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

October 2016
The Journal of sports medicine and physical fitness 58(3)

DOI:10.23736/S0022-4707.16.06698-6

Authors:

Fabrício Eduardo Rossi

São Paulo State University

Brad J Schoenfeld

City University of New York City - Lehman College

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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

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

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

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

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

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 form—for 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

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

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

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

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

± 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

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

(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

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

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 (90–120º 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

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

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

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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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

frame or use framing techniques to enclose any trademark, logo, or other proprietary information of the Publish er.

Running Head: Squat versus Leg Press

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

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-

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Running Head: Squat versus Leg Press

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)

Squat

(n=8)

%Δ (ES)

Leg Press +

Squat

(n=9)

%Δ (ES)

FFM (Kg)

Pre

64.9 ± 12.3

1.4%

(0.10)

62.6 ± 10.6

2.2%

(0.15)

62.4 ± 4.8

1.9%

(0.13)

Post

65.8 ± 13.2

64.0 ± 10.4

63.6 ± 4.9

FFM (%)

Pre

81.6±8.4

-0.5%

(0.06)

79.8±8.7

-0.5%

(0.06)

83.4±8.7

-0.5%

(0.06)

Post

81.1±9.0

79.3±8.4

82.9±9.2

FM (Kg)

Pre

15.6±9.9

5.1%

(0.08)

17.4±11.4

4.6%

(0.09)

13.3±9.0

5.3%

(0.08)

Post

16.4±11.2

18.3±11.5

14.1±9.8

FM (%)

Pre

18.4±8.4

0.4%

(0.05)

20.2±8.7

0.5%

(0.06)

16.6±8.7

0.5%

(0.06)

Post

18.8±9.0

20.7±8.4

17.1±9.2

Body Mass (Kg)

Pre

80.6±18.2

2.1%

(0.10)

80.0±20.5

2.8%

(0.14)

75.7±10.9

2.5%

(0.12)

Post

82.2±19.8

82.3±20.4

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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-10

-5

Anterior Anteriolateral Lateral Posteriolateral Posterior Posteriomedial Medial Anteriomedial Sum

Left Right

*** * ** *

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Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance – a systematic review and meta-analysis

Article

Full-text available

Aug 2023

Background The effectiveness of strength training with free-weight vs. machine equipment is heavily debated. Thus, the purpose of this meta-analysis was to summarize the data on the effect of free-weight versus machine-based strength training on maximal strength, jump height and hypertrophy. Methods The review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, and the systematic search of literature was conducted up to January 1st, 2023. Studies that directly compared free-weight vs. machine-based strength training for a minimum of 6 weeks in adults (18–60 yrs.) were included. Results Thirteen studies (outcomes: maximal strength [n = 12], jump performance [n = 5], muscle hypertrophy [n = 5]) with a total sample of 1016 participants (789 men, 219 women) were included. Strength in free-weight tests increased significantly more with free-weight training than with machines (SMD: -0.210, CI: -0.391, -0.029, p = 0.023), while strength in machine-based tests tended to increase more with machine training than with free-weights (SMD: 0.291, CI: -0.017, 0.600, p = 0.064). However, no differences were found between modalities in direct comparison (free-weight strength vs. machine strength) for dynamic strength (SMD: 0.084, CI: -0.106, 0.273, p = 0.387), isometric strength (SMD: -0.079, CI: -0.432, 0.273, p = 0.660), countermovement jump (SMD: -0.209, CI: -0.597, 0.179, p = 0.290) and hypertrophy (SMD: -0.055, CI: -0.397, 0.287, p = 0.751). Conclusion No differences were detected in the direct comparison of strength, jump performance and muscle hypertrophy. Current body of evidence indicates that strength changes are specific to the training modality, and the choice between free-weights and machines are down to individual preferences and goals.

The Use of Free Weight Squats in Sports: A Narrative Review—Terminology and Biomechanics

Article

Full-text available

Feb 2024

Abstract: There is substantial evidence indicating that increased maximum strength as a result of training with squats, particularly full and parallel squats, is associated with superior athletic capabilities, such as sprinting, jumping and agility. Although full and parallel squats have been strongly associated with sport performance, there is also some evidence that the use of partial squats may provide angle specific adaptations that are likely advantageous for specific sporting activities. Partial squats may be particularly advantageous when trained in conjunction with full or parallel squats, as this practice results in a greater training effect. There is a paucity of evidence that squatting is associated with excessive injuries to the knees, lower back, or other structures. Evidence does indicate that squatting, including full squats, can be undertaken safely, provided an appropriate training methodology is applied. Indeed, based on scientific data, the cost/benefit ratio indicates that squats should be recommended and should be a central strength training exercise for the preparation of athletes in most sports, particularly those requiring strong and powerful whole body and lower body movements.

Association of multi-phase rates of force development during an isometric leg press with vertical jump performances

Article

Full-text available

Feb 2024
PLOS ONE

Purpose This study aimed to elucidate characteristics of explosive force-production capabilities represented by multi-phase rate of force developments (IRFDs) during isometric single-leg press (ISLP) through investigating relationships with countermovement (CMJ) and rebound continuous jump (RJ) performances. Methods Two-hundred-and-thirty male athletes performed ISLP, CMJ with an arm swing (CMJAS), and RJ with an arm swing (RJAS). IRFDs were measured during ISLP using a custom-built dynamometer, while CMJAS and RJAS were measured on force platforms. The IRFDs were obtained as rates of increase in force across 50 ms in the interval from the onset to 250 ms. Jump height (JH) was obtained from CMJAS, while RJAS provided JH, contact time (CT), and reactive strength index (RSI) values. Results All IRFDs were correlated with CMJAS-JH (ρ = 0.20–0.45, p ≤ 0.003), RJAS-JH (ρ = 0.22–0.46, p ≤ 0.001), RJAS-RSI (ρ = 0.29–0.48, p < 0.001) and RJAS-CT (ρ = −0.29 to −0.25, p ≤ 0.025). When an influence of peak force was considered using partial rank correlation analysis, IRFDs during onset to 150 ms were correlated with CMJAS-JH (ρxy/z = 0.19–0.36, p ≤ 0.004), IRFDs during onset to 100 ms were correlated with RJAS-JH and RJAS-RSI (ρxy/z = 0.33–0.36, p < 0.001), and IRFD during onset to 50 ms was only correlated with RJAS-CT (ρxy/z = −0.23, p < 0.001). Conclusion The early phase (onset to 150 ms) IRFDs measured using ISLP enabled the assessment of multiple aspects of leg-extension strength characteristics that differ from maximal strength; these insights might be useful in the assessment of the athletes’ leg-extension strength capabilities.

Lengthened Partial Repetitions Elicit Similar Muscular Adaptations as a Full Range of Motion During Resistance Training in Trained Individuals

Preprint

Full-text available

Sep 2024

Cardiovascular responses to leg-press exercises during head-down tilt

Article

Full-text available

Aug 2024

Introduction Physical exercise and gravitational load affect the activity of the cardiovascular system. How these factors interact with one another is still poorly understood. Here we investigate how the cardiovascular system responds to leg-press exercise during head-down tilt, a posture that reduces orthostatic stress, limits gravitational pooling, and increases central blood volume. Methods Seventeen healthy participants performed leg-press exercise during head-down tilt at different combinations of resistive force, contraction frequency, and exercise duration (30 and 60 s), leading to different exercise power. Systolic (sBP), diastolic (dBP), mean arterial pressure (MAP), pulse pressure (PP) and heart rate (HR) were measured continuously. Cardiovascular responses were evaluated by comparing the values of these signals during exercise recovery to baseline. Mixed models were used to evaluate the effect of exercise power and of individual exercise parameter on the cardiovascular responses. Results Immediately after the exercise, we observed a clear undershoot in sBP (Δ = −7.78 ± 1.19 mmHg), dBP (Δ = −10.37 ± 0.84 mmHg), and MAP (Δ = −8.85 ± 0.85 mmHg), an overshoot in PP (Δ = 7.93 ± 1.13 mmHg), and elevated values of HR (Δ = 33.5 ± 0.94 bpm) compared to baseline ( p < 0.0001). However, all parameters returned to similar baseline values 2 min following the exercise ( p > 0.05). The responses of dBP, MAP and HR were significantly modulated by exercise power (correlation coefficients: r dBP = −0.34, r MAP = −0.25, r HR = 0.52, p < 0.001). All signals’ responses were modulated by contraction frequency ( p < 0.05), increasing the undershoot in sBP (Δ = −1.87 ± 0.98 mmHg), dBP (Δ = −4.85 ± 1.01 and Δ = −3.45 ± 0.98 mmHg for low and high resistive force respectively) and MAP (Δ = −3.31 ± 0.75 mmHg), and increasing the overshoot in PP (Δ = 2.57 ± 1.06 mmHg) as well as the value of HR (Δ = 16.8 ± 2.04 and Δ = 10.8 ± 2.01 bpm for low and high resistive force respectively). Resistive force affected only dBP (Δ = −4.96 ± 1.41 mmHg, p < 0.0001), MAP (Δ = −2.97 ± 1.07 mmHg, p < 0.05) and HR (Δ = 6.81 ± 2.81 bpm, p < 0.0001; Δ = 15.72 ± 2.86 bpm, p < 0.0001; Δ = 15.72 ± 2.86 bpm, p < 0.05, depending on the values of resistive force and contraction frequency), and exercise duration affected only HR (Δ = 9.64 ± 2.01 bpm, p < 0.0001). Conclusion Leg exercises caused only immediate cardiovascular responses, potentially due to facilitated venous return by the head-down tilt position. The modulation of dBP, MAP and HR responses by exercise power and that of all signals by contraction frequency may help optimizing exercise prescription in conditions of limited orthostatic stress.

Comparative Electromyographic Analysis in Leg Press of Traditional Fitness Equipment, Traditional Outdoor Fitness Equipment, and a New Model of Outdoor Fitness Equipment in Trained Young Men

Article

Full-text available

Aug 2024

This study compares the electromyographic activity (EMG) of different muscle groups (rectus femoris, vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius) of the lower limbs when performing a traditional seated leg press (SLP) with a classic piece of outdoor fitness equipment (OFE-SLP), and with a new OFE leg press that allows the user to adjust the intensity of the exercise by means of a selectorized system (BIOFIT-LP). It was found that the EMG of the OFE-SLP was significantly lower than that of the SLP, but similar activations to those of the SLP were achieved with the BIOFIT-LP. In conclusion, the inclusion of a system to be able to change intensity of the exercise in OFE achieves an EMG activity similar to traditional machinery in trained young men.

The effects of squat variations on strength and quadriceps hypertrophy adaptations in recreationally trained females

Article

Full-text available

Jan 2024
EUR J SPORT SCI

The barbell squat is a multijoint exercise often employed by athletes and fitness enthusiasts due to its beneficial effects on functional and morphological neuromuscular adaptations. This study compared the effects of squat variations on lower limb muscle strength and hypertrophy adaptations. Twenty‐four recreationally trained females were assigned to a 12‐week front squat (FS; n = 12) or back squat (BS; n = 12) resistance training protocol (twice per week). Maximum dynamic strength (1‐RM) on the 45° leg press, a nonspecific strength test, and muscle thickness of the proximal, middle, and distal portions of the lateral thigh were assessed at baseline and post‐training. A significant time versus group interaction was observed for 1‐RM values (F(1,22) = 10.53; p = 0.0004), indicating that BS training elicits greater improvements in muscle strength compared with FS training (p = 0.048). No time versus group interactions were found for muscle thickness (F(1,22) = 0.103; p = 0.752); however, there was a significant main effect of time for the proximal (F(1,22) = 7.794; p = 0.011), middle (F(1,22) = 7.091; p = 0.014), and distal portions (F(1,22) = 7.220; p = 0.013) of the lateral thigh. There were no between‐group differences for any muscle thickness portion (proximal: p = 0.971; middle: p = 0.844; and distal: p = 0.510). Our findings suggest that BS elicits greater improvements in lower limb muscle strength on the 45° leg press than FS, but hypertrophic adaptations are similar regardless of variations during the squat exercise.

Upright versus Horizontal Squat Jumps: A comparison of peak force, peak velocity, peak power and muscle activity in male athletes

Article

Full-text available

Dec 2023

Sports performance coaches and rehabilitation specialists commonly prescribe explosive squat jumps (SJ) in the upright position to improve lower body power using loads based upon an individual's one-repetition maximum (1RM) back squat. Recently, using a horizontal leg press to perform SJ has become popular purportedly due to its less technical nature. To date, little research exists comparing upright and horizontal SJ. Therefore, this investigation examined peak force, peak velocity, peak power and muscle activity of upright versus horizontal SJ using loads based upon each condition's respective 1RM. Twelve males completed two sets of three repetitions of SJ at 20%, 30%, 40%, 50% and 60%1RM. Statistical significance was set to P ≤ 0.05. No significant differences existed between trial 1 and 2 for any measures. Two-way analysis of variance revealed a) no significant difference in peak force between the SJ conditions at any intensity; b) significantly greater peak velocity during upright SJ at all intensities; c); significantly greater peak power during upright SJ at all intensities; and d) no difference in muscle activity between SJ conditions. In conclusion, in a key measure of performance, power output during upright SJ was significantly greater than during horizontal SJ.

Weight training exercises anatomy: Legs and core muscles

Preprint

Full-text available

Oct 2024

Barouch Giechaskiel

Book (colored) on weight training exercises (legs, abs, lower back, neck, respiratory muscles). It includes anatomical illustrations and photos.

Muscle Hypertrophy and Strength Adaptations to Systematically Varying Resistance Exercises

Article

Full-text available

Sep 2024

We compared the effects of varied and constant resistance exercises on muscular adaptations in young women. Seventy young women (21.8 ± 3.4 yrs, 62.0 ± 12.3 kg, 162.3 ± 5.7 cm) were randomly divided into two groups: constant resistance exercises (CON-RE, n = 38) or varied resistance exercises (VAR-RE, n = 32). The resistance training (RT) was performed thrice a week over 10 weeks. CON-RE performed a 45º leg press and stiff-leg deadlift every training session, while VAR-RE performed 45º leg press and stiff-leg deadlift in the first training session of the week, hack squat and prone leg curl in the second, and Smith machine squat and seated-leg curl in the third. Both groups performed two sets of 10–15 repetitions maximum per resistance exercise. We measured the muscle thickness of the thigh's anterior, lateral, and posterior aspects by ultrasonography at different muscle sites (proximo-distal). Muscular strength was analyzed from the one-repetition maximum (1RM) tests in the 45° leg press and leg extension (non-trained exercise). The muscle thickness increased similarly in both groups for all muscles and sites (CON-RE: +7.8–17.7% vs. VAR-RE: +7.5–19.3%, P > 0.05). The 1RM increased similarly in both groups (CON-RE: +24.4–32.1% vs. VAR-RE: +29.0–30.1%, P > 0.05). Both RT routines resulted in virtually similar muscular strength gains and hypertrophy. Therefore, both strategies should be considered for the improvement of strength and muscle growth.

The Impact of Back Squat and Leg-Press Exercises on Maximal Strength and Speed-Strength Parameters

Article

Full-text available

Apr 2016

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.

Effect of an herbal/botanical supplement on strength, balance, and muscle function following 12-weeks of resistance training: A placebo controlled study

Article

Full-text available

May 2014
Sports Nutr Rev J

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.

The effects of strength and power training on single-step balance recovery in older adults: a preliminary study

Article

Full-text available

Apr 2014

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.

The effectiveness of exercise interventions to prevent sports injuries: A systematic review and meta-analysis of randomised controlled trials

Article

Full-text available

Oct 2013
BRIT J SPORT MED

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.

Effect of range of motion in heavy load squatting on muscle and tendon adaptations

Article

Full-text available

Apr 2013
EUR J APPL PHYSIOL

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.

Essentials of Strength Training and Conditioning, 2E

Book

Jul 2000

Roger Earle

The Acute Hormonal Response to Free Weight and Machine Weight Resistance Exercise

Article

Nov 2013
J STRENGTH COND RES

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.

Machine Versus Free Weights

Article

Jeffrey M McBride

Estimating Effect Sizes From Pretest-Posttest-Control Group Designs

Article

Apr 2008

Scott B Morris

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.

Considerations for Normalizing Measures of the Star Excursion Balance Test

Article

Jun 2003
Meas Phys Educ Exerc Sci

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.