noted research that in a 5RM
for bench press, the speed of the repetitions varied from
1.2 to 3.3 seconds, depending on fatigue (33). Thus, the
speed of our protocol was consistent with documented
speeds during dynamic resistance exercise. Within 2
weeks, subjects returned and completed a retest trial.
Statistical Analyses
Resistances were recorded and data were reduced into
percentage of CON for ECC maximal lifts to compare
ECC strength to CON strength in young men and women.
All results were considered significant at p ? 0.05. To
compare ECC and CON strength ratio between genders
for each resistance exercise, t-tests were used. Test-retest
reliability was determined using intraclass correlations
(43).
RESULTS
Demographic data are presented in Table 1. Height and
weight were significantly greater for the men (p ? 0.01),
whereas age was not. When comparing test-retest reli-
ability between the first and second maximal attempts,
correlations were r ? 0.99 or better for all resistance ex-
ercise trials. Maximal ECC and CON values are present-
ed in Table 2.
Independent t-tests revealed that women, on all ex-
ercises except the LTP and LP, had a significantly higher
ECC to CON difference when compared to men (t ?
?3.98, ?2.38, ?2.97, and ?2.91; p ? 0.05). As shown in

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38HOLLANDER, KRAEMER, KILPATRICK ET AL.
FIGURE 7.
values represented as percentage of concentric (CON) 1RMs in
young men and women. LTP ? lat pulldown; LP ? leg press;
BP ? bench press; LE ? leg extension; MP ? military press;
LC ? leg curl. Significant difference for ECC to CON strength
ratios for women when compared to men, p ? 0.05.
Eccentric (ECC) 1 repetition maximum (1RM)
Figure 7, men demonstrated greater ECC than CON
strength within previously proposed parameters of 20–
60% of 1RM (LTP ? 32%, LP ? 44%, BP ? 40%, LE ?
35% MP ? 50%, LC ? 27%), but women did not. Wom-
en’sstrength exceeded the proposed parameters for great-
er ECC than CON strength in 4 exercises (LP ? 66%, BP
? 146%, MP ? 161%, LC ? 82%).
Table 3 indicates the average ECC/CON 1RM ratio for
men and women for each strength exercise. This table
also provides the effect size statistic for each exercise, in-
dicating the magnitude of the difference between men
and women. Women’s ratios were higher than those of
men for all exercises, and effect sizes ranged from 2.68 to
0.52. The largest gender differences were for the BP, LC,
MP, and LP, with mean effect sizes for these exercises all
over 1.0; the smallest difference was for the LTP exercise,
with this effect size at 0.52. Post hoc power estimates
were conducted using the given study parameters (e.g., N
? 20) and effect sizes observed (23). It was determined
that power to detect differences with effect sizes as large
as those found to be significant (effect size ? 1.0) was
approximately 0.60. However, with the number of sub-
jects in the study, power to find the difference between
women and men for LTP as significant was approximate-
ly 0.20. Overall, the effect size calculations and the power
comparison indicated that the number of subjects to de-
tect differences with the current design was adequate for
all but the LTP exercise.
DISCUSSION
The findings revealed large interexercise variability for
the ECC/CON strength ratios among different exercises.
It also demonstrated that dynamic ECC compared with
CON strength was greater in young women than in young
men for some resistance exercises and that these strength
ratios in women exceeded previously described isokinetic
ECC/CON strength ratios (14, 17). Moreover, upper-body
movements of the bench press and the military press
demonstrated considerably larger ECC/CON ratios (BP ?
146%, MP ? 161%) than leg movements (LP ? 66%, LC
? 82%) for women.
Previous studies have shown greater ECC relative to
CON isokinetic strength (17). In an early investigation of
ECC and CON strength employing a manual isokinetic
dynomometer, Doss and Karpovich found that ECC force
was 39.7% greater than CON force of elbow flexors (7).
Singh and Karpovich (41) reported isokinetic ECC forces
of flexors and extensors to be 32.65% and 14.22% greater
than CON forces employing an electronically-operateddy-
namometer, respectively. Using a Cybex isokinetic dy-
namometer, Rodgers and Berger (37) found approximate-
ly 80% greater torque produced with ECC than with CON
contractions. Hortobagyi and Katch (16) reported that
ECC isokinetic strength was 22–60% greater than isoki-
netic CON strength when testing subjects on a Biodex
dynamometer. Both upper-body (primarily the biceps bra-
chii in elbow extension and flexion) and lower-body
strength (primarily the quadriceps in knee flexion and
extension) have been evaluated (12). Thus, research has
established isokinetic ECC strength ranging from 14 to
89% above CON strength (17, 41) with results of the ma-
jority of studies ranging from 22 to 60% (16, 20). The pre-
sent study adds to our understanding of strength ratios,
demonstrating dynamic ECC/CON strength ratios for
men and women that were dissimilar.
The gender differences in the present study were con-
sistent to some extent with previous isokinetic research.
Specifically, past research demonstrated that women gen-
erated greater isokinetic ECC compared with CON torque
than men for upper- and lower-body muscle groups (12,
26). A similar result in greater strength ratios in women
than men was reported by Colliander and Tesch who
found that knee flexion extension at 90 to 150?·s?1, but
not at a lower velocity of 30?·s?1, were greater for women
(5). Our data demonstrated greater dynamic (as opposed
to isokinetic) ECC /CON ratios for young women across
upper- (BP and MP) and lower-body (LE and LC) exer-
cises. Previous research has supported the notion that
gender differences could be a result of differences in
stored and elastic energy of muscles, central nervous in-
hibition of maximal voluntary muscle actions, and the
ability to recruit motor units during contractions in up-
per- and lower-body muscle actions (5, 12, 21, 46).
A secondary explanation of why our results did not
match those of past isokinetic strength ratios can be seen
in the work of Lindle et al. (26). Lindle et al. reported a
decline in muscle quality as well as in peak torque in the
knee extensors from a sample of 654 men and women
across the ages of 20–93 years. Interestingly, although
muscle quality declined for both sexes, the men demon-
strated a significantly greater decline across age for ECC
peak torque, and women seemed to decline to a lesser
degree (26). Furthermore, these investigators concluded
that older women had an enhanced capacity to store and
utilize elastic energy when compared to men. Collectively,
these data may point to the need for specific strength
training protocols for young men and women, as 1RM
comparisons for dynamic ECC/CON strength may be dif-
ferent.
Because sample size was low, a power analysis was
warranted. This analysis demonstrated that with the bal-
anced, within-subjects design, the sample was able to cap-
ture the ECC/CON strength differences with reasonable
power for most of the lifts performed. Moreover, the effect

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ECCENTRIC AND CONCENTRIC STRENGTH IN MEN AND WOMEN
39
sizes were relatively large (ranging from 0.97 to 2.68 in
5 lifts), which further supports the validity of the com-
parison made in the present study between genders.
PRACTICAL APPLICATIONS
The results of the study may help strength and condi-
tioning professionals understand the potentially large
ECC/CON strength ratio differences in young women
compared with young men who are not competitive
weightlifters. Moreover, data from the present study may
eventually allow more precise development of ECC over-
load resistance training protocols to improve strength and
performance as well as rehabilitate athletes from injury,
because our data provide a protocol for determining ECC
1RMs. In addition, a challenge when training eccentri-
cally has been delayed onset muscle soreness accompa-
nying ECC movements, and this has been attributed to
fewer motor units recruited compared to CON movements
(1, 3, 9). Although soreness has been shown to dissipate
within 1–2 weeks of the initial bout (22), caution in ap-
plying ECC overload training is still warranted because
ECC 1RM determination and ECC overloading have re-
ceived limited attention. Careful implementation of ECC
overloading periodically throughout a training cycle with
DOMS monitoring could potentially complement a tradi-
tional periodized strength and conditioning program for
young men and women. Thus, an accurate ECC 1RM can
become useful in determining proper resistance training
loads and evaluating specific muscular contraction (ECC/
CON) deficits. This study presents a protocol for testing
maximal ECC strength so that optimal training loads can
be determined and applied.
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Acknowledgments
Financial support was provided by the Center for Faculty
Excellence,Faculty Development
Louisiana University.
Grant,Southeastern
Address correspondence to Dr. Daniel B. Hollander,
dhollander@selu.edu.