Coordination of hamstrings is individual specific and is related to motor performance

The torque-sharing strategies between synergistic muscles may have important functional consequences. This study involved two experiments. The first experiment ( n = 22) aimed 1) to determine the relationship between the distribution of activation and the distribution of torque-generating capacity among the heads of the hamstring, and 2) to describe individual torque-sharing strategies and to determine whether these strategies are similar between legs. The second experiment ( n = 35) aimed to determine whether the distribution of activation between the muscle heads affects endurance performance during a sustained submaximal knee flexion task. Surface electromyography (EMG) was recorded from biceps femoris (BF), semimembranosus (SM), and semitendinosus (ST) during submaximal isometric knee flexions. Torque-generating capacity was estimated by measuring muscle volume, fascicle length, pennation angle, and moment arm. The product of the normalized EMG amplitude and the torque-generating capacity was used as an index of muscle torque. The distributions of muscle activation and of torque-generating capacity were not correlated significantly (all P > 0.18). Thus, there was a torque imbalance between the muscle heads (ST torque > BF and SM torque; P < 0.001), the magnitude of which varied greatly between participants. A significant negative correlation was observed between the imbalance of activation across the hamstring muscles and the time to exhaustion ( P < 0.001); i.e., the larger the imbalance of activation across muscles, the lower the muscle endurance performance. Torque-sharing strategies between the heads of the hamstrings are individual specific and related to muscle endurance performance. Whether these individual strategies play a role in hamstring injury remains to be determined. NEW & NOTEWORTHY The distribution of activation among the heads of the hamstring is not related to the distribution of torque-generating capacity. The torque-sharing strategies within hamstring muscles vary greatly between individuals but are similar between legs. Hamstring coordination affects endurance performance; i.e., the larger the imbalance of activation across the muscle heads, the lower the muscle endurance.

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The effects of 12 weeks of static stretch training on the functional, mechanical, and architectural characteristics of the triceps surae muscle–tendon complex

European Journal of Applied Physiology ◽

10.1007/s00421-021-04654-z ◽

2021 ◽

Author(s):

Stefano Longo ◽

Emiliano Cè ◽

Angela Valentina Bisconti ◽

Susanna Rampichini ◽

Christian Doria ◽

...

Keyword(s):

Muscle Activation ◽

Maximum Voluntary Contraction ◽

Muscle Stiffness ◽

Triceps Surae ◽

Maximum Force ◽

Passive Stiffness ◽

Electromechanical Delay ◽

Fascicle Length ◽

Generating Capacity ◽

Plantarflexor Muscles

Abstract Purpose We investigated the effects of 12 weeks of passive static stretching training (PST) on force-generating capacity, passive stiffness, muscle architecture of plantarflexor muscles. Methods Thirty healthy adults participated in the study. Fifteen participants (STR, 6 women, 9 men) underwent 12-week plantarflexor muscles PST [(5 × 45 s-on/15 s-off) × 2exercises] × 5times/week (duration: 2250 s/week), while 15 participants (CTRL, 6 women, 9 men) served as control (no PST). Range of motion (ROM), maximum passive resistive torque (PRTmax), triceps surae architecture [fascicle length, fascicle angle, and thickness], passive stiffness [muscle–tendon complex (MTC) and muscle stiffness], and plantarflexors maximun force-generating capacity variables (maximum voluntary contraction, maximum muscle activation, rate of torque development, electromechanical delay) were calculated Pre, at the 6th (Wk6), and the 12th week (Wk12) of the protocol in both groups. Results Compared to Pre, STR ROM increased (P < 0.05) at Wk6 (8%) and Wk12 (23%). PRTmax increased at Wk12 (30%, P < 0.05), while MTC stiffness decreased (16%, P < 0.05). Muscle stiffness decreased (P < 0.05) at Wk6 (11%) and Wk12 (16%). No changes in triceps surae architecture and plantarflexors maximum force-generating capacity variables were found in STR (P > 0.05). Percentage changes in ROM correlated with percentage changes in PRTmax (ρ = 0.62, P = 0.01) and MTC stiffness (ρ = − 0.78, P = 0.001). In CTRL, no changes (P > 0.05) occurred in any variables at any time point. Conclusion The expected long-term PST-induced changes in ROM were associated with modifications in the whole passive mechanical properties of the ankle joint, while maximum force-generating capacity characteristics were preserved. 12 weeks of PST do not seem a sufficient stimulus to induce triceps surae architectural changes.

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Electrically-induced quadriceps fatigue in the contralateral leg impairs ipsilateral knee extensors performance

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00363.2020 ◽

2021 ◽

Author(s):

Fabio Giuseppe Laginestra ◽

Markus Amann ◽

Emine Kirmizi ◽

Gaia Giuriato ◽

Chiara Barbi ◽

...

Keyword(s):

Muscle Activation ◽

Central Fatigue ◽

Endurance Performance ◽

Voluntary Exercise ◽

Peripheral Fatigue ◽

Knee Extensors ◽

Motor Drive ◽

Time To Exhaustion ◽

Crossover Effect ◽

The Impact

Muscle fatigue induced by voluntary exercise, which requires central motor drive, causes central fatigue that impairs endurance performance of a different, non-fatigued muscle. This study investigated the impact of quadriceps fatigue induced by electrically-induced (no central motor drive) contractions on single-leg knee-extension (KE) performance of the subsequently exercising ipsilateral quadriceps. On two separate occasions, eight males completed constant-load (85% of maximal power-output) KE exercise to exhaustion. In a counterbalanced manner, subjects performed the KE exercise with no pre-existing quadriceps fatigue in the contralateral leg on one day (No-PreF), while on the other day, the same KE exercise was repeated following electrically-induced quadriceps fatigue in the contralateral leg (PreF). Quadriceps fatigue was assessed by evaluating pre- to post-exercise changes in potentiated twitch force (ΔQtw,pot; peripheral-fatigue), and voluntary muscle activation (ΔVA; central-fatigue). As reflected by the 57±11% reduction in electrically-evoked pulse force, the electrically-induced fatigue protocol caused significant knee-extensors fatigue. KE endurance time to exhaustion was shorter during PreF compared to No-PreF (4.6±1.2 vs 7.7±2.4 min; p<0.01). While ΔQtw,pot was significantly larger in No-PreF compared to PreF (-60% vs -52%, p<0.05), ΔVA was greater in PreF (-14% vs -10%, p<0.05). Taken together, electrically-induced quadriceps fatigue in the contralateral leg limits KE endurance performance and the development of peripheral fatigue in the ipsilateral leg. These findings support the hypothesis that the crossover-effect of central fatigue is mainly mediated by group III/IV muscle afferent feedback and suggest that impairments associated with central motor drive may only play a minor role in this phenomenon.

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A functional MRI Exploration of Hamstring Activation During the Supine Bridge Exercise

International Journal of Sports Medicine ◽

10.1055/s-0043-121150 ◽

2017 ◽

Vol 39 (02) ◽

pp. 104-109 ◽

Cited By ~ 5

Author(s):

Matthew Bourne ◽

Morgan Williams ◽

Tania Pizzari ◽

Anthony Shield

Keyword(s):

Muscle Activation ◽

Biceps Femoris ◽

Hamstring Injury ◽

Clinical Test ◽

Activation Patterns ◽

Rehabilitation Programs ◽

Intensity Changes ◽

Long Head ◽

Exercise Induced ◽

Biceps Femoris Long Head

AbstractThe single leg supine bridge (SLB) is a commonly employed strengthening exercise and is used as a clinical test for hamstring function in sports, however, little is known about the patterns of muscle activation in this task. To explore these activation patterns, nine healthy, recreationally active males underwent functional magnetic resonance imaging (fMRI) of their thighs at rest and immediately after 5 sets of 10 repetitions of the SLB exercise. Exercise-induced increases in the transverse (T2) relaxation time of the biceps femoris long and short heads, semitendinosus and semimembranosus, were determined via signal intensity changes in pre- and post-exercise images and used as an index of muscle activation. The Bonferroni adjusted alpha was set at p<0.008. The semitendinosus exhibited a greater T2 increase than the biceps femoris short head (p<0.001, d=2.0) and semimembranosus (p=0.001, d=1.2), but not biceps femoris long head (p=0.029, d=0.9). Furthermore, the percentage change in T2 for biceps femoris long head was greater than its short head (p=0.003, d=1.4). During the SLB exercise, the semitendinosus is most selectively targeted and the biceps femoris long head is preferentially activated over its short head. These findings may have implications for the use of the SLB in hamstring injury prevention and rehabilitation programs.

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Acute Static Stretching Results in Muscle-Specific Alterations amongst the Hamstring Muscles

Sports ◽

10.3390/sports8090119 ◽

2020 ◽

Vol 8 (9) ◽

pp. 119

Author(s):

Manon Riccetti ◽

Jules Opplert ◽

Joao L. Q. Durigan ◽

Carole Cometti ◽

Nicolas Babault

Keyword(s):

Biceps Femoris ◽

Hamstring Injury ◽

Myotendinous Junction ◽

Static Stretching ◽

Semitendinosus Muscle ◽

Biceps Femoris Muscle ◽

Passive Torque ◽

Hamstring Muscles ◽

Long Head ◽

Femoris Muscle

This study aimed to explore the acute effects of static stretching on the musculotendinous properties of two hamstring muscles. Twelve male volunteers underwent two testing sessions. One session was dedicated to the evaluation of the semitendinosus muscle before (PRE) and after (POST) static stretching (five sets of 30-s stretching), and the other session similarly explored the long head of biceps femoris muscle. In addition to the displacement of the myotendinous junction (MTJ), passive torque and maximal voluntary isometric torque (MVIT) were evaluated. MVIT (−8.3 ± 10.2%, p = 0.0036, d = 0.497) and passive torque (−28.4 ± 16.9%, p = 0.0003, d = 1.017) were significantly decreased POST stretching. PRE stretching, MTJ displacement was significantly greater for semitendinosus muscle than biceps femoris muscle (27.0 ± 5.2 vs. 18.6 ± 3.6, p = 0.0011, d = 1.975). After the stretching procedure, greater MTJ displacement relative changes were observed for biceps femoris muscle as compared to semitendinosus muscle (22.4 ± 31.6 vs. −8.4 ± 17.9, p = 0.0167, d = 1.252). Because of the smaller MTJ displacement PRE stretching and greater alteration POST stretching in biceps femoris muscles, the present study demonstrated muscle-specific acute responses of hamstring muscles during stretching. Although stretching acutely impairs torque production, the passive torque reduction and alteration of MTJ displacement might impact hamstring injury prevention.

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Muscle Activation Differences During Eccentric Hamstring Exercises

Sports Health A Multidisciplinary Approach ◽

10.1177/1941738120938649 ◽

2020 ◽

pp. 194173812093864

Author(s):

Sonay Guruhan ◽

Nihan Kafa ◽

Zeynep B. Ecemis ◽

Nevin A. Guzel

Keyword(s):

Muscle Activation ◽

Critical Role ◽

Biceps Femoris ◽

Level Of Evidence ◽

Cross Sectional ◽

Maximum Voluntary Isometric Contraction ◽

Hamstring Muscles ◽

Limb Injuries ◽

Exercise Type ◽

Muscular Activation

Background: The hamstring muscles play a critical role in the prevention of lower limb injuries. However, it is still unclear which exercises are more effective in terms of muscle activation. Hypothesis: In healthy individuals, there are differences between muscular activations of the biceps femoris (BF), semitendinosus (ST), and semimembranosus (SM) muscles during eccentric hamstring exercises. Study Design: Cross-sectional. Level of Evidence: Level 2. Methods: A total of 31 healthy participants (18 male; mean age, 22.5 years; SD, 3.1) were included in this study. The maximum voluntary isometric contraction of the hamstring muscles was measured using an isokinetic dynamometer. The participants were asked to perform one of the following exercises randomly (3 repetitions each): stiff-leg deadlift (SLDL), unilateral stiff-leg deadlift (USLDL), Nordic hamstring exercise (NHE), and ball leg curl (BLC). Activation of the BF, ST, and SM muscles was measured using surface electromyography during the exercises. In the statistical analysis of this study, factorial analysis of variance was used to compare the effects of each exercise on the muscle groups and to analyze which exercise type was more effective for each muscle group. Results: The NHE led to higher muscle activation than the other exercises ( P < 0.001). When exercise type and muscle interaction were examined, SM activation was lower than BF ( P = 0.04) and ST ( P = 0.001) during NHE ( P < 0.05). The highest level of muscular activation was recorded during the NHE in both male and female participants. Conclusion: The NHE may be the most effective exercise for the hamstring muscles as it leads to greater muscle activation. SLDL, USLDL, and BLC exercises may be preferred at the beginning of strength training programs since they lead to lower muscular activation compared with the NHE. Clinical Relevance: To select the optimum hamstring exercise, it is important to know the activation levels of the hamstring muscles during different eccentric exercises.

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Bilateral differences in hamstring coordination in previously injured elite athletes

Journal of Applied Physiology ◽

10.1152/japplphysiol.00411.2019 ◽

2020 ◽

Vol 128 (3) ◽

pp. 688-697

Author(s):

Simon Avrillon ◽

François Hug ◽

Gaël Guilhem

Keyword(s):

Biceps Femoris ◽

Hamstring Injury ◽

Muscle Coordination ◽

Injured Limb ◽

Cross Sectional ◽

Hamstring Muscles ◽

History Of ◽

Total Knee ◽

Bilateral Differences ◽

Lower Contribution

Hamstring strain injuries (HSIs) involve tissue disruption and pain, which can trigger long-term adaptations of muscle coordination. However, little is known about the effect of previous HSIs on muscle coordination and in particular, after the completion of rehabilitation and in the absence of symptoms. This study aimed to determine if elite athletes with a prior unilateral HSI have bilateral differences in coordination between the hamstring muscle heads after returning to sport. Seventeen athletes with a unilateral history of biceps femoris (BF) injury participated in the experiment. Surface electromyography was recorded from three hamstring muscles [BF, semimembranosus (SM), and semitendinosus] during submaximal isometric torque-matched tasks at 20% and 50% of maximal voluntary contraction. The product of normalized electromyographic amplitude with functional physiological cross-sectional area (PCSA) and moment arm was considered as an index of individual muscle torque. The contribution of the injured muscle to total knee flexion torque was lower in the injured than the uninjured limb (−5.6 ± 10.2%, P = 0.038). This reduced contribution of BF was compensated by a higher contribution of the SM muscle in the injured limb (+5.6 ± 7.5%, P = 0.007). These changes resulted from a lower contribution of PCSA from the injured muscle (BF) and a larger contribution of activation from an uninjured synergist muscle (SM). In conclusion, bilateral differences in coordination were observed in previously injured athletes despite the completion of rehabilitation. Whether these bilateral differences in hamstring coordination could constitute an intrinsic risk factor that contributes to the high rate of hamstring injury recurrence remains to be investigated. NEW & NOTEWORTHY We used an experimental approach, combining the assessment of muscle activation, physiological cross-sectional area, and moment arm to estimate force-sharing strategies among hamstring muscles during isometric knee flexions. We tested athletes with a history of hamstring injury. We observed a lower contribution of the injured biceps femoris to the total knee flexor torque in the injured limb than in the contralateral limb. This decreased contribution was mainly due to selective atrophy of the injured biceps femoris muscle and was compensated by an increased activation of the semimembranosus muscle.

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Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises

Journal of Human Kinetics ◽

10.1515/hukin-2017-0105 ◽

2017 ◽

Vol 60 (1) ◽

pp. 29-37 ◽

Cited By ~ 4

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.

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Ankle Muscle Activations during Different Foot-Strike Patterns in Running

Sensors ◽

10.3390/s21103422 ◽

2021 ◽

Vol 21 (10) ◽

pp. 3422

Author(s):

Jian-Zhi Lin ◽

Wen-Yu Chiu ◽

Wei-Hsun Tai ◽

Yu-Xiang Hong ◽

Chung-Yu Chen

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Stance Phase ◽

Inertial Sensors ◽

Plantar Flexion ◽

Intraclass Correlation ◽

Biceps Femoris ◽

Ankle Muscle ◽

Foot Strike ◽

Muscle Activations

This study analysed the landing performance and muscle activity of athletes in forefoot strike (FFS) and rearfoot strike (RFS) patterns. Ten male college participants were asked to perform two foot strikes patterns, each at a running speed of 6 km/h. Three inertial sensors and five EMG sensors as well as one 24 G accelerometer were synchronised to acquire joint kinematics parameters as well as muscle activation, respectively. In both the FFS and RFS patterns, according to the intraclass correlation coefficient, excellent reliability was found for landing performance and muscle activation. Paired t tests indicated significantly higher ankle plantar flexion in the FFS pattern. Moreover, biceps femoris (BF) and gastrocnemius medialis (GM) activation increased in the pre-stance phase of the FFS compared with that of RFS. The FFS pattern had significantly decreased tibialis anterior (TA) muscle activity compared with the RFS pattern during the pre-stance phase. The results demonstrated that the ankle strategy focused on controlling the foot strike pattern. The influence of the FFS pattern on muscle activity likely indicates that an athlete can increase both BF and GM muscles activity. Altered landing strategy in cases of FFS pattern may contribute both to the running efficiency and muscle activation of the lower extremity. Therefore, neuromuscular training and education are required to enable activation in dynamic running tasks.

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Healthy subjects with lax knees use less knee flexion rather than muscle control to limit anterior tibia translation during landing

Journal of Experimental Orthopaedics ◽

10.1186/s40634-020-00246-6 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Michèle N. J. Keizer ◽

Juha M. Hijmans ◽

Alli Gokeler ◽

Anne Benjaminse ◽

Egbert Otten

Keyword(s):

Knee Flexion ◽

Muscle Activation ◽

Reaction Force ◽

Rectus Femoris ◽

Knee Laxity ◽

Biceps Femoris ◽

Level Of Evidence ◽

Jump Landing ◽

Muscle Activation Patterns ◽

Healthy Participants

Abstract Purpose It has been reported that there is no correlation between anterior tibia translation (ATT) in passive and dynamic situations. Passive ATT (ATTp) may be different to dynamic ATT (ATTd) due to muscle activation patterns. This study aimed to investigate whether muscle activation during jumping can control ATT in healthy participants. Methods ATTp of twenty-one healthy participants was measured using a KT-1000 arthrometer. All participants performed single leg hops for distance during which ATTd, knee flexion angles and knee flexion moments were measured using a 3D motion capture system. During both tests, sEMG signals were recorded. Results A negative correlation was found between ATTp and the maximal ATTd (r = − 0.47, p = 0.028). An N-Way ANOVA showed that larger semitendinosus activity was seen when ATTd was larger, while less biceps femoris activity and rectus femoris activity were seen. Moreover, larger knee extension moment, knee flexion angle and ground reaction force in the anterior-posterior direction were seen when ATTd was larger. Conclusion Participants with more ATTp showed smaller ATTd during jump landing. Muscle activation did not contribute to reduce ATTd during impact of a jump-landing at the observed knee angles. However, subjects with large ATTp landed with less knee flexion and consequently showed less ATTd. The results of this study give information on how healthy people control knee laxity during jump-landing. Level of evidence III

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