Impact of performing heavy-loaded barbell back squats to volitional failure on lower limb and lumbo-pelvis mechanics in skilled lifters

Brice, Sara M.; Doma, Kenji; Harland, Liam; Spratford, Wayne

doi:10.1080/02640414.2019.1683385

Cited by 5 publications

(18 citation statements)

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“…Alternatively, the mean moment increased at the hip and lumbopelvis and decreased at the knee during the flat-heel condition. This finding for the flat-heel condition aligns with what we have previously reported (2) and indicates that compensatory changes may be taking place as the knee musculature is physically stressed. Thus, the way in which the squat dynamics changed with exhaustion seems to differ based on the type of footwear.…”

Section: Discussionsupporting

confidence: 92%

“…When squatting with a raised heel, power output decreased between T second and T final at all 3 lower-limb joints. When squatting with a flat heel, power output decreased between T second and T final at the hip and knee, which aligns with what we have previously reported for a flat-heel shoe condition (2). When the shoe conditions were compared, we found that the concentric power output at the knee was significantly less at T final during the raised-heel condition.…”

Section: Discussionsupporting

confidence: 91%

“…The mean moment is a measure of joint loading, and the lack of difference in the mean moments of the shoe conditions suggests that neither type of footwear has an advantage when it comes to reducing loading. If joint loading is reduced, then stress to the structures within the joint will be less and that may lower the risk of acquiring an injury (2,22,24). It has been suggested that using a raised heel may assist in reducing injury, particularly in the lower back region (17).…”

Section: Discussionmentioning

confidence: 99%

“…Data Processing and Analysis. Marker trajectory and analog force plate data were postprocessed within Vicon Nexus using the filter methods previously described by Brice et al (2). A standard inverse dynamics approach was used to calculate joint kinetics (1,5,6).…”

Section: Subjectsmentioning

confidence: 99%

“…Previous work has found that as a lifter fatigues there are reductions in knee joint loading (2,13) and increases in hip and lumbopelvic loading (2). There are also reductions in power output (2,20), joint range-of-motion (ROM) (9,10), and movement speed (2,20). These changes may impair training performance and increase stress on the soft tissues within joints, which may increase the risk of sustaining an injury (9).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Footwear on the Biomechanics of Loaded Back Squats to Volitional Exhaustion in Skilled Lifters

Brice

Doma

Spratford

2021

Journal of Strength and Conditioning Research

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Brice, SM, Doma, K, and Spratford, W. Effect of footwear on the biomechanics of loaded back squats to volitional exhaustion in skilled lifters. J Strength Cond Res 36(10): 2676-2684, 2022-This study examined whether footwear influences the movement dynamics of barbell back squats to volitional exhaustion in experienced lifters. Eleven men (1 repetition maximum [1RM] 5 138 6 19 kg; 1RM % body mass 5 168 6 18%) performed 3 sets (5-12 6 4 repetitions per set) of loaded barbell back squats to volitional exhaustion using raised-heel and flat-heel footwear. Barbell motion as well as moments, angles, angular velocity, and power in the sagittal plane at the ankle, knee, hip, and lumbopelvis were examined during the second repetition of the first set (T second ) and the final repetition of the third set (T final ). There were significant reductions (p , 0.05) in lower-limb concentric angular velocity and power output for both footwear conditions. For the raised-heel condition at T final , hip and knee concentric angular velocities were significantly slower (p , 0.05), and knee concentric power output was significantly less (p , 0.05) compared with the flat-heel condition. A reduction in barbell velocity was not observed for the raised-heel condition despite there being reduction in hip and knee angular velocities. Furthermore, no differences were identified in lower-limb joint moments or any of the biomechanical characteristics of the lumbopelvis between the footwear conditions. The findings of this study suggest that neither type of footwear reduced joint loading or improved joint range-of-motion.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Subjectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Footwear on the Biomechanics of Loaded Back Squats to Volitional Exhaustion in Skilled Lifters

Brice

Doma

Spratford

2021

Journal of Strength and Conditioning Research

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An investigation of movement dynamics and muscle activity during traditional and accentuated-eccentric squatting

Armstrong

Baltzopoulos²,

Langan-Evans³

et al. 2022

PLoS ONE

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Introduction Accentuated-eccentric loading (AEL) takes advantage of the high force producing potential of eccentric muscle contractions, potentially maximising mechanical tension within the muscle. However, evidence is lacking on how AEL squatting may load the involved musculature, limiting scientifically justified programming recommendations. The purpose of this study was to investigate the effects of concentric and eccentric loads on joint loading and muscle activity of the lower limbs. Methods Resistance trained males performed traditional squatting (20–100% of concentric one-repetition maximum [1RM]) and AEL squatting with eccentric loads (110–150% of 1RM) provided by a novel motorised isotonic resistance machine (Kineo). Kinetics and kinematics of the hip, knee, and ankle joints were collected, with electromyography from the gluteus maximus, vastus lateralis, biceps femoris, and gastrocnemius medialis. A secondary cohort underwent a kinematic and electromyography analysis of squatting technique to compare Kineo and back and front barbell squatting. Results Knee joint peak eccentric moments occurred at 120% 1RM (P = 0.045), with no further increase thereafter. As eccentric load increased, the time course of moment development occurred earlier in the eccentric phase. This resulted in a 37% increase in eccentric knee extensor work from the 80% 1RM trial to the 120% 1RM trial (P<0.001). Neither hip nor ankle joints displayed further change in kinetics as eccentric load increased above 100% 1RM. Electromyographic activity during traditional squatting was ~15–30% lower in all eccentric trials than in concentric trials for all muscles. EMG plateaued between a load of 80–100% 1RM during the eccentric trials and did not increase with AEL. No significant differences in kinematics were found between Kineo and barbell squatting. Conclusions The knee extensors appear to be preferentially loaded during AEL squatting. The greater work performed during the eccentric phase of the squat as eccentric load increased suggests greater total mechanical tension could be the cause of adaptations from AEL. Our data suggest that AEL should be programmed with a load of 120% of 1RM. Further studies are needed to confirm the longer-term training effects of AEL.

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A Brief Review on the Effects of the Squat Exercise on Lower-Limb Muscle Hypertrophy

Ribeiro

Santos

Nunes

et al. 2022

Strength &Amp; Conditioning Journal

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The squat is one of the most widely used exercises in resistance training programs. The aim of this narrative review was to analyze the effect of the squat on lower-limb muscle hypertrophy. Briefly, the available literature indicates that the squat is an effective exercise for inducing hypertrophy of the quadriceps, mainly the vastii, but also the rectus femoris, although to a reduced magnitude. Multiple lines of evidence suggest little to no hamstring hypertrophy from the back squat. Although the gluteus maximus clearly participates mechanically in the back squat, few longitudinal studies exist on the topic. The limited evidence available on this topic suggests deeper squats may be more hypertrophic for the gluteus maximus, and that, squat depth beyond 90° of knee flexion may not provide further hypertrophy of the knee extensors. Despite the popularity of the many squat variations, there are still controversies surrounding their hypertrophic potential for lower-limb musculature. Further studies are needed to investigate the hypertrophic effects of different squat variations, as well as differences in hypertrophy because of squat depth, stance, barbell position, and different squat apparatuses/machines.

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Impact of performing heavy-loaded barbell back squats to volitional failure on lower limb and lumbo-pelvis mechanics in skilled lifters

Abstract: Impact of performing heavy-loaded barbell back squats to volitional failure on lower limb and lumbo-pelvis mechanics in skilled lifters.

Cited by 5 publications

References 21 publications

Effect of Footwear on the Biomechanics of Loaded Back Squats to Volitional Exhaustion in Skilled Lifters

Effect of Footwear on the Biomechanics of Loaded Back Squats to Volitional Exhaustion in Skilled Lifters

An investigation of movement dynamics and muscle activity during traditional and accentuated-eccentric squatting

A Brief Review on the Effects of the Squat Exercise on Lower-Limb Muscle Hypertrophy

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