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Journal articles on the topic 'Hamstring coactivation'

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Author: Grafiati

Published: 11 March 2023

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1

Miller, John P., and Ronald V. Croce. "Analyses of Isokinetic and Closed Chain Movements for Hamstring Reciprocal Coactivation." Journal of Sport Rehabilitation 16, no. 4 (November 2007): 319–25. http://dx.doi.org/10.1123/jsr.16.4.319.

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Context:Researchers have postulated that coactivation of the hamstrings during active knee extension assists the anterior cruciate ligament in maintaining knee joint stability by exerting an opposing force to anterior tibial translation.Objective:To compare the reciprocal coactivation of the hamstrings while performing low and high velocity isokinetic movements and two closed chain movements.Design:Within subject’s comparison of isokinetic and closed chain exercises.Setting:Biomechanics laboratory utilizing a Cybex norm isokinetic dynamometer and Biopac Data Collection system.Participants:12 healthy women.Main Outcome Measures:The root mean square of the Electromyogram (rmsEMG) was used as a measure of overall muscle activity.Results:The rmsEMG for hamstring coactivation during knee extension showed significant differences between the isokinetic movements and the closed chain exercises with greater coactivation when performing the isokinetic movements. In addition, greater activity was seen at the higher isokinetic velocity and during the one legged squat.Conclusions:These results suggest isokinetic movements, particularly at high speed, can more effectively increase the coactivation activity of the hamstrings when compared to two closed chain activities.

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Shields, Richard K., Sangeetha Madhavan, Emy Gregg, Jennifer Leitch, Ben Petersen, Sara Salata, and Stacey Wallerich. "Neuromuscular Control of the Knee during a Resisted Single-Limb Squat Exercise." American Journal of Sports Medicine 33, no. 10 (October 2005): 1520–26. http://dx.doi.org/10.1177/0363546504274150.

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Background Closed kinetic chain exercises such as single-limb squats are preferred for knee rehabilitation. A complete understanding of the neuromuscular control of the knee during the single-limb squat is essential to increase the efficiency of rehabilitation programs. Hypothesis Performing a controlled single-limb squat with resistance to knee flexion and extension will increase the coactivation of the hamstring muscle group, thus reducing the quadriceps/hamstrings ratio. Study Design Descriptive laboratory study. Methods A total of 15 healthy human subjects (7 women, 8 men) performed controlled single-limb squats in a custom mechanical device that provided resistance to both flexion and extension. Subjects performed the task at 3 levels of resistance, set as a percentage of body weight. Surface electromyographic recordings from 7 muscles (gluteus medius, rectus femoris, vastus medialis oblique, vastus lateralis, biceps femoris, semitendinosus, and medial gastrocnemius) were collected during the task. Results Biceps femoris activity during knee flexion increased from approximately 12% maximum voluntary isometric contractions during low resistance (0% body weight) to approximately 27% maximum voluntary isometric contractions during high resistance (8% body weight). Although the quadriceps had greater activity than the hamstrings at all levels of resistance, the quadriceps/hamstrings ratio declined significantly with resistance (F2,27 = 29.05; P=. 012) from 3.0 at low resistance to 2.32 at the highest resistance. Conclusions Performing controlled resisted single-limb squats may help to simultaneously strengthen the quadriceps and facilitate coactivation of the hamstrings, thus reducing anterior tibial shear forces. The coactivation may also increase the dynamic control of the knee joint. Clinical Relevance The typical single-limb squat exercise performed in the clinic does not usually control for bidirectional resistance and knee joint excursion. As seen in this study, controlled single-limb squats at increased levels of resistance help to increase the coactivation of the hamstring muscles, which is essential to optimize neuromuscular control of the knee.

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Carolan, B., and E. Cafarelli. "Adaptations in coactivation after isometric resistance training." Journal of Applied Physiology 73, no. 3 (September 1, 1992): 911–17. http://dx.doi.org/10.1152/jappl.1992.73.3.911.

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Twenty sedentary male university students were randomly assigned to an experimental or a control group. The experimental group trained the knee extensors of one leg by producing 30 isometric extension maximal voluntary contractions (MVC) per day, three times per week for 8 wk. After 8 wk of training, extensor MVC in the trained leg increased 32.8% (P less than 0.05), but there was no change in vastus lateralis maximal integrated electromyographic activity (IEMGmax). The most important finding was that the degree of hamstring coactivation during extension MVC decreased by approximately 20% (P less than 0.05) after the 1st wk of training. Less pronounced adaptations occurred in the untrained leg: extension MVC force increased 16.2% (P less than 0.05), hamstring coactivity decreased 13% (P less than 0.05) after 2 wk of training, and vastus lateralis IEMGmax was unchanged. The same measures in legs of the control group were not changed during the study. There were no changes in flexion MVC, biceps femoris IEMGmax, or the degree of quadriceps coactivity during flexion MVC in either leg of the control or experimental group. A reduction in hamstring coactivity in the trained and untrained legs indicates that these muscles provide less opposing force to the contracting quadriceps. We conclude that this small but significant decrease in hamstring coactivation that occurs during the early stages of training is a nonhypertrophic adaptation of the neuromuscular system in response to static resistance training of this type.

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Harput, Gulcan, A. Ruhi Soylu, Hayri Ertan, Nevin Ergun, and Carl G. Mattacola. "Effect of Gender on the Quadriceps-to-Hamstrings Coactivation Ratio During Different Exercises." Journal of Sport Rehabilitation 23, no. 1 (February 2014): 36–43. http://dx.doi.org/10.1123/jsr.2012-0120.

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Context:Coactivation ratio of quadriceps to hamstring muscles (Q:H) and medial to lateral knee muscles (M:L) contributes to the dynamic stability of the knee joint during movement patterns recommended during rehabilitation and important for daily function.Objective:To compare the quadriceps-to-hamstring and medial-to-lateral knee muscles' coactivation ratios between men and women during the following closed kinetic chain exercises performed on a balance board: forward lunge, side lunge, single-leg stance, and single-leg squat.Design:Cross-sectional.Participants:20 healthy subjects (10 female and 10 male).Main Outcome Measures:Surface electromyography was used to measure the activation level of quadriceps (vastus lateralis and medialis) and hamstrings (biceps femoris and medial hamstrings) during forward- and side-lunge, single-leg-stance, and single-leg-squat exercises. Subjects were instructed during each exercise to move into the test position and to hold that position for 15 s. EMG was recorded during the 15-s isometric period where subjects tried to maintain a “set” position while the foot was on a balance board. Analysis of variance was used for statistical analysis.Results:There was a significant exercise-by-gender interaction for Q:H ratio (F3,48 = 6.63, P = .001), but the exercise-by-gender interaction for M:L ratio was not significant (F3,48 = 1.67, P = .18). Women showed larger Q:H ratio in side-lunge exercises than men (P = .002). Both genders showed larger M:L and lower Q:H ratio in a single-leg-stance exercise than in the other exercises.Conclusions:The results indicate that the forward- and side-lunge and single-leg-squat exercises should not be recommended as exercise where a balanced coactivation between quadriceps and hamstring muscles is warranted. Single-leg-stance exercise could be used when seeking an exercise where the ratio is balanced for both women and men.

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Hortobágyi, Tibor, Paul DeVita, Robert Brady, and Patrick Rider. "Training History-Dependent Functional Role of EMG Model-Predicted Antagonist Moments in Knee Extensor Moment Generation in Healthy Young Adults." Biomechanics 2, no. 1 (January 6, 2022): 7–19. http://dx.doi.org/10.3390/biomechanics2010002.

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Resistance training (RT) improves the skeletal muscle’s ability to generate maximal voluntary force and is accompanied by changes in the activation of the antagonist muscle which is not targeted primarily by RT. However, the nature and role of neural adaptation to RT in the antagonist muscle is paradoxical and not well understood. We compared moments, agonist muscle activation, antagonist activation, agonist-antagonist coactivation, and electromyographic (EMG) model-predicted moments generated by antagonist hamstring muscle coactivation during isokinetic knee extension in leg strength-trained (n = 10) and untrained (n = 11) healthy, younger adults. Trained vs. untrained adults were up to 58% stronger. During knee extension, hamstring activation was 1.6-fold greater in trained vs. untrained adults (p = 0.022). This hamstring activation produced 2.6-fold greater model-predicted antagonist moments during knee extension in the trained (42.7 ± 19.55 Nm) vs. untrained group (16.4 ± 12.18 Nm; p = 0.004), which counteracted (reduced) quadriceps knee extensor moments ~43 Nm (0.54 Nm·kg−1) and by ~16 Nm (0.25 Nm·kg−1) in trained vs. untrained. Antagonist hamstring coactivation correlated with decreases and increases, respectively, in quadriceps moments in trained and untrained. The EMG model-predicted antagonist moments revealed training history-dependent functional roles in knee extensor moment generation.

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Osternig, L. R., B. L. Caster, and C. R. James. "1069 CONTRALATERAL HAMSTRING COACTIVATION PATTERNS AND ANTERIOR CRUCIATE LIGAMENT DYSFUNCTION." Medicine & Science in Sports & Exercise 26, Supplement (May 1994): S190. http://dx.doi.org/10.1249/00005768-199405001-01071.

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Weir, Joseph P., Dennis A. Keefe, Jason F. Eaton, Robert T. Augustine, and Dawn M. Tobin. "Effect of fatigue on hamstring coactivation during isokinetic knee extensions." European Journal of Applied Physiology 78, no. 6 (October 1, 1998): 555–59. http://dx.doi.org/10.1007/s004210050460.

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Torres, Gonzalo, David Chorro, Archit Navandar, Javier Rueda, Luís Fernández, and Enrique Navarro. "Assessment of Hamstring: Quadriceps Coactivation without the Use of Maximum Voluntary Isometric Contraction." Applied Sciences 10, no. 5 (February 29, 2020): 1615. http://dx.doi.org/10.3390/app10051615.

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This study aimed to study the coactivation patterns of the hamstring and quadriceps muscle groups during submaximal strength exercises commonly used in injury prevention in soccer without the use of maximum voluntary isometric contraction testing. This was used to compare: (i) the inter-limb differences in muscle activation; (ii) the intra-muscular group activation pattern and (iii) the activation pattern during different phases of the exercise. Muscle activation was recorded by surface electromyography in 19 elite, male, youth soccer players. Participants performed the following: Bulgarian squat, lunge and squat. Electrical activity was recorded for the rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus. No significant inter-limb differences were found (F1, 13 = 619; p = 0.82; η2 = 0.045). Significant differences were found in the muscle activation between individual muscles within the quadriceps and hamstrings muscle group for each of the exercises: Bulgarian squat (F1,18 = 331: p < 0.001; η2 = 0.80), lunge (F4,72 = 114.5; p < 0.001; η2 = 0.86) and squat (F1,16 = 247.31; p < 0.001; η2 = 0.93). Differences were found between the different phases of each of the exercises (F2,26 = 52.27; p = 0.02; η2 = 0.80). The existence of an activation pattern of each of the muscles in the three proposed exercises could be used for muscle assessment and as a tool for reconditioning post-injury.

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OSTERNIG, LOUIS R., BRIAN L. CASTER, and C. ROGER JAMES. "Contralateral hamstring (biceps femoris) coactivation patterns and anterior cruciate ligament dysfunction." Medicine & Science in Sports & Exercise 27, no. 6 (June 1995): 805???808. http://dx.doi.org/10.1249/00005768-199506000-00003.

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Eken, Maaike M., Annet J. Dallmeijer, Caroline A. M. Doorenbosch, Hurnet Dekkers, Jules G. Becher, and Han Houdijk. "Coactivation During Dynamometry Testing in Adolescents With Spastic Cerebral Palsy." Physical Therapy 96, no. 9 (September 1, 2016): 1438–47. http://dx.doi.org/10.2522/ptj.20140448.

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Abstract Background Dynamometry has been used extensively to measure knee extensor strength in individuals with cerebral palsy (CP). However, increased coactivation can lead to underestimation of knee extensor strength and, therefore, reduce validity of strength measurements. It is yet unknown to what extent coactivation occurs during dynamometry testing and whether coactivation is influenced by severity of CP, load levels, and muscle fatigue. Objectives The aims of this study were: (1) to investigate coactivation in adolescents with and without CP during dynamometer tests and (2) to assess the effect of Gross Motor Function Classification System (GMFCS) level, load level, and muscle fatigue on coactivation. Design A cross-sectional observational design was used. Method Sixteen adolescents with CP (GMFCS levels I and II: n=10/6; age range=13–19 years) and 15 adolescents without CP (n=15; age range=12–19 years) performed maximal isometric contractions (maximal voluntary torque [MVT]) and a series of submaximal dynamic contractions at low (±65% MVT), medium (±75% MVT), and high (±85% MVT) loads until fatigue. A coactivation index (CAI) was calculated for each contraction from surface electromyography recordings from the quadriceps and hamstring muscles. Results Adolescents with CP classified in GMFCS level II showed significantly higher CAI values than adolescents classified in GMFCS level I and those without CP during maximal and submaximal contractions. No differences were observed among load levels. During the series of fatiguing submaximal contractions, CAI remained constant in both the CP group and the group with typical development (TD), except for adolescents with TD at the low-load condition, which showed a significant decrease. Limitations Electromyography tracings were normalized to amplitudes during maximal isometric contractions, whereas previous studies suggested that these types of contractions could not be reliably determined in the CP population. Conclusion Coactivation was higher in adolescents with CP classified in GMFCS level II than in adolescents with TD and those with CP in GMFCS level I at different load levels. Within all groups, coactivation was independent of load level and fatigue. In individuals with CP, coactivation can lead to an underestimation of agonist muscle strength, which should be taken into account while interpreting the results of both maximal and submaximal dynamometer tests.

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Sisante, Jason‐Flor, Na Wang, David T. Felson, Michael C. Nevitt, Cora E. Lewis, Laura Frey‐Law, Neil A. Segal, et al. "Influence of Antagonistic Hamstring Coactivation on Measurement of Quadriceps Strength in Older Adults." PM&R 12, no. 5 (November 25, 2019): 470–78. http://dx.doi.org/10.1002/pmrj.12253.

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Segal, N. A., M. C. Nevitt, R. D. Welborn, U. S. D. T. Nguyen, J. Niu, C. E. Lewis, D. T. Felson, and L. Frey-Law. "The association between antagonist hamstring coactivation and episodes of knee joint shifting and buckling." Osteoarthritis and Cartilage 23, no. 7 (July 2015): 1112–21. http://dx.doi.org/10.1016/j.joca.2015.02.773.

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Dashti Rostami, Komeil, Aynollah Naderi, and Abbey Thomas. "Hip Abductor and Adductor Muscles Activity Patterns During Landing After Anterior Cruciate Ligament Injury." Journal of Sport Rehabilitation 28, no. 8 (November 1, 2019): 871–76. http://dx.doi.org/10.1123/jsr.2018-0189.

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Context: Hamstring and quadriceps activity adaptations are well known in individuals with anterior cruciate ligament deficiency (ACLD) and reconstructed (ACLR) to potentially compensate for knee joint instability. However, few studies have explored hip muscles activity patterns after ACL injury. Objective: To examine the activation characteristics of gluteus medius (GMED) and adductor longus in ACLR and ACLD subjects compared with controls. Design: Case–control study. Setting: Athletic training room and university lab. Participants: Twelve healthy and 24 ACL-injured (12 ACLR and 12 ACLD) recreationally active male volunteers. Interventions: Surface electromyography of the GMED and adductor longus were recorded during a single-leg vertical drop landing and normalized to maximum voluntary isometric contractions. Main Outcome Measures: Preparatory and reactive muscle activity and coactivation were analyzed from 100 milliseconds prior to initial contact to 250 milliseconds postcontact. Results: During reactive activity, ACL-injured (ACLR and ACLD) participants demonstrated significantly lower peak GMED activity compared with controls (F = 4.33, P = .02). In addition, ACLR participants exhibited significantly lower reactive GMED:adductor longus coactivation muscle activity compared with controls (F = 4.09, P = .03). Conclusion: Our findings suggest neuromuscular adaptations of the hip musculature are present in people at least 2 years from ACL injury. GMED activation exercises should be considered in designing rehabilitation programs for ACL-injured individuals.

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Bryant, A., R. Clark, and Y. Pua. "Hamstring force control following ACL injury and reconstruction and its relation to quadriceps coactivation and dynamic knee joint stability." Journal of Science and Medicine in Sport 13 (December 2010): e5-e6. http://dx.doi.org/10.1016/j.jsams.2010.10.473.

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Jeong, Jiyoung, Dai-Hyuk Choi, and Choongsoo S. Shin. "Core Strength Training Can Alter Neuromuscular and Biomechanical Risk Factors for Anterior Cruciate Ligament Injury." American Journal of Sports Medicine 49, no. 1 (December 31, 2020): 183–92. http://dx.doi.org/10.1177/0363546520972990.

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Background: Core stability is influential in the incidence of lower extremity injuries, including anterior cruciate ligament (ACL) injuries, but the effects of core strength training on the risk for ACL injury remain unclear. Hypothesis: Core muscle strength training increases the knee flexion angle, hamstring to quadriceps (H:Q) coactivation ratio, and vastus medialis to vastus lateralis (VM:VL) muscle activation ratio, as well as decreases the hip adduction, knee valgus, and tibial internal rotation angles. Study Design: Controlled laboratory study. Methods: A total of 48 male participants were recruited and randomly assigned to either the intervention group (n = 32) or the control group (n = 16). Three-dimensional trunk, hip, knee, and ankle kinematic data and muscle activations of selected trunk and lower extremity muscles were obtained while the participants performed side-step cutting. The core endurance scores were measured before and after training. Two-way analyses of variance were conducted for each dependent variable to determine the effects of 10 weeks of core strength training. Results: The trunk endurance scores in the intervention group significantly increased after training ( P < .05 for all comparisons). The intervention group showed decreased knee valgus ( P = .038) and hip adduction angles ( P = .032) but increased trunk flexion angle ( P = .018), rectus abdominis to erector spinae coactivation ratio ( P = .047), H:Q coactivation ratio ( P = .021), and VM:VL activation ratio ( P = .016). In addition, the knee valgus angle at initial contact was negatively correlated with the VM:VL activation ratio in the precontact phase ( R2 = 0.188; P < .001) but was positively correlated with the hip adduction angle ( R2 = 0.120; P < .005). No statistically significant differences were observed in the trunk endurance scores, kinematics, and muscle activations for the control group. Conclusion: Core strength training altered the motor control strategies and joint kinematics for the trunk and the lower extremity by increasing the trunk flexion angle, VM:VL activation ratio, and H:Q activation ratio and reducing the knee valgus and hip adduction angles. Clinical Relevance: Training core muscles can modify the biomechanics associated with ACL injuries in a side-step cutting task; thus, core strength training might be considered in ACL injury prevention programs to alter the lower extremity alignment in the frontal plane and muscle activations during sports-related tasks.

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Segal, N. A., G. Rabasa, M. C. Nevitt, L. A. Frey Law, C. E. Lewis, A. Guermazi, F. Roemer, and D. T. Felson. "ASSOCIATION BETWEEN ELEVATED HAMSTRING COACTIVATION AND KNEE CARTILAGE WORSENING IS INDEPENDENT OF ISOKINETIC QUADRICEPS STRENGTH IN THE MULTICENTER OSTEOARTHRITIS STUDY." Osteoarthritis and Cartilage 30 (April 2022): S52. http://dx.doi.org/10.1016/j.joca.2022.02.058.

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Pierce, Samuel R., Mary F. Barbe, Ann E. Barr, Patricia A. Shewokis, and Richard T. Lauer. "Roles of Reflex Activity and Co-contraction During Assessments of Spasticity of the Knee Flexor and Knee Extensor Muscles in Children With Cerebral Palsy and Different Functional Levels." Physical Therapy 88, no. 10 (October 1, 2008): 1124–34. http://dx.doi.org/10.2522/ptj.20070331.

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Background and Purpose Spasticity is a common impairment in children with cerebral palsy (CP). The purpose of this study was to examine differences in passive resistive torque, reflex activity, coactivation, and reciprocal facilitation during assessments of the spasticity of knee flexor and knee extensor muscles in children with CP and different levels of functional ability. Subjects Study participants were 20 children with CP and 10 children with typical development (TD). The 20 children with CP were equally divided into 2 groups: 10 children classified in Gross Motor Function Classification Scale (GMFCS) level I and 10 children classified in GMFCS level III. Methods One set of 10 passive movements between 25 and 90 degrees of knee flexion and one set of 10 passive movements between 90 and 25 degrees of knee flexion were completed with an isokinetic dynamometer at 15°/s, 90°/s, and 180°/s and concurrent surface electromyography of the vastus lateralis and medial hamstring muscles. Results Children in the GMFCS level III group demonstrated significantly more peak knee flexor torque with passive movements at 180°/s than children with TD. Children in the GMFCS level I and level III groups demonstrated significantly more repetitions with medial hamstring muscle activity, vastus lateralis muscle activity, and co-contraction than children with TD during the assessment of knee flexor spasticity at a velocity of 180°/s. Discussion and Conclusion Children with CP and more impaired functional mobility may demonstrate more knee flexor spasticity and reflex activity, as measured by isokinetic dynamometry, than children with TD. However, the finding of increased reflex activity with no increase in torque in the GMFCS I group in a comparison with the TD group suggests that reflex activity may play a less prominent role in spasticity.

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Segal, N. A., G. Rabasa, M. C. Nevitt, and D. T. Felson. "ISOKINETIC QUADRICEPS WEAKNESS, BUT NOT ANTAGONISTIC HAMSTRING COACTIVATION, IS ASSOCIATED WITH HIGHER RISK FOR TOTAL KNEE ARTHROPLASTY IN THE MULTICENTER OSTEOARTHRITIS STUDY." Osteoarthritis and Cartilage 30 (April 2022): S256. http://dx.doi.org/10.1016/j.joca.2022.02.348.

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TANZILA, TAJ, and SUBHRA CHATTERJEE. "Comparison of the Electromyographic activity, Quadriceps: Hamstring coactivation ratio and strength changes of dominant leg muscles in collegiate football and volleyball players during different forms of exercises." biology of exercise 11, no. 2 (2015): 73–88. http://dx.doi.org/10.4127/jbe.2015.0093.

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Begalle, Rebecca L., Lindsay J. DiStefano, Troy Blackburn, and Darin A. Padua. "Quadriceps and Hamstrings Coactivation During Common Therapeutic Exercises." Journal of Athletic Training 47, no. 4 (July 1, 2012): 396–405. http://dx.doi.org/10.4085/1062-6050-47.4.01.

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Context: Anterior tibial shear force and knee valgus moment increase anterior cruciate ligament (ACL) loading. Muscle coactivation of the quadriceps and hamstrings influences anterior tibial shear force and knee valgus moment, thus potentially influencing ACL loading and injury risk. Therefore, identifying exercises that facilitate balanced activation of the quadriceps and hamstrings might be beneficial in ACL injury rehabilitation and prevention. Objective: To quantify and compare quadriceps with hamstrings coactivation electromyographic (EMG) ratios during commonly used closed kinetic chain exercises. Design: Cross-sectional study. Setting: Research laboratory. Patients or Other Participants: Twenty-seven healthy, physically active volunteers (12 men, 15 women; age = 22.1 ± 3.1 years, height = 171.4 ± 10 cm, mass = 72.4 ± 16.7 kg). Intervention(s): Participants completed 9 separate closed chain therapeutic exercises in a randomized order. Main Outcome Measure(s): Surface electromyography quantified the activity level of the vastus medialis (VM), vastus lateralis (VL), medial hamstrings (MH), and biceps femoris (BF) muscles. The quadriceps-to-hamstrings (Q:H) coactivation ratio was computed as the sum of average quadriceps (VM, VL) EMG amplitude divided by the sum of average hamstrings (MH, BF) EMG amplitude for each trial. We used repeated-measures analyses of variance to compare Q:H ratios and individual muscle contributions across exercises (α = .05), then used post hoc Tukey analyses. Results: We observed a main effect for exercise (F3,79 = 22.6, P < .001). The post hoc Tukey analyses revealed smaller Q:H ratios during the single-limb dead lift (2.87 ± 1.77) than the single-limb squat (5.52 ± 2.89) exercise. The largest Q:H ratios were observed during the transverse-lunge (7.78 ± 5.51, P < .001), lateral-lunge (9.30 ± 5.53, P < .001), and forward-lunge (9.70 ± 5.90, P < .001) exercises. Conclusions: The most balanced (smallest) coactivation ratios were observed during the single-limb dead-lift, lateral-hop, transverse-hop, and lateral band-walk exercises. These exercises potentially could facilitate balanced activation in ACL rehabilitation and injury-prevention programs. They also could be used in postinjury rehabilitation programs in a safe and progressive manner.

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Grabiner, M. D., and G. G. Weiker. "Anterior cruciate ligament injury and hamstrings coactivation." Clinical Biomechanics 8, no. 4 (July 1993): 215–19. http://dx.doi.org/10.1016/0268-0033(93)90017-c.

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Croce, Ronald V., John P. Miller, Robert Confessore, and James C. Vailas. "Reciprocal Coactivation Patterns of the Lateral and Medial Quadriceps and Hamstrings during Low- and Moderate-Speed Isokinetic Movement." Journal of Sport Rehabilitation 7, no. 3 (August 1998): 182–96. http://dx.doi.org/10.1123/jsr.7.3.182.

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The purpose of this study was to examine coactivation patterns of the lateral and medial quadriceps and the lateral and medial hamstrings during low- and moderate-speed isokinetic movements. Twelve female athletes performed isokinetic knee assessments at 60 and 180°/s. Root mean square electromyographic (rmsEMG) activity and the median frequency of the EMG (mfEMG) were determined by placing bipolar surface electrodes on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial hamstrings (MH). Results of rmsEMG indicated that the VM showed almost twice the coactivation of the VL (p< .05), and that the BF showed almost four times the coactivation of the MH (p <.05). Finally, differences were noted in the mfEMG (p< .05), with the VM displaying different recruitment patterns at 180°/s as an agonist compared to that as an antagonist. Results indicated that when acting as antagonists, the VM and BE display the greatest EMG patterns during isokinetic knee joint movement.

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Zajac, F. E. "Thigh muscle activity during maximum-height jumps by cats." Journal of Neurophysiology 53, no. 4 (April 1, 1985): 979–94. http://dx.doi.org/10.1152/jn.1985.53.4.979.

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Cats were trained to jump from a force plate and touch a cotton ball suspended as high as 1.6 m. Force-plate reaction forces and double-joint hamstring muscle activity observed early in propulsion varied from one maximal jump to another. This variability is consistent with theory (31, 32, 42); that is, different coordination strategies can be implemented prior to the heels losing contact with the force plate (heel-off). Single-joint hip extensor and double-joint posterior thigh (hip extensor-knee flexor) muscles were coactivated prior to heel-off. This coactivation is probably partially responsible for the observed backward rotation of the trunk. Forepaws, observed to contact the force plate prior to heel-off, probably assist the hindlimbs in generating trunk rotation. Both single-joint knee extensor and hip extensor muscles exhibited greatest activation between heel-off and body lift-off. Single-joint flexor muscles were inactive throughout propulsion. Double-joint posterior thigh muscles were deactivated at heel-off and remained inactivated until lift-off. These observations agree with the theoretical notion that muscles should be either fully activated, inactivated, or switched from one extreme to the other (i.e., bang-bang control) between heel-off and body lift-off (31, 32, 42, 44). All seven muscles studied shortened while activated. Using computations based on muscle geometry, fiber architecture, and joint angle trajectories, I propose that sarcomeres shorten along the flat and ascending regions of the force-length curve. De- and inactivation of double-joint posterior thigh muscles between heel-off and lift-off coincided with muscle stretch. The reason for inactivation of these muscles is that the negative work that would have been generated had these muscles stayed activated would have hindered propulsion. Contractions preceded by active stretch were not observed. Enhancement of positive work by previous storage of energy in elastic musculotendinous structures is thus not used by cat thigh musculature in jumps starting from the squat. Adductor femoris, semimembranosus anterior, and biceps femoris anterior muscles were activated synergistically as one group yet differently from the synergistic activation of gracilis, semitendinosus, and biceps femoris posterior muscles. The separation of these muscles into two groups based on their activation patterns during jumping is compatible with the classification of these muscles into hip extensor and knee flexor muscle groups, respectively, based on their reflex patterns (37), spinal cord reflex connectivity (18, 30), and firing patterns during locomotion (20).(ABSTRACT TRUNCATED AT 400 WORDS)

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Draganich, L. F., R. J. Jaeger, and A. R. Kralj. "Coactivation of the hamstrings and quadriceps during extension of the knee." Journal of Biomechanics 23, no. 7 (January 1990): 728. http://dx.doi.org/10.1016/0021-9290(90)90232-r.

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WU, RUI, EAMONN DELAHUNT, MASSIMILIANO DITROILO, MADELEINE M. LOWERY, and GIUSEPPE DE VITO. "Effect of Knee Joint Angle and Contraction Intensity on Hamstrings Coactivation." Medicine & Science in Sports & Exercise 49, no. 8 (August 2017): 1668–76. http://dx.doi.org/10.1249/mss.0000000000001273.

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Draganich, L. F., R. J. Jaeger, and A. R. Kralj. "Coactivation of the hamstrings and quadriceps during extension of the knee." Journal of Bone & Joint Surgery 71, no. 7 (August 1989): 1075–81. http://dx.doi.org/10.2106/00004623-198971070-00015.

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Ruas, Cassio, Lee Brown, Camila Lima, G. Gregory Haff, and Ronei Pinto. "Different Muscle Action Training Protocols on Quadriceps-Hamstrings Neuromuscular Adaptations." International Journal of Sports Medicine 39, no. 05 (March 21, 2018): 355–65. http://dx.doi.org/10.1055/s-0044-100391.

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AbstractThe aim of this study was to compare three specific concentric and eccentric muscle action training protocols on quadriceps-hamstrings neuromuscular adaptations. Forty male volunteers performed 6 weeks of training (two sessions/week) of their dominant and non-dominant legs on an isokinetic dynamometer. They were randomly assigned to one of four groups; concentric quadriceps and concentric hamstrings (CON/CON, n=10), eccentric quadriceps and eccentric hamstrings (ECC/ECC, n=10), concentric quadriceps and eccentric hamstrings (CON/ECC, n=10), or no training (CTRL, n=10). Intensity of training was increased every week by decreasing the angular velocity for concentric and increasing it for eccentric groups in 30°/s increments. Volume of training was increased by adding one set every week. Dominant leg quadriceps and hamstrings muscle thickness, muscle quality, muscle activation, muscle coactivation, and electromechanical delay were tested before and after training. Results revealed that all training groups similarly increased MT of quadriceps and hamstrings compared to control (p<0.05). However, CON/ECC and ECC/ECC training elicited a greater magnitude of change. There were no significant differences between groups for all other neuromuscular variables (p>0.05). These findings suggest that different short-term muscle action isokinetic training protocols elicit similar muscle size increases in hamstrings and quadriceps, but not for other neuromuscular variables. Nevertheless, effect sizes indicate that CON/ECC and ECC/ECC may elicit the greatest magnitude of change in muscle hypertrophy.

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Mills, P. M., D. Sturnieks, A. Dempsey, S. Ilich, T. Ackland, D. G. Lloyd, and T. Besier. "Quadriceps-hamstrings coactivation during maximal strength testing does not reflect coactivation during walking 3 months following arthroscopic partial meniscectomy." Osteoarthritis and Cartilage 21 (April 2013): S275. http://dx.doi.org/10.1016/j.joca.2013.02.576.

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Hanson, Ashley M., Darin A. Padua, J. Troy Blackburn, William E. Prentice, and Christopher J. Hirth. "Muscle Activation During Side-Step Cutting Maneuvers in Male and Female Soccer Athletes." Journal of Athletic Training 43, no. 2 (March 1, 2008): 133–43. http://dx.doi.org/10.4085/1062-6050-43.2.133.

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Abstract Context: Female soccer athletes are at greater risk of anterior cruciate ligament (ACL) injury than males. Sex differences in muscle activation may contribute to the increased incidence of ACL injuries in female soccer athletes. Objective: To examine sex differences in lower extremity muscle activation between male and female soccer athletes at the National Collegiate Athletic Association Division I level during 2 side-step cutting maneuvers. Design: Cross-sectional with 1 between-subjects factor (sex) and 2 within-subjects factors (cutting task and phase of contact). Setting: Sports medicine research laboratory. Patients or Other Participants: Twenty males (age = 19.4 ± 1.4 years, height = 176.5 ± 5.5 cm, mass = 74.6 ± 6.0 kg) and 20 females (age = 19.8 ± 1.1 years, height = 165.7 ± 4.3 cm, mass = 62.2 ± 7.2 kg). Intervention(s): In a single testing session, participants performed the running-approach side-step cut and the box-jump side-step cut tasks. Main Outcome Measure(s): Surface electromyographic activity of the rectus femoris, vastus lateralis, medial hamstrings, lateral hamstrings, gluteus medius, and gluteus maximus was recorded for each subject. Separate mixed-model, repeated-measures analysis of variance tests were used to compare the dependent variables across sex during the preparatory and loading contact phases of each cutting task. Results: Females displayed greater vastus lateralis activity and quadriceps to hamstrings coactivation ratios during the preparatory and loading phases, as well as greater gluteus medius activation during the preparatory phase only. No significant differences were noted between the sexes for muscle activation in the other muscles analyzed during each task. Conclusions: The quadriceps-dominant muscle activation pattern observed in recreationally active females is also present in female soccer athletes at the Division I level when compared with similarly trained male soccer athletes. The relationship between increased quadriceps activation and greater incidence of noncontact ACL injury in female soccer athletes versus males requires further study.

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Chow, John W., and Dobrivoje S. Stokic. "Characteristics of rectus femoris activation and rectus femoris–hamstrings coactivation during force-matching isometric knee extension in subacute stroke." Experimental Brain Research 239, no. 8 (July 2, 2021): 2621–33. http://dx.doi.org/10.1007/s00221-021-06162-0.

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Miller, John P., Ronald V. Croce, and Ronald Hutchins. "Reciprocal coactivation patterns of the medial and lateral quadriceps and hamstrings during slow, medium and high speed isokinetic movements." Journal of Electromyography and Kinesiology 10, no. 4 (August 2000): 233–39. http://dx.doi.org/10.1016/s1050-6411(00)00012-2.

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Yu, Shiqi, Timothy Lowe, Lisa Griffin, and Xuanliang Neil Dong. "Single bout of vibration-induced hamstrings fatigue reduces quadriceps inhibition and coactivation of knee muscles after anterior cruciate ligament (ACL) reconstruction." Journal of Electromyography and Kinesiology 55 (December 2020): 102464. http://dx.doi.org/10.1016/j.jelekin.2020.102464.

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Steldt, Robert E., and Brian D. Schmit. "Modulation of Coordinated Muscle Activity During Imposed Sinusoidal Hip Movements in Human Spinal Cord Injury." Journal of Neurophysiology 92, no. 2 (August 2004): 673–85. http://dx.doi.org/10.1152/jn.00677.2003.

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Individuals with chronic spinal cord injury (SCI) often demonstrate multijoint reflex activity that is clinically classified as an extensor spasm. These responses are commonly observed in conjunction with an imposed extension movement of the hips, such as movement from a sit to a supine position. Coincidentally, afferent feedback from hip proprioceptors has also been implicated in the control of locomotion in the spinalized cat. Because of this concurrence, we postulated that extensor spasms that are triggered by hip extension might involve activation of organized interneuronal circuits that also have a role in locomotion. If true, imposed oscillations of the hip would be expected to produce activity of the leg musculature in a locomotor pattern. Furthermore, this muscle activity would be entrained to the hip movement. The right hip joints of 10 individuals with chronic SCI, consisting of both complete [American Spinal Injury Association (ASIA) A] and incomplete (ASIA B,C) injuries, were subjected to ramp and hold (10 s) movements at 60°/s and sinusoidal oscillations at 1.2, 1.88, and 2.2 rad/s over ranges from 40 to –15° (±5°) using a custom servomotor system. Surface EMG from seven lower extremity muscles and sagittal-plane joint torques were recorded to characterize the response. Ramp and hold perturbations produced coactivation at the hip, knee, and ankle joints, with a long duration (5–10 s). Sinusoidal perturbations yielded consistent muscle timing patterns that resulted in alternating flexor and extensor joint torques. EMG and joint torques were commonly entrained to the frequency of movement, with rectus femoris, vastus medialis, and soleus activity coinciding with hip extension and medial hamstrings activity occurring during hip flexion. Individual muscle timing patterns were consistent with hip position during normal gait, except for the vastus medialis. These results suggest that reflexes associated with extensor spasms may occur through organized interneuronal pathways, such as spinal centers for locomotion.

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Wu, Hong-Wen, Yi-Shuo Chang, Md Samsul Arefin, Yu-Lin You, Fong-Chin Su, and Cheng-Feng Lin. "Six-Week Remodeled Bike Pedal Training Improves Dynamic Control of Lateral Shuffling in Athletes With Functional Ankle Instability." Sports Health: A Multidisciplinary Approach, August 16, 2021, 194173812110357. http://dx.doi.org/10.1177/19417381211035781.

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Background: Remodeled bicycle pedal training with multidirectional challenges through muscle strengthening and neuromuscular facilitation may increase dynamic postural control and performance during lateral shuffling for athletes with functional ankle instability (FAI). Hypothesis: The 6-week remodeled bicycle pedal training is effective on the ankle joint control and muscle activation, and especially that of the ankle evertor muscle co-contraction to improve dynamic postural control during lateral shuffling for athletes with FAI. Study Design: Laboratory randomized controlled trial. Level of Evidence: Level 2. Methods: Fourteen healthy athletes (healthy group) and 26 athletes with FAI aged 18 to 30 years were included in the study. The athletes with FAI were randomly assigned to either the training group (FAI-T group) or the nontraining group (FAI-NT group). The athletes in the FAI-T group underwent 6 weeks of remodeled bicycle pedal training, whereas those in the FAI-NT group did not undergo any intervention. Muscle co-contraction index and muscle activation in the initial contact (IC) and propulsion phases, and ankle joint angle in the IC and propulsion phases were measured during lateral shuffling before and after 6 weeks of training. Results: After remodeled bicycle pedal training, the FAI-T group demonstrated greater muscle activation in the hamstring ( P = 0.01), greater muscle coactivation of the tibialis anterior (TA) and the peroneus longus ( P = 0.01), and greater ankle eversion angle in the IC phase. Significantly greater muscle activation of the TA ( P = 0.01), greater coactivation of quadriceps and hamstring ( P = 0.03), and a smaller ankle inversion angle ( P = 0.04) in the propulsion phase were observed in the FAI-T group after training compared with those in the FAI-NT group. Conclusion: Remodeled bicycle pedal training facilitates the TA and peroneus longus activation and the coactivation of the quadriceps and hamstring muscles during lateral shuffling and resulted in enhanced ankle and knee joint stability. In addition, a better ankle movement strategy during a dynamic task can be achieved via a 6-week remodeled pedal training program. Clinical Relevance: This remodeled bicycle pedal training can be effective for rehabilitating athletes with FAI to recover lateral dynamic movement capability.

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Murphy, M. T., N. Wang, D. T. Felson, M. C. Nevitt, C. E. Lewis, L. Frey-Law, A. Guermazi, and N. A. Segal. "Association between hamstring coactivation during isokinetic quadriceps strength testing and knee cartilage worsening over 24 months." Osteoarthritis and Cartilage, March 2022. http://dx.doi.org/10.1016/j.joca.2022.03.002.

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Paravlic, Armin H., Simon Kovač, Rado Pisot, and Uros Marusic. "Neurostructural correlates of strength decrease following total knee arthroplasty: A systematic review of the literature with meta-analysis." Bosnian Journal of Basic Medical Sciences, January 14, 2019. http://dx.doi.org/10.17305/bjbms.2019.3814.

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Recent literature suggests that alterations in both neural and structural components of the neuromuscular system are major determinants of knee extensor muscle weakness after total knee arthroplasty (TKA). Therefore, the goal of this study was to investigate the maximal voluntary strength (MVS), voluntary muscle activation (VMA), and the cross-sectional area (CSA) of the muscle, up to 33 months after the TKA. We searched relevant scientific databases and literature for outcomes of interest, including quadriceps MVS, VMA, and CSA. Ten studies met the inclusion criteria and involved a total of 289 patients. The quality of the studies was evaluated by Methodological Index for Non-Randomized Studies (MINORS). Results showed that quadriceps MVS markedly declines in the early postoperative period, after which it slowly and linearly recovers over time. However, the same phenomenon was not observed for VMA and CSA, which were not significantly altered after the TKA. Furthermore, a meta-regression analysis revealed that the change in VMA accounted for 39% of the relative change in quadriceps strength (R2=0.39; p=0.015) in the early postoperative period. Patients treated with TKA had considerable weakness of the quadriceps muscle, which was detectable up to 3 months after surgery. Although the change in VMA largely explains quadriceps weakness, this change and CSA differences were not significant, suggesting that other neural correlates, such as hamstrings coactivation, might alter quadriceps muscle function. Thus, more attention should be paid to address VMA failure and coactivation of antagonist muscles. More comprehensive rehabilitation approaches may be required to target the whole neural circuit controlling the motor action.

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