scholarly journals Knee Angle Affects Posterior Chain Muscle Activation During an Isometric Test Used in Soccer Players

Sports ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 13 ◽  
Author(s):  
Paul James Read ◽  
Anthony Nicholas Turner ◽  
Richard Clarke ◽  
Samuel Applebee ◽  
Jonathan Hughes
Keyword(s):  
Muscle Activation ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Strength Test ◽  
Isometric Strength ◽  
Medial Gastrocnemius ◽  
Soccer Players ◽  
Emg Activity ◽  
Hamstring Muscle ◽  
Knee Angle

Background: It has been suggested that altering the knee flexion angle during a commonly used supine isometric strength test developed with professional soccer players changes preferential hamstring muscle recruitment. The aim of this study was to examine the electromyography (EMG) knee joint-angle relationship during this test, as these data are currently unknown. Methods: Ten recreational male soccer athletes (age: 28 ± 2.4 years) were recruited and performed a supine isometric strength test on their dominant leg with the knee placed at two pre-selected flexion angles (30° and 90°). The surface EMG of the gluteus maximus, biceps femoris, semitendinosus, and medial gastrocnemius was measured, in addition to the within-session reliability (intraclass correlation coefficient (ICC) and coefficient of variation (CV)). Results: Within-session reliability showed large variation dependent upon the test position and muscle measured (CV% = 8.8–36.1) Absolute mean EMG activity and percentage of maximum voluntary isometric contraction (MVIC) indicated different magnitudes of activation between the two test positions; however, significant mean differences were present for the biceps femoris only with greater activation recorded at the 30° knee angle (% MVIC: 31 ± 9 vs. 22 ± 7; p = 0.002). These differences (30% mean difference) were greater than the observed typical measurement error (CV% = 13.1–14.3 for the 90° and 30° test positions, respectively). Furthermore, the percentage MVIC showed a trend of heightened activation of all muscles with the knee positioned at 30°, but there was also more within-subject variation, and this was more pronounced for the gluteus maximus (CV% = 36.1 vs. 19.8) and medial gastrocnemius (CV% 31 vs. 22.6). Conclusions: These results indicate that biceps femoris and overall posterior chain muscle activation is increased with the knee positioned at 30° of flexion; however, the 90° angle displayed less variation in performance within individual participants, especially in the gluteus maximus and medial gastrocnemius. Thus, practitioners using this test to assess hamstring muscle strength should ensure appropriate familiarisation is afforded, and then may wish to prioritise the 30° knee position.

The Effect of Strength Shoes on Muscle Activity during Quiet Standing

2000 ◽  
Vol 16 (2) ◽  
pp. 204-209 ◽  
Author(s):  
Karl Frank ◽  
Richard V. Baratta ◽  
Moshe Solomonow ◽  
Mackie Shilstone ◽  
Kevin Riché
Keyword(s):  
Center Of Pressure ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Surface Emg ◽  
Erector Spinae ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Quiet Standing ◽  
Emg Activity

The goal of this work was to study the effect of Strength Shoes on the activity of leg and postural muscles to gain insight into the mechanisms by which the shoes may improve athletic performance. Surface EMG signals were obtained from the tibialis anterior, medial gastrocnemius, rectus femoris, biceps femoris, gluteus maximus, and erector spinae of 18 healthy athletic subjects. The subjects stood quietly while wearing either normal athletic shoes or Strength Shoes. EMG root mean square value was compared in each muscle using trimmed paired t tests. Significant (p < .002) increases in EMG activity were found in the MG, TA, GM, and ES muscles when the subjects were wearing Strength Shoes as compared to normal shoes. These changes served to stiffen the ankle, counteracting the dorsiflexion moment created by the shoes, and to support an anterior leaning posture, which compensates for the anterior shift in center of pressure. No significant changes were detected in the activities of RF or BF muscles. Using Strength Shoes increased activity in the triceps surae complex and in other muscles mat support the changes in postural requirements caused by the anterior shift in center of pressure.

Biceps Femoris Compensates for Semitendinosus After Anterior Cruciate Ligament Reconstruction With a Hamstring Autograft: A Muscle Functional Magnetic Resonance Imaging Study in Male Soccer Players

2021 ◽  
pp. 036354652110033
Author(s):  
Thomas Tampere ◽  
Jan Victor ◽  
Thomas Luyckx ◽  
Hannes Vermue ◽  
Nele Arnout ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Cruciate Ligament ◽  
Biceps Femoris ◽  
Soccer Players ◽  
Hamstring Muscle ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
History Of ◽  
Anterior Cruciate ◽  
Tendon Autograft

Background: Rates of reinjury, return to play (RTP) at the preinjury level, and hamstring strain injuries in male soccer players after anterior cruciate ligament reconstruction (ACLR) remain unsatisfactory, due to multifactorial causes. Recent insights on intramuscular hamstring coordination revealed the semitendinosus (ST) to be of crucial importance for hamstring functioning, especially during heavy eccentric hamstring loading. Scientific evidence on the consequences of ST tendon harvest for ACLR is scarce and inconsistent. This study intended to investigate the repercussions of ST harvest for ACLR on hamstring muscle function. Hypothesis: Harvest of the ST tendon for ACLR was expected to have a significant influence on hamstring muscle activation patterns during eccentric exercises, evaluated at RTP in a population of male soccer athletes. Study Design: Controlled laboratory study. Methods: A total of 30 male soccer players with a history of ACLR who were cleared for RTP and 30 healthy controls were allocated to this study during the 2018-2019 soccer season. The influence of ACLR on hamstring muscle activation patterns was assessed by comparing the change in T2 relaxation times [ΔT2 (%) = [Formula: see text]] of the hamstring muscle tissue before and after an eccentric hamstring loading task between athletes with and without a recent history of ACLR through use of muscle functional magnetic resonance imaging, induced by an eccentric hamstring loading task between scans. Results: Significantly higher exercise-related activity was observed in the biceps femoris (BF) of athletes after ACLR compared with uninjured control athletes (13.92% vs 8.48%; P = .003), whereas the ST had significantly lower activity (19.97% vs 25.32%; P = .049). Significant differences were also established in a within-group comparison of the operated versus the contralateral leg in the ACLR group (operated vs nonoperated leg: 14.54% vs 11.63% for BF [ P = .000], 17.31% vs 22.37% for ST [ P = .000], and 15.64% vs 13.54% for semimembranosus [SM] [ P = .014]). Neither the muscle activity of SM and gracilis muscles nor total posterior thigh muscle activity (sum of exercise-related ΔT2 of the BF, ST, and SM muscles) presented any differences in individuals who had undergone ACLR with an ST tendon autograft compared with healthy controls. Conclusion: These findings indicate that ACLR with a ST tendon autograft might notably influence the function of the hamstring muscles and, in particular, their hierarchic dimensions under fatiguing loading circumstances, with increases in relative BF activity contribution and decreases in relative ST activity after ACLR. This between-group difference in hamstring muscle activation pattern suggests that the BF partly compensates for deficient ST function in eccentric loading. These alterations might have implications for athletic performance and injury risk and should probably be considered in rehabilitation and hamstring injury prevention after ACLR with a ST tendon autograft.

scholarly journals Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises

2017 ◽  
Vol 60 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Alireza Monajati ◽  
Eneko Larumbe-Zabala ◽  
Mark Goss-Sampson ◽  
Fernando Naclerio
Keyword(s):  
Muscle Activation ◽  
Female Athletes ◽  
Angular Displacement ◽  
Biceps Femoris ◽  
Voluntary Contraction ◽  
Hamstring Muscle ◽  
Knee Angle ◽  
Hamstring Muscles ◽  
Strengthening Exercises ◽  
Knee Flexors

Abstract The aim of this study was to perform an electromyographic and kinetic comparison of two commonly used hamstring eccentric strengthening exercises: Nordic Curl and Ball Leg Curl. After determining the maximum isometric voluntary contraction of the knee flexors, ten female athletes performed 3 repetitions of both the Nordic Curl and Ball Leg Curl, while knee angular displacement and electromyografic activity of the biceps femoris and semitendinosus were monitored. No significant differences were found between biceps femoris and semitendinosus activation in both the Nordic Curl and Ball Leg Curl. However, comparisons between exercises revealed higher activation of both the biceps femoris (74.8 ± 20 vs 50.3 ± 25.7%, p = 0.03 d = 0.53) and semitendinosus (78.3 ± 27.5 vs 44.3 ± 26.6%, p = 0.012, d = 0.63) at the closest knee angles in the Nordic Curl vs Ball Leg Curl, respectively. Hamstring muscles activation during the Nordic Curl increased, remained high (>70%) between 60 to 40° of the knee angle and then decreased to 27% of the maximal isometric voluntary contraction at the end of movement. Overall, the biceps femoris and semitendinosus showed similar patterns of activation. In conclusion, even though the hamstring muscle activation at open knee positions was similar between exercises, the Nordic Curl elicited a higher hamstring activity compared to the Ball Leg Curl.

scholarly journals Muscle Activation Patterns Correlate With Race Walking Economy in Elite Race Walkers: A Waveform Analysis

2019 ◽  
Vol 14 (9) ◽  
pp. 1250-1255
Author(s):  
Josu Gomez-Ezeiza ◽  
Jordan Santos-Concejero ◽  
Jon Torres-Unda ◽  
Brian Hanley ◽  
Nicholas Tam
Keyword(s):  
Muscle Activation ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Initial Contact ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Race Walking ◽  
Walking Economy

Purpose: To analyze the association between muscle activation patterns on oxygen cost of transport in elite race walkers over the entire gait waveform. Methods: A total of 21 Olympic race walkers performed overground walking trials at 14 km·h−1 where muscle activity of the gluteus maximus, adductor magnus, rectus femoris, biceps femoris, medial gastrocnemius, and tibialis anterior were recorded. Race walking economy was determined by performing an incremental treadmill test ending at 14 km·h−1. Results: This study found that more-economical race walkers exhibit greater gluteus maximus (P = .022, r = .716), biceps femoris (P = .011, r = .801), and medial gastrocnemius (P = .041, r = .662) activation prior to initial contact and weight acceptance. In addition, during the propulsive and the early swing phase, race walkers with higher activation of the rectus femoris (P = .021, r = .798) exhibited better race walking economy. Conclusions: This study suggests that the neuromuscular system is optimally coordinated through varying muscle activation to reduce the metabolic demand of race walking. These findings highlight the importance of proximal posterior muscle activation during initial contact and hip-flexor activation during early swing phase, which are associated with efficient energy transfer. Practically, race walking coaches may find this information useful in the development of specific training strategies on technique.

scholarly journals Relative index of ankle muscle activations on agonistic phase between subjects with and without flat foot

2015 ◽  
Vol 2 (1) ◽  
pp. 129 ◽  
Author(s):  
Paul S. Sung
Keyword(s):  
Muscle Activation ◽  
Time Window ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Flat Foot ◽  
Relative Index ◽  
Ankle Motion ◽  
Co Activation ◽  
Relative Activation ◽  
Ankle Muscle

Background: Although co-activation of ankle muscles has been reported, relative ankle muscle activation in subjects with flat foot has not been carefully investigated. The aim of this study was to compare the relative activation index (RAI) on the tibialis anterior (TA) and medial gastrocnemius (GTN) muscles during active ankle range of motion (ROM) between subjects with and without flat foot. Methods: There were 17 subjects with flat foot and 17 age- and gender-matched control subjects who participated in this study. The RAI based on electromyography (EMG) was measured during the agonist phase at a controlled velocity of ankle motion (10°/second). The subject was seated upright with the tested foot held firmly onto a footplate that was attached to a torque sensor. The ankle being measured was strapped to the leg support of the Intel stretch device at 60° of knee flexion. The RAI was analyzed by the summation of EMG activity from the agonistic time window divided by the total EMG activity during full active ankle ROM. Results: The RAI was significantly different on the TA muscle (t = 3.08, P = 0.004), but no difference was found on the GTN muscle (t = -1.24, P = 0.23) in subjects with flat foot. There was an interaction between group and RAI (F =7.89, P = 0.007); however, the RAI demonstrated no interaction with age (F = 2.59, P = 0.14), height (F = 3.73, P = 0.06), or weight (F = 2.96, P = 0.09). Conclusions: The RAI indicated a lack of TA muscle activation in the flat foot group. Such dissociated activation in the flat foot group might be relevant to the inefficiency of synergistic motions. The relative activation of the agonistic phase needs to be further investigated to compare co-activation of synergistic muscle activation with various functional tasks. 

Muscle coordination in cycling: effect of surface incline and posture

1998 ◽  
Vol 85 (3) ◽  
pp. 927-934 ◽  
Author(s):  
Li Li ◽  
Graham E. Caldwell
Keyword(s):  
Lower Extremity ◽  
High Speed ◽  
Vastus Lateralis ◽  
Activity Patterns ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extensors ◽  
Emg Activity ◽  
Muscle Coordination

The purpose of the present study was to examine the neuromuscular modifications of cyclists to changes in grade and posture. Eight subjects were tested on a computerized ergometer under three conditions with the same work rate (250 W): pedaling on the level while seated, 8% uphill while seated, and 8% uphill while standing (ST). High-speed video was taken in conjunction with surface electromyography (EMG) of six lower extremity muscles. Results showed that rectus femoris, gluteus maximus (GM), and tibialis anterior had greater EMG magnitude in the ST condition. GM, rectus femoris, and the vastus lateralis demonstrated activity over a greater portion of the crank cycle in the ST condition. The muscle activities of gastrocnemius and biceps femoris did not exhibit profound differences among conditions. Overall, the change of cycling grade alone from 0 to 8% did not induce a significant change in neuromuscular coordination. However, the postural change from seated to ST pedaling at 8% uphill grade was accompanied by increased and/or prolonged muscle activity of hip and knee extensors. The observed EMG activity patterns were discussed with respect to lower extremity joint moments. Monoarticular extensor muscles (GM, vastus lateralis) demonstrated greater modifications in activity patterns with the change in posture compared with their biarticular counterparts. Furthermore, muscle coordination among antagonist pairs of mono- and biarticular muscles was altered in the ST condition; this finding provides support for the notion that muscles within these antagonist pairs have different functions.

scholarly journals TRAINING LOAD DEMANDS MEASURED BY SURFACE ELECTROMYOGRAPHY WEARABLE TECHNOLOGY WHEN PERFORMING LAW ENFORCEMENT-SPECIFIC BODY DRAGS

2020 ◽  
pp. 001
Author(s):  
Robert George Lockie ◽  
Ashley Bloodgood ◽  
Matthew Moreno ◽  
Megan McGuire ◽  
Katherine Balfany ◽  
...  
Keyword(s):  
Law Enforcement ◽  
Surface Electromyography ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Wearable Technology ◽  
Training Load ◽  
Semg Signal ◽  
Body Drag

The use of surface electromyography (sEMG) wearable technology to measure training load (TL) during law enforcement-specific tasks (e.g. a body drag) requires investigation. This study determined muscle activation differences represented as TL during a 9.75-m drag with 74.84 kg and 90.72 kg dummies. Eight men and three women were fitted with a compression short or legging embedded with sEMG wearable technology to measure the quadriceps (QUAD; vastus medialis+vastus lateralis), biceps femoris (BF), and gluteus maximus (GM). After fitting on day one, participants completed maximal voluntary isometric contractions for each muscle to normalize the sEMG signal and calculate TL units. On days two and three, participants performed a 9.75 m body drag using either the 74.84 kg or the 90.72 kg dummy while wearing the technology. Participants lifted the dummy off the floor to a standing position and dragged it as quickly as possible over 9.75 m. Paired samples t-tests calculated between-drag differences for: time; QUAD, BF, GM, and total TL; and QUAD-BF, GM-BF, anterior-posterior (QUAD-GM+BF) ratios. QUAD TL was 9% greater (p=0.035), and GM TL was 8% lower (p=0.043), in the 90.72 kg body drag compared to the 74.84 kg drag. There were no between-mass differences in time, BF TL, total TL, or the ratios. QUAD TL increased while GM TL decreased when participants dragged a 90.72 kg dummy. As drag time was not different between the masses, drag mechanics may have changed leading to increased QUAD TL. sEMG wearable technology could be a useful method to measure TL in law enforcement-specific dragging tasks.

scholarly journals Metabolic Demand and Muscle Activation during Different Forms of Bodyweight Supported Locomotion in Men with Incomplete SCI

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Alyssa M. Fenuta ◽  
Audrey L. Hicks
Keyword(s):  
Body Weight ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Locomotor Training ◽  
Metabolic Demand ◽  
Metabolic Equivalents ◽  
Weight Support ◽  
Cord Injury

Body weight supported locomotor training uses neuroplasticity principles to improve recovery following a spinal cord injury (SCI). Steady state locomotion using the same body weight support (BWS) percent was compared in 7 males (42.6±4.29 years) with incomplete SCI and matched (gender, age) noninjured controls (42.7±5.4 years) using the Lokomat, Manual Treadmill, and ZeroG. The VO2000, Polar Heart Rate (HR) Monitor, and lower limb electromyography (EMG) electrodes were worn during the 2-minute sessions. Oxygen uptake (VO2) and HR were expressed as percentage of peak values obtained using progressive arm ergometry; VO2was also expressed relative to resting metabolic equivalents (METS). Filtered EMG signals from tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF), and medial gastrocnemius (MG) were normalized to ZeroG stepping. The Lokomat required 30% of VO2peak (2METS) compared to ~54% (3METS) for Manual Treadmill and ZeroG sessions. HR was 67% of peak during Lokomat sessions compared to ~83% for Manual Treadmill and ZeroG. Muscle activation was higher in treadmill conditions compared to the ZeroG primarily due to increased BF activity. At the same level of BWS, locomotion using the Manual Treadmill or the ZeroG is more aerobically demanding than the Lokomat. Treadmill modalities encourage greater hip extensor activation compared to overground locomotion.

Specific modulation of spinal and cortical excitabilities during lengthening and shortening submaximal and maximal contractions in plantar flexor muscles

2014 ◽  
Vol 117 (12) ◽  
pp. 1440-1450 ◽  
Author(s):  
Julien Duclay ◽  
Benjamin Pasquet ◽  
Alain Martin ◽  
Jacques Duchateau
Keyword(s):  
Muscle Activation ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
H Reflex ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Plantar Flexor ◽  
Lengthening Contractions ◽  
Flexor Muscles ◽  
Plantar Flexor Muscles

This study investigated the influence of the torque produced by plantar flexor muscles on cortical and spinal excitability during lengthening and shortening voluntary contractions. To that purpose, modulations of motor-evoked potential (MEP) and Hoffmann (H) reflex were compared in the soleus (SOL) and medial gastrocnemius (MG) during anisometric submaximal and maximal voluntary contraction (MVC) of the plantar flexor muscles. For the submaximal shortening and lengthening contractions, the target torque was set at 50% of their respective MVC force. The results indicate that the amplitudes of both MEP and H-reflex responses, normalized to the maximal M wave, were significantly ( P < 0.05) lower during lengthening compared with shortening submaximal contraction. For these two parameters, the reduction reached, respectively, 22.1 and 31.9% for the SOL and 34.5 and 29.3% for the MG. During MVC, normalized MEP and H reflex of the SOL were both reduced significantly by 19.9% ( P < 0.05) and 29.9% ( P < 0.001) during lengthening and shortening contraction, respectively, whereas no significant change ( P > 0.05) was observed for MG. In addition, the silent period in the ongoing electromyogram (EMG) activity following the MEP was significantly ( P < 0.01) briefer during lengthening than shortening contractions but did not differ ( P > 0.05) between contraction intensities and muscles. Together, these results indicate that cortical and spinal mechanisms involved in the modulation of muscle activation during shortening and lengthening contractions differ between synergistic muscles according to the torque produced. Data further document previous studies reporting that the specific modulation of muscle activation during lengthening contraction is not torque dependent.

scholarly journals The Effect of Repetitive Rugby Scrummaging on Force Output and Muscle Activity

2017 ◽  
Vol 01 (03) ◽  
pp. E89-E93 ◽  
Author(s):  
Darryl Cochrane ◽  
Keegan Harnett ◽  
Nicolas Lopez-Villalobos ◽  
Jeremy Hapeta
Keyword(s):  
Force Production ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Mean Amplitude ◽  
Erector Spinae ◽  
Medial Gastrocnemius ◽  
Median Frequency ◽  
Force Output ◽  
Subsequent Performance

AbstractDuring rugby scrummaging, front row forwards encounter high levels of force that has been suggested to cause transient fatigue and is likely to reduce subsequent performance. However, little is known about the effect of repetitive scrummaging on force output and onset of fatigue. Twelve male front row forwards (21.5±2.3 yr; height 185.7±4.4 cm; body mass 108.5±7.1 kg) each performed three sets of five maximal-effort isometric scrums for 10 s, with 40 s rest separating each repetition; 2 min recovery was provided between each set. Force output and electromyography (EMG) of the right medial gastrocnemius (MG), biceps femoris (BF), gluteus maximus (GM), erector spinae (ES), rectus abdominis (RA), external oblique (EO), internal oblique (IO), and rectus femoris (RF) were assessed. There was no significant force decrement from performing 15 scrums and no fatigue was detected from EMG median frequency and mean amplitude. For training and practice purposes, coaches and trainers can be confident that 15 individual repetitive static scrums against a machine are unlikely to cause a reduction in force production and promote fatigue. However, the effect of rugby-related activities in conjunction with scrummaging requires further research to determine if transient fatigue is causal to scrummaging for subsequent performance.

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