Synergy of medial and lateral hamstrings at three positions of tibial rotation during maximum isometric knee flexion

In vivo knee biomechanics during badminton lunges at different distances and different foot positions by using the dual fluoroscopic imaging system

Background: Lunges are common in badminton. Distance and foot position affect knee joint loadings under lunges, which are closely related to knee injury incidence. Investigations involving dynamic knee motion in vivo, kinetics, and muscle activation in lunges, especially during lunges of different distances and foot positions, are instrumental for understanding knee performance and injury risks of players. Methods: A total of 10 experienced badminton athletes (10 females; height, 164.5 ± 5.0 cm; weight, 59.3 ± 6.0 kg; and age, 22 ± 1.0 years) were recruited. By using a high-speed dual fluoroscopic imaging system, Qualisys motion capture system, Kistler force plate, and Delsys electromyography simultaneously, data were collected during players' 1.5 times leg length lunge, the maximum lunge, and the maximum lunge while the foot rotated externally. Magnetic resonance and dual fluoroscopic imaging techniques were used to analyze the in vivo knee kinematics. Results: Compared with the 1.5 times leg length lunge, knee flexion for the maximum lunge increased significantly (p < 0.05). The anterior-posterior ground reaction force (GRF) and vertical GRF of the maximum lunge were significantly higher than those of the 1.5 times leg length lunge. During the two different foot position lunges with the maximum distance, the posterior translation of knee joint was larger (p < 0.05) when the foot rotated externally than the normal maximum lunge. Moreover, the anterior-posterior GRF and vertical GRF increased significantly when the foot rotated externally. Significant differences were observed in valgus-varus rotation torque and internal-external rotation torque of the knee joint under the two distance lunges and two foot position lunges (p < 0.05). No significant difference was found in knee muscle activation during the two distance lunges and during the two foot position lunges. Conclusion: High knee torque and compressive loadings with increasing lunge distance may cause knee injuries in badminton. When lunging in the external foot rotation under the maximum distance, high quadriceps force and posterior tibia translation force could result in knee injuries among badminton players.

Comparison of muscle activity of hamstrings as knee flexors and hip extensors and effect of tibial and hip rotation on the contribution of hamstrings

BACKGROUND

Limited studies have compared the muscle activity of the medial and lateral hamstrings as knee flexors with tibial internal and external rotation and hip extensors with hip internal and external rotation. In particular, hamstring activity during hip extension with hip rotation has rarely been investigated.

OBJECTIVE

This study aimed to compare the muscle activity of the medial and lateral hamstrings as knee flexors and hip extensors and to compare the activity of these muscles according to tibial rotation during isometric knee flexion and hip rotation during isometric hip extension.

METHODS

A total of 23 healthy adults participated in the study. The electromyographic (EMG) activity of the hamstrings was measured during maximal isometric knee flexion and maximal isometric hip extension. In addition, tibial rotation was applied actively during maximal isometric knee flexion, whereas hip rotation was applied actively during maximal isometric hip extension.

RESULTS

EMG activity during maximal isometric knee flexion with tibial internal and external rotation was significantly higher than that during maximal isometric hip extension with hip internal and external rotation, respectively. For EMG activity according to tibial and hip rotation, there was no significant difference between tibial internal and external rotation during maximal isometric knee flexion, whereas there was a significant difference between hip internal and external rotation during maximal isometric hip extension.

CONCLUSION

Hamstring activity was higher for knee flexors than for hip extensors. However, hip rotation during maximal isometric hip extension is an effective intervention for selective muscle activation of the medial and lateral hamstrings.

Hamstrings force-length relationships and their implications for angle-specific joint torques: a narrative review

Temporal biomechanical and physiological responses to physical activity vary between individual hamstrings components as well as between exercises, suggesting that hamstring muscles operate differently, and over different lengths, between tasks. Nevertheless, the force-length properties of these muscles have not been thoroughly investigated. The present review examines the factors influencing the hamstrings’ force-length properties and relates them to in vivo function. A search in four databases was performed for studies that examined relations between muscle length and force, torque, activation, or moment arm of hamstring muscles. Evidence was collated in relation to force-length relationships at a sarcomere/fiber level and then moment arm-length, activation-length, and torque-joint angle relations. Five forward simulation models were also used to predict force-length and torque-length relations of hamstring muscles. The results show that, due to architectural differences alone, semitendinosus (ST) produces less peak force and has a flatter active (contractile) fiber force-length relation than both biceps femoris long head (BFlh) and semimembranosus (SM), however BFlh and SM contribute greater forces through much of the hip and knee joint ranges of motion. The hamstrings’ maximum moment arms are greater at the hip than knee, so the muscles tend to act more as force producers at the hip but generate greater joint rotation and angular velocity at the knee for a given muscle shortening length and speed. However, SM moment arm is longer than SM and BFlh, partially alleviating its reduced force capacity but also reducing its otherwise substantial excursion potential. The current evidence, bound by the limitations of electromyography techniques, suggests that joint angle-dependent activation variations have minimal impact on force-length or torque-angle relations. During daily activities such as walking or sitting down, the hamstrings appear to operate on the ascending limbs of their force-length relations while knee flexion exercises performed with hip angles 45–90° promote more optimal force generation. Exercises requiring hip flexion at 45–120° and knee extension 45–0° (e.g. sprint running) may therefore evoke greater muscle forces and, speculatively, provide a more optimum adaptive stimulus. Finally, increases in resistance to stretch during hip flexion beyond 45° result mainly from SM and BFlh muscles.

Effects of the abdominal drawing-in maneuver on hamstring rotational activity and pelvic stability in females

BACKGROUND

The medial hamstring (MH) and lateral hamstring (LH) can be selectively trained through tibial internal and external rotation during prone knee flexion. However, no study has identified how a combined tibial rotation and lumbo-pelvic stability strategy influences MH and LH muscle activities.

OBJECTIVE

To investigate the combined effects of tibial rotation and the abdominal drawing-in maneuver (ADIM) on MH and LH muscle activities as well as pelvic rotation during prone knee flexion.

METHODS

Fifteen female volunteers performed prone knee flexion with tibial internal and external rotation, with and without the ADIM. Under each condition, MH and LH muscle activities were measured by surface electromyography (EMG), and the pelvic rotation angle by a smartphone inclinometer application.

RESULTS

The results showed increased MH (without the ADIM: p< 0.001, effect size (d) = 2.05; with the ADIM: p< 0.001, d= 1.71) and LH (without the ADIM: p< 0.001, d= 1.64; with the ADIM: p= 0.001, d= 1.58) muscle activities under internal and external tibial rotation, respectively. However, addition of the ADIM led to increased MH (internal tibial rotation: p= 0.001, d= 0.67; external tibial rotation: p= 0.019, d= 0.45) and LH (internal tibial rotation: p= 0.003, d= 0.79; external tibial rotation: p< 0.001, d= 1.05) muscle activities combined with reduced pelvic rotation (internal tibial rotation: p< 0.001, d= 3.45; external tibial rotation: p< 0.001, d= 3.01) during prone knee flexion.

CONCLUSIONS

These findings suggest that the ADIM could be useful for reducing compensatory pelvic rotation and enhancing selective muscle activation in the MH and LH, according to the direction of tibial rotation, during prone knee flexion.

Effects of hip rotation on the electromyographic activity of the medial and lateral hamstrings and muscle force

BACKGROUND

In clinical practice, knee flexion at the prone position for manual muscle testing of hamstrings and hip extension at the supine position for stretching of hamstring muscles are typically proposed.

OBJECTIVE

Although different positions have been proposed for different purposes in hamstrings, the understanding of the changing the functional role of hamstrings with position changes is poorly understood.

METHODS

The electromyographic (EMG) activity and hip extension force were compared among different postures; hip neutral, internal, and external rotation. EMG and force were measured in prone position during knee flexion and those were additionally measured in supine position during hip extension. In supine position, additional measurements were made in hip neutral, internal and external rotation.

RESULTS

Hamstrings showed high EMG activity during knee flexion. Knee flexion force in prone position was significantly decreased at hip extension force in supine position. In supine position, EMG activity was significantly higher in semitendinosus (ST) than biceps femoris (BF) during internal rotation.

CONCLUSIONS

It should be noted that bi-articular muscles may have different functional dependencies on the corresponding muscles for each joint. In addition, because the altered alignment of the hamstring muscles that was affected by hip rotation had a significant effect on muscle activity, and hip rotation may be helpful for selective training of medial or lateral hamstrings.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

Superimposing hip extension on knee flexion evokes higher activation in biceps femoris than knee flexion alone

Hamstring muscle function during knee flexion has been linked to hamstring injury and performance. However, it is unclear whether knee flexion alone (KF) requires similar hamstring electromyography (EMG) activity pattern to simultaneous hip extension and knee flexion (HE-KF), a combination that occurs in the late swing phase of sprinting. This study examined whether HE-KF maximal voluntary isometric contraction (MVIC) evokes higher (EMG) activity in biceps femoris long head (BFlh) and semitendinosus (ST) than KF alone. Effects of shank rotation angles were also tested. Twenty-one males performed the above-mentioned MVICs while EMG activity was measured along ST and BFlh. Conditions were compared using a one-way mixed functional ANOVA model under a fully Bayesian framework. Higher EMG activity was found in HE-KF in all shank rotation positions than in KF in the middle region of BFlh (highest in the 9th channel, by 0.022 mV [95%CrI 0.014 to 0.030] in neutral shank position). For ST, this was only observed in the neutral shank position and in the most proximal channel (by 0.013 mV [95%CrI 0.001 to 0.025]). We observed muscle- and region-specific responses to HE-KF. Future studies should examine whether hamstring activation in this task is related to injury risk and sprint performance.

Kinetic analysis of tandem gait on a sine-wave-shaped walkway

[Purpose] The purpose of this study was to ascertain the kinetic characteristics on a horizontal plane, including knee joint rotation, when performing tandem gait on a sine-wave walkway. [Participants and Methods] The participants were 10 healthy adults. The movement task included tandem gait on a sine-wave walkway. The instruments used were an electromyograph and a three-dimensional motion analysis system. Regarding data analysis, we determined the knee joint rotation angle and muscle activity of the biceps femoris and semitendinosus muscle. [Results] The knee joint rotation angle range was 48.1 ± 6.7°. Two strategies were confirmed with regard to the direction of knee joint rotation: a case in which the agonist muscle acts actively and a case in which the antagonist muscle acts passively. [Conclusion] It has been suggested that the knee joint rotational angle and muscular activity of the rotator muscle group are important for tandem gait on a sine-wave-shaped walking path.

MEDIAL AND LATERAL HAMSTRINGS RESPONSE AND FORCE PRODUCTION AT VARYING DEGREES OF KNEE FLEXION AND TIBIAL ROTATION IN HEALTHY INDIVIDUALS

Background

Hamstring weakness is a contributor to lower extremity pathology. Influence of knee flexion and tibial rotation on hamstrings muscle activation and knee flexion force has not been documented in the literature.

Hypothesis/Purpose

The purpose of the study was to determine the angle of knee flexion and tibial rotation that elicits the greatest knee flexion force and hamstrings activation in healthy, physically active adults.

Study Design

Descriptive, observational cohort study.

Methods

Eighteen young healthy adults were recruited for study participation. Each individual performed maximal voluntary isometric hamstrings contractions at six different knee flexion angles (15 °, 30 °, 45 °, 60 °, 75 ° & 90 °), each positioned at three different tibial rotation positions (internal rotation, neutral rotation and external rotation). Electromyographic activity of the medial and lateral hamstrings and knee flexion force production were recorded.

Results

On average, greatest force production was recorded at 30 ° knee flexion with tibia either in neutral rotation (124.1% of max) or in external rotation (123.5% of max). This same lower limb orientation also produced the highest amount of lateral hamstring activation (156.4% of max). Results also showed that force production and lateral hamstring activation decreased as knee flexion angle increased. Muscle activation for the medial hamstrings was not affected by knee flexion angle but did show higher activation in neutral or tibial internal rotation.

Conclusion

The results of the current research describe the relationship between knee flexion and tibial rotation and their effect on overall knee flexion force production and hamstrings activation. This research provides key insights about the specific knee joint angles and tibial orientation that may be preferred in exercise prescription for maximizing hamstring activation.

Level of Evidence

Level III.

Effect of a pelvic wedge and belt on the medial and lateral hamstring muscles during knee flexion

[Purpose] This study developed a pelvic wedge and belt and investigated their effects on the selective activation of medial and lateral hamstring muscles during knee flexion. [Subjects and Methods] Nine adults were enrolled. The participants performed exercises without and with the pelvic wedge and belt, and the electromyographic activities of the medial and lateral hamstring muscles were recorded. [Results] The activity of the medial hamstring was increased significantly when using the pelvic wedge and belt, while the activity of the lateral hamstring did not differ significantly. [Conclusion] The pelvic wedge and belt provide a self-locked position during knee flexion in the prone position. Prone knee flexion in this position is an effective self-exercise for balanced strengthening of the medial hamstring.

The Effect of Tibial Rotation on the Contribution of Medial and Lateral Hamstrings During Isometric Knee Flexion

Background:

Selective atrophy of hamstring components may result from muscle strain or graft harvesting for anterior cruciate ligament reconstruction. Assessment and rehabilitation that specifically targets medial (MH) or lateral (LH) hamstring components may improve patient outcomes. The purpose of this study was to evaluate effects of volitional tibial rotation medially (MR) versus laterally (LR) on activation levels of MH versus LH and strength measures during isometric testing of knee flexors.

Hypothesis:

Muscle activation of MH and LH during knee flexor strength testing will be augmented when coupled with MR and LR of the tibia, respectively, without affecting knee flexor strength measures.

Study Design:

Cross-sectional laboratory study.

Level of Evidence:

Level 3.

Methods:

Surface electrodes were used to record neuromuscular activity from MH and LH of the right lower limb in 40 healthy young men and women during isometric knee flexor strength testing at 40° of knee flexion, where participants maintained concurrent volitional MR or LR of the tibia. Statistical analyses of variance included general linear models for repeated measures.

Results:

A significant interaction was found for tibial rotation and hamstring component variables (P < 0.01). When isometric knee flexion was coupled with LR, normalized activation levels were similar for MH and LH. When performed with MR, a significant drop in LH activation led to dissimilar activation levels of the 2 components. Significantly greater strength measures were found when isometric knee flexion was performed with concurrent LR of the tibia (P < 0.01). Both sexes demonstrated the same rotation-dependent differences.

Conclusion:

Coupling tibial rotation with knee flexor activities primarily affects the LH component.

Clinical Relevance:

Strategies involving volitional tibial rotation may be considered for specific assessment/rehabilitation of the MH or LH component.

The Effect of Shoulder Flexion Angles on the Recruitment of Upper-extremity Muscles during Isometric Contraction

The purpose of this study was to investigate the differences in muscle activation patterns of the biceps brachii (BB) and flexor carpi radialis (FCR) muscles, while measuring the resultant force (RF) at different shoulder flexion angles. [Subjects] Thirteen healthy males (age 24.85±3.4 years, weight; 77.8±7.9 kg; height, 1.7±0.05 m) were enrolled in this study. [Methods] The resultant force was measured by a force transducer . The elbow angle remained constant and the flexion shoulder angle was changed (30°, 45°, 60°, 75° and 90°). [Results] The results of the surface EMG show the largest muscle activities occurred at a shoulder flexion of 75° for BB and 90° for FCR. The largest resultant force was measured at a shoulder flexion angle of 75°. We conclude, that when performing the biceps curl exercise using an arm curl machine, the shoulder should be flexed at 75° to maximize the focus of the exercise for the BB. [Conclusion] These results are useful from the perspective of design as they highlight the differences in the muscle activation of BB and FCR with postural change. Ultimately this knowledge can be used in the design of rehabilitation training for the shoulder as they show that posture can affect muscle activation.

Current concepts in the recognition and treatment of posterolateral corner injuries of the knee

SYNOPSIS

Injuries to the posterolateral corner of the knee pose a significant challenge to sports medicine team members due to their complex nature. Identifying posterolateral corner injuries is paramount to determining proper surgical management of the injured athlete, with the goal of preventing chronic pain, instability, and/or surgical failure. Postoperative rehabilitation is based on the specific structural involvement and surgical procedures. A firm understanding of the anatomy and biomechanics of the structures of the posterolateral corner is essential for successful rehabilitation outcomes. Emphasis is placed on protection of the healing surgical repair/reconstruction, with gradual restoration of range of motion, strength, proprioception, and dynamic function of the knee. The purpose of this paper is to provide an overview of the anatomy, biomechanics, and mechanism of injury for posterolateral corner injuries, with a review of clinical examination techniques for identifying these injuries. Furthermore, a review of current surgical management and postoperative guidelines is provided.

LEVEL OF EVIDENCE

Diagnosis/therapy, level 5.

Effect of foot rotation on knee kinetics and hamstring activation in older adults with and without signs of knee osteoarthritis

BACKGROUND

To determine the effects of changing the natural foot progression angle during gait (internal and external foot rotation) on the knee's adduction moment, lateral-medial shear force, and the ratio of medial-lateral hamstring muscle activation in those with signs of knee osteoarthritis and a matched healthy control group.

METHODS

Twelve subjects with signs of knee osteoarthritis and 12 matched healthy control subjects were evaluated. A 3D gait analysis system calculated forces and moments at the knee while the subjects walked in three conditions: (1) normal foot position, (2) external foot rotation, (3) internal foot rotation. Medial and lateral hamstring EMG data was also collected simultaneously and used to calculate the medial-lateral hamstring activation ratio during the stance phase of the gait cycle. Repeated measures ANOVAs were used to compare foot rotation conditions within each group; while between group comparisons were performed in the normal rotation condition only using t-tests.

FINDINGS

Those with knee osteoarthritis (OA) had an increased late stance knee adduction moment and a decreased medial-lateral hamstring activation ratio as compared to the healthy control group. Also, external foot rotation decreased the late stance knee adduction moment, lateral-medial shear force, and hamstring activation ratio. However, internal foot rotation did not increase these measures.

INTERPRETATION

Changes in foot position during gait have the ability to alter both the external loading of the knee joint and hamstring muscle activation patterns during gait. This may have implication in helping to unload the knee's articular cartilage.

Hamstring antagonist moment estimation using clinically applicable models: Muscle dependency and synergy effects

The purpose of this study was to examine whether prediction of antagonist moment (M(flx)) of the hamstrings using clinically applicable models depends on the muscles examined. Nine healthy males performed maximal isometric knee extension and flexion contractions at 0 degrees , 45 degrees and 90 degrees angles. Calibration knee flexion efforts were also performed at different levels of intensity. The resulting electromyographic (EMG) - moment curves were fitted using polynomial equations which were then used to estimate M(flx) from the antagonist EMG. Analysis of variance designs showed that the M(flx) predicted using the biceps femoris EMG was not significantly different compared with those predicted using the semitendinosus EMG data (p>0.05). Further, prediction of M(flx) using the EMG of both muscles or a combination of EMGs and architectural properties reduced estimation error but did not provide significantly different predicted values compared with the simpler single-muscle EMG - moment models (p<0.05). It appears that M(flx) prediction using the present EMG - moment model is not muscle specific. Prediction using models which combine EMG data and anatomic parameters of the hamstring muscle components yielded more accurate estimates and therefore their use to examine co-contraction levels is recommended.