scholarly journals Kinematic and Electromyographic Activity Changes during Back Squat with Submaximal and Maximal Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hasan U. Yavuz ◽  
Deniz Erdag
Keyword(s):  
Repeated Measures ◽  
Injury Risk ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Gluteus Maximus ◽  
Movement Pattern ◽  
Erector Spinae ◽  
Electromyographic Activity ◽  
Vastus Medialis ◽  
Significant Difference

The aim of this study was to investigate the possible kinematic and muscular activity changes with maximal loading during squat maneuver. Fourteen healthy male individuals, who were experienced at performing squats, participated in this study. Each subject performed squats with 80%, 90%, and 100% of the previously established 1 repetition maximum (1RM). Electromyographic (EMG) activities were measured for the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, and erector spinae by using an 8-channel dual-mode portable EMG and physiological signal data acquisition system (Myomonitor IV, Delsys Inc., Boston, MA, USA). Kinematical data were analyzed by using saSuite 2D kinematical analysis program. Data were analyzed with repeated measures analysis of variance (p<0.05). Overall muscle activities increased with increasing loads, but significant increases were seen only for vastus medialis and gluteus maximus during 90% and 100% of 1RM compared to 80% while there was no significant difference between 90% and 100% for any muscle. The movement pattern in the hip joint changed with an increase in forward lean during maximal loading. Results may suggest that maximal loading during squat may not be necessary for focusing on knee extensor improvement and may increase the lumbar injury risk.

Comparison of Hip- and Back-Muscle Activity and Pelvic Compensation in Healthy Subjects During 3 Different Prone Table Hip-Extension Exercises

2017 ◽  
Vol 26 (4) ◽  
pp. 216-222 ◽  
Author(s):  
In-cheol Jeon ◽  
Oh-yun Kwon ◽  
Jong-hyuck Weon ◽  
Ui-jae Hwang ◽  
Sung-hoon Jung
Keyword(s):  
Outcome Measures ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Motion Tracking ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Erector Spinae ◽  
Repeated Measure ◽  
Significant Difference ◽  
Hip Extension

Context:Prone hip extension has been recommended for strengthening the back and hip muscles. Previous studies have investigated prone hip extension conducted with subjects on the floor in the prone position. However, no study has compared 3 different table hip-extension (THE) positions in terms of the activities of the back- and hip-joint muscles with lumbopelvic motion.Objective:To identify more effective exercises for strengthening the gluteus maximus (GM) by comparing 3 different exercises (THE alone, THE with the abdominal drawing-in maneuver [THEA], and THEA with chair support under the knee [THEAC]) based on electromyographic muscle activity and pelvic compensation.Design:Repeated-measure within-subject intervention.Setting:University research laboratory.Participants:16 healthy men.Main Outcome Measures:Surface electromyography (EMG) was used to obtain data on the GM, erector spinae (ES), multifidus, biceps femoris (BF), and semitendinosus (ST). Pelvic compensation was monitored using an electromagnetic motion-tracking device. Exertion during each exercise was recorded. Any significant difference in electromyographic muscle activity and pelvic motion among the 3 conditions (THE vs THEA vs THEAC) was assessed using a 1-way repeated-measures analysis of variance (ANOVA) with Bonferroni post hoc test.Results:The muscle activities recorded by EMG differed significantly among the 3 exercises (P < .01). GM activity was increased significantly during THEAC (P < .01). There was a significant difference in lumbopelvic kinematics in terms of anterior tilting (F = 19.49, P < .01) and rotation (F= 27.38, P < .01) among the 3 exercises.Conclusions:The THEAC exercise was the most effective for strengthening the GM without overactivity of the ES, BF, and ST muscles and lumbopelvic compensation compared with THE and THEA.

Evaluating electromyographic activity of vastus medialis obliqus, vastus lateralis, and hamstrings in women with patellofemoral pain syndrome

2020 ◽  
Author(s):  
Mahsa Mazaheri ◽  
Alireza Motealleh ◽  
sobhan sobhani ◽  
amin kordi yoosefinejad
Keyword(s):  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Pain Syndrome ◽  
Patellofemoral Pain Syndrome ◽  
Patellofemoral Pain ◽  
Emg Activity ◽  
Tibial Rotation ◽  
Electromyographic Activity ◽  
Vastus Medialis ◽  
Significant Difference

Abstract Background: Temporal difference in activation of medial-lateral hamstrings could lead to external tibial rotation. It was assumed that patients with patellofemoral pain syndrome (PFPS) exhibit altered medial-lateral hamstrings muscular pattern during functional tasks. Objectives: The aim of this study was to compare the electromyography (EMG) activity of quadriceps and hamstrings in patients with PFPS and healthy subjects during stair descending. Design: cross sectional comparative study Setting: Motion analysis Lab, Rehabilitation research center, Shiraz University of Medical Sciences Participants: 24 women with PFPS and 24 healthy subjects, aged 18-40 years recruited through convenience sampling method participated in this study. Interventions: The EMG activity of vastus medialis obliqus (VMO), vastus lateralis (VL), medial (MH) and lateral hamstrings (LH) recorded during stair descending. Main outcome measures: Onset latency and intensity of muscle activity measured relative to the moment of foot contact. Results: There were statistically significant difference in onset of hamstrings heads (LH-MH) between groups (p=0.014). The BF activated before ST in PFPS group. Normalized muscular activity was significantly reduced for VMO (p=0.002), VL (p=.045), and LH (p=0.019) in PFPS patients. Conclusions: Difference in temporal activation patterns of BF and ST may result in lack of rotational knee stabilization and lead to increased patellofemoral joint pressure. Earlier activation of LH rotates tibia externally, and hence, produced lateral patellar tracking.

scholarly journals Optimizing athlete assessment of maximal force and rate of development: A comparison of the isometric squat and mid-thigh pull

2020 ◽  
Author(s):  
Joao Renato Silva ◽  
Vasileios Sideris ◽  
Bryna C.R. Chrismas ◽  
Paul J. Read
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Peak Force ◽  
Erector Spinae ◽  
Vastus Medialis ◽  
Rate Of Development ◽  
Hamstring Muscles ◽  
Force Time

ABSTRACTThis study compared force-time characteristics and muscle activity between the isometric squat (ISQ) and mid-thigh pull (IMTP) in both bilateral (ISQBI and IMTPBI) and unilateral (ISQUNI and IMTPUNI) stance. Peak force (PF), rate-of-force (RFD) (e.g. 0-300ms) and EMG of the multifidus, erector spinae (ES), gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST), vastus medialis (VM), vastus lateralis (VL) and soleus were recorded in ten recreationally trained males. PF was significantly greater during the ISQBI vs. IMTPBI (p=0.016, ES=1.08) but not in the unilateral test mode although effects remained moderate (ES=0.62). A trend indicated heightened RFD300ms (p = 0.083; ES=0.81) during the IMTPBI vs. the ISQBI, but these effects were smaller in the unilateral test (ES = 0.51). Greater (p<0.0001) EMG for VL (ES=1.00-1.13) and VM were recorded during the ISQ compared to IMTP modes in both modes (ES = 0.97 – 1.18). Greater BF EMG (p = 0.030, ES = 0.31) was shown in IMTPBI vs. ISQBI and these effects were stronger in the unilateral modes (p = < 0.05; ES = 0.81 – 0.83). Significantly greater ST activation was shown in both IMTPUNI (p < 0.05; ES = 0.69-0.76) and IMTPBI (p < 0.001; ES = 1.08). These findings indicate that ISQ results in elevated PF, whereas, RFD is heightened during the IMTP and these differences are more pronounced in bilateral modes. Greater activation of the quadriceps and hamstring muscles are expected in ISQ and IMPT respectively.

Alterations in Quadriceps Neurologic Complexity After Anterior Cruciate Ligament Reconstruction

2020 ◽  
pp. 1-6
Author(s):  
Steven M. Davi ◽  
Colleen K. Woxholdt ◽  
Justin L. Rush ◽  
Adam S. Lepley ◽  
Lindsey K. Lepley
Keyword(s):  
Anterior Cruciate Ligament ◽  
Anterior Cruciate Ligament Reconstruction ◽  
Ligament Reconstruction ◽  
Vastus Lateralis ◽  
Cruciate Ligament ◽  
Neuromuscular Control ◽  
Electromyographic Activity ◽  
Vastus Medialis ◽  
Cruciate Ligament Reconstruction ◽  
Anterior Cruciate

Context: Traditionally, quadriceps activation failure after anterior cruciate ligament reconstruction (ACLR) is estimated using discrete isometric torque values, providing only a snapshot of neuromuscular function. Sample entropy (SampEn) is a mathematical technique that can measure neurologic complexity during the entirety of contraction, elucidating qualities of neuromuscular control not previously captured. Objective: To apply SampEn analyses to quadriceps electromyographic activity in order to more comprehensively characterize neuromuscular deficits after ACLR. Design: Cross-sectional. Setting: Laboratory. Participants: ACLR: n = 18; controls: n = 24. Interventions: All participants underwent synchronized unilateral quadriceps isometric strength, activation, and electromyography testing during a superimposed electrical stimulus. Main Outcome Measures: Group differences in strength, activation, and SampEn were evaluated with t tests. Associations between SampEn and quadriceps function were evaluated with Pearson product–moment correlations and hierarchical linear regressions. Results: Vastus medialis SampEn was significantly reduced after ACLR compared with controls (P = .032). Vastus medialis and vastus lateralis SampEn predicted significant variance in activation after ACLR (r2 = .444; P = .003). Conclusions: Loss of neurologic complexity correlates with worse activation after ACLR, particularly in the vastus medialis. Electromyographic SampEn is capable of detecting underlying patterns of variability that are associated with the loss of complexity between key neurophysiologic events after ACLR.

Hip and Trunk Muscle Activity During the Star Excursion Balance Test in Healthy Adults

2019 ◽  
Vol 28 (7) ◽  
pp. 682-691 ◽  
Author(s):  
Kunal Bhanot ◽  
Navpreet Kaur ◽  
Lori Thein Brody ◽  
Jennifer Bridges ◽  
David C. Berry ◽  
...  
Keyword(s):  
Dynamic Balance ◽  
Gluteus Maximus ◽  
Gluteus Medius ◽  
Healthy Adults ◽  
Rectus Abdominis ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Electromyographic Activity ◽  
Balance Test ◽  
External Oblique

Context:Dynamic balance is a measure of core stability. Deficits in the dynamic balance have been related to injuries in the athletic populations. The Star Excursion Balance Test (SEBT) is suggested to measure and improve dynamic balance when used as a rehabilitative tool.Objective:To determine the electromyographic activity of the hip and the trunk muscles during the SEBT.Design:Descriptive.Setting:University campus.Participants:Twenty-two healthy adults (11 males and 11 females; 23.3 [3.8] y, 170.3 [7.6] cm, 67.8 [10.3] kg, and 15.1% [5.0%] body fat).Intervention:Surface electromyographic data were collected on 22 healthy adults of the erector spinae, external oblique, and rectus abdominis bilaterally, and gluteus medius and gluteus maximus muscle of the stance leg. A 2-way repeated measures analysis of variance was used to determine the interaction between the percentage maximal voluntary isometric contraction (%MVIC) and the reach directions. The %MVIC for each muscle was compared across the 8 reach directions using the Sidak post hoc test withαat .05.Main Outcome Measures:%MVIC.Results:Significant differences were observed for all the 8 muscles. Highest electromyographic activity was found for the tested muscles in the following reach directions—ipsilateral external oblique (44.5% [38.4%]): anterolateral; contralateral external oblique (52.3% [40.8%]): medial; ipsilateral rectus abdominis (8% [6.6%]): anterior; contralateral rectus abdominis (8% [5.3%]): anteromedial; ipsilateral erector spinae (46.4% [20.2%]): posterolateral; contralateral erector spinae (33.5% [11.3%]): posteromedial; gluteus maximus (27.4% [11.7%]): posterior; and gluteus medius (54.6% [26.1%]): medial direction.Conclusions:Trunk and hip muscle activation was direction dependent during the SEBT. This information can be used during rehabilitation of the hip and the trunk muscles.

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

2012 ◽  
Vol 47 (1) ◽  
pp. 15-23 ◽  
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&lt;.001), ABD-ER (F3,57 = 10.458, P&lt;.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.

The Association of Obesity With Quadriceps Activation During Sit-to-Stand

2020 ◽  
Vol 100 (12) ◽  
pp. 2134-2143
Author(s):  
Lance M Bollinger ◽  
Amanda L Ransom
Keyword(s):  
Vastus Lateralis ◽  
Knee Extensor ◽  
Quadriceps Muscle ◽  
Knee Extensors ◽  
Emg Activity ◽  
Vastus Medialis ◽  
Trunk Flexion ◽  
Maximal Voluntary Isometric Contraction ◽  
Sit To Stand ◽  
The Mean

Abstract Objective Obesity reduces voluntary recruitment of quadriceps during single-joint exercises, but the effects of obesity on quadriceps femoris muscle activation during dynamic daily living tasks, such as sit-to-stand (STS), are largely unknown. The purpose of this study was to determine how obesity affects quadriceps muscle recruitment during STS. Methods In this cross-sectional study, 10 women who were lean and 17 women who were obese completed STS from a chair with arms crossed over the chest. Three-dimensional motion analysis was used to define 3 distinct phases (I–III) of the STS cycle. The electromyographic (EMG) activity of the vastus medialis, vastus lateralis, and semitendinosus was measured. Results STS duration was greater (3.02 [SD = 0.75] seconds vs 1.67 [SD = 0.28] seconds) and peak trunk flexion angle was lower (28.9 degrees [SD = 10.4 degrees] vs 35.8 degrees [SD = 10.1 degrees]) in the women who were obese than in the women who were lean. The mean EMG activity of the knee extensors increased from phase I to phase II in both groups; however, the mean EMG activities of both the vastus medialis (32.1% [SD = 16.6%] vs 47.3% [SD = 19.6%] maximal voluntary isometric contraction) and the vastus lateralis (31.8% [SD = 19.4%] vs 47.5% [SD = 19.6%] maximal voluntary isometric contraction) were significantly lower during phase II in the women who were obese. The mean EMG activity of the semitendinosus increased throughout STS but was not significantly different between the 2 groups. Coactivation of the semitendinosus and knee extensors tended to be greater in the women who were obese but failed to reach statistical significance. Conclusions Knee extensor EMG amplitude was reduced in women who were obese during STS, despite reduced trunk flexion. Impact Reduced knee extensor recruitment during STS in obesity may redistribute forces needed to complete this task to other joints. Functional movement training may help improve knee extensor recruitment during STS in people who are obese. Lay Summary People with obesity often have low quadriceps muscle strength and impaired mobility during daily activities. This study shows that women who are obese have lower voluntary recruitment of quadriceps when rising from a chair than women who are lean do, which could increase workload on hip or ankle muscles during this important daily task. Quadriceps strengthening exercises might improve the ability to rise from sitting to standing.

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