Characteristics of rectus femoris activation and rectus femoris–hamstrings coactivation during force-matching isometric knee extension in subacute stroke

2021 ◽  
Author(s):  
John W. Chow ◽  
Dobrivoje S. Stokic
Keyword(s):  
Rectus Femoris ◽  
Knee Extension ◽  
Force Matching ◽  
Subacute Stroke ◽  
Isometric Knee Extension

scholarly journals Muscles Recruited During an Isometric Knee Extension is Defined by Proprioceptive Feedback

2019 ◽  
Author(s):  
Gareth York ◽  
Hugh Osborne ◽  
Piyanee Sriya ◽  
Sarah Astill ◽  
Marc de Kamps ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Conflict Of Interest ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Proprioceptive Feedback ◽  
Muscle Synergy ◽  
Knee Angle ◽  
Potential Conflict ◽  
Dynamic Task ◽  
Isometric Knee Extension

AbstractProprioceptive feedback and its role in control of isometric tasks is often overlooked. In this study recordings were made from upper leg muscles during an isometric knee extension task. Internal knee angle was fixed and subjects were asked to voluntarily activate their rectus femoris muscle. Muscle synergy analysis of these recordings identified canonical temporal patterns in the data. These synergies were found to encode two separate features: one concerning the coordinated contraction of the recorded muscles and the other indicating agonistic/antagonistic interactions between these muscles. The second synergy changed with internal knee angle reflecting the influence of afferent activity. This is in contrast to previous studies of dynamic task experiments which have indicated that proprioception has a negligible effect on synergy expression. Using the MIIND neural simulation platform, we developed a spinal population model with an adjustable input representing proprioceptive feedback. The model is based on existing spinal population circuits used for dynamic tasks. When the same synergy analysis was performed on the output from the model, qualitatively similar muscle synergy patterns were observed. These results suggest proprioceptive feedback is integrated in the spinal cord to control isometric tasks via muscle synergies.Significance statementSensory feedback from muscles is a significant factor in normal motor control. It is often assumed that instantaneous muscle stretch does not influence experiments where limbs are held in a fixed position. Here, we identified patterns of muscle activity during such tasks showing that this assumption should be revisited. We also developed a computational model to propose a possible mechanism, based on a network of populations of neurons, that could explain this phenomenon. The model is based on well established neural circuits in the spinal cord and fits closely other models used to simulate more dynamic tasks like locomotion in vertebrates.Conflict of interest statementThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

scholarly journals The Effect of Limb Position on a Static Knee Extension Task can be Explained with a Simple Spinal Cord Circuit Model

2021 ◽  
Author(s):  
Gareth James Richard York ◽  
Hugh Osborne ◽  
Piyanee Sriya ◽  
Sarah Astill ◽  
Marc de Kamps ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Muscle Activity ◽  
Neural Circuits ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Afferent Input ◽  
Muscle Synergy ◽  
Knee Angle ◽  
Activation Patterns ◽  
Isometric Knee Extension

The influence of proprioceptive feedback on muscle activity during isometric tasks is the subject of conflicting studies. We performed an isometric knee extension task experiment based on two common clinical tests for mobility and flexibility. The task was carried out at four pre-set angles of the knee and we recorded from five muscles for two different hip positions. We applied muscle synergy analysis using non-negative matrix factorisation on surface electromyograph recordings to identify patterns in the data which changed with internal knee angle, suggesting a link between proprioception and muscle activity. We hypothesised that such patterns arise from the way proprioceptive and cortical signals are integrated in neural circuits of the spinal cord. Using the MIIND neural simulation platform, we developed a computational model based on current understanding of spinal circuits with an adjustable afferent input. The model produces the same synergy trends as observed in the data, driven by changes in the afferent input. In order to match the activation patterns from each knee angle and position of the experiment, the model predicts the need for three distinct inputs: two to control a non-linear bias towards the extensors and against the flexors, and a further input to control additional inhibition of rectus femoris. The results show that proprioception may be involved in modulating muscle synergies encoded in cortical or spinal neural circuits.

Force control of quadriceps muscle is bilaterally impaired in subacute stroke

2011 ◽  
Vol 111 (5) ◽  
pp. 1290-1295 ◽  
Author(s):  
John W. Chow ◽  
Dobrivoje S. Stokic
Keyword(s):  
Force Control ◽  
Maximum Voluntary Contraction ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Force Variability ◽  
Stroke Patients ◽  
Subacute Stroke ◽  
Peak Knee ◽  
Isometric Knee Extension

We tested the hypothesis that force variability and error during maintenance of submaximal isometric knee extension are greater in subacute stroke patients than in controls and are related to motor impairments. Contralesional (more-affected) and ipsilesional (less-affected) legs of 33 stroke patients with sufficiently high motor abilities (62 ± 13 yr, 16 ± 2 days postinjury) and the dominant leg of 20 controls (62 ± 10 yr) were tested in sitting position. After peak knee extension torque [maximum voluntary contraction (MVC)] was established, subjects maintained 10, 20, 30, and 50% of MVC as steady and accurate as possible for 10 s by matching voluntary force to the target level displayed on a monitor. Coefficient of variation (CV) and root-mean-square error (RMSE) were used to quantify force variability and error, respectively. The MVC was significantly smaller in the more-affected than less-affected leg, and both were significantly lower than in controls. The CV was significantly larger in the more-affected than less-affected leg at 20 and 50% MVC, whereas both were significantly larger compared with controls across all force levels. Both more-affected and less-affected legs of patients showed significantly greater RMSE than controls at 30 and 50% MVC. The CV and RMSE were not related to the Fugl-Meyer motor score or to the Rivermead Mobility Index. The CV negatively correlated with MVC in controls but only in the less-affected leg of patients. It is concluded that isometric knee extension strength and force control are bilaterally impaired soon after stroke but more so in the more-affected leg. Future studies should examine possible mechanisms and the evolution of these changes.

scholarly journals Improvements in force variability and structure from vision- to memory-guided submaximal isometric knee extension in subacute stroke

2018 ◽  
Vol 124 (3) ◽  
pp. 592-603 ◽  
Author(s):  
John W. Chow ◽  
Dobrivoje S. Stokic
Keyword(s):  
Visual Feedback ◽  
Memory Retrieval ◽  
Spectral Power ◽  
Maximum Voluntary Contraction ◽  
Knee Extension ◽  
Force Variability ◽  
Median Frequency ◽  
Subacute Stroke ◽  
Isometric Knee Extension ◽  
Force Signal

We examined changes in variability, accuracy, frequency composition, and temporal regularity of force signal from vision-guided to memory-guided force-matching tasks in 17 subacute stroke and 17 age-matched healthy subjects. Subjects performed a unilateral isometric knee extension at 10, 30, and 50% of peak torque [maximum voluntary contraction (MVC)] for 10 s (3 trials each). Visual feedback was removed at the 5-s mark in the first two trials (feedback withdrawal), and 30 s after the second trial the subjects were asked to produce the target force without visual feedback (force recall). The coefficient of variation and constant error were used to quantify force variability and accuracy. Force structure was assessed by the median frequency, relative spectral power in the 0–3-Hz band, and sample entropy of the force signal. At 10% MVC, the force signal in subacute stroke subjects became steadier, more broadband, and temporally more irregular after the withdrawal of visual feedback, with progressively larger error at higher contraction levels. Also, the lack of modulation in the spectral frequency at higher force levels with visual feedback persisted in both the withdrawal and recall conditions. In terms of changes from the visual feedback condition, the feedback withdrawal produced a greater difference between the paretic, nonparetic, and control legs than the force recall. The overall results suggest improvements in force variability and structure from vision- to memory-guided force control in subacute stroke despite decreased accuracy. Different sensory-motor memory retrieval mechanisms seem to be involved in the feedback withdrawal and force recall conditions, which deserves further study. NEW & NOTEWORTHY We demonstrate that in the subacute phase of stroke, force signals during a low-level isometric knee extension become steadier, more broadband in spectral power, and more complex after removal of visual feedback. Larger force errors are produced when recalling target forces than immediately after withdrawing visual feedback. Although visual feedback offers better accuracy, it worsens force variability and structure in subacute stroke. The feedback withdrawal and force recall conditions seem to involve different memory retrieval mechanisms.

Changes in muscle activities and kinematics due to simulated leg length inequalities

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hannah Lena Siebers ◽  
Jörg Eschweiler ◽  
Filippo Migliorini ◽  
Valentin Michael Quack ◽  
Markus Tingart ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Pelvic Obliquity ◽  
Lateral Flexion ◽  
Leg Length ◽  
Joint Angles ◽  
Leg Muscles ◽  
Compensation Mechanisms ◽  
Musculoskeletal Problems

Abstract Muscle imbalances are a leading cause of musculoskeletal problems. One example are leg length inequalities (LLIs). This study aimed to analyze the effect of different (simulated) LLIs on back and leg muscles in combination with kinematic compensation mechanics. Therefore, 20 healthy volunteers were analyzed during walking with artificial LLIs (0–4 cm). The effect of different amounts of LLIs and significant differences to the reference condition without LLI were calculated of maximal joint angles, mean muscle activity, and its symmetry index. While walking, LLIs led to higher muscle activity and asymmetry of back muscles, by increased lumbar lateral flexion and pelvic obliquity. The rectus femoris showed higher values, independent of the amount of LLI, whereas the activity of the gastrocnemius on the shorter leg increased. The hip and knee flexion of the long leg increased significantly with increasing LLIs, like the knee extension and the ankle plantarflexion of the shorter leg. The described compensation mechanisms are explained by a dynamic lengthening of the short and shortening of the longer leg, which is associated with increased and asymmetrical muscle activity. Presenting this overview is important for a better understanding of the effects of LLIs to improve diagnostic and therapy in the future.

scholarly journals Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats

2021 ◽  
Vol 2 ◽  
Author(s):  
Rand Hidayah ◽  
Dongbao Sui ◽  
Kennedi A. Wade ◽  
Biing-Chwen Chang ◽  
Sunil Agrawal
Keyword(s):  
Outcome Measures ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Lower Limbs ◽  
Flexion Angle ◽  
Coil Spring ◽  
Foot Pressure ◽  
Low Profile ◽  
Muscle Activations

Abstract Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

scholarly journals EARLY STRENGTH TESTING AFTER ACL RECONSTRUCTION IMPACTS ISOKINETIC STRENGTH PERFORMANCE AT TIME OF RETURN TO SPORT

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0011
Author(s):  
Adam Weaver ◽  
Dylan Roman ◽  
Maua Mosha ◽  
Nicholas Giampetruzzi
Keyword(s):  
Test Performance ◽  
Knee Extension ◽  
Strength Test ◽  
Strength Testing ◽  
Isokinetic Strength ◽  
Rehabilitation Process ◽  
Strength Performance ◽  
Knee Extension Strength ◽  
Isometric Knee Extension ◽  
Strength Tests

Background: The standard of care in ACL reconstruction (ACLR) typically involves standardized strength testing at 6 months or later to assess a patient’s readiness to return to play (RTP) using isokinetic and isometric testing, and functional strength testing. Recent literature suggests that isokinetic knee extension strength should demonstrate 89% limb symmetry index (LSI) or greater prior to returning to sport. However, there is little known on the effects of strength testing early in the rehabilitation process and the relationship to strength test performance at time of RTP. Purpose: The purpose of this study was to examine how early post-operative strength test performance impacts isokinetic strength outcomes at RTP testing in adolescents. Methods: The retrospective cohort study included patients undergoing primary ACLR between 12 and 18 years of age, early post-operative strength measures, and isokinetic dynamometer strength at RTP from July 2017 and April 2019. Data was dichotomized into desired outcomes at 3 months: >70% isometric knee extension LSI, > 20 repetitions on anterior stepdown test (AST), > 90% LSI Y Balance. At RTP testing, isokinetic knee extension strength data was categorized into >89% LSI at 3 speeds (300, 180, 60°/sec). Chi square testing and odds ratio statistics were used to examine association and its magnitude. Results: 63 patients met inclusion criteria (38 females; 15.37±1.66 years old). >70% LSI isometric knee extension strength at 3 months showed a significant association (Table 2) and demonstrated the strongest odds of having >89% LSI on isokinetic strength tests at all 3 speeds at RTP with 180°/sec being the highest (OR=14.5; 95% CI=4.25,49.43; p= <0.001). Performance on AST showed a significant association (χ2 (1, n=63) = 17.00, p <0.001), and highest odds at 180°/sec (OR=4.61; 95% CI = 1.59, 13.39, p=<0.001) and 60°/sec (OR= 3.07; 95% CI = 1.10, 8.63, p= 0.04). Combination of performance on isometric strength tests and AST showed a significant association to isokinetic strength at all three speeds, but less predictive then isometrics in isolation. (Table 2). There was no significant relationship between YBR LSI at 3 months and isokinetic strength at 6 months. Conclusion: Standardized strength testing early in rehabilitation can help identify patients that will successfully complete RTP testing. Our results suggest that isometric knee extension strength and timed anterior stepdown test provide meaningful clinical information early in the rehabilitation process. This data also suggests that the use of YBAL for predicting isokinetic strength performance is limited. [Table: see text][Table: see text]

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

2019 ◽  
Vol 44 (8) ◽  
pp. 827-833 ◽  
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.

scholarly journals Midterm outcome and strength assessment after proximal rectus femoris refixation in athletes

2021 ◽  
Author(s):  
Maximilian Hinz ◽  
Stephanie Geyer ◽  
Felix Winden ◽  
Alexander Braunsperger ◽  
Florian Kreuzpointner ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Harris Hip Score ◽  
Postoperative Results ◽  
Postoperative Result ◽  
Strength Assessment ◽  
Competitive Athletes ◽  
Hip Flexion

Abstract Purpose Proximal rectus femoris avulsions (PRFA) are relatively rare injuries that occur predominantly among young soccer players. The aim of this study was to evaluate midterm postoperative results including strength potential via standardized strength measurements after proximal rectus femoris tendon refixation. It was hypothesized that the majority of competitive athletes return to competition (RTC) after refixation of the rectus femoris tendon without significant strength or functional deficits compared to the contralateral side. Methods Patients with an acute (< 6 weeks) PRFA who underwent surgical refixation between 2012 and 2019 with a minimum follow-up of 12 months were evaluated. The outcome measures compiled were the median Tegner Activity Scale (TAS) and mean RTC time frames, Harris Hip Score (HHS), Hip and Groin Outcome Score (HAGOS) subscales, International Hip Outcome Tool-33 (iHOT-33), and Visual Analog Scale (VAS) for pain. In addition, a standardized isometric strength assessment of knee flexion, knee extension, and hip flexion was performed to evaluate the functional result of the injured limb in comparison to the uninjured side. Results Out of 20 patients, 16 (80%) patients were available for final assessment at a mean follow-up of 44.8 ± SD 28.9 months. All patients were male with 87.5% sustaining injuries while playing soccer. The average time interval between trauma and surgery was 18.4 ± 8.5 days. RTC was possible for 14 out of 15 previously competitive athletes (93.3%) at a mean 10.5 ± 3.4 months after trauma. Patients achieved a high level of activity postoperatively with a median (interquartile range) TAS of 9 (7–9) and reported good to excellent outcome scores (HHS: 100 (96–100); HAGOS: symptoms 94.6 (89.3–100), pain 97.5 (92.5–100), function in daily living 100 (95–100), function in sport and recreation 98.4 (87.5–100), participation in physical activities 100 (87.5–100), quality of life 83.1 ± 15.6; iHot-33: 95.1 (81.6–99.8)). No postoperative complications were reported. Range of motion, isometric knee flexion and extension, as well as hip flexion strength levels were not statistically different between the affected and contralateral legs. The majority of patients were “very satisfied” (56.3%) or “satisfied” (37.5%) with the postoperative result and reported little pain (VAS 0 (0–0.5)). Conclusion Surgical treatment of acute PRFA yields excellent postoperative results in a young and highly active cohort. Hip flexion and knee extension strength was restored fully without major surgical complications. Level of evidence Retrospective cohort study; III.

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