Effect of Different Slopes of the Lower Leg during the Nordic Hamstring Exercise on Hamstring Electromyography Activity

The purpose of this study was to examine whether the NHE with an increased lower leg slope angle would enhance hamstring EMG activity in the final phase of the descend. The hamstring EMG activity was measured, the biceps femoris long head (BFlh) and the semitendinosus (ST). Fifteen male volunteers participated in this study. Subjects performed a prone leg curl with maximal voluntary isometric contraction to normalize the hamstring EMG activity. Subsequently, subjects performed the NHE, with the help of a certified strength and conditioning specialist, while the lower leg slope angle were randomly set at 0° (NH), 20° (N20), and 40° (N40). To compare hamstring EMG activity during the NHE variations, the knee flexion angle was set in the range from 0° to 50°, divided into five phases (0–10°, 10–20°, 20–30°, 30–40° and 40–50°), where 0° indicated that the knee was fully extended. To calculate the knee extension angular velocity, the knee flexion angle divided by time, and break point angle (BPA) was the angle at which 10°/s was exceeded. In the statistical analysis, a two-way repeated measures ANOVA was used for the hamstring EMG activity and a one-way repeated measures ANOVA was used for the BPA. The EMG activity of the BFlh and the ST in N20 and N40 was significantly higher than in NH at knee flexion angle of 0–20° (p < 0.05). For the BPA, NH (57.75° ± 13.28°), N20 (36.27° ± 9.89°) and N40 (16.26° ± 9.58°) were significantly higher in that order (p < 0.05). The results of this study revealed that the NHE with an increased lower leg slope angle shifted the BPA to the lower knee flexion angle and enhanced the hamstring EMG activity in the final phase of the descent.

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Biceps Femoris Muscle is Activated by Performing Nordic Hamstring Exercise at a Shallow Knee Flexion Angle

Journal of Sports Science and Medicine ◽

10.52082/jssm.2021.275 ◽

2021 ◽

pp. 275-283

Author(s):

Norikazu Hirose ◽

Masaaki Tsuruike ◽

Ayako Higashihara

Keyword(s):

Knee Flexion ◽

Gluteus Maximus ◽

Biceps Femoris ◽

Flexion Angle ◽

Hamstring Injury ◽

Emg Activity ◽

Knee Flexion Angle ◽

Male Athletes ◽

Biceps Femoris Muscle ◽

Long Head

The semitendinosus (ST) muscle is primarily used during Nordic hamstring exercise (NHE), which is often prescribed for preventing hamstring injury, though the biceps femoris long head (BFlh) muscle that is more susceptible to injuries. Thus, this study aimed to identify the modulation of BFlh muscle activity with different knee flexion angles during NHE using an inclined platform. Fourteen male athletes performed NHE and maintained their position at maximum inclination (NH). Subjects also performed isometric NHE using a platform inclined to 50° (ICL) and 40° (ICH), and the knee flexion angle was controlled to 50° and 30°. The electromyography (EMG) activity of the BFlh, ST, semimembranosus, gluteus maximus, elector spinae, and rectus abdominus muscles was determined during each exercise. The EMG of the ST was higher than that of the BFlh during NHE and the highest of all muscles in all exercises (p < 0.05). Moreover, the activity of the BFlh tended to be higher than that of the ST for ICH than for ICL, regardless of the knee joint angle. The activity of the BFlh becomes equivalent to that of the ST during NHE at a knee flexion angle of less than 50°. These results indicate that performing NHE at a shallow knee flexion angle will enhance the activity of the BFlh muscle.

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A high degree of knee flexion after TKA promotes the ability to perform high-flexion activities and patient satisfaction in Asian population

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04369-4 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Hyuk-Soo Han ◽

Jong Seop Kim ◽

Bora Lee ◽

Sungho Won ◽

Myung Chul Lee

Keyword(s):

Quality Of Life ◽

Patient Satisfaction ◽

Clinical Data ◽

Knee Flexion ◽

Male Gender ◽

Flexion Angle ◽

Knee Flexion Angle ◽

High Flexion ◽

Standing Up

Abstract Background This study investigated whether achieving a higher degree of knee flexion after TKA promoted the ability to perform high-flexion activities, as well as patient satisfaction and quality of life. Methods Clinical data on 912 consecutive primary TKA cases involving a single high-flexion posterior stabilized fixed-bearing prosthesis were retrospectively analyzed. Demographic and clinical data were collected, including knee flexion angle, the ability to perform high-flexion activities, and patient satisfaction and quality of life. Results Of the cases, 619 (68%) achieved > 130° of knee flexion after TKA (high flexion group). Knee flexion angle and clinical scores showed significant annual changes, with the maximum improvement seen at 5 years and slight deterioration observed at 10 years postoperatively. In the high flexion group, more than 50% of the patients could not kneel or squat, and 35% could not stand up from on the floor. Multivariate analysis revealed that > 130° of knee flexion, the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient satisfaction after TKA, while the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient quality of life after TKA. Conclusions High knee flexion angle (> 130°) after TKA increased the ease of high-flexion activities and patient satisfaction. The ease of high-flexion activities also increased quality of life after TKA in our Asian patients, who frequently engage in these activities in daily life.

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Kinematic Comparison between Medially Congruent and Posterior-Stabilized Third-Generation TKA Designs

Journal of Functional Morphology and Kinesiology ◽

10.3390/jfmk6010027 ◽

2021 ◽

Vol 6 (1) ◽

pp. 27

Author(s):

Stefano Ghirardelli ◽

Jessica L. Asay ◽

Erika A. Leonardi ◽

Tommaso Amoroso ◽

Thomas P. Andriacchi ◽

...

Keyword(s):

Knee Flexion ◽

Knee Kinematics ◽

Primary Total Knee Arthroplasty ◽

Flexion Angle ◽

Heel Strike ◽

Third Generation ◽

Knee Flexion Angle ◽

Posterior Stabilized ◽

Rotational Angle ◽

Peak Knee

Background: This study compares knee kinematics in two groups of patients who have undergone primary total knee arthroplasty (TKA) using two different modern designs: medially congruent (MC) and posterior-stabilized (PS). The aim of the study is to demonstrate only minimal differences between the groups. Methods: Ten TKA patients (4 PS, 6 MC) with successful clinical outcomes were evaluated through 3D knee kinematics analysis performed using a multicamera optoelectronic system and a force platform. Extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA), and knee rotational angle at heel-strike. Data were compared with a group of healthy controls. Results: There were no differences in preferred walking speed between MC and PS groups, but we found consistent differences in knee function. At heel-strike, the knee tended to be more flexed in the PS group compared to the MC group; the MSKFA tended to be higher in the PS group compared to the MC group. There was a significant fluctuation in KAA during the swing phase in the PS group compared to the MC group, PS patients showed a higher peak knee flexion moment compared to MC patients, and the PS group had significantly less peak internal rotation moments than the MC group. Conclusions: Modern, third-generation TKA designs failed to reproduce normal knee kinematics. MC knees tended to reproduce a more natural kinematic pattern at heel-strike and during axial rotation, while PS knees showed better kinematics during mid-flexion.

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Quadriceps Strength Symmetry Does Not Modify Gait Mechanics After Anterior Cruciate Ligament Reconstruction, Rehabilitation, and Return-to-Sport Training

The American Journal of Sports Medicine ◽

10.1177/0363546520980079 ◽

2020 ◽

pp. 036354652098007

Author(s):

Elanna K. Arhos ◽

Jacob J. Capin ◽

Thomas S. Buchanan ◽

Lynn Snyder-Mackler

Keyword(s):

Knee Flexion ◽

Cruciate Ligament ◽

Return To Sport ◽

Quadriceps Muscle ◽

Quadriceps Strength ◽

Flexion Angle ◽

Knee Flexion Angle ◽

Sport Training ◽

Gait Biomechanics ◽

Peak Knee

Background: After anterior cruciate ligament (ACL) reconstruction (ACLR), biomechanical asymmetries during gait are highly prevalent, persistent, and linked to posttraumatic knee osteoarthritis. Quadriceps strength is an important clinical measure associated with preoperative gait asymmetries and postoperative function and is a primary criterion for return-to-sport clearance. Evidence relating symmetry in quadriceps strength with gait biomechanics is limited to preoperative and early rehabilitation time points before return-to-sport training. Purpose/Hypothesis: The purpose was to determine the relationship between symmetry in isometric quadriceps strength and gait biomechanics after return-to-sport training in athletes after ACLR. We hypothesized that as quadriceps strength symmetry increases, athletes will demonstrate more symmetric knee joint biomechanics, including tibiofemoral joint loading during gait. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Of 79 athletes enrolled in the ACL-SPORTS Trial, 76 were participants in this study after completing postoperative rehabilitation and 10 return-to-sport training sessions (mean ± SD, 7.1 ± 2.0 months after ACLR). All participants completed biomechanical walking gait analysis and isometric quadriceps strength assessment using an electromechanical dynamometer. Quadriceps strength was calculated using a limb symmetry index (involved limb value / uninvolved limb value × 100). The biomechanical variables of interest included peak knee flexion angle, peak knee internal extension moment, sagittal plane knee excursion at weight acceptance and midstance, quadriceps muscle force at peak knee flexion angle, and peak medial compartment contact force. Spearman rank correlation (ρ) coefficients were used to determine the relationship between limb symmetry indexes in quadriceps strength and each biomechanical variable; alpha was set to .05. Results: Of the 76 participants, 27 (35%) demonstrated asymmetries in quadriceps strength, defined by quadriceps strength symmetry <90% (n = 23) or >110% (n = 4) (range, 56.9%-131.7%). For the biomechanical variables of interest, 67% demonstrated asymmetry in peak knee flexion angle; 68% and 83% in knee excursion during weight acceptance and midstance, respectively; 74% in internal peak knee extension moment; 57% in medial compartment contact force; and 74% in quadriceps muscle force. There were no significant correlations between quadriceps strength index and limb symmetry indexes for any biomechanical variable after return-to-sport training ( P > .129). Conclusion: Among those who completed return-to-sport training after ACLR, subsequent quadriceps strength symmetry was not correlated with the persistent asymmetries in gait biomechanics. After a threshold of quadriceps strength is reached, restoring strength alone may not ameliorate gait asymmetries, and current clinical interventions and return-to-sport training may not adequately target gait.

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Relationship between Quadriceps Tendon Young’s Modulus and Maximum Knee Flexion Angle in the Swing Phase of Gait in Patients with Severe Knee Osteoarthritis

Medicina ◽

10.3390/medicina56090437 ◽

2020 ◽

Vol 56 (9) ◽

pp. 437

Author(s):

Bungo Ebihara ◽

Takashi Fukaya ◽

Hirotaka Mutsuzaki

Keyword(s):

Young’S Modulus ◽

Gait Speed ◽

Knee Flexion ◽

Young's Modulus ◽

Quadriceps Tendon ◽

Swing Phase ◽

Flexion Angle ◽

Knee Flexion Angle ◽

Knee Oa ◽

Analysis System

Background and objectives: Decreased knee flexion in the swing phase of gait can be one of the causes of falls in severe knee osteoarthritis (OA). The quadriceps tendon is one of the causes of knee flexion limitation; however, it is unclear whether the stiffness of the quadriceps tendon affects the maximum knee flexion angle in the swing phase. The purpose of this study was to clarify the relationship between quadriceps tendon stiffness and maximum knee flexion angle in the swing phase of gait in patients with severe knee OA. Materials and Methods: This study was conducted from August 2018 to January 2020. Thirty patients with severe knee OA (median age 75.0 (interquartile range 67.5–76.0) years, Kellgren–Lawrence grade: 3 or 4) were evaluated. Quadriceps tendon stiffness was measured using Young’s modulus by ShearWave Elastography. The measurements were taken with the patient in the supine position with the knee bent at 60° in a relaxed state. A three-dimensional motion analysis system measured the maximum knee flexion angle in the swing phase. The measurements were taken at a self-selected gait speed. The motion analysis system also measured gait speed, step length, and cadence. Multiple regression analysis by the stepwise method was performed with maximum knee flexion angle in the swing phase as the dependent variable. Results: Multiple regression analysis identified quadriceps tendon Young’s modulus (standardized partial regression coefficients [β] = −0.410; p = 0.013) and gait speed (β = 0.433; p = 0.009) as independent variables for maximum knee flexion angle in the swing phase (adjusted coefficient of determination = 0.509; p < 0.001). Conclusions: Quadriceps tendon Young’s modulus is a predictor of the maximum knee flexion angle. Clinically, decreasing Young’s modulus may help to increase the maximum knee flexion angle in the swing phase in those with severe knee OA.

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Interobserver Reliability and Change in the Sagittal Tibial Tubercle–Trochlear Groove Distance with Increasing Knee Flexion Angles

The Journal of Knee Surgery ◽

10.1055/s-0041-1729547 ◽

2021 ◽

Author(s):

Ian S. MacLean ◽

Taylor M. Southworth ◽

Ian J. Dempsey ◽

Neal B. Naveen ◽

Hailey P. Huddleston ◽

...

Keyword(s):

Knee Flexion ◽

Sagittal Plane ◽

Interobserver Reliability ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Flexion Angle ◽

Tibial Tubercle ◽

Trochlear Groove ◽

Knee Flexion Angle ◽

Intraclass Correlation Coefficients

AbstractThe tibial tubercle–trochlear groove (TT-TG) distance is currently utilized to evaluate knee alignment in patients with patellar instability. Sagittal plane pathology measured by the sagittal tibial tubercle–trochlear groove (sTT-TG) distance has been described in instability but may also be important to consider in patients with cartilage injury. This study aims to (1) describe interobserver reliability of the sTT-TG distance and (2) characterize the change in the sTT-TG distance with respect to changing knee flexion angles. In this cadaveric study, six nonpaired cadaveric knees underwent magnetic resonance imaging (MRI) studies at each of the following degrees of knee flexion: −5, 0, 5, 10, 15, and 20. The sTT-TG distance was measured on the axial T2 sequence. Four reviewers measured this distance for each cadaver at each flexion angle. Intraclass correlation coefficients were calculated to determine interobserver reliability and reproducibility of the sTT-TG measurement. Analysis of variance (ANOVA) tests and Friedman's tests with a Bonferroni's correction were performed for each cadaver to compare sTT-TG distances at each flexion angle. Significance was defined as p < 0.05. There was excellent interobserver reliability of the sTT-TG distance with all intraclass correlation coefficients >0.9. The tibial tubercle progressively becomes more posterior in relation to the trochlear groove (more negative sTT-TG distance) with increasing knee flexion. The sTT-TG distance is a measurement that is reliable between attending surgeons and across training levels. The sTT-TG distance is affected by small changes in knee flexion angle. Awareness of knee flexion angle on MRI is important when this measurement is utilized by surgeons.

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Auditory biofeedback decreases jump performance in figure skaters

Brazilian Journal of Motor Behavior ◽

10.20338/bjmb.v8i1.66 ◽

2014 ◽

Vol 8 (1) ◽

Author(s):

Joao A. C. Barros ◽

Llanel Florendo ◽

Yvonne Le

Keyword(s):

Repeated Measures ◽

Knee Flexion ◽

Critical Factor ◽

Cycling Performance ◽

Emg Activity ◽

Jump Height ◽

Jump Performance ◽

Figure Skaters ◽

Female Adolescence ◽

Do So

The few studies that attempted to increase jump height in figure skaters (Haguenauer et al., 2005, Law & Ste-Marie, 2005) have failed to do so. These studies did not focus on increasing knee flexion, a critical factor for jump height (Moran & Wallace, 2007, Vanezis & Lees, 2005). Auditory biofeedback has been shown to modify posture, balance and cycling performance (Dozza et al., 2011; Nicolai et al., 2010; Liu & Jensen, 2009) and could potentially be used to increase knee flexion in figure skaters. To investigate the effects of auditory biofeedback on the performance of Lutz jumps. Thirteen intermediate level female adolescence figure skaters performed 6 off-ice Lutz jumps under each of 2 conditions: 1) WITH auditory biofeedback; 2) and WITHOUT auditory biofeedback. Auditory biofeedback was provided via EMG Retrainer. Separate repeated measures ANOVAs were conducted for time in the air, knee flexion and EMG activity. Differences between conditions for time in the air (p = .012) and knee flexion (p = .049) were identified. Auditory biofeedback increased knee flexion and decreased jump height. In this case, auditory biofeedback might have directed performers attention to an internal cue disrupting performance (Wulf, 2007).

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