Effect of Hip Abduction Maximal Voluntary Isometric Contraction on Lumbar Motion and Power Output During the Back Squat

Background: Post-activation potentiation (PAP) is a neuromuscular phenomenon that has been shown to augment muscular force generating attributes as well as neural and sensory recruitment. While PAP has demonstrated to acutely enhance muscular performance during high-intensity activities, the effect of PAP on lumbopelvic kinematics under load remains unknown. Objectives: The purpose of this study was to examine the potential PAP effect of a hip abduction maximal voluntary isometric contraction (MVIC) on lumbar motion and power output during the barbell back squat. Methods: Nine resistance-trained men (22.9±2.3 y; 85.0±13.8 kg; 174.3±5.1 cm) performed a set of 5 repetitions of the barbell back squat using 80% one-repetition maximum with and without a hip abduction MVIC prior to performance. Experimental and control trials were randomized and counterbalanced among participants. MVIC was carried out via manual long-lever hip abduction. During the back squat exercise, lumbar motion analysis was performed using wireless motion-sensor technology, and power output was assessed via an accelerometer. Results: No significant differences were observed between trials for lumbar flexion range of motion (ROM) (p=0.32), lumbar flexion maximum deviation (p=0.32), lumbar lateral flexion ROM (p=0.81), lumbar lateral flexion maximum deviation (p=0.98), lumbar rotation maximum deviation (p=0.70), average peak power (p=0.98), or average mean power output (p=0.99) during the squat protocol. Conclusions: Implementation of a manual long-lever hip abduction MVIC prior to the back squat exercise did not significantly alter lumbar motion or augment power output in resistance trained males.

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Central Activation Ratio Is a Reliable Measure for Gluteal Neuromuscular Function

Journal of Sport Rehabilitation ◽

10.1123/jsr.2019-0243 ◽

2020 ◽

Vol 29 (7) ◽

pp. 956-962

Author(s):

Daniel Gilfeather ◽

Grant Norte ◽

Christopher D. Ingersoll ◽

Neal R. Glaviano

Keyword(s):

Isometric Contraction ◽

Outcome Measure ◽

Intraclass Correlation ◽

Neuromuscular Function ◽

Healthy Population ◽

Maximal Voluntary Isometric Contraction ◽

Central Activation ◽

Central Activation Ratio ◽

Hip Abduction ◽

Activation Ratio

Context: Central activation ratio (CAR) is a common outcome measure used to quantify gross neuromuscular function of the quadriceps using the superimposed burst technique, yet this outcome measure has not been validated in the gluteal musculature. Objective: To quantify gluteus medius (GMed) and gluteus maximus (GMax) CAR in a healthy population and evaluate its validity and reliability over a 1-week period. Design: Descriptive. Setting: Laboratory. Patients or Other Participants: A total of 20 healthy participants (9 males and 11 females; age 22.2 [1.4] y, height 173.4 [11.1] cm, mass 84.8 [25.8] kg) were enrolled in this study. Interventions: Participants were assessed at 2 sessions, separated by 1 week. Progressive electrical stimuli (25%, 50%, 75%, and 100%) were delivered to the GMed and GMax at rest, and 100% stimuli were delivered during progressive hip abduction and extension contractions (25%, 50%, 75%, and 100% maximal voluntary isometric contraction). Main Outcome Measures: GMed and GMax CAR, and hip abduction and hip extension maximal voluntary isometric contraction torque. Line of best fit and coefficient of determination (r2) were used to assess the relationship between torque output and CAR at varying levels of stimuli. Intraclass correlation coefficients, ICCs(3,k), were used to assess the between-session reliability. Results: GMed CAR was 96.1% (3.4%) and 96.6% (3.2%), on visits 1 and 2, respectively, whereas GMax CAR was 86.5% (7.5%) and 87.2% (10.7%) over the 2 sessions. A third-order polynomial demonstrated the best line of fit between varying superimposed burst intensities at rest for both GMed (r2 = .156) and GMax (r2 = .602). Linear relationships were observed in the CAR during progressive contractions with a maximal superimposed burst, GMed (r2 = .409) and GMax (r2 = .639). Between-session reliability was excellent for GMed CAR, ICC(3,k) = .911, and moderate for GMax CAR, ICC(3,k) = .704. Conclusion: CAR appears to be an acceptable measure of GMed and GMax neuromuscular function in healthy individuals. Gluteal CAR measurements are reliable measures over a 1-week test period.

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Maximal oxygen uptake, maximal voluntary isometric contraction and physical activity in young Danish adults

European Journal of Applied Physiology and Occupational Physiology ◽

10.1007/bf00357629 ◽

1993 ◽

Vol 67 (4) ◽

pp. 315-320 ◽

Cited By ~ 8

Author(s):

Lars Bo Andersen ◽

J�hanna Haraldsd�ttir

Keyword(s):

Physical Activity ◽

Oxygen Uptake ◽

Isometric Contraction ◽

Maximal Oxygen Uptake ◽

Maximal Voluntary Isometric Contraction

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Joint-Level Analyses of the Back Squat With and Without Intraset Rest

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0662 ◽

2019 ◽

Vol 14 (5) ◽

pp. 583-589 ◽

Cited By ~ 1

Author(s):

Jason D. Stone ◽

Adam C. King ◽

Shiho Goto ◽

John D. Mata ◽

Joseph Hannon ◽

...

Keyword(s):

Sagittal Plane ◽

Movement Pattern ◽

Joint Angles ◽

Mean Power ◽

Joint Power ◽

Joint Level ◽

Back Squat ◽

Squat Exercise ◽

Limb Kinematics ◽

Plane Joint

Purpose: To provide a joint-level analysis of traditional (TS) and cluster (CS) set structure during the back-squat exercise. Methods: Eight men (24 [3] y, 177.3 [7.9] cm, 82.7 [11.0] kg, 11.9 [3.5] % body fat, and 150.3 [23.0] kg 1-repetition maximum [1RM]) performed the back-squat exercise (80%1RM) using TS (4 × 6, 2-min interset rest) and CS (4 × [2 × 3], 30-s intraset rest, 90-s interset rest), randomly. Lower-limb kinematics were collected by motion capture, as well as kinetic data by bilateral force platforms. Results: CS attenuated the loss in mean power (TS −21.6% [3.9%]; CS −12.4% [7.5%]; P = .042), although no differences in gross movement pattern (sagittal-plane joint angles) within and between conditions were observed (P ≥ .05). However, joint power produced at the hip increased from repetition (REP) 1 through REP 6 during TS, while a decrease was noted at the knee. A similar pattern was observed in the CS condition but was limited to the hip. Joint power produced at the hip increased from REP 1 through REP 3 but returned to REP 1 values before a similar increase through REP 6, resulting in differences between conditions (REP 4, P = .018; REP 5, P = .022). Conclusions: Sagittal-plane joint angles did not change in either condition, although CS elicited greater power. Differing joint power contributions (hip and knee) suggest potential central mechanism that may contribute to enhanced power output during CS and warrant further study. Practitioners should consider incorporating CS into training to promote greater power adaptations and to mitigate fatigue.

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Effects of front and back squat techniques on patellofemoral joint kinetics in males

Journal of Biomedical Engineering and Informatics ◽

10.5430/jbei.v2n1p76 ◽

2015 ◽

Vol 2 (1) ◽

pp. 76 ◽

Cited By ~ 1

Author(s):

J Sinclair ◽

S Atkins ◽

N Kudiersky ◽

PJ Taylor ◽

H Vincent

Keyword(s):

Patellofemoral Joint ◽

Pain Syndrome ◽

Current Investigation ◽

Strength And Conditioning ◽

Joint Kinetics ◽

Associated Injury ◽

Back Squat ◽

Squat Exercise ◽

Experienced Male ◽

Joint Load

Purpose: The barbell squat is fundamental in strength and conditioning, with two principal variants; the back and front squat. Unfortunately, the propensity for injury is high particularly at the knee. The aim of the current investigation was examine the influence of front and back squat variations on patellofemoral joint load. Methods: Patellofemoral loads were obtained from thirty-five experienced male participants, who completed both back and front squats at 70% of 1 RM. Differences between squat conditions were examined using Bonferroni adjusted (P = .008) paired t-tests. Results: The results showed that significant differences (P < .008) in patellofemoral load were identified between both conditions with the highest load being experienced during the back squat exercise. Conclusions: Given the proposed relationship between the magnitude of the load experienced by the patellofemoral joint and associated injury pathology, the back squat appears to place lifters at greater risk from injury. Therefore, it may be prudent therefore for lifters who are predisposed to patellofemoral pain syndrome to utilize the front squat in their training.

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A Study Of The Resistive Forces Provided By Elastic Supplemental Band Resistance During The Back Squat Exercise: A Case Report

The Journal of Strength and Conditioning Research ◽

10.1097/01.jsc.0000367183.94397.56 ◽

2010 ◽

Vol 24 ◽

pp. 1 ◽

Cited By ~ 1

Author(s):

Kurt Neelly ◽

Sean A Carter ◽

Joe G Terry

Keyword(s):

Case Report ◽

Back Squat ◽

Squat Exercise ◽

Resistive Forces

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Cardiovascular and nitric oxide response after maximal voluntary isometric contraction in adolescents with and without Down Syndrome v1

10.17504/protocols.io.bztgp6jw ◽

2021 ◽

Author(s):

Geiziane Leite Rodrigues Melo ◽

Dahan Cunha Nascimento ◽

Weldson Abreu ◽

Rafael Olher ◽

Lysleine Deus ◽

...

Keyword(s):

Nitric Oxide ◽

Down Syndrome ◽

Isometric Contraction ◽

Cardiovascular Response ◽

Exercise Session ◽

Isometric Handgrip ◽

Maximal Voluntary Isometric Contraction ◽

Post Exercise ◽

Muscle Groups ◽

Familiarization Session

Background This study was designed to compare the cardiovascular and nitric oxide (NO) responses to maximal voluntary isometric contraction (MVIC) with different muscle groups (leg press [LEP] and isometric handgrip [IHG] exercise) of adolescents with Down syndrome (DS) and age-matched non-DS peers. We also aimed to compare the absolute and relative IHG strength between groups. MethodsEleven adolescents with DS (14.1 ± 1.0 years) and ten without DS (13.7 ± 1.25 years)participants performed two experimental sessions of LEP and IHG exercises: 1) familiarization session and 2) 3 attempts x 5-sec contraction at MVIC with 3-min rest interval. Blood pressure (BP), heart rate (HR) and NO were collected at rest, immediately post-exercise session, and 10-min post-exercise. Results There were no differences for cardiovascular and NO responses between groups for MVIC test using different muscle groups. However, DS group displayed a lower but not significantly cardiovascular response at rest and after MVIC tests than controls. Furthermore, DS group displayed a higher NO- concentration at rest, recovery and after IHG when compared to controls (P< 0.05). In addition, DS adolescents displayed a significantly lower level in absolute and relative IHG strength when compared to controls (P = 0.001). Conclusions Individuals with DS display a lower cardiovascular response at rest and after MVIC tests than controls and higher NO response after exercise.

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Estimation of Relative Load From Bar Velocity in the Full Back Squat Exercise

Sports Medicine International Open ◽

10.1055/s-0043-102933 ◽

2017 ◽

Vol 01 (02) ◽

pp. E80-E88 ◽

Cited By ~ 49

Author(s):

Luis Sánchez-Medina ◽

Jesús Pallarés ◽

Carlos Pérez ◽

Ricardo Morán-Navarro ◽

Juan González-Badillo

Keyword(s):

Relative Strength ◽

Loading Test ◽

Mean Velocity ◽

Relative Load ◽

Back Squat ◽

Training Approach ◽

Velocity Relationship ◽

Squat Exercise ◽

Close Relationship ◽

Bar Velocity

AbstractThe use of bar velocity to estimate relative load in the back squat exercise was examined. 80 strength-trained men performed a progressive loading test to determine their one-repetition maximum (1RM) and load-velocity relationship. Mean (MV), mean propulsive (MPV) and peak (PV) velocity measures of the concentric phase were analyzed. Both MV and MPV showed a very close relationship to %1RM (R2=0.96), whereas a weaker association (R2=0.79) and larger SEE (0.14 vs. 0.06 m·s−1) were found for PV. Prediction equations to estimate load from velocity were obtained. When dividing the sample into 3 groups of different relative strength (1RM/body mass), no differences were found between groups for the MPV attained against each %1RM. MV attained with the 1RM was 0.32±0.03 m·s−1. The propulsive phase accounted for ~82% of concentric duration at 40% 1RM, and progressively increased until reaching 100% at 1RM. Provided that repetitions are performed at maximal intended velocity, a good estimation of load (%1RM) can be obtained from mean velocity as soon as the first repetition is completed. This finding provides an alternative to the often demanding, time-consuming and interfering 1RM or nRM tests and allows implementing a velocity-based resistance training approach.

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Hip Muscle Activity During 3 Side-Lying Hip-Strengthening Exercises in Distance Runners

Journal of Athletic Training ◽

10.4085/1062-6050-47.1.15 ◽

2012 ◽

Vol 47 (1) ◽

pp. 15-23 ◽

Cited By ~ 28

Author(s):

Joseph M. McBeth ◽

Jennifer E. Earl-Boehm ◽

Stephen C. Cobb ◽

Wendy E. Huddleston

Keyword(s):

Muscle Activity ◽

Repeated Measures ◽

External Rotation ◽

Gluteus Maximus ◽

Gluteus Medius ◽

Electromyographic Activity ◽

Maximal Voluntary Isometric Contraction ◽

Strengthening Exercises ◽

Hip Abduction ◽

Hip Strengthening

Context: Lower extremity overuse injuries are associated with gluteus medius (GMed) weakness. Understanding the activation of muscles about the hip during strengthening exercises is important for rehabilitation. Objective: To compare the electromyographic activity produced by the gluteus medius (GMed), tensor fascia latae (TFL), anterior hip flexors (AHF), and gluteus maximus (GMax) during 3 hip-strengthening exercises: hip abduction (ABD), hip abduction with external rotation (ABD-ER), and clamshell (CLAM) exercises. Design: Controlled laboratory study. Setting: Laboratory. Patients or Other Participants: Twenty healthy runners (9 men, 11 women; age = 25.45 ± 5.80 years, height = 1.71 ± 0.07 m, mass = 64.43 ± 7.75 kg) participated. Intervention(s): A weight equal to 5% body mass was affixed to the ankle for the ABD and ABD-ER exercises, and an equivalent load was affixed for the CLAM exercise. A pressure biofeedback unit was placed beneath the trunk to provide positional feedback. Main Outcome Measure(s): Surface electromyography (root mean square normalized to maximal voluntary isometric contraction) was recorded over the GMed, TFL, AHF, and GMax. Results: Three 1-way, repeated-measures analyses of variance indicated differences for muscle activity among the ABD (F3,57 = 25.903, P<.001), ABD-ER (F3,57 = 10.458, P<.001), and CLAM (F3,57 = 4.640, P=.006) exercises. For the ABD exercise, the GMed (70.1 ± 29.9%), TFL (54.3 ± 19.1%), and AHF (28.2 ± 21.5%) differed in muscle activity. The GMax (25.3 ± 24.6%) was less active than the GMed and TFL but was not different from the AHF. For the ABD-ER exercise, the TFL (70.9 ± 17.2%) was more active than the AHF (54.3 ± 24.8%), GMed (53.03 ± 28.4%), and GMax (31.7 ± 24.1 %). For the CLAM exercise, the AHF (54.2 ± 25.2%) was more active than the TFL (34.4 ± 20.1%) and GMed (32.6 ± 16.9%) but was not different from the GMax (34.2 ± 24.8%). Conclusions: The ABD exercise is preferred if targeted activation of the GMed is a goal. Activation of the other muscles in the ABD-ER and CLAM exercises exceeded that of GMed, which might indicate the exercises are less appropriate when the primary goal is the GMed activation and strengthening.

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