THE EFFECTIVENESS OF TRADITIONAL AND SLING
EXERCISE STRENGTH TRAINING IN WOMEN
BETHANY D. DANNELLY, SARAH C. OTEY, TED CROY, BLAIN HARRISON, COREY A. RYNDERS,
JAY N. HERTEL, AND ARTHUR WELTMAN
Department of Human Services, Curry School of Education, University of Virginia, Charlottesville, Virginia
ABSTRACT
Dannelly, BD, Otey, SC, Croy, T, Harrison, B, Rynders, CA,
Hertel, JN and Weltman, A. The effectiveness of traditional and
sling exercise strength training in women. J Strength Cond Res
25(2): 464–471, 2011—Strength training often combines
closed-kinetic-chain exercises (CKCEs) and open kinetic-chain
exercises (OKCEs). The CKCE may be more effective for
improving performance in lower-body training. Recently, we
reported upper-body CKCE (using a commercially available
system of ropes and slings, Redcord AS, Staubo, Norway) was
as effective as OKCE training for strength gains and that CKCE
was more effective than OKCE for improving throwing
performance. To our knowledge the effectiveness of a strength
training program that uses exclusively CKCE is unknown. In this
study, we examined the effectiveness of CKCE vs. OKCE
strength training programs in women enrolled in an introductory
strength training program. Twenty-six participants were randomized to OKCE (traditional exercises) or CKCE (sling-based
exercises). Participants completed 6 sets per week for 13
weeks. Pre and posttraining evaluations included the following:
1 repetition maximum (1RM) leg and bench press; sling exercise push-ups; isokinetic dynamometry; lateral step-down test;
and the Star Excursion Balance Test. Both groups significantly
improved bench press (by an average of 4–6 kg) and leg press
(by an average of 23–35 kg) (p , 0.001). There was a significant group 3 time interaction (p , 0.001) for sling exercise
push-ups (OKCE pre = 5.5 6 8.6, OKCE post = 6.1 6 8.2,
CKCE pre = 6.8 6 6.0, CKCE post = 16.9 6 6.6). Isokinetic
measures of knee extension, knee flexion, shoulder internal
rotation, and shoulder external rotation increased (improvements ranged from 2.7 to 27.7%), with no group differences.
Both OKCE and CKCE strength training elicited similar
changes in balance. We conclude that CKCE training is
equally as effective as OKCE training during the initial phases of
a strength training program in women. The fact that only CKCE
Address correspondence to Arthur Weltman, [email protected].
25(2)/464–471
Journal of Strength and Conditioning Research
Ó 2011 National Strength and Conditioning Association
464
the
improved sling exercise push-ups supports previous findings
suggesting functional superiority of CKCE.
KEY WORDS closed-kinetic chain, open-kinetic chain, Redcord,
1RM, isokinetic dynamometry, balance
INTRODUCTION
S
trength training programs typically combine
closed- and open-kinetic-chain exercises to improve overall strength. Open-kinetic-chain exercises (OKCEs) are performed with the terminal
segment, typically the hand or foot, free to move with the load
applied to the distal portion of the limb such as in the bench
press or leg extension exercise. These exercises are usually non–
weight bearing, with the movement occurring at the elbow or
knee joint (6,13). Closed-kinetic-chain exercises (CKCEs) are
exercises performed where the hand (for arm movement) or
foot (for leg movement) is fixed and cannot move, such as
a squat or push-up. The hand or foot remains in constant
contact with the surface, usually the ground or the base of
a machine. These exercises are typically weight-bearing
exercises, where exercisers use their own body weight with or
without external weight. The CKCEs tend to work more than
1 muscle group and joint simultaneously (6,13).
Several studies have shown that CKCEs may be more
effective than OKCEs in improving performance-related
measures in lower-body training (1,3). For example, lowerbody CKCE training is more effective than OKCE training
for improving vertical jump performance (1,3,13). Further,
CKCEs are commonly prescribed for athletes, possibly
because they result in less anterior and posterior tibiofemoral
shear force than lower-body OKCEs do (6,10,16). Studies
also have shown that lower-body CKCE generate muscular
co-contraction, which provides greater joint stability than
OKCE (7,16).
Studies conducted on upper-body strength training have
shown that CKCEs are typically limited by body weight as
a source of resistance so low repetition, high-intensity
strength training can be difficult to execute (4,11). Thus,
OKCEs are commonly employed in upper-body strength
programs. Despite these perceived limitations, it has been
shown that CKCEs can be effective for upper-body training
(4,11). Similar to the lower-body exercises, upper-body
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CKCEs elicit muscular co-contractions, thus providing
dynamic joint stability, which does not occur with OKCEs
(11,13). A recent study from our laboratory found that
substituting 4 upper-body CKCEs was as effective as OKCE
training in producing maximal strength gains in collegiate
softball players (13); however, only CKCE training significantly improved throwing velocity. Based on these findings,
it is reasonable to conclude that CKCE training can be
incorporated into upper-body strength training without
sacrificing gains in maximal strength or performance criteria.
Although some studies have shown that CKCE training may
be as or more effective than OKCE training, to our
knowledge, no data exist on the effectiveness of a strength
training program that uses CKCEs exclusively (1,3,6,7,10,11,
13,16). The use of CKCE may have particular utility for
individuals who may be intimidated by traditional weight
training settings.
For example, women beginning a weight training program
are often uncomfortable in a typical weight room setting and
as such may choose not to engage in this important activity
(8). In this study, we compared a sling-based CKCE training
program to an OKCE training program in a group of women
enrolled in an introductory strength training program. We
hypothesized that after training, both CKCE training and
OKCE training would increase 1 repetition maximum (1RM)
bench and leg press, and Biodex peak torque (PT) and power
to a similar degree. We also hypothesized that performance
on CKCE and dynamic balance would improve more with
CKCE training because of specificity of training and the extra
demands CKCE place on core stability.
METHODS
Experimental Approach to the Problem
This study included 1 independent variable with 2 levels (preand post-13 weeks of strength training) and 13 dependent
variables. The independent variable was the type of training in
which the subject engaged (CKCE or OKCE). Dependent
variables included isokinetic concentric phase PT for knee
flexion and extension and for shoulder internal and external
rotation; isokinetic concentric phase peak power (PP) for
knee flexion and extension and for shoulder internal and
external rotation; 1RM bench press and 1RM leg press; lateral
step-down test; Star Excursion Balance Test (SEBT); and
maximum sling exercise push-ups.
Subjects
The study was approved by the university’s institutional
review board. Twenty-nine female undergraduate students at
the University of Virginia were recruited from Lifetime
Physical Activity weight training classes (mean age = 19.6 6
1.11 years, mean weight = 60.5 6 7.2 kg, mean height =
166.4 6 5.9 cm). All participants were enrolled in an introductory strength training class and provided written informed
consent. Participants had 1 week (2 or 3 sessions) to learn
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basic weight training techniques and safety guidelines. Three
subjects withdrew from the study. Two subjects dropped
the course, and 1 subject was unable to complete the study
because of work-related conflicts. Three additional subjects
were unable to complete all aspects of performance testing
because of pre-existing orthopedic injuries, but measures
they were able to complete are included (resulting in n = 23 to
n = 26, depending on the variable tested).
Procedures
Performance Testing. Pre and posttraining testing consisted of
isokinetic concentric phase PT for knee flexion and extension
and for shoulder internal and external rotation; isokinetic
concentric phase PP for knee flexion and extension and for
shoulder internal and external rotation; 1RM bench press and
1RM leg press; lateral step-down test; SEBT; and maximum
sling exercise push-ups.
Isokinetic Strength Testing. Isokinetic strength testing was
performed using a Biodex System 3 multijoint dynamometer
(Shirley, NY, USA). All subjects performed 3 sets of 5 trials
of each exercise with 90 seconds between sets. Verbal
encouragement was given for each repetition and testing was
preceded with 10–15 practice repetitions to familiarize the
subject with the isokinetic device. Concentric internal rotation and external rotation tests intraclass correlation
coefficients [ICCs] = 0.81 and 0.74 for internal and external
rotation, respectively) were conducted at 180° s21 through
a 65° arc of motion, with the seatback angle set at 85°. The
tested extremity was abducted approximately 25°, and
shoulder flexed slightly to place the shoulder in the scapular
plane for testing. Dynamometer and seat height were
adjusted such that the humerus was in line with the rotor,
as recommended by the manufacturer. The isokinetic knee
flexion and extension test (ICCs = 0.91 and 0.92 for flexion
and extension, respectively) was also performed at 180° s21
from full knee extension (0°) to approximately 85–90° of
flexion for 3 sets of 5 test repetitions with a 90-second rest
period between sets. The seatback angle was set at 85°, and
the hips were in 90° of flexion. Values from the 3 sets were
averaged to find PT and power values for each subject.
1RM Testing. The 1RM testing was performed using the
National Strength and Conditioning Association 1RM protocol (2). Participants began the 1RM bench press and leg
press assessments by warming up with repetitions on the
bench press on 45-lb bars and free weights (York Barbell,
York, PA, USA) and repetitions on the leg press machine
(Hammer Strength, Schiller Park, IL, USA). The goal was to
build to the 1RM load by approximately the fifth set. For the
bench press, a successful repetition was scored if the weight
was lowered to the chest and raised to full arm extension
without subject losing foot, hip, back, or shoulder contact
with the bench or the floor, and no help was provided by the
spotter. For the leg press, a successful repetition was scored if
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Strength Training in Women
the weight was lowered such that the knees created a 90°
angle and raised to full leg extension without the subject
losing back or shoulder contact with the machine and
without help from the spotter. Three failed repetitions at
a given weight or voluntary termination ended each test.
Lateral Step-Down Test. The quality of movement during the
lateral step-down test was assessed by a trained investigator
using a scale designed for this purpose. Each participant was
asked to stand on single-leg support with hands on the waist,
knee straight, and weight-bearing foot on the edge of
Figure 1. Examples of open-kinetic-chain (OKCE) and closed-kinetic-chain (CKCE) pairs used in training intervention.
466
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a 20-cm-high step. The contralateral leg was held, fully
extended, over the floor adjacent to the step. The participant
was then asked to bend the tested knee until the contralateral
leg lightly touched the floor and then re-extend the knee to
the start position. This was repeated for 3 repetitions. The
investigator faced the subject and scored the test based on
5 criteria, described in detail elsewhere (12): (a) Arm strategy,
(b) Trunk movement, (c) Pelvis plane, (d) Knee position,
and (e) Maintenance of steady unilateral stance. A point was
added for an unsuccessful execution of each of the 5 criteria
during any of the 3 repetitions. Each subject received a score
between 0 and 6.
Star Excursion Balance Test. The anterior, posteromedial, and
posterolateral components of the SEBT were conducted by
a trained investigator using a ‘‘Y’’ that was taped the floor
(ICCs range from 0.85 to 0.96 depending on movement).
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Participants were asked to stand on 1 leg with their toe at the
base of the upper part of the ‘‘Y.’’ While maintaining this
single-leg stance, the participant was asked to reach with
the free leg in the specified direction (5,9). Reach was
measured in centimeters, and each participant completed
3 trials. Measurements from the 3 trials were averaged and
normalized to subject leg length. Reach was also measured
on the opposite foot in all 3 planes of movement.
Sling Exercise Push-Ups. Sling exercise push-ups were
performed with a Redcord minitrainer (Kilsund, Norway).
Handles were approximately 10 cm above the ground with
participants positioned on their knees. An investigator
instructed each participant in proper push-up form and
counted the number of successful repetitions. A repetition
was considered successful if the subject lowered her chest to
the height of her hands while maintaining core stability and
TABLE 1. Mean (6SD) pre and posttraining results for OKCE and CKCE training (n = 13 for OKCE, n = 13 for CKCE).*†
Parameter
OKCE pre
OKCE post
CKCE pre
CKCE post
Leg press (kg)
Bench (kg)
Sling push-ups§
Torque knee flex (Nm)
Torque knee ext (Nm)
Torque shoulder IR (Nm)
Torque shoulder ER (Nm)
Power knee flex (W)
Power knee ext (W)
Power shoulder IR (W)
Power shoulder ER (W)
Lateral step-down (L)
Lateral step-down (R)
Anterior SEBT (R)
Posteromedial SEBT (R)
Posterolateral SEBT (R)
Anterior SEBT (L)
Posteromedial SEBT (L)
Posterolateral SEBT (L)
54.6 (26.9)
30.9 (4.4)
5.5 (8.6)
49.4 (10.5)
68.9 (15.0)
19.2 (5.5)
9.4 (2.6)
89.7 (17.1)
129.1 (18.0)
26.4 (10.0)
12.1 (4.7)
2.4 (1.6)
2.0 (0.9)
0.8 (0.05)
0.8 (0.07)
0.8 (0.1)
0.7 (0.06)
0.8 (0.09)
0.8 (0.1)
90.4 (30.6)‡
36.5 (7.3)‡
6.1 (8.2)
53.9 (12.5)‡
74.4 (14.3)‡
22.1 (5.5)‡
10.0 (3.1)
99.9 (16.1)‡
143.3 (13.1)‡
33.7 (9.2)‡
13.2 (4.3)‡
1.3 (1.5)‡
1.3 (1.3)‡
0.7 (0.09)
0.9 (0.1)
0.8 (0.1)
0.7 (0.09)
0.9 (0.1)‡
0.8 (0.08)‡
85.1 (32.3)
34.8 (6.8)
6.8 (6.0)
47.9 (8.3)
71.4 (18.5)
20.4 (6.0)
10.9 (3.3)
88.3 (14.5)
136.7 (26.3)
30.4 (9.7)
14.8 (4.7)
1.8 (1.0)
1.6 (1.1)
0.7 (0.06)
0.8 (0.1)
0.8 (0.1)
0.7 (0.06)
0.8 (0.1)
0.8 (0.1)
108.2 (41.9)‡
38.7 (6.3)‡
16.9 (6.6)‡
53.7 (14.4)‡
73.4 (20.6)‡
23.6 (7.9)‡
11.5 (3.6)
103.7 (22.8)‡
146.1 (32.7)‡
37.2 (12.4)‡
16.9 (7.6)‡
1.3 (0.9)‡
1.4 (1.2)‡
0.7 (0.06)
0.9 (0.07)
0.8 (0.08)
0.7 (0.07)
0.9 (0.8)‡
0.9 (0.08)‡
*OKCE pre = open-kinetic-chain group pretraining test; OKCE post = open-kinetic-chain posttraining test; CKCE pre = closedkinetic-chain pretraining test; CKCE post = closed-kinetic-chain posttraining test; leg press = 1 repetition maximum leg press (lbs);
bench = 1 repetition maximum bench press (lbs); sling push-ups = maximum sling push-ups; torque knee flex = peak torque knee flexion
(Nm); torque knee ext = peak torque knee extension (Nm); torque shoulder IR = peak torque shoulder internal rotation (Nm); torque
shoulder ER = peak torque shoulder external rotation (Nm); power knee flex = peak power knee flexion (W); power knee ext = peak
power knee extension (W); power shoulder IR = peak power shoulder internal rotation (W); power shoulder ER = peak power shoulder
external rotation (W); lateral step-down (L) = left leg lateral step-down test; lateral step-down (R) = right leg lateral step-down test;
anterior SEBT (R) = right leg anterior star excursion balance test; posteromedial SEBT (R) = right leg posteromedial direction star
excursion balance test; posterolateral SEBT (R) = right leg posterolateral direction star excursion balance test; anterior SEBT (L) = left
leg anterior direction star excursion balance test; posteromedial SEBT (L) = left leg posteromedial direction star excursion balance test;
posterolateral SEBT (L) = left leg posterolateral direction star excursion balance test; ANOVA = analysis of variance.
†For the following variables, n was slightly different: n = 8 for CKCE lateral step-down; n = 10 for OKCE lateral step-down; n = 11
for OKCE bench and OKCE sling push-ups; n = 12 for OKCE leg press, OKCE torque knee extension and flexion, and OKCE power
knee extension and flexion, CKCE bench press, CKCE sling push-ups, CKCE shoulder internal and external rotation average torque,
and CKCE shoulder internal and external rotation peak power.
‡ANOVA analyses revealed the following: Significantly greater than pre-testing score, p , 0.05.
§Significant group 3 time interaction, p , 0.05.
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Strength Training in Women
posture. Failure to maintain proper form or failure to continuously progress from 1 repetition to the next terminated
the test.
Training Intervention. Participants were randomized to 1 of
2 training intervention groups: OKCE training and CKCE
training. Participants completed 6 sets of strength training
exercises per week for 13 weeks. Based on course enrollment
and time, some participants completed 3 sessions per week,
performing 2 sets during each session, whereas others
completed 2 sessions per week, performing 3 sets during
each session. Investigators supervised all exercise sessions.
The duration, relative intensity, and volume of each set were
the same for both treatment groups. All participants were
instructed to refrain from strength training outside of
treatment sessions.
The CKCE group completed a full-body strength training
program with Redcord minitrainers hung from ceiling beams,
which consists of ropes with slings and handles that can be
adjusted. Exercise intensity was controlled by adjusting
handle height relative to the floor, foot height, and leg and
hand position relative to the rope fulcrum. Although there
was some trial and error in the determination of relative
intensity of major pull and press lifts, all subjects realized
their full capabilities within the first full week of training.
By keeping the handles elevated, subjects could complete
exercises with intensity and volume comparable with those
in the OKCE group.
The OKCE group trained with free weights, dumbbells
(York Barbell, York, PA, USA), and machines (Hammer
Strength, Schiller Park, IL, USA). Exercise intensity and
volume were adjusted relative to a subject’s 1RM for major
press and pull lifts. Intensity for exercises was determined
by subject familiarity and proper form.
Examples of commonly selected OKCE and their CKCE
analogs, in italics, are shown: (a) Barbell flat bench press/
bilateral push-ups, (b) Cable seated row/bilateral inverted row,
(c) Dumbbell biceps curl/biceps curl, (d) Triceps pulldown/
triceps extension, (e) Shoulder extension/shoulder extension,
(f ) Pullover/Pullover, (g) Hip abduction/hip abduction,
(h) Hip adduction/hip adduction, (i) Leg extension/leg
extension-prone bridge, and (j) Leg curl/leg curl–supine
bridge–leg press.
Figure 1 provides visual examples of OKCE–CKCE
exercise pairs.
0.05 level. When baseline differences between groups were
observed, analysis of covariance results were used with the
baseline scores as the covariate. The Tukey–Kramer post hoc
tests were used to locate differences.
RESULTS
Table 1 shows mean (SD) pre and posttraining data for
the selected performance parameters. Both the OKCE and
CKCE conditions had significant (p , 0.05) and similar
improvements on most performance measures. The OKCE
group improved 1RM leg press by 35.7 kg, with a 23.0-kg
increase in the CKCE group (group 3 time interaction,
p = 0.13). The OKCE group improved 1RM bench press by
5.6 kg, with an 4.0-kg increase in the CKCE group (group 3
time interaction, p = 0.36).
Figures 2 and 3 show the individual responses for 1RM leg
and bench press, respectively. There was a significant
group 3 time interaction (p = 0.003) for sling exercise
push-ups. The CKCE group improved by 148.5%, with an
observed mean 11% increase in the OKCE group. Individual
responses are shown in Figure 4.
For most Biodex measures, including PT and PP, there
were significant increases seen in both groups posttraining
Statistical Analyses
Statistical calculations were performed using Statview version
5.0.1 (SAS Institute, Cary, NC, USA). A 2-factor analysis of
variance (ANOVA) with repeated measures was executed
with the treatment group (CKCE or OKCE) as the independent variable. The dependent variables were the outcome
measures for the various performance tests. Thus, there was
1 between-subjects factor (training group) and 1 withinsubjects factor (time). The threshold for significance was set at
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Figure 2. Pre to posttraining individual changes (dashed lines) and group
mean change 6 SEM (bold line) in the 1 repetition maximum (1RM) leg
press of closed- and open-kinetic-chain training subjects (n = 25). OKCE
= open-kinetic-chain subjects; CKCE = closed-kinetic-chain subjects;
pre = pretraining 1RM leg press; post = posttraining 1RM leg press. A
significant increase over time was observed (p , 0.001).
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Figure 3. Pre to posttraining individual changes (dashed lines) and group
mean change 6 SEM (bold line) in the 1 repetition maximum (1RM)
bench press of closed- and open-kinetic-chain training subjects (n = 23).
OKCE = open-kinetic-chain subjects; CKCE = closed-kinetic-chain
subjects; pre = pretraining 1RM bench press; post = posttraining 1RM
bench press. A significant increase over time was observed (p , 0.001).
for knee extension (p = 0.002 [PT], p = 0.003 [PP]), knee
flexion (p = 0.003 [PT], p , 0.001 [PP]), and shoulder
internal rotation (p , 0.001 [PT], p , 0.001 [PP]). Shoulder
external rotation did not have a significant group effect
(p = 0.25 [PT], p = 0.08 [PP]). There were no significant
differences between groups.
There was a significant improvement in lateral step-down
performance posttraining with no significant differences
between groups in both the right and left legs (p , 0.001).
Strength training had little overall effect on anterior,
posteromedial, and posterolateral direction performance on
the SEBT. For both the right and left legs, there was not
a significant difference between pre and posttraining
performance on the anterior direction of the SEBT (p =
0.16 [RL], p = 0.90 [LL]). For the right leg, there was also no
significant difference between pre and posttraining performances on the posteromedial direction (p = 0.10), but for the
left leg, there was an increase in the posteromedial direction
(p = 0.003). For the right leg in the posterolateral direction,
overall improvement approached significance (p = 0.067),
whereas there was a significant increase in reach in the
posterolateral direction for the left leg (p = 0.023).
Additionally, posterolateral measurements trended toward
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Figure 4. Pre to posttraining individual changes (dashed lines) and group
mean change 6 SEM (bold line) in sling exercise push-ups of closed- and
open-kinetic-chain training subjects (n = 23). OKCE = open-kinetic-chain
subjects; CKCE = closed-kinetic-chain subjects; pre = pretraining sling
exercise push-ups; post = posttraining sling exercise push-ups. A
significant group 3 time interaction was observed (p , 0.001).
a group 3 time interaction, with CKCE eliciting more
improvement than OKCE (p = 0.085 [LL], p = 0.12 [RL]).
DISCUSSION
This study compared the effectiveness of CKCE training and
OKCE training on several strength and balance measures in
women initiating a strength training program. The major
findings of this study were as follows: (a) both OKCE and
CKCE strength training were equally effective for improving
traditional measures of strength (e.g., 1 RM, isokinetic power)
(Table 1, Figures 2 and 3); (b) only CKCE exercise improved
sling exercise push-ups indicating both specificity of training
and functional training superiority of CKCE exercise (Table
1, Figure 4); and (c) both OKCE and CKCE strength training
elicited similar changes on balance with the exception of the
posterolateral direction measure, where posterolateral measurements trended toward a group x time interaction, with
CKCE eliciting more improvement than OKCE (Table 1).
The similar improvements in strength between the
conditions suggest that solely using CKCE training is equally
as effective as OKCE training during the initial phases of
strength training. Previous studies have also found that CKCE
training elicits strength and performance gains similar to or
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Strength Training in Women
better than OKCE training (1,3,7,13,16). For example, lowerbody CKCE training has been shown to be more effective
than OKCE training for improving vertical jump performance (1,3,13), and CKCE training generates muscular cocontraction, resulting in greater joint stability (7,16). Another
study found that substituting 4 upper-body CKCE was as
effective as OKCE training in producing maximal strength
gains (13). To our knowledge, this is the first study to
examine the effectiveness of a strength training program that
uses CKCEs exclusively.
It is interesting to note that the changes observed in
strength outcomes after training were similar between groups,
despite the fact that the Redcord group had higher initial
strength values after random assignment. One could
hypothesize that individuals who were less strong to begin
would be more likely to experience great change in strength
with training (14). It is possible that if subjects started with
similar initial strength values, we might have observed greater
improvements with CKCEs, similar to what has been
observed in previous studies (1,3,6,7,10,11,13,16).
These findings have important implications for women
initiating a weight training program, showing that CKCEs
can be substituted for OKCEs without a detrimental effect
on strength. Women initiating weight training programs are
often hesitant to begin an OKCE program because of
intimidation and fear of a weight room (8). These women
may be more inclined to undertake a CKCE training program
that can be conducted outside of a weight room. Further,
a CKCE that uses a Redcord device are beneficial because it
removes several barriers to strength training. The Redcord
device is a convenient and effective strength training device
that is portable, and time efficient, which eliminates the time
factor that is a barrier for many people trying to consistently
strength train (15).
Our hypothesis that performance on CKCE would
improve more with CKCE training was supported. The
significant group 3 time interaction for sling exercise pushups shows that specificity of training impacts performance.
The subjects in the CKCE training group used inherently
unstable sling-based equipment, which likely activated both
core and stabilizing muscles to a greater extent, and led to an
improvement in performance. In a recent study from our
laboratory (13), we investigated the relationship between
strength training method and throwing velocity. That study
reported that subjects in the CKCE training group
significantly improved throwing velocity compared to the
subjects in the OKCE training group, despite similar
improvements in maximal strength. The instability of the
sling-based training method again likely enhanced activation
of the musculature involved in the torso and shoulder
stabilization. The activation of these muscles along with
more time spent on the eccentric portion of a given exercise
could have contributed to the improvement in throwing
velocity (13). Through core activation and activation of
smaller stabilizing muscles, CKCE sling-based strength
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the
training appears to develop functional strength more so
than OKCE training, which is beneficial for both performance and everyday living.
This study shows similar changes in balance for CKCE and
OKCE training on the SEBT, with the exception of the
posterolateral direction. Both strength training methods
resulted in a significant improvement for left leg balance in
the posteromedial direction and marginally significant
improvements for right leg balance in the posteromedial
direction. There was no significant change in balance in
the anterior direction in both legs. The improvement in the
posteromedial direction was expected. Movement in the
posteromedial direction is a functional movement and
recruits both the quadriceps and hamstrings; thus, strength
training is expected to improve performance on this measure
(5). The lack of change in anterior balance was not expected.
The anterior component of the SEBT is mostly quadriceps
dependent, demonstrated by significant quadriceps electromyographic activation during this task (5). Thus, with
strength training, specifically quadriceps strength training,
performance on the anterior component of the SEBT has
been shown to improve (5). We do not have an explanation
at this time for the lack of training effect for both the CKCE
and OKCE training groups.
Our hypothesis that performance on balance measures
would improve more with CKCE training was supported in
the posterolateral direction on the SEBT. Our hypothesis was
based on the idea that the extra demands CKCEs place on
core stability would help with balance performance. Given
the rotational component of the posterolateral direction, it is
possible that the CKCEs facilitated more recruitment
strategies and core stabilization, allowing for more controlled
pelvic rotation (5). It is reasonable to hypothesize that CKCE
training develops better joint coupling at the hip and knee
than OKCE training, allowing for more stable pelvic rotation
and core stabilization during the SEBT. In conclusion, both
CKCE training and OKCE training for 13 weeks significantly
improved overall strength and balance in women beginning
weight training.
PRACTICAL APPLICATIONS
On the basis of the current data, it can be concluded that
CKCE training is equally as effective as OKCE training in
eliciting improvements during the initial phases of a strength
training program in women starting a strength training
program. The fact that only CKCEs improved sling exercise
push-ups supports previous findings suggesting functional
superiority of CKCEs. Further, women beginning strength
training are often hesitant to begin an OKCE program
because of intimidation and fear of a weight room. These
women may be more inclined to undertake a CKCE training
program that can be conducted outside of a weight room and
can substitute CKCEs for OKCEs without a detrimental effect
on strength. Although only beginners were examined, data
from this study and data from previous studies indicate that
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the
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substituting sling-based CKCEs for traditional OKCEs is
effective for both strength gains and functional improvement.
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