Biarticular Hamstring Muscles Can Act as Knee Extensors – A Computer Simulation Study

Abstract Purpose: It is unclear whether biarticular hamstring muscles (HAM) can act as knee extensors or not. The purpose of this study is to identify the conditions that HAM can act as a knee extensor by using a computational simulation approach.Methods: The modified Gait2392 musculoskeletal model was used in this study. The posture was determined with a hip flexion angle that ranged from -30° to 90° and a knee flexion angle that ranged from -10 ° to 90 °. The simulations were executed under two conditions: all segments are free to move, non-contact with the ground (nCG), and the foot is constrained on the ground, contact with the ground (CG). Induced acceleration analysis was applied to determine the contribution of the HAM to the knee angular acceleration.Results: Three key findings were discovered. 1) HAM can act as knee extensors that have CG condition as well as nCG condition. 2) The HAM function changes depending on the posture. 3) The range of the hip joint that HAM was able to act as a knee extensor was expanded for the CG condition from the nCG condition.Conclusions: We identified the situations in which HAM can act as knee extensors and demonstrated that the HAM function on the knee joint changes depending on the posture and the foot contact condition. Our findings suggest that HAM can be used as compensatory movement strategy for patients with a reduced capacity to generate knee extension if the patients have enough HAM strength.

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Regional and muscle-specific adaptations in knee extensor hypertrophy using flywheel versus conventional weight-stack resistance exercise

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2018-0774 ◽

2019 ◽

Vol 44 (8) ◽

pp. 827-833 ◽

Cited By ~ 4

Author(s):

Tommy R. Lundberg ◽

Maria T. García-Gutiérrez ◽

Mirko Mandić ◽

Mats Lilja ◽

Rodrigo Fernandez-Gonzalo

Keyword(s):

Resistance Exercise ◽

Muscle Hypertrophy ◽

Vastus Lateralis ◽

Knee Extensor ◽

Rectus Femoris ◽

Knee Extension ◽

Knee Extensors ◽

Cross Sectional ◽

Proximal Site ◽

Before And After

This study compared the effects of the most frequently employed protocols of flywheel (FW) versus weight-stack (WS) resistance exercise (RE) on regional and muscle-specific adaptations of the knee extensors. Sixteen men (n = 8) and women (n = 8) performed 8 weeks (2–3 days/week) of knee extension RE employing FW technology on 1 leg (4 × 7 repetitions), while the contralateral leg performed regular WS training (4 × 8–12 repetitions). Maximal strength (1-repetition maximum (1RM) in WS) and peak FW power were determined before and after training for both legs. Partial muscle volume of vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF) were measured using magnetic resonance imaging. Additionally, quadriceps cross-sectional area was assessed at a proximal and a distal site. There were no differences (P > 0.05) between FW versus WS in muscle hypertrophy of the quadriceps femoris (8% vs. 9%), VL (10% vs. 11%), VM (6% vs. 8%), VI (5% vs. 5%), or RF (17% vs. 17%). Muscle hypertrophy tended (P = 0.09) to be greater at the distal compared with the proximal site, but there was no interaction with exercise method. Increases in 1RM and FW peak power were similar across legs, yet the increase in 1RM was greater in men (31%) than in women (20%). These findings suggest that FW and WS training induces comparable muscle-specific hypertrophy of the knee extensors. Given that these robust muscular adaptations were brought about with markedly fewer repetitions in the FW compared with WS, it seems FW training can be recommended as a particularly time-efficient exercise paradigm.

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Effect of Hip Flexion Angle on the Hamstring to Quadriceps Strength Ratio

Sports ◽

10.3390/sports7020043 ◽

2019 ◽

Vol 7 (2) ◽

pp. 43

Author(s):

Eleftherios Kellis ◽

Athanasios Ellinoudis ◽

and Nikolaos Kofotolis

Keyword(s):

Muscle Activation ◽

Rectus Femoris ◽

Biceps Femoris ◽

Knee Extension ◽

Quadriceps Strength ◽

Flexion Angle ◽

Electromyographic Activity ◽

H:Q Ratio ◽

Hip Flexion ◽

Selection Of

The purpose of this study was to compare the hamstring to quadriceps ratio (H:Q) obtained from three different hip flexion angles. Seventy-three young athletes performed maximum isokinetic concentric and eccentric knee extension and flexion efforts at 60 °·s−1 and 240 °·s−1 from hip flexion angles of 90°, 60°, and 120°. The conventional (concentric to concentric), functional (eccentric to concentric) and mixed (eccentric at 30 °·s−1 to concentric torque at 240 °·s−1) H: Q torque ratios and the electromyographic activity from the rectus femoris and biceps femoris were analyzed. The conventional H:Q ratios and the functional H:Q ratios at 60 °·s−1 did not significantly differ between the three testing positions (p > 0.05). In contrast, testing from the 90° hip flexion angle showed a greater functional torque ratio at 240 °·s−1 and a mixed H:Q torque ratio compared with the other two positions (p < 0.05). The hip flexion angle did not influence the recorded muscle activation signals (p > 0.05). For the range of hip flexion angles tested, routine isokinetic assessment of conventional H:Q ratio and functional H:Q ratio at slow speed is not angle-dependent. Should assessment of the functional H:Q ratio at fast angular velocity or the mixed ratio is required, then selection of hip flexion angle is important.

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Proprioceptive Neuromuscular Facilitation Improves Balance and Knee Extensors Strength of Older Fallers

ISRN Rehabilitation ◽

10.5402/2012/402612 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

Marcelo Pinto Pereira ◽

Mauro Gonçalves

Keyword(s):

Exercise Program ◽

Knee Extensor ◽

Training Group ◽

Knee Extension ◽

Knee Extensors ◽

Control Group ◽

Extension Rate ◽

Neuromuscular Activation ◽

Activation Level ◽

Proprioceptive Neuromuscular Facilitation

Falls are one of the major problems for elderly people and proprioceptive exercises have been suggested as an alternative in rehabilitation and preventive programs. The purpose of this study was to investigate the influence of a proprioceptive neuromuscular facilitation (PNF) exercise program on balance, knee extension and flexion isometric torque, and knee extension rate of force development (RFD). Fourteen older faller subjects (>60 years) were equally assigned into two groups: a control group (CG: n=7) and a training group (TG: n=7). The PNF training program was performed for 10 weeks on TG, with a frequency of three times per week. Patients were assessed before and after the PNF program, with respect to balance (Berg Balance Scale score—BBS), knee maximal isometric extension and flexion torque, knee extensor RFD, and knee extensors and flexors neuromuscular activation level and coactivation level around the knee. After 10 weeks, balance (P<0.001) and knee extension torque (P=0.05) were improved in TG while no differences were found for CG. These improvements were mainly attributed to central nervous system adaptations, since no differences were found for neuromuscular activation level and coactivation.

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Hyperthermia and central fatigue during prolonged exercise in humans

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.3.1055 ◽

2001 ◽

Vol 91 (3) ◽

pp. 1055-1060 ◽

Cited By ~ 349

Author(s):

Lars Nybo ◽

Bodil Nielsen

Keyword(s):

Core Temperature ◽

Maximal Oxygen Consumption ◽

Knee Extensor ◽

Central Fatigue ◽

Knee Extension ◽

Voluntary Contraction ◽

Voluntary Activation ◽

Knee Extensors ◽

Total Force ◽

Impaired Performance

The present study investigated the effects of hyperthermia on the contributions of central and peripheral factors to the development of neuromuscular fatigue. Fourteen men exercised at 60% maximal oxygen consumption on a cycle ergometer in hot (40°C; hyperthermia) and thermoneutral (18°C; control) environments. In hyperthermia, the core temperature increased throughout the exercise period and reached a peak value of 40.0 ± 0.1°C (mean ± SE) at exhaustion after 50 ± 3 min of exercise. In control, core temperature stabilized at ∼38.0 ± 0.1°C, and exercise was maintained for 1 h without exhausting the subjects. Immediately after the cycle trials, subjects performed 2 min of sustained maximal voluntary contraction (MVC) either with the exercised legs (knee extension) or with a “nonexercised” muscle group (handgrip). The degree of voluntary activation during sustained maximal knee extensions was assessed by superimposing electrical stimulation (EL) to nervus femoralis. Voluntary knee extensor force was similar during the first 5 s of contraction in hyperthermia and control. Thereafter, force declined in both trials, but the reduction in maximal voluntary force was more pronounced in the hyperthermic trial, and, from 30 to 120 s, the force was significantly lower in hyperthermia compared with control. Calculation of the voluntary activation percentage (MVC/MVC + EL) revealed that the degree of central activation was significantly lower in hyperthermia (54 ± 7%) compared with control (82 ± 6%). In contrast, total force of the knee extensors (MVC + force from EL) was not different in the two trials. Force development during handgrip contraction followed the same pattern of response as was observed for the knee extensors. In conclusion, these data demonstrate that the ability to generate force during a prolonged MVC is attenuated with hyperthermia, and the impaired performance is associated with a reduction in the voluntary activation percentage.

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The Effect of Prolonged Running on the Symmetry of Biomechanical Variables of the Lower Limb Joints

Symmetry ◽

10.3390/sym12050720 ◽

2020 ◽

Vol 12 (5) ◽

pp. 720

Author(s):

Zixiang Gao ◽

Qichang Mei ◽

Gusztáv Fekete ◽

Julien S Baker ◽

Yaodong Gu

Keyword(s):

Lower Limb ◽

Force Plate ◽

Knee Extension ◽

Lower Limbs ◽

Flexion Angle ◽

Camera Motion ◽

Long Distance ◽

Therapy Assessment ◽

Long Distance Running ◽

Hip Flexion

The aim of this study was to examine whether there are kinematic and kinetic differences in the lower limb and whether the symmetry of the lower extremities is different after prolonged-running. Fifteen healthy male amateur runners (age: 22 ± 1 years, height: 173 ± 8 cm, mass: 65 ± 7 kg, BMI: 21.62 ± 2 kg/m2) were recruited as participants for this study. A Vicon eight-camera motion capture system and Kistler force plate were used to collect kinematic and kinetic parameters. A motorized treadmill, 15-point Borg scale and heart rate bands were used to monitor fatigue during a running-induced fatigue protocol. Paired sample T tests were used to check statistical difference (p = 0.05) between the lower limbs and the symmetry changes in pre-fatigue and post-fatigue running sessions. The symmetry angle (SA) of the knee flexion angle, hip flexion angle and hip extension angle in post-fatigue was significantly greater than in pre-fatigue, increasing by 4.32%, 10.71%, and 23.12%, respectively. Moreover, the SA of hip flexion moment increased by 2.61%. However, the knee extension velocity and hip flexion velocity became more symmetrical than in pre-fatigue (p < 0.05), the SA decreased by 5.91% and 5.45%, respectively. Differences in limb function during post-fatigue may lead to changes of symmetry in the lower limbs. The variables of asymmetry may be used as a compensation mechanism to maintain gait stability. Physical therapy assessment of fatigue injuries and long-distance running training programs may want to consider the changes in symmetry due to limb dominance.

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Effects of Hip Flexion on Knee Extension and Flexion Isokinetic Angle-Specific Torques and HQ-Ratios

Sports Medicine - Open ◽

10.1186/s40798-021-00330-w ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Christian Baumgart ◽

Eduard Kurz ◽

Jürgen Freiwald ◽

Matthias Wilhelm Hoppe

Keyword(s):

Hip Joint ◽

Knee Flexion ◽

Daily Life ◽

Knee Extension ◽

Flexion Angle ◽

Strength Testing ◽

Knee Strength ◽

Sporting Activities ◽

Torque Values ◽

Hip Flexion

Abstract Background and Methods During isokinetic knee strength testing, the knee flexion angles that correspond to the measured torque values are rarely considered. Additionally, the hip flexion angle during seated testing diverges from that in the majority of daily life and sporting activities. Limited information concerning the influence of hip angle, muscle contraction mode, and velocity on the isokinetic knee strength over the entire range of motion (ROM) is available. Twenty recreational athletes (10 females, 10 males; 23.3 ± 3.2 years; 72.1 ± 16.5 kg; 1.78 ± 0.07 m) were tested for isokinetic knee flexion and extension at 10° and 90° hip flexion with the following conditions: (i) concentric at 60°/s, (ii) concentric at 180°/s, and (iii) eccentric at 60°/s. The effects of hip angle, contraction mode, and velocity on angle-specific torques and HQ-ratios as well as conventional parameters (peak torques, angles at peak torque, and HQ-ratios) were analyzed using statistical parametric mapping and parametric ANOVAs, respectively. Results Generally, the angle-specific and conventional torques and HQ-ratios were lower in the extended hip compared to a flexed hip joint. Thereby, in comparison to the knee extension, the torque values decreased to a greater extent during knee flexion but not consistent over the entire ROM. The torque values were greater at the lower velocity and eccentric mode, but the influence of the velocity and contraction mode were lower at shorter and greater muscle lengths, respectively. Conclusions Isokinetic knee strength is influenced by the hip flexion angle. Therefore, a seated position during testing and training is questionable, because the hip joint is rarely flexed at 90° during daily life and sporting activities. Maximum knee strength is lower in supine position, which should be considered for training and testing. The angle-specific effects cannot be mirrored by the conventional parameters. Therefore, angle-specific analyses are recommended to obtain supplemental information and consequently to improve knee strength testing.

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Adaptive control for backward quadrupedal walking. II. Hindlimb muscle synergies

Journal of Neurophysiology ◽

10.1152/jn.1990.64.3.756 ◽

1990 ◽

Vol 64 (3) ◽

pp. 756-766 ◽

Cited By ~ 69

Author(s):

J. A. Buford ◽

J. L. Smith

Keyword(s):

High Speed ◽

Vastus Lateralis ◽

Knee Extensor ◽

Biceps Femoris ◽

Knee Extension ◽

Knee Joints ◽

Emg Activity ◽

Step Cycle ◽

Cine Film ◽

Hip Flexion

1. To compare the basic hindlimb synergies for backward (BWD) and forward (FWD) walking, electromyograms (EMG) were recorded from selected flexor and extensor muscles of the hip, knee, and ankle joints from four cats trained to perform both forms of walking at a moderate walking speed (0.6 m/s). For each muscle, EMG measurements included burst duration, burst latencies referenced to the time of paw contact or paw off, and integrated burst amplitudes. To relate patterns of muscle activity to various phases of the step cycle, EMG records were synchronized with kinematic data obtained by digitizing high-speed cine film. 2. Hindlimb EMG data indicate that BWD walking in the cat was characterized by reciprocal flexor and extensor synergies similar to those for FWD walking, with flexors active during swing and extensors active during stance. Although the underlying synergies were similar, temporal parameters (burst latencies and durations) and amplitude levels for specific muscles were different for BWD and FWD walking. 3. For both directions, iliopsoas (IP) and semitendinosus (ST) were active as the hip and knee joints flexed at the onset of swing. For BWD walking, IP activity decreased early, and ST activity continued as the hip extended and the knee flexed. For FWD walking, in contrast, ST activity ceased early, and IP activity continued as the hip flexed and the knee extended. For both directions, tibialis anterior (TA) was active throughout swing as the ankle flexed and then extended. A second ST burst occurred at the end of swing for FWD walking as hip flexion and knee extension slowed for paw contact. 4. For both directions, knee extensor (vastus lateralis, VL) activity began at paw contact. Ankle extensor (lateral gastrocnemius, LG) activity began during midswing for BWD walking but just before paw contact for FWD walking. At the ankle joint, flexion during the E2 phase (yield) of stance was minimal or absent for BWD walking, and ankle extension during BWD stance was accompanied by a ramp increase in LG-EMG activity. At the knee joint, the yield was also small (or absent) for BWD walking, and increased VL-EMG amplitudes were associated with the increased range of knee extension for BWD stance. 5. Although the uniarticular hip extensor (anterior biceps femoris, ABF) was active during stance for both directions, the hip flexed during BWD stance and extended during FWD stance.(ABSTRACT TRUNCATED AT 400 WORDS)

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Quadriceps Activation during Knee Extension Exercises in Patients with ACL Pathologies

Journal of Applied Biomechanics ◽

10.1123/jab.17.2.87 ◽

2001 ◽

Vol 17 (2) ◽

pp. 87-102 ◽

Cited By ~ 15

Author(s):

Esther Suter ◽

Walter Herzog ◽

Robert Bray

Keyword(s):

Vastus Lateralis ◽

Cruciate Ligament ◽

Knee Extensor ◽

Quadriceps Muscle ◽

Knee Extension ◽

Knee Extensors ◽

Muscle Inhibition ◽

The Individual ◽

Hip Extension ◽

Acl Deficient

This study assessed muscle inhibition in patients with chronic anterior cruciate ligament (ACL) deficiency or ACL reconstruction. A series of protocols were tested for their effectiveness in increasing activity of the individual knee extensor muscles and decreasing muscle inhibition of the whole quadriceps group. Quadriceps muscle inhibition was measured by superimposing an electrical twitch onto the quadriceps muscle during a maximal voluntary knee extension. The level of activation of the individual knee extensor and knee flexor muscles was assessed via electromyography (EMG). Patients with ACL pathologies showed strength deficits and muscle inhibition in the knee extensors of the involved leg and the contralateral leg. Muscle inhibition was statistically significantly greater in ACL-deficient patients compared to ACL-reconstructed patients. When a knee extension was performed in combination with a hip extension, there was a significant increase,p< 0.05, in activation of the vastus medialis and vastus lateralis muscles compared to isolated knee extension. The use of an anti-shear device, designed to help stabilize the ACL-deficient knee, resulted in increased inhibition in the quadriceps muscle. Furthermore, a relatively more complete activation of the vasti compared to the rectus femoris was achieved during a fatiguing isometric contraction. Based on the results of this study, it is concluded that performing knee extension in combination with hip extension, or performing fatiguing knee extensor contractions, may be more effective in fully activating the vasti muscles than an isolated knee extensor contraction. Training interventions are needed to establish whether these exercise protocols are more effective than traditional rehabilitation approaches in decreasing muscle inhibition and achieving better functional recovery, including equal muscle strength in the injured and the contralateral leg.

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A New Concept For Isokinetic Hamstring: Quadriceps Muscle Strength Ratio

The American Journal of Sports Medicine ◽

10.1177/03635465980260021201 ◽

1998 ◽

Vol 26 (2) ◽

pp. 231-237 ◽

Cited By ~ 231

Author(s):

Per Aagaard ◽

Erik B. Simonsen ◽

S. Peter Magnusson ◽

Benny Larsson ◽

Poul Dyhre-Poulsen

Keyword(s):

Muscle Strength ◽

Angular Velocity ◽

Knee Joint ◽

Knee Extensor ◽

Quadriceps Muscle ◽

Knee Extension ◽

Quadriceps Strength ◽

Strength Ratio ◽

Joint Stability ◽

Hamstring Muscles

Conventionally, the hamstring:quadriceps strength ratio is calculated by dividing the maximal knee flexor (hamstring) moment by the maximal knee extensor (quadriceps) moment measured at identical angular velocity and contraction mode. The agonist-antagonist strength relationship for knee extension and flexion may, however, be better described by the more functional ratios of eccentric hamstring to concentric quadriceps moments (extension), and concentric hamstring to eccentric quadriceps moments (flexion). We compared functional and conventional isokinetic hamstring: quadriceps strength ratios and examined their relation to knee joint angle and joint angular velocity. Peak and angle-specific (50°, 40°, and 30° of knee flexion) moments were determined during maximal concentric and eccentric muscle contractions (10° to 90° of motion; 30 and 240 deg/sec). Across movement speeds and contraction modes the functional ratios for different moments varied between 0.3 and 1.0 (peak and 50°), 0.4 and 1.1 (40°), and 0.4 and 1.4 (30°). In contrast, conventional hamstring:quadriceps ratios were 0.5 to 0.6 based on peak and 50° moments, 0.6 to 0.7 based on 40° moment, and 0.6 to 0.8 based on 30° moment. The functional hamstring:quadriceps ratio for fast knee extension yielded a 1:1 relationship, which increased with extended knee joint position, indicating a significant capacity of the hamstring muscles to provide dynamic knee joint stability in these conditions. The evaluation of knee joint function by use of isokinetic dynamometry should comprise data on functional and conventional hamstring:quadriceps ratios as well as data on absolute muscle strength.

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Hip-Extensor Strength, Trunk Posture, and Use of the Knee-Extensor Muscles During Running

Journal of Athletic Training ◽

10.4085/1062-6050-51.8.05 ◽

2016 ◽

Vol 51 (7) ◽

pp. 519-524 ◽

Cited By ~ 13

Author(s):

Hsiang-Ling Teng ◽

Christopher M. Powers

Keyword(s):

Muscle Strength ◽

Sagittal Plane ◽

Knee Injuries ◽

Knee Extensor ◽

Extensor Muscle ◽

Muscle Performance ◽

Flexion Angle ◽

Knee Extensors ◽

Trunk Flexion ◽

Trunk Posture

Context: Diminished hip-muscle performance has been proposed to contribute to various knee injuries. Objective: To determine the association between hip-extensor muscle strength and sagittal-plane trunk posture and the relationships among hip-extensor muscle strength and hip- and knee-extensor work during running. Design: Descriptive laboratory study. Setting: Musculoskeletal biomechanical laboratory. Patients or Other Participants: A total of 40 asymptomatic recreational runners, 20 men (age = 27.1 ± 7.0 years, height = 1.74 ± 0.69 m, mass = 71.1 ± 8.2 kg) and 20 women (age = 26.2 ± 5.8 years, height = 1.65 ± 0.74 m, mass = 60.6 ± 6.6 kg), participated. Main Outcome Measure(s): Maximum isometric strength of the hip extensors was assessed using a dynamometer. Sagittal-plane trunk posture (calculated relative to the global vertical axis) and hip- and knee-extensor work (sum of energy absorption and generation) during the stance phase of running were quantified while participants ran over ground at a controlled speed of 3.4 m/s. We used Pearson product moment correlations to examine the relationships among hip-extensor strength, mean sagittal-plane trunk-flexion angle, hip-extensor work, and knee-extensor work. Results: Hip-extensor strength was correlated positively with trunk-flexion angle (r = 0.55, P < .001) and hip-extensor work (r = 0.46, P = .003). It was correlated inversely with knee-extensor work (r = −0.39, P = .01). All the correlations remained after adjusting for sex. Conclusions: Our findings suggest that runners with hip-extensor weakness used a more upright trunk posture. This strategy led to an overreliance on the knee extensors and may contribute to overuse running injuries at the knee.

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