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Strength, body composition, and functional outcomes in the squat versus leg press exercises

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Background: The purpose of this study was to compare strength, body composition, and functional outcome measures following performance of the back squat, leg press, or a combination of the two exercises. Methods: Subjects were pair-matched based on initial strength levels and then randomly assigned to 1 of 3 groups: A squat-only group (SQ) that solely performed squats for the lower body; a leg press-only group (LP) that solely performed leg presses for the lower body, or; a combined squat and leg press group (SQ-LP) that performed both squats and leg presses for the lower body. All other RT variables were held constant. The study period lasted 10 weeks with subjects performing 2 lower body workouts per week comprising 6 sets per session at loads corresponding to 8-12 RM with 90 to 120 second rest intervals. Results: Results showed that SQ had greater transfer to maximal squat strength compared to the leg press. Effect sizes favored SQ and SQ-LP versus LP with respect to countermovement jump while greater effect sizes for dynamic balance were noted for SQ-LP and LP compared to SQ, although no statistical differences were noted between conditions. Conclusions: These findings suggest that both free weights and machines can improve functional outcomes, and that the extent of transfer may be specific to the given task.
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Strength, body composition, and functional outcomes in the
squat versus leg press exercises
Fabrício Eduardo ROSSI, Brad J SCHOENFELD, Skyler OCETNIK, Jonathan
YOUNG, Andrew D VIGOTSKY, Bret CONTRERAS, James KRIEGER, Michael
MILLER, Jason CHOLEWA
J Sports Med Phys Fitness 2016 Oct 13 [Epub ahead of print]
THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
Rivista di Medicina, Traumatologia e Psicologia dello Sport
pISSN 0022-4707 - eISSN 1827-1928
Article type: Original Article
The online version of this article is located at http://www.minervamedica.it
Running Head: Squat versus Leg Press
1
Strength, body composition, and functional outcomes in the squat versus leg press exercises
Fabrício E. Rossi1,2
Brad J. Schoenfeld3
Skyler Ocetnik1,
Jonathan Young1
Andrew Vigotsky4
Bret Contreras5
James W. Krieger6
Michael G. Miller7
*Jason Cholewa2
1. Institute of Bioscience, Department of Physical Education Univ. Estadual Paulista, Rio
Claro, São Paulo, Brazil.
2. Department of Kinesiology, Recreation, and Sport Studies, Coastal Carolina University,
Conway, SC, USA
3. Department of Health Sciences, CUNY Lehman College, Bronx, NY
4. Kinesiology Program, Arizona State University , Phoenix, AZ , USA
5. Sport Performance Research Institute, AUT University, Auckland, New Zealand
6. Weightology, LLC, Issaquah, WA, USA
7. Department of Human Performance and Health Education, Western Michigan University,
Kalamazoo, MI
*Corresponding author:
Jason Cholewa, PhD
Coastal Carolina University
PO Box 261954
Conway, SC 29528
P: 843-349-2041
F: 843-349-2875
jcholewa@coastal.edu
Word Count: 3864
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Running Head: Squat versus Leg Press
2
Abstract
BACKGROUND: The purpose of this study was to compare strength, body composition, and
functional outcome measures following performance of the back squat, leg press, or a
combination of the two exercises. METHODS: Subjects were pair-matched based on initial
strength levels and then randomly assigned to 1 of 3 groups: A squat-only group (SQ) that solely
performed squats for the lower body; a leg press-only group (LP) that solely performed leg
presses for the lower body, or; a combined squat and leg press group (SQ-LP) that performed
both squats and leg presses for the lower body. All other RT variables were held constant. The
study period lasted 10 weeks with subjects performing 2 lower body workouts per week
comprising 6 sets per session at loads corresponding to 8-12 RM with 90 to 120 second rest
intervals. RESULTS: Results showed that SQ had greater transfer to maximal squat strength
compared to the leg press. Effect sizes favored SQ and SQ-LP versus LP with respect to
countermovement jump while greater effect sizes for dynamic balance were noted for SQ-LP and
LP compared to SQ, although no statistical differences were noted between conditions.
CONCLUSIONS: These findings suggest that both free weights and machines can improve
functional outcomes, and that the extent of transfer may be specific to the given task.
KEYWORDS: Functional fitness; specificity of training; exercise machines; free weights
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Running Head: Squat versus Leg Press
3
Introduction
Resistance training (RT) can be carried out using a variety of implements. Two of the
most commonly used types of implements are free weights and machines. Machines can be
operationally defined as devices that contain cables, pin-loaded weight stacks, or fixed lever
arms, while free weights refer to dumbbells and plates that are loaded onto the ends of a barbell
(1). Generally, but not always, machines move in a fixed plane of motion while free weight
exercise is carried out in three-dimensional space.
It is widely believed that free weight exercise promotes better transfer to sports specific
and functional skills compared to machine-based exercises. This purported superiority has been
attributed to mechanical specificity, whereby free weights more closely replicate movement
patterns, force application, and velocities of movement during functional tasks (2). Free weight
squats have also been suggested to activate more muscles in the lower limbs than smith machine
squats (3) and induce a greater acute hormonal response than the leg press (4). Despite a sound
logical basis, however, there is a paucity of controlled research that lends support to this
hypothesis. Recently, Wirth et al. (5) randomized recreationally trained university students to
perform lower body exercise consisting of either the squat or leg press. Both groups performed 5
sets of 6-10 repetition maximum (RM) for 8 weeks. Results showed statistically greater increases
in both countermovement and squat jump performance for those performing the squat versus the
leg press. These finding suggest that free weight exercise promotes greater transfer to vertical
jump performance compared to machine-based exercise.
It should be noted that there are many components of functionality in particular,
components of dynamic balance that have not been studied with respect to the influence of
differenttrainingmodalities.Moreover,totheauthors’knowledge,nostudiestodatehave
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Running Head: Squat versus Leg Press
4
investigated the effects of combining free weight and machine-based exercises compared to
performing either type of modality alone. The purpose of this study therefore was to compare
strength, body composition, and functional outcome measures following performance of the back
squat, leg press, or a combination of the two exercises over an 8-week study period.
Methods
Experimental Approach to the Problem
Subjects were pair-matched based on initial strength levels and then randomly assigned to
1 of 3 groups: A squat-only group (SQ) that solely performed squats for the lower body; a leg
press-only group (LP) that solely performed leg presses (Prestige Strength VRS, Cybex
International, Inc . Medway, MA,USA) for the lower body, or; a combined squat and leg press
group (SQ-LP) that performed both squats and leg presses for the lower body. All other RT
variables were held constant. The study period lasted 10 weeks with subjects performing 2 lower
body workouts per week comprising 6 sets per session at loads corresponding to 8-12 RM with
90 to 120 second rest intervals. Total training volume (reps × sets) was equated between groups.
Testing was carried out pre- and post-study for indices of muscle strength, body composition,
and functional performance.
Subjects
Subjects were a convenience sample of 26 male volunteers recruited from a university
population (age = 22.0±3.9 years; height = 175.4±7.7 cm; body mass = 80.7±17 kg). Subjects
were reported to be without any existing musculoskeletal disorders, free from consumption of
anabolic steroids or any other illegal agents known to increase muscle size for the previous year,
and had not performed any regimented resistance training for the past 6 months. Subjects were
instructed to avoid taking any performance-enhancing supplements during the study period.
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Running Head: Squat versus Leg Press
5
Participants were pair-matched according to baseline strength and then randomly
assigned to 1 of 3 groups: A squat-only group (SQ) that solely performed squats for the lower
body (n = 8); a leg press-only group (LP) that solely performed leg presses (n = 9); or a
combined squat and leg press group (SQ-LP) that performed both squats and leg presses (n = 9).
Approval for the study was obtained from the university’sInstitutional Review Board (IRB).
Informed consent was obtained from all participants.
Resistance Training Procedures
The per-session RT protocol consisted of 6 sets of squats for the SQ group, 6 sets of leg
presses for the LP group, and 3 sets of squats and 3 sets of leg presses for the SQ-LP group.
Training for each protocol consisted of 2 weekly sessions performed on non-consecutive days for
10 weeks. All groups had a target of 8-12 repetitions per set. The first 2 weeks of training
consisted of an acclimation phase, whereby sets were terminated 1 or 2 repetitions short of
failure. Thereafter, sets were carried out to the point of momentary concentric muscular failure
the inability to perform another concentric repetition while maintaining proper formfor the
final 8 weeks of the study. Cadence of repetitions were carried out in a controlled fashion, with a
concentric action of approximately one second and an eccentric action of approximately two
seconds. Subjects were afforded 90 to 120 seconds of rest between sets. The load was adjusted
for each exercise as needed on successive sets to ensure that subjects achieved failure in the
target repetition range. All sessions were directly supervised by the research team to ensure
proper performance of the respective routines. Attempts were made to progressively increase the
loads lifted each week within the confines of maintaining the target repetition range. Initial loads
for each exercise were based on 80% of subjects’1RM, as determined during initial testing,
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Running Head: Squat versus Leg Press
6
consistent with recognized guidelines established by the National Strength and Conditioning
Association (6).
Dietary Adherence
To avoid potential dietary confounding of results, subjects were advised to maintain their
customary nutritional regimen. Attempts to monitor adherence to these instructions were
unsuccessful due to poor subject compliance in filling out and submitting food journals.
Measurements
Pre intervention body composition was assessed prior to the strength training
familiarization sessions. At least 72 hours following familiarization, balance and jump testing
was assessed on day one, and 48 hours later strength testing was assessed on day two. Post
testing body composition was assessed at least 24 hours following the completion of all
resistance training on a Friday. Subjects then reported to the lab on the following Monday for
balance and jump testing, and then 48 hours later for strength testing.
Muscle Strength: Lower body strength was assessed by 1RM testing in the parallel back
squat (1RMSQUAT) and the leg press (1RMLEGPRESS) exercises, in that order. Subjects reported to
the lab having refrained from any exercise other than activities of daily living for at least 48
hours prior to baseline testing and at least 48 hours prior to testing at the conclusion of the study.
RM testing was consistent with recognized guidelines established by the National Strength and
Conditioning Association (6). Two familiarization sessions separated by at least 48 hours were
performed prior to 1 RM testing. Subjects performed a general warm-up prior to testing that
consisted of light cardiovascular exercise lasting approximately 5-10 minutes. A specific warm-
up set of the given exercise of 5 repetitions was performed at ~50% 1RM followed by one to two
sets of 2-3 repetitions at a load corresponding to ~60-80% 1RM. Subjects then performed sets of
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Running Head: Squat versus Leg Press
7
1 repetition of increasing weight for 1RM determination. Three to 5 minutes of rest was provided
between each successive attempt. All 1RM determinations were made within 5 attempts.
Subjects were required to reach parallel in the 1RMSQUAT for the attempt to be considered
successful as determined by the research team. For the 1RMLEGPRESS a goniometer was used to
ensure that all subjects began the movement with a 90-degree angle at the knee and a 60-degree
angle at the hip. The attempt was deemed successful when subjects were able to fully extend at
the knee while maintaining contact between the hips and the seat. Two members of the research
team supervised all testing sessions and an attempt was only deemed successful when a
consensus was reached between the two. Based on results of a small pilot study (n=5), the test-
retest intraclass correlation coefficient (ICC) from our lab for the 1RMLEGPRESS and 1RMSQUAT
was 0.961 and 0.969, respectively.
Dynamic Balance: The Star Excursion Balance Test (SEBT) was used to assess changes
in dynamic balance. The SEBT was selected because of its high reliability and validity as a non-
instrumented dynamic balance test for physically active people (7, 8). Testing was carried out as
follows: The floor was marked with a star pattern in 8 directions, 45° apart from each other:
anterior, posterior, medial, lateral, posterolateral, posteromedial, anterolateral, and anteromedial.
Subjects placed one foot in the center of the star pattern and then reached as far as possible with
the other foot in clockwise fashion in all eight directions. The subject lightly tapped the floor,
and then returned the leg to the center of the star after each tap. The trial was repeated if the
subject made any of the following errors: rested his foot on the ground, tapped the floor heavily,
lost balance, or was unable to return to the starting position in a controlled manner (7). The order
of limb performance was randomized to help prevent confounding issues from adverse effects of
fatigue on balance. Measurements were obtained from the distance from the center of the star to
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Running Head: Squat versus Leg Press
8
the tap. Subjects performed 3 trials and the results from these trials were averaged. Excursion
values were normalized to leg length, as measured from the anterior superior iliac spine to the
medial malleolus, to account for the significant correlation between SEBT and leg length (9).
Four practice trials were provided to subjects prior to actual testing in order to diminish any
effects of motor learning (10).
Vertical Jump: Jump height was determined by performance of a countermovement jump
(CMJ) as assessed by Just Jump! Mat (Probotics Inc: Huntsville, AL). Prior to testing, subjects
engaged in a brief, general warm-up consisting of several minutes of light cardiovascular
exercise, followed by 6 submaximal jumps to heighten neural responses. Vertical jumps were
measured in inches using the Just Jump! mat. Subjects were instructed to perform a rapid lower
body eccentric contraction followed immediately by a maximal intensity concentric contraction.
Subjects were instructed to jump straight up and minimize any in-air hip flexion. The movement
was completed by landing on both feet at the same time while maintaining balance on the mat.
The best of the three trials was recorded as vertical jump height.
Body Composition: Height was measured using standard anthropometry and body mass
was measured using a calibrated scale. Body composition was measured pre- and post-treatment
as determined by whole body densitometry using Air Displacement Plethysmography (Bod
Pod®, Cosmed, Concord, CA USA). All testing was performed in accordance with the
manufacturer’sinstructions.Briefly,subjectswere tested while wearing only tight fitting
compression shorts and an acrylic swim cap. The subjects wore the exact same clothing for all
testing. Thoracic gas volume was estimated for all subjects using a predictive equation integral to
the Bod Pod® software. The calculated value for body density used the Siri equation to estimate
body composition. Data obtained from the Bod Pod® included body weight, percent body fat, fat
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Running Head: Squat versus Leg Press
9
free mass, and fat mass. All testing was done with each subject at approximately the same time
of day.
Statistical Analyses
Pre- and post-intervention data were modeled using a linear mixed model for repeated
measures, estimated by a restricted maximum likelihood algorithm. Training intervention (leg
press, squat, or combination) was included as the between-subject factor, time was included as
the repeated within-subjects factor, time × intervention was included as the interaction, and
subject was included as a random effect. In cases where statistical interactions were present,
post-hoc analyses on within-subject changes were carried out using t-tests with a Holm-
Bonferroni adjustment. Effect sizes were calculated as the mean pre-post change divided by the
pooled pretest standard deviation (11) and 95% confidence intervals (CI) were reported for all
primary outcomes. All analyses were performed using R version 3.2.3 (The R Foundation for
Statistical Computing, Vienna, Austria). A priori alpha level was set to P≤0.05,andtrendswere
declared at 0.05 > P≤0.10.Effect sizes were defined as small, medium, and large for 0.20, 0.50,
and 0.80, respectively. Data are reported as
x
± SD, unless otherwise specified.
Results
Body Composition
There were significant increases in body mass and fat-free mass from pre- to post- in all 3
groups, with no differences in changes between groups (Table 1). Effect sizes were small,
ranging from 0.10 to 0.15. There was a trend for fat mass to increase in all 3 groups (P = 0.06),
with no differences between groups; effect sizes were very small (0.08 to 0.09). There were no
significant main effects or interactions for percent body fat.
Insert Table 1 About Here
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Running Head: Squat versus Leg Press
10
Performance
For the squat, there was a significant group by time interaction (P = 0.0004, Table 2). All
3 groups improved over time (P < 0.0001), but the increase was largest in the squat group (+76.2,
CI 54.3, 98.2, ES 1.35), followed by the combination group (+53.9, CI 33.2, 74.6, ES 0.95), and
lastly the leg press group (+21.1, CI 0.38, 41.8, ES 0.37). For the leg press, all 3 groups
improved over time (P < 0.0001), with no differences in improvements between groups; effect
sizes ranged from 1.45 to 1.49 (Table 2). For the vertical jump, all 3 groups improved over time
(P < 0.0001), with no significant differences in changes between groups (P = 0.15, Table 2).
Effect sizes were largest for the squat group (0.62), followed by the combo group (0.49) and the
leg press group (0.24).
Insert Table 2 About Here
Balance
SEBT outcomes by group are shown in Table 3. There were significant improvements
over time for all measures (P < 0.05), with no significant group by time interactions. Effect sizes
favored the combo group in most metrics, followed by the leg press group, with the lowest effect
sizes in the squat group. There was a significant effect of group for left anterior (P = 0.02), with
the combo group showing a significantly greater value compared to the squat group collapsed
over pre- and post (Difference: 7.4, CI 1.0, 13.8, P = 0.02). There was a significant group effect
for the left leg sum (P = 0.04), with the combo group showing a significantly greater value
compared to the squat group collapsed over pre- and post (Difference: 26.7, CI 0.8, 52.6, P =
0.05). There was a significant group effect for the right anterior (P = 0.004), with the squat
showing a significantly greater value than the leg press group (Difference: 5.7, CI: 0.2, 11.3, P =
0.03), as well as the combo showing a significantly greater value than the leg press group
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Running Head: Squat versus Leg Press
11
(Difference: 7.9, CI 2.5, 13.2, P = 0.004). For right posteriolateral, there was a significant group
effect (P = 0.01), with the combo showing a significantly greater value than the leg press group
(Difference: 11.5, CI 2.4, 20.5, P = 0.01). There was also a significant group effect for the right
leg sum (P = 0.01), with the combo group showing a significantly greater value compared to the
squat group collapsed over pre- and post (Difference: 28.1, CI 6.2, 49.9, P = 0.01). Since there
were no significant group by time interactions, SEBT outcomes were collapsed across groups.
Changes over time for SEBT outcomes are shown in figure 1. Fifteen out of 18 outcomes
showed significant improvements (P < 0.05).
Insert Table 3 About Here
Insert Figure 1 About Here
Discussion
Totheauthors’knowledge,thisisthefirststudytoinvestigatetheeffectsoftrainingona
machine versus free weights as well as a combination of the two modalities. In addition, we are
aware of no other studies that have investigated the effects of different training modalities on
dynamic balance. As such, the study helps to fill gaps in the literature on this important topic.
Wirth et al. (5) demonstrated that the squat was superior to the leg press for improving
countermovement jump performance. Although our findings suggest this to be the case given the
increasing effect sizes from LP (0.24), to SQ-LP (0.49), to SQ (0.62), it cannot be said that this
group × time interaction is not due to chance alone. And while Wirth et al. (5) also did not
observe an increase in countermovement jump height in the leg press group, Correa et al. (12)
recently found that a machine-based program (including the leg press) improved
countermovement jump in older women. While the literature on leg press is equivocal, the
literature suggesting that squats increase vertical jump performance is compelling, and that
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Running Head: Squat versus Leg Press
12
deeper is better (13, 14). These apparent advantages to the squat may be attributed to a number
of reasons. For one, the knee moved through a greater range of motion in the squat than it did in
the leg press. As with previous studies that examined the effects of squat depth on performance
(13, 14), the subjects in this study were untrained or detrained, and were therefore conceivably
more likely to realize greater adaptations from greater ranges of motion. Furthermore, it appears
that the largest mechanical demands from the hip during the countermovement jump occur close
to 45º (15), which is where the leg press movement was completed. It may be that greater hip
range of motion and net extension moment requisites are required in order to maximize and
optimize hip extensor strength adaptations for the vertical jump, as the squat effectively moved
through this range of motion (hip flexion < 45º) with resistance. Lastly, it is possible that the
differential angular velocities and displacement of the hip and knee during the leg press and
squat have implications for transference, in that the triple extension pattern in the squat more
closely mimics the vertical jump than does the leg press.
The changes in strength reported by Wirth et al. (5) applied only to the lift that each
respective group trained; that is, the LP and SQ groups were only tested in the leg press and
squat, respectively, and there were no evaluations of transference. However, in this study, a
statistical group × time interaction was observed for the squat, with, increasing effect sizes from
LP (0.37), to SQ-LP (0.95), to SQ (1.35), just as was the case with the vertical jump. This
reinforces the principle of specificity. Despite the seemingly similar biomechanics of the squat
and leg press, in that both involve triple extension and have somewhat similar net knee extension
moment requisite-angle relationships (16), the net hip extension moment requisite-angle
relationship in the leg press is different from that in the squat. This is in part due to the 45º-angle
of the hip in the leg press at lockout (0º knee flexion), while during the squat, when one is in 45º
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Running Head: Squat versus Leg Press
13
of hip flexion during the concentric phase, they are at approximately 35º of knee flexion (17).
Simplistically, the differential hip-to-knee angles inherent to the squat and leg press necessitate
unique muscle recruitment strategies for the distinct interjoint, or intersegmental, dynamic
interaction of each movement for the purposes of dynamic optimization (18). An example of
such a recruitment strategy is the greater electromyography amplitude of the biceps femoris
observed in the concentric phase of squat over that in the leg press (16). Moreover, the knee
range of motion utilized during the squat was approximately 30º more (33.3%) than during the
leg press (19). It is therefore likely that those performing the squat experienced range of motion-
specific adaptations (90120º knee flexion), for which the leg press group did not train. Lastly, it
is possible that self-efficacy played a role in these outcomes, as self-efficacy is task-specific (20)
and may have a significant effect on strength capacity (21-23).
Unlike the squat, no statistical differences were observed between the SQ, LP or SQ-LP
groups, which suggests that leg press strength is not as specific as squat strength; that is,
increasing hip and knee extensor strength will increase leg press strength no matter how it is
accomplished. However, unlike the squat, the leg press was completed within a range of motion
that all groups utilized throughout the trial, in that the knees moved through 90º flexion and
extension and the hips did not extend past 45º flexion; however, during a parallel squat, the
knees flex to about 120º and the hips well past 45º flexion, to about 20º (17, 19).
The SEBT is a reliable and valid measure of dynamic balance for physically active
people (7, 8), and may also be an accurate predictor of lower extremity injury (24). SEBT scores
in all three groups statistically increased over the course of the study, with no differences noted
between groups. Interestingly, the effect sizes for SQ were much lower than that observed in the
SQ-LP and LP groups, suggesting that the leg press, or a combination of exercises, may be more
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Running Head: Squat versus Leg Press
14
beneficial than squatting alone. These findings are contradictory to Furlong et al. (25), who
found no increases in SEBT scores following 12-week training program that incorporated the leg
press. Alternatively, Pamukoff et al. (26) found that performance of the leg press, in combination
with a number of lower-body focused machine exercises, improved balance recovery in an aging
population. Nevertheless, the finding that increasing lower body strength, regardless of mode,
appears to increase scores in a test that is predictive of lower-extremity injury. Such findings are
supported by meta-analysis showing that strength training helps to prevent injury (27). Further
research is warranted to identify whether or not one or multiple mediums (i.e., SQ vs. LP vs. SQ-
LP) is more efficacious for enhancing balance and preventing injury.
Conclusion
The results of our study indicate that both free weights and machines can improve
functional outcomes, and that the extent of transfer may be specific to the given task. From a
practical standpoint, these findings serve two primary functions: First, results reinforce to
coaches and athletes the importance of specificity. Back squat training significantly improved
back squat strength and tended to improve vertical jump more so than leg press alone or a
combination thereof. That said, all of the conditions employed had positive effects on functional
outcomes, indicating that functional transfer exists on a continuum and simply improving
strength will enhance various measures of function regardless of the modality (28). Second, this
study underscores the importance of strength training to improve balance and thereby reduce
injury risk. The data demonstrates that, contrary to popular suggestion, strength training
exercises that rely exclusively on or include machines are able to enhance dynamic balance in
non-athletes, perhaps to an even greater extent than free weight exercise. As such, coaches and
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Running Head: Squat versus Leg Press
15
practitioners shouldconsidertheindividualclientand/orathlete’sneedswhenselecting
resistance training movements.
Disclosure Statement: The authors declare no conflicts of interest associated with this
manuscript.
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Running Head: Squat versus Leg Press
16
References
1. McBride JM. Machines versus free weights. NSCA Hot Topic Series [Internet]. Available
from: http://www.nsca-lift.org. [cited 2016, Sep 9].
2. Stone M, Plisk S, Collins D. Training principles: evaluation of modes and methods of
resistance training--a coaching perspective. Sports Biomech. 2002 Jan;1(1):79-103.
3. Schwanbeck S, Chilibeck PD, Binsted G. A comparison of free weight squat to Smith machine
squat using electromyography. J Strength Cond Res. 2009 Dec;23(9):2588-91.
4. Shaner AA, Vingren JL, Hatfield DL, Budnar RG,Jr, Duplanty AA, Hill DW. The acute
hormonal response to free weight and machine weight resistance exercise. J Strength Cond Res.
2014 Apr;28(4):1032-40.
5. Wirth K, Hartmann H, Sander A, Mickel C, Szilvas E, Keiner M. The impact of back squat
and leg-press exercises on maximal strength and speed-strength parameters. J Strength Cond
Res. 2015 Sep 25.
6. Baechle TR, Earle RW, editors. Essentials of Strength Training and Conditioning. 3rd ed.
Champaign, IL: Human Kinetics; 2008.
7. Flanagan SP. NSCA's Guide to Tests and Assessments. Miller T, editor. Champaign, IL:
Human Kinetics; 2012.
8. Gribble PA, Hertel J, Plisky P. Using the Star Excursion Balance Test to assess dynamic
postural-control deficits and outcomes in lower extremity injury: a literature and systematic
review. J Athl Train. 2012 May-Jun;47(3):339-57.
9. Gribble PA, Hertel J. Considerations for normalizing measures of the star excursion balance
test. Measure Phys Educ Exerc Sci. 2003;7:89-100.
10. Robinson RH, Gribble PA. Support for a reduction in the number of trials needed for the star
excursion balance test. Arch Phys Med Rehabil. 2008 Feb;89(2):364-70.
11. Morris B. Estimating effect sizes from pretest-posttest-control group designs. Organizational
Research Methods. 2008;11(2):364-86.
12. Correa CS, LaRoche DP, Cadore EL, Reischak-Oliveira A, Bottaro M, Kruel LF, et al. 3
Different types of strength training in older women. Int J Sports Med. 2012 Dec;33(12):962-9.
13. Hartmann H, Wirth K, Klusemann M, Dalic J, Matuschek C, Schmidtbleicher D. Influence of
squatting depth on jumping performance. J Strength Cond Res. 2012 Feb 15.
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the electronic c opy of the article thr ough online internet an d/or intranet file s haring systems, electronic mailing or any other means which may allow acces s to the Article. The use of all or any
part of the Article for any Commercial Us e is not p ermitted. The creatio n of derivative works from the Article is not permitted. T he production of reprints f or personal or commercial us e is not
permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or term s of us e which the Publisher may post on the A rticle. It is not permitted to
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Running Head: Squat versus Leg Press
17
14. Bloomquist K, Langberg H, Karlsen S, Madsgaard S, Boesen M, Raastad T. Effect of range
of motion in heavy load squatting on muscle and tendon adaptations. Eur J Appl Physiol. 2013
Aug;113(8):2133-42.
15. Vanrenterghem J, Lees A, Clercq DD. Effect of forward trunk inclination on joint power
output in vertical jumping. J Strength Cond Res. 2008 May;22(3):708-14.
16. Escamilla RF, Fleisig GS, Zheng N, Barrentine SW, Wilk KE, Andrews JR. Biomechanics of
the knee during closed kinetic chain and open kinetic chain exercises. Med Sci Sports Exerc.
1998 Apr;30(4):556-69.
17. Escamilla RF, Fleisig GS, Lowry TM, Barrentine SW, Andrews JR. A three-dimensional
biomechanical analysis of the squat during varying stance widths. Med Sci Sports Exerc. 2001
Jun;33(6):984-98.
18. Zajac FE, Gordon ME. Determining muscle's force and action in multi-articular movement.
Exerc Sport Sci Rev. 1989;17:187-230.
19. Cotter JA, Chaudhari AM, Jamison ST, Devor ST. Knee joint kinetics in relation to
commonly prescribed squat loads and depths. J Strength Cond Res. 2013 Jul;27(7):1765-74.
20. Yeo GB, Neal A. An examination of the dynamic relationship between self-efficacy and
performance across levels of analysis and levels of specificity. J Appl Psychol. 2006
Sep;91(5):1088-101.
21. Ness G, Patton RW. The effect of beliefs on maximum weight-lifting performance. Cognitive
Therapy and Research. 1979;3(2):205-11.
22. Fitzsimmons PA, Landers DM, Thomas JR, van der Mars H. Does self-efficacy predict
performance in experienced weightlifters? Res Q Exerc Sport. 1991 Dec;62(4):424-31.
23. Wells CM, Collins D, Hale BD. The self-efficacy-performance link in maximum strength
performance. J Sports Sci. 1993 Apr;11(2):167-75.
24. Plisky PJ, Rauh MJ, Kaminski TW, Underwood FB. Star Excursion Balance Test as a
predictor of lower extremity injury in high school basketball players. J Orthop Sports Phys Ther.
2006 Dec;36(12):911-9.
25. Furlong J, Rynders CA, Sutherlin M, Patrie J, Katch FI, Hertel J, et al. Effect of an
herbal/botanical supplement on strength, balance, and muscle function following 12-weeks of
resistance training: a placebo controlled study. J Int Soc Sports Nutr. 2014 May 28;11:23,2783-
11-23. eCollection 2014.
26. Pamukoff DN, Haakonssen EC, Zaccaria JA, Madigan ML, Miller ME, Marsh AP. The
effects of strength and power training on single-step balance recovery in older adults: a
preliminary study. Clin Interv Aging. 2014 Apr 17;9:697-704.
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Running Head: Squat versus Leg Press
18
27. Lauersen JB, Bertelsen DM, Andersen LB. The effectiveness of exercise interventions to
prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials. Br
J Sports Med. 2014 Jun;48(11):871-7.
28. Schoenfeld B. Is functional training really functional? ACSM Certified News. 2010;20(3):5-
6.
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Running Head: Squat versus Leg Press
19
Figure Captions
Figure 1: Graphical representation of pre- and post-intervention changes over time for SEBT
outcomes, mean (±SD).
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Table 1: Body Composition
Variables
Time
Leg Press
(n=9)
%Δ (ES)
%Δ (ES)
Leg Press +
Squat
(n=9)
%Δ (ES)
FFM (Kg)
Pre
64.9 ± 12.3
1.4%
(0.10)
2.2%
(0.15)
62.4 ± 4.8
1.9%
(0.13)
Post
65.8 ± 13.2
63.6 ± 4.9
FFM (%)
Pre
81.6±8.4
-0.5%
(0.06)
-0.5%
(0.06)
83.4±8.7
-0.5%
(0.06)
Post
81.1±9.0
82.9±9.2
FM (Kg)
Pre
15.6±9.9
5.1%
(0.08)
4.6%
(0.09)
13.3±9.0
5.3%
(0.08)
Post
16.4±11.2
14.1±9.8
FM (%)
Pre
18.4±8.4
0.4%
(0.05)
0.5%
(0.06)
16.6±8.7
0.5%
(0.06)
Post
18.8±9.0
17.1±9.2
Body Mass (Kg)
Pre
80.6±18.2
2.1%
(0.10)
2.8%
(0.14)
75.7±10.9
2.5%
(0.12)
Post
82.2±19.8
77.7±11.4
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Table 2: Strength and Power
Variables
Time
Leg Press
(n=9)
Δ (ES)
Squat
(n=8)
Δ (ES)
Leg Press +
Squat
(n=9)
Δ (ES)
Squat (Kg)
Pre
121.0±23.7
7.9%
(0.37)
109.7±32.0
31.5% *
(1.35)
124.0±22.1
19.8% *
(0.95)
Post
130.6±29.8
144.3±38.5
148.5±16.8
Leg Press
(Kg)
Pre
188.6±45.1
34.2%
(1.45)
202.5±54.3
34.0%
(1.50)
220.9±37.3
31.1%
(1.49)
Post
255.0±73.5
271.3±94.8
289.6±40.5
Power (cm)
Pre
61.5±8.6
3.3%
(0.24)
57.4±8.4
8.9%
(0.62)
62.0±7.9
6.5%
(0.49)
Post
63.5±11.4
62.5±9.9
66.0±7.6
* = Significantly different compared to the leg press group.
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Table 3: Balance
Variables
Time
Leg Press
(n=9)
%Δ
(ES)
Squat
(n=8)
%Δ
(ES)
Leg Press +
Squat
(n=9)
%Δ(ES)
Left Anterior
Pre
60.2 ± 7.7
7.3%
(0.60)
63.6 ± 7.8
1.4%
(0.13)
66.4 ± 5.7
10.2%
(0.93)
Post
64.6 ± 3.5
64.5 ± 4.4
73.2 ± 7.0
Left
Posteriolateral
Pre
65.5 ± 12.6
10.4%
(0.61)
69.0 ± 9.9
5.8%
(0.36)
75.0 ± 9.5
12.1%
(0.83)
Post
72.3 ± 8.1
73.0 ± 9.6
84.1 ± 9.3
Left
Posteriomedial
Pre
61.8 ± 12.0
11.0%
(0.66)
63.6 ± 9.3
12.1%
(0.75)
69.0 ± 8.4
14.1%
(0.95)
Post
68.6 ± 9.9
71.3 ± 8.7
78.7 ± 10.4
Left Sum
Pre
187.5 ± 29.9
9.5%
(0.68)
196.2 ± 25.8
6.4%
(0.48)
210.3 ± 19.2
12.2%
(0.98)
Post
205.4 ± 18.9
208.8 ± 20.3
236.0 ± 24.0
Right Anterior
Pre
56.9 ± 6.5
7.2%
(0.56)
64.6 ± 9.0
0.3%
(0.03)
64.2 ± 4.0
8.1%
(0.69)
Post
61.0 ± 2.2
64.8 ± 2.3
69.4 ± 4.9
Right
Posteriolateral
Pre
60.4 ± 11.6
14.7%
(0.85)
69.5 ± 10.3
8.5%
(0.56)
72.6 ± 5.8
10.5%
(0.71)
Post
69.3 ± 6.8
75.4 ± 8.2
80.1 ± 6.4
Right
Posteriomedial
Pre
55.3 ± 12.2
14.3%
(0.82)
62.3 ± 9.7
5.9%
(0.38)
62.7 ± 4.5
16.6%
(1.08)
Post
63.2 ± 10.8
66.0 ± 8.2
73.1 ± 8.1
Right Sum
Pre
172.5 ± 27.5
12.2%
(0.83)
196.4 ± 26.6
4.9%
(0.39)
199.5 ± 12.0
11.6%
(0.9
Post
193.5 ± 18.5
206.1 ± 16.1
222.6 ± 16.5
Scores reported as normalized % of leg length
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... In addition, a recent study by Schott et al. (2019) observed that the relative increase in exercise load from baseline was higher in older adults training with free weights as compared to those using the machine alternative, but only for the triceps brachialis and knee and hip extensor muscles [10]. Also, Rossi et al. (2018) concluded that free weight squat training elicited better strength outcomes than training with the leg press machine, whilst balance improved equally regardless of the exercise used [11]. In contrast, Schwartz et al. (2019) observed a higher increase in peak jump power in recreationally active women training on the machine squat as compared to peers performing free weight squat training, whilst similar improvements in agility and sprint performances were observed in both training groups [12]. ...
... In addition, a recent study by Schott et al. (2019) observed that the relative increase in exercise load from baseline was higher in older adults training with free weights as compared to those using the machine alternative, but only for the triceps brachialis and knee and hip extensor muscles [10]. Also, Rossi et al. (2018) concluded that free weight squat training elicited better strength outcomes than training with the leg press machine, whilst balance improved equally regardless of the exercise used [11]. In contrast, Schwartz et al. (2019) observed a higher increase in peak jump power in recreationally active women training on the machine squat as compared to peers performing free weight squat training, whilst similar improvements in agility and sprint performances were observed in both training groups [12]. ...
... Regardless of RT group, participants' mean estimated 1-RM improved with 27% up to 43% from pre-to post-intervention depending on the targeted muscle groups. Similar gains in strength performance were observed by Rossi et al. (2018), who compared three groups (i.e., leg press-only group, squat only group, combined squat and leg press group) and found that squat training was significantly better in comparison to both other training groups [11]. However, an important difference compared to the present study to consider is that in the study of Rossi et al. (2018) only the leg press and/or squat were trained, targeting the knee and hip extensors as primary movers, and that a different training volume was administered (6 sets of squat or leg press vs. 3 sets of each exercise in the present study). ...
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This study compared the effect of a resistance training (RT) program with machines, free weights, or a combination of both on changes in anthropometrics, strength, and functional ability in novice adult males. Thirty-six male novices in RT (18–45 years) followed a 10-week RT program. Participants were randomly assigned to one of three groups (N = 12 each): machines only; free weights only; or switching from machines to free weights (after 5 weeks). Muscle size (circumferences of upper arm, thigh and chest), strength (1 Repetition Maximum) on both machines and free weights, and functional ability (Functional Movement ScreenTM (Functional Movement Systems Inc., Chatham, VA, USA)) were assessed prior to the RT program, halfway at 5 weeks, and within one week after the final training bout. Repeated measures MANOVAs showed no significant time by RT group interactions for the different outcome measures. Regardless of RT group, significant improvements over time were observed for anthropometrics (F = 9.144, p < 0.001), strength (F = 6.918, p < 0.001), and functional ability (F = 25.578, p < 0.001). To conclude, similar gains in muscularity, strength, and functional ability can be expected for male novices in RT regardless of the equipment being used and without a fallback when changing from machines to free weights. Accordingly, any choice of RT equipment can be made, considering individual preferences.
... T he leg press is a typical exercise for lower limb strengthening. 21,45,50 The widespread applicability offered by this exercise is explained by the simplicity of its technique since it is a guided movement, 8 along with its transference to functional movements such as walking, squatting, running, or jumping. 6,8,13,17 This means that the exercise can be included in any training program regardless of the participants' age 10,19,32 or training goal, whether it be for rehabilitation, 2,6,8,43 injury prevention and return to play, 17,26 health, 2,52 or athletic performance. ...
... 13,17 Given the leg press exercise's versatility, it is essential that trainers and athletes understand the muscle activation elicited during its use, as a key factor in the concomitant development of muscle mass and strength. 31,38,45 Surface electromyography (sEMG) has been widely used in research 5 as a noninvasive method for assessing muscle activation and neuromuscular function. 6,11,17 This has resulted in studies assessing the muscle activation during the horizontal leg press, [16][17][18]46,50,52 unilateral leg press, 6 and inclined leg press. ...
Article
Background: The leg press is one of the most typical exercises for strengthening the lower limbs. The objectives of this study were to compare 5 inclined leg press exercise conditions, varying the feet width stance (100% or 150% hip width), the feet rotation (0° or 45° external rotation) on the footplate and using 2 different movement velocities (MVs; maximum intended, and 2:2 seconds steady-paced velocities) to determine their effect on muscle activation as well as on the kinematic parameters between trained men and trained women. Hypotheses: There will be no significant differences in muscle activation with regard to the feet position. The higher the MV, the greater the muscle activation. Study design: A cross-sectional cohort study. Level of evidence: Level 3. Methods: A repeated-measures between-group design was performed to examine muscle activation and kinematic parameters for the different conditions between gender groups. The level of significance was set at alpha = 0.05 for all statistical analyses. Results: Muscle activation presented no differences between conditions regarding feet width stance or feet rotation. Furthermore, muscle activation was greater during positive phases than negative phases of the exercise for all conditions and was also greater under maximum intended velocity conditions compared with steady-paced conditions. Otherwise, the muscle activation pattern presented slight differences by gender. In men, the greatest muscle activation was for the vastus medialis, followed by the vastus lateralis (VL), rectus femoris (RF), and gluteus medialis (GMED), while in women, the greatest muscle activation was for the vastus medialis, followed by the RF, VL, and GMED. Finally, greater mean propulsive velocity, maximum velocity, maximum power, and footplate displacement values were reported for men than for women under all the conditions. Conclusion: The inclined leg press exercise produces the highest muscle activation in the vastus medialis, regardless of the velocity, feet stance, or gender. Clinical relevance: Given that there are no differences in muscle activation regarding the feet stance, a participant's preferred feet stance should be encouraged during the inclined leg press exercise. Furthermore, the MV would preferably depend on the session objective (a training or a rehabilitation program), being aware that there is greater muscle activation at higher speeds. The inclined leg press exercise could be performed as a closed kinetic chain exercise when the main objective is to activate the vastus medialis.
... Though the change in location may have implications such as loss of the typical psychosocial benefits of the gym environment [13], and also access to certain equipment (i.e. resistance machines), evidence suggests that a range of modalities of RT are broadly speaking similarly efficacious [34][35][36][37]. Free weight 10 and bodyweight exercises were the most common modality used during lockdown, in addition to a shift towards use of higher repetition ranges which may reflect the use of lower loads perhaps due to the difficulty of accessing and storing large amounts of free weights, in addition to the use of bodyweight exercise. ...
... Free weight 10 and bodyweight exercises were the most common modality used during lockdown, in addition to a shift towards use of higher repetition ranges which may reflect the use of lower loads perhaps due to the difficulty of accessing and storing large amounts of free weights, in addition to the use of bodyweight exercise. Evidence suggests that both heavier-and lighter-load RT can produce similar adaptations in both general strength and muscular growth [34]; and further, when employed in a similar manner (as appears to have been done by respondents in this study), a variety Fig. 13 Frequencies and proportions of responses for perceived effectiveness of current training for a current goals in those whose goals remained the same, b prior goals in those whose goals changed, and c current goals in those whose goals changed of modes of external resistance appear to produce largely similar outcomes [34][35][36][37]. Thus, although many perceived their training to be less effective during lockdown, evidence suggests that engagement was likely similarly efficacious. ...
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IntroductionUnderstanding the impact of lockdown upon resistance training (RT), and how people adapted their RT behaviours, has implications for strategies to maintain engagement in similar positive health behaviours. Further, doing so will provide a baseline for investigation of the long-term effects of these public health measures upon behaviours and perceptions, and facilitate future follow-up study.Objectives To determine how the onset of coronavirus (COVID-19), and associated ‘lockdown’, affected RT behaviours, in addition to motivation, perceived effectiveness, enjoyment, and intent to continue, in those who regularly performed RT prior to the pandemic.Methods We conducted an observational, cross-sectional study using online surveys in multiple languages (English, Danish, French, German, Italian, Portuguese, Slovakian, Swedish, and Japanese) distributed across social media platforms and through authors’ professional and personal networks. Adults (n = 5389; median age = 31 years [interquartile range (IQR) = 25, 38]), previously engaged in RT prior to lockdown (median prior RT experience = 7 years [IQR = 4, 12]) participated. Outcomes were self-reported RT behaviours including: continuation of RT during lockdown, location of RT, purchase of specific equipment for RT, method of training, full-body or split routine, types of training, repetition ranges, exercise number, set volumes (per exercise and muscle group), weekly frequency of training, perception of effort, whether training was planned/recorded, time of day, and training goals. Secondary outcomes included motivation, perceived effectiveness, enjoyment, and intent to continue RT.ResultsA majority of individuals (82.8%) maintained participation in RT during-lockdown. Marginal probabilities from generalised linear models and generalised estimating equations for RT behaviours were largely similar from pre- to during-lockdown. There was reduced probability of training in privately owned gyms (~ 59% to ~ 7%) and increased probability of training at home (~ 18% to ~ 89%); greater probability of training using a full-body routine (~ 38% to ~ 51%); reduced probability of resistance machines (~ 66% to ~ 13%) and free weight use (~ 96% to ~ 81%), and increased probability of bodyweight training (~ 62% to ~ 82%); reduced probability of moderate repetition ranges (~ 62–82% to ~ 55–66%) and greater probability of higher repetition ranges (~ 27% to ~ 49%); and moderate reduction in the perception of effort experienced during-training (r = 0.31). Further, individuals were slightly less likely to plan or record training during lockdown and many changed their training goals. Additionally, perceived effectiveness, enjoyment, and likelihood of continuing current training were all lower during-lockdown.Conclusions Those engaged in RT prior to lockdown these behaviours with only slight adaptations in both location and types of training performed. However, people employed less effort, had lower motivation, and perceived training as less effective and enjoyable, reporting their likelihood of continuing current training was similar or lower than pre-lockdown. These results have implications for strategies to maintain engagement in positive health behaviours such as RT during-restrictive pandemic-related public health measures.Pre-registrationhttps://osf.io/qcmpf.PreprintThe preprint version of this work is available on SportRχiv: https://osf.io/preprints/sportrxiv/b8s7e/.
... Squat and leg press are 2 exercises frequently performed to elicit hypertrophy and strength gains in the lower-limb musculature in regular strength conditioning (16,41) and to prevent musculoskeletal deconditioning in prolonged actual or simulated weightlessness (37,39,48). Practically all multijoint resistance exercises targeting the lower limbs involve considerable loading to the lower back, as do squat and leg press regimens regardless of whether the external load is applied to the shoulders, as in conventional weightlifting, or to the thorax by a harness, as in flywheel exercise (23,45). ...
Article
Sjöberg, M, Eiken, O, Norrbrand, L, Berg, HE, and Gutierrez-Farewik, EM. Lumbar loads and muscle activity during flywheel and barbell leg exercises. J Strength Cond Res XX(X): 000-000, 2021-It is anticipated that flywheel-based leg resistance exercise will be implemented in future long-duration space missions, to counter deconditioning of weight-bearing bones and postural muscles. The aim was to examine low back loads and muscle engagements during flywheel leg press (FWLP) and flywheel squat (FWS) and, for comparisons, free-weight barbell back squat (BBS). Eight resistance-trained subjects performed 8 repetition maximums of FWLP, FWS, and BBS. Motion analysis and inverse dynamics-based musculoskeletal modeling were used to compute joint loads and muscle forces. Muscle activities were measured with electromyography (EMG). At the L4-L5 level, peak vertebral compression force was similarly high in all exercise modes, whereas peak vertebral posteroanterior shear force was greater (p < 0.05) in FWLP and BBS than in FWS. Among the back-extensor muscles, the erector spinae longissimus exerted the greatest peak force, with no difference between exercises. Peak force in the lumbar multifidus was lower (p < 0.05) during FWLP than during FWS and BBS. Peak EMG activity in the lumbar extensor muscles ranged between 31 and 122% of maximal voluntary isometric contraction across muscles and exercise modes, with the greatest levels in the lumbar multifidus. The vertebral compression forces and muscle activations during the flywheel exercises were sufficiently high to presume that when implementing such exercise in space countermeasure regimens, they may be capable of preventing muscle atrophy and vertebral demineralization in the lumbar region.
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Altering set configurations during a resistance training program can provide a novel training variation that can be used to modify the external and internal training loads that induce specific training outcomes. To design training programs that better target the defined goal(s) of a specific training phase, strength and conditioning professionals need to better understand how different set configurations impact the training adaptations that result from resistance training. Traditional and cluster set structures are commonly implemented by strength and conditioning. The purpose of this review is to offer examples of the practical implementation of traditional and cluster sets that can be integrated into a periodized resistance training program.
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Fitness professionals routinely employ a variety of resistance training exercises in program design as a strategy to enhance muscular adaptations. However, it remains uncertain whether such an approach offers advantages over a fixed-exercise selection. The objective of this paper was to review the effects of exercise variation on muscle hypertrophy and strength. A search of literature was conducted using PubMed/MEDLINE, Scopus, and Web of Science databases. Eight studies were identified as meeting inclusion criteria. The combined total sample of the studies was n = 241, comprising all young men. The methodological quality of included studies was considered "good" and "excellent" based on the PEDro Scale. The available studies indicate that varying exercise selection can influence muscle hypertrophy and strength gains. Some degree of systematic variation appears to enhance regional hypertrophic adaptations, and maximize dynamic strength, whereas excessive, random variation may compromise muscular gains. We conclude that exercise variation should be approached systematically with a focus on applied anatomical and biomechanical constructs; on the contrary, employing different exercises that provide a redundant stimulus, as well as excessive rotation of different exercises (i.e., high frequency of change), may actually hinder muscular adaptations.
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Introduction: To compare changes in muscle size, strength, and power between free-weight and machine-based exercises. Evidence acquisition: The online databases of Pubmed, Scopus, and Web of Science were each searched using the following terms: ""free weights" OR barbells OR dumbbells AND machines" up until September 15, 2020. A three-level random effects meta-analytic model was used to compute effect sizes. Evidence synthesis: When strength was tested using a free-weight exercise, individuals training with free-weights gained more strength than those training with machines [ES: 0.655; (95% CI: 0.269, 1.041)]. When strength was tested a machine-based exercise incorporated as part of the machine-based training program, individuals training with machines gained more strength than those training with free-weights [ES: -0.784 (95% CI: -1.223, -0.344)]. When strength was tested using a neutral device, machines and free-weight exercises resulted in similar strength gains [ES: 0.128 (95% CI: -0303, 0.559)]. There were no differences in the change in power [ES: -0.049 (95% CI: -0.557, 0.460)] or muscle hypertrophy [ES: -0.01 (95% CI: -0.525, 0.545)] between exercise modes. Conclusions: Individuals looking to increase strength and power should take into account the specificity of exercise, and how their strength and power will be tested and applied. Individuals looking to increase general strength and muscle mass to maintain health may choose whichever activity they prefer and are more likely to adhere to.
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Introduction The main objective of this study was to analyze more effective muscle work on some explosive strength performance variables. The secondary objectives were to determine how gender influences results and influence of the muscle work type on physiological parameters. Material and method Randomized controlled trial single-blind clinical trial, allocated by blocks and by sex. The study sample consisted of 80 healthy and active subjects divided into four muscle work groups: concentric, eccentric, concentric-eccentric and isometric. 4 sets of 12 repetitions, 1-min rest between series, were performed for dynamic workgroups. For the isometric work 6 s with 20 rest. 12-min time in 12 consecutive days. Results Main Outcomes Measures: sex, age, weight, height, body mass index, blood pressure and heart rate, jumping power, vertical jumping, horizontal jumping and speed 60 m. The concentric-eccentric group achieved the best results without statistically significant differences. The men improved the speed more by 60 m. Women improved in jumping power, vertical jumping and horizontal jumping. Results were statistically significant if p < 0.05. Conclusions The group that performed the dynamic concentric-eccentric muscle work improved the performance variables analyzed further. Women are equally improved by men and heart rate dropped to the same extent. ClinicalTrials.gov ID: NCT03973060 (June 1; 2019)
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Résumé Objectifs Nous avons évalué la sévérité des troubles alimentaires de patients en surpoids avant et après un programme de soins pluridisciplinaires, chez des patients suivis entre 2016 et 2018. Méthodes Le programme comportait quatre volets : psychothérapie comportementale, psycho-nutrition, kinésithérapie et activité physique adaptée. L’objectif principal était d’observer les modifications du « Three Factors Eating Questionnaire » (TFEQ) avant et après le programme. Résultats Cent soixante-huit patients, dont la majorité avait des compulsions alimentaires (65,5 %), ont poursuivi l’intégralité du programme. Après intervention, le score moyen du TFEQ avait diminué (p < 10⁻⁴), et ce de manière plus marquée chez les patients hors parcours de chirurgie bariatrique que chez les patients opérés ou en attente de chirurgie. Les facteurs F2 (désinhibition) et F3 (faim) ont également diminué, bien que le facteur F1 (restriction) n’était pas modifié, indépendamment de la prise en charge chirurgicale et de l’IMC. Conclusions La sévérité des troubles alimentaires a diminué après le programme sur les compulsions et la perception de la faim. Chez certains patients la diminution de la restriction pouvait induire une augmentation des ingestas. Ce type de programme pourrait être étendu à tous les patients en surpoids.
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Strength training-induced increases in speed-strength seem indisputable. For trainers and athletes the most efficient exercise selection in the phase of preparation is of interest. Therefore, this study determined how the selection of training exercise influences the development of speed-strength and maximal strength during an 8-week training intervention. 78 students participated in this study (39 in the training group and 39 as controls). Both groups were divided into two subgroups. The first training group (squat training group [SQ]) completed an 8-week strength training protocol using the parallel squat. The 2nd training group (leg-press training group [LP]) used the same training protocol using the leg-press (45[degrees]-leg-press). The control group was divided in two subgroups as controls for the SQ or the LP. A two-factorial analyses of variance was performed using a repeated measures model for all group comparisons and comparisons between pre- and post-test results. The SQ exhibited a statistically significant (p<0.05) increase in jump performance in Squat jump (SJ, 12.4%) and Countermovement jump (CMJ, 12.0%). Whereas, the changes in the LP did not reach statistical significance and amounted to improvements in SJ of 3.5% and CMJ 0.5%. The differences between groups were statistically significant (p<0.05). There are also indications that the squat exercise is more effective to increase Drop Jump performance. Therefore, the squat exercise increased the performance in SJ, CMJ and RSI more effectively compared to the leg-press in a short-term intervention. Consequently, if the strength training aims at improving jump performance the squat should be preferred because of the better transfer effects.
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Background StemSport (SS; StemTech International, Inc. San Clemente, CA) contains a proprietary blend of the botanical Aphanizomenon flos-aquae and several herbal antioxidant and anti-inflammatory substances. SS has been purported to accelerate tissue repair and restore muscle function following resistance exercise. Here, we examine the effects of SS supplementation on strength adaptations resulting from a 12-week resistance training program in healthy young adults. Methods Twenty-four young adults (16 males, 8 females, mean age = 20.5 ± 1.9 years, mass = 70.9 ± 11.9 kg, stature = 176.6 ± 9.9 cm) completed the twelve week training program. The study design was a double-blind, placebo controlled parallel group trial. Subjects either received placebo or StemSport supplement (SS; mg/day) during the training. 1-RM bench press, 1-RM leg press, vertical jump height, balance (star excursion and center of mass excursion), isokinetic strength (elbow and knee flexion/extension) and perception of recovery were measured at baseline and following the 12-week training intervention. Results Resistance training increased 1-RM strength (p < 0.008), vertical jump height (p < 0.03), and isokinetic strength (p < 0.05) in both SS and placebo groups. No significant group-by-time interactions were observed (all p-values >0.10). Conclusions These data suggest that compared to placebo, the SS herbal/botanical supplement did not enhance training induced adaptations to strength, balance, and muscle function above strength training alone.
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Improving muscle strength and power may mitigate the effects of sarcopenia, but it is unknown if this improves an older adult's ability to recover from a large postural perturbation. Forward tripping is prevalent in older adults and lateral falls are important due to risk of hip fracture. We used a forward and a lateral single-step balance recovery task to examine the effects of strength training (ST) or power (PT) training on single-step balance recovery in older adults. Twenty older adults (70.8±4.4 years, eleven male) were randomly assigned to either a 6-week (three times/week) lower extremity ST or PT intervention. Maximum forward (FLeanmax) and lateral (LLeanmax) lean angle and strength and power in knee extension and leg press were assessed at baseline and follow-up. Fifteen participants completed the study (ST =7, PT =8). Least squares means (95% CI) for ΔFLeanmax (ST: +4.1° [0.7, 7.5]; PT: +0.6° [-2.5, 3.8]) and ΔLLeanmax (ST: +2.2° [0.4, 4.1]; PT: +2.6° [0.9, 4.4]) indicated no differences between groups following training. In exploratory post hoc analyses collapsed by group, ΔFLeanmax was +2.4° (0.1, 4.7) and ΔLLeanmax was +2.4° (1.2, 3.6). These improvements on the balance recovery tasks ranged from ~15%-30%. The results of this preliminary study suggest that resistance training may improve balance recovery performance, and that, in this small sample, PT did not lead to larger improvements in single-step balance recovery compared to ST.
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Physical activity is important in both prevention and treatment of many common diseases, but sports injuries can pose serious problems. To determine whether physical activity exercises can reduce sports injuries and perform stratified analyses of strength training, stretching, proprioception and combinations of these, and provide separate acute and overuse injury estimates. PubMed, EMBASE, Web of Science and SPORTDiscus were searched and yielded 3462 results. Two independent authors selected relevant randomised, controlled trials and quality assessments were conducted by all authors of this paper using the Cochrane collaboration domain-based quality assessment tool. Twelve studies that neglected to account for clustering effects were adjusted. Quantitative analyses were performed in STATA V.12 and sensitivity analysed by intention-to-treat. Heterogeneity (I(2)) and publication bias (Harbord's small-study effects) were formally tested. 25 trials, including 26 610 participants with 3464 injuries, were analysed. The overall effect estimate on injury prevention was heterogeneous. Stratified exposure analyses proved no beneficial effect for stretching (RR 0.963 (0.846-1.095)), whereas studies with multiple exposures (RR 0.655 (0.520-0.826)), proprioception training (RR 0.550 (0.347-0.869)), and strength training (RR 0.315 (0.207-0.480)) showed a tendency towards increasing effect. Both acute injuries (RR 0.647 (0.502-0.836)) and overuse injuries (RR 0.527 (0.373-0.746)) could be reduced by physical activity programmes. Intention-to-treat sensitivity analyses consistently revealed even more robust effect estimates. Despite a few outlying studies, consistently favourable estimates were obtained for all injury prevention measures except for stretching. Strength training reduced sports injuries to less than 1/3 and overuse injuries could be almost halved.
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Manipulating joint range of motion during squat training may have differential effects on adaptations to strength training with implications for sports and rehabilitation. Consequently, the purpose of this study was to compare the effects of squat training with a short vs. a long range of motion. Male students (n = 17) were randomly assigned to 12 weeks of progressive squat training (repetition matched, repetition maximum sets) performed as either a) deep squat (0-120° of knee flexion); n = 8 (DS) or (b) shallow squat (0-60 of knee flexion); n = 9 (SS). Strength (1 RM and isometric strength), jump performance, muscle architecture and cross-sectional area (CSA) of the thigh muscles, as well as CSA and collagen synthesis in the patellar tendon, were assessed before and after the intervention. The DS group increased 1 RM in both the SS and DS with ~20 ± 3 %, while the SS group achieved a 36 ± 4 % increase in the SS, and 9 ± 2 % in the DS (P < 0.05). However, the main finding was that DS training resulted in superior increases in front thigh muscle CSA (4-7 %) compared to SS training, whereas no differences were observed in patellar tendon CSA. In parallel with the larger increase in front thigh muscle CSA, a superior increase in isometric knee extension strength at 75° (6 ± 2 %) and 105° (8 ± 1 %) knee flexion, and squat-jump performance (15 ± 3 %) were observed in the DS group compared to the SS group. Training deep squats elicited favourable adaptations on knee extensor muscle size and function compared to training shallow squats.
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Resistance exercise can acutely increase concentrations of circulating neuroendocrine factors, but the effect of mode on this response is not established. The purpose of this study was to examine the effect of resistance exercise selection on the acute hormonal response using similar lower-body multi-joint movement free weight and machine weight exercises. Ten resistance trained men (25±3 yr, 179±7 cm, 84.2±10.5 kg) completed 6 sets of 10 repetitions of squat or leg press at the same relative intensity separated by one week. Blood samples were collected before (PRE), immediately after (IP), and 15 (P15) and 30 min (P30) after exercise and analyzed for testosterone (T), growth hormone (GH), and cortisol (C) concentrations. Exercise increased (p<0.05) T and GH at IP but the concentrations at IP were greater for the squat (T: 31.4±10.3 nmol•L; GH: 9.5±7.3 μg•L) than for the leg press (T: 26.9±7.8 nmol•L; GH: 2.8±3.2 μg•L). At P15 and P30, GH was greater for the squat (P15: 12.3±8.9 μg•L; P30: 12.0±8.9 μg•L) than for the leg press (P15: 4.8±3.4 μg•L; P30: 5.4±4.1 μg•L). C was increased after exercise and was greater for the squat than for the leg press. Although total work (external load and body mass moved) was greater for the squat than for the leg press, rating of perceived exertion did not differ between modes. Free weight exercises appear to induce greater hormonal responses to resistance exercise than machine weight exercises utilizing similar lower-body multi-joint movements and primary movers.
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Previous research has recommended several measures of effect size for studies with repeated measurements in both treatment and control groups. Three alternate effect size estimates were compared in terms of bias, precision, and robustness to heterogeneity of variance. The results favored an effect size based on the mean pre-post change in the treatment group minus the mean pre-post change in the control group, divided by the pooled pretest standard deviation.
This study was designed to examine the role of foot type, height, leg length, and range of motion (ROM) measurements on excursion distances while performing the Star Excursion Balance Test (SEBT), a test of dynamic postural control. Participants (n = 30) performed 3 trials of the SEBT in each of the 8 directions while balancing on the right and left legs. No statistically significant relations were found between foot type or ROM measurements and excursion distances with the SEBT. Significant cor- relations were revealed between height and excursion distance and leg length and ex- cursion distance with leg length having the stronger correlation. Using raw excursion measures, males were found to have significantly greater excursion distances than fe- males; however, after normalizing excursion distances to leg length, there were no significant differences related to gender. In conclusion, when using the SEBT for ex- perimental or clinical purposes, participants' excursion distances should be normal- ized to leg length to allow for a more accurate comparison of performance among participants.