scholarly journals Motor cortical and corticospinal function differ during an isometric squat compared with isometric knee extension

2018 ◽  
Vol 103 (9) ◽  
pp. 1251-1263 ◽  
Author(s):  
Callum G. Brownstein ◽  
Paul Ansdell ◽  
Jakob Škarabot ◽  
Ash Frazer ◽  
Dawson Kidgell ◽  
...  
Keyword(s):  
Knee Extension ◽  
Isometric Knee Extension ◽  
Motor Cortical

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 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 Familiarization and Reliability of the Isometric Knee Extension Test for Rapid Force Production Assessment

2020 ◽  
Vol 10 (13) ◽  
pp. 4499
Author(s):  
Javier Courel-Ibáñez ◽  
Alejandro Hernández-Belmonte ◽  
Alejandro Cava-Martínez ◽  
Jesús G. Pallarés
Keyword(s):  
Force Production ◽  
Force Sensor ◽  
Knee Extension ◽  
Positive Effects ◽  
Concentric Force ◽  
Isometric Knee Extension ◽  
Test Retest Reliability ◽  
New Evidence ◽  
Practical Field ◽  
Familiarization Session

Despite the rising interest in the use of portable force sensors during isometric exercises to inform on neuromuscular performance, the design of practical field-based methods to obtain reliable measures is an ongoing challenge. We aim at identifying the intra-session and test-retest reliability of a rapid, isometric knee extension test to evaluate the maximal voluntary concentric force (MVC), rate of force development (RFD) and impulse following a field-based approach. On two occasions, 14 athletes unfamiliar with the test completed three sets of 2 s ballistic contractions (as fast and hard as possible) with 30 s rest. Raw and filtered data were collected in real time using a portable force sensor. RFD and impulse were highly reliability during “late” phases of the contraction (0–250 ms) since the first session (coefficient of variation (CV) < 9.8%). Earlier phases (0–150 ms) achieved a moderate reliability after one familiarization session (CV < 7.1%). Measures at 0–50 ms did not reach sufficient reliability (CV~14%). MVC was accurately assessed. Dominant limbs were not importantly altered by the familiarization. In opposite, non-dominant limbs showed large variations. New evidence is provided about the positive effects of a single familiarization session to improve the reliability the isometric knee extension test for rapid force production assessment. Coaches and practitioners may benefit of from these findings to conduct practical and reliable assessments of the rapid force production using a portable force sensor and a field-based approach.

scholarly journals Isometric knee extension force in Japanese type 2 diabetic patients without apparent diabetic polyneuropathy: Data from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study

2019 ◽  
Vol 7 ◽  
pp. 205031211882341 ◽  
Author(s):  
Takuo Nomura ◽  
Tomoyasu Ishiguro ◽  
Masayoshi Ohira ◽  
Hiroyuki Oka ◽  
Yukio Ikeda
Keyword(s):  
Type 2 Diabetes ◽  
Diabetic Polyneuropathy ◽  
Knee Extension ◽  
Diabetic Patients ◽  
Control Subjects ◽  
Multicenter Survey ◽  
Isometric Knee Extension ◽  
Extension Force ◽  
Healthy Control

Objectives: To determine standard reference values for isometric knee extension force using a cohort of Japanese type 2 diabetic patients without diabetic polyneuropathy. Methods: Patient data were collected from the Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes study and compared with previously published data of healthy control subjects. In total, we enrolled 898 patients with type 2 diabetes aged 30–87 years, who did not have diabetic polyneuropathy. The control group included 510 healthy subjects aged 30–88 years. Maximum isometric knee extension force (KEF) values were obtained by using a hand-held dynamometer with belt stabilization. In addition, KEF (kgf) was adjusted for bodyweight (kg) to calculate %KEF. Results: KEF and %KEF decreased with age in both patients with diabetes and healthy control subjects. The mean values of KEF and %KEF in patients with diabetes were reduced by 9.7% and 20.8%, respectively, in males, and by 11.6% and 23.0%, respectively, in females compared to the values in healthy control subjects. Conclusion: KEF and %KEF in patients with type 2 diabetes without diabetic polyneuropathy may reduce by approximately 10% and 20%, respectively, compared to these values in healthy control subjects. This study provides reference values for isometric KEF with respect to sex in a population covering a wide age range.

Kilohertz and Low-Frequency Electrical Stimulation With the Same Pulse Duration Have Similar Efficiency for Inducing Isometric Knee Extension Torque and Discomfort

2017 ◽  
Vol 96 (6) ◽  
pp. 388-394 ◽  
Author(s):  
Flávia Vanessa Medeiros ◽  
Martim Bottaro ◽  
Amilton Vieira ◽  
Tiago Pires Lucas ◽  
Karenina Arrais Modesto ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Pulse Duration ◽  
Low Frequency ◽  
Knee Extension ◽  
Isometric Knee Extension

Motor units in vastus lateralis and in different vastus medialis regions show different firing properties during low-level, isometric knee extension contraction

2018 ◽  
Vol 58 ◽  
pp. 307-314 ◽  
Author(s):  
Leonardo Mendes Leal de Souza ◽  
Hélio Veiga Cabral ◽  
Liliam Fernandes de Oliveira ◽  
Taian Martins Vieira
Keyword(s):  
Vastus Lateralis ◽  
Motor Units ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Low Level ◽  
Isometric Knee Extension ◽  
Firing Properties
Sign in / Sign up

Export Citation Format

Share Document