The Relative Orientation of the Trunk and Tibia can be Used to Estimate the Demands on the Hip and Knee Extensors During the Barbell Back Squat

2021 ◽  
pp. 174795412199795
Author(s):  
Adam J Barrack ◽  
Rachel K Straub ◽  
Jordan Cannon ◽  
Christopher M Powers
Keyword(s):  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Knee Extensor ◽  
Knee Extensors ◽  
Back Squat ◽  
Relative Demand ◽  
Moment Ratio ◽  
Peak Knee ◽  
The Difference ◽  
The Relationship

Sagittal plane inclination of the trunk and tibia have been shown to independently modulate hip and knee extensor moments during squatting. The purpose of this study was to determine if the difference between sagittal plane trunk and tibia inclinations can be used to approximate the relative demand of the hip and knee extensors across a range of squatting conditions. Kinematic and kinetic data were obtained from 16 participants during 8 squat conditions in which trunk and tibia inclination were manipulated. The average hip/knee extensor moment ratio (HKR) was calculated during the lowering (eccentric) phase of each squat condition using inverse dynamics equations. Linear regression evaluated the association between the difference in trunk and tibia inclination at peak knee flexion and the average HKR. Across all squat conditions, the difference between trunk and tibia inclinations explained 70% of the variance in the average HKR (p < 0.001). The squat was knee extensor biased (HKR ≤ 1.0) when the tibia was at least 8 degrees more inclined than the trunk. The results of this study indicate that the relationship between sagittal plane trunk and tibia inclination can be used to estimate the relative demand of the hip and knee extensors.

Clinical Estimation of the Use of the Hip and Knee Extensors During Athletic Movements Using 2D Video

2021 ◽  
pp. 1-5
Author(s):  
Rachel K. Straub ◽  
Alex Horgan ◽  
Christopher M. Powers
Keyword(s):  
Sagittal Plane ◽  
Linear Regression Analysis ◽  
Knee Injuries ◽  
Knee Extensor ◽  
Practical Method ◽  
Movement Behavior ◽  
Knee Extensors ◽  
Deceleration Phase ◽  
Moment Ratio ◽  
Peak Knee

Given that increased use of the knee extensors relative to the hip extensors may contribute to various knee injuries, there is a need for a practical method to characterize movement behavior indicative of how individuals utilize the hip and knee extensors during dynamic tasks. The purpose of the current study was to determine whether the difference between sagittal plane trunk and tibia orientations obtained from 2D video (2D trunk–tibia) could be used to predict the average hip/knee extensor moment ratio during athletic movements. Thirty-nine healthy athletes (15 males and 24 females) performed 6 tasks (step down, drop jump, lateral shuffle, deceleration, triple hop, and side-step-cut). Lower-extremity kinetics (3D) and sagittal plane video (2D) were collected simultaneously. Linear regression analysis was performed to determine if the 2D trunk–tibia angle at peak knee flexion predicted the average hip/knee extensor moment ratio during the deceleration phase of each task. For each task, an increase in the 2D trunk–tibia angle predicted an increase in the average hip/knee extensor moment ratio when adjusted for body mass (all P < .013, R2 = .17–.77). The 2D trunk–tibia angle represents a practical method to characterize movement behavior that is indicative of how individuals utilize the hip and knee extensors during dynamic tasks.

Effect of voluntary vs. artificial activation on the relationship of muscle torque to speed

1990 ◽  
Vol 69 (6) ◽  
pp. 2215-2221 ◽  
Author(s):  
G. A. Dudley ◽  
R. T. Harris ◽  
M. R. Duvoisin ◽  
B. M. Hather ◽  
P. Buchanan
Keyword(s):  
Knee Extensor ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Angular Velocities ◽  
The Central Nervous System ◽  
The Right ◽  
Artificial Activation ◽  
Relationship Of ◽  
The Relationship ◽  
Eccentric Actions

The speed-torque relationship of the right knee extensor muscle group was investigated in eight untrained subjects (28 +/- 2 yr old). Torque was measured at a specific knee angle during isokinetic concentric or eccentric actions at nine angular velocities (0.17-3.66 rad/s) and during isometric actions. Activation was by "maximal" voluntary effort or by transcutaneous tetanic electrical stimulation that induced an isometric torque equal to 60% (STIM 1) or 45% (STIM 2) of the voluntary isometric value. Torque increased (P less than 0.05) to 1.4 times isometric as the speed of eccentric actions increased to 1.57 rad/s for STIM 1 and STIM 2. Thereafter, increases in eccentric speed did not further increase torque. Torque did not increase (P greater than 0.05) above isometric for voluntary eccentric actions. As the speed of concentric actions increased from 0.00 to 3.66 rad/s, torque decreased (P less than 0.05) more (P less than 0.05) for both STIM 1 and STIM 2 (two-thirds) than for voluntary activation (one-half). As a result of these responses, torque changed three times as much (P less than 0.05) across speeds of concentric and eccentric actions with artificial (3.4-fold) than voluntary (1.1-fold) activation. The results indicate that with artificial activation the normalized speed-torque relationship of the knee extensors in situ is remarkably similar to that of isolated muscle. The relationship for voluntary activation, in contrast, suggests that the ability of the central nervous system to activate the knee extensors during maximal efforts depends on the speed and type of muscle action performed.

Acute exposure to foot orthoses affects joint stiffness characteristics in recreational male runners

2015 ◽  
Vol 11 (3) ◽  
pp. 183-190 ◽  
Author(s):  
P.J. Taylor ◽  
H. Vincent ◽  
S. Atkins ◽  
J. Sinclair
Keyword(s):  
Sagittal Plane ◽  
Reaction Force ◽  
Joint Stiffness ◽  
Knee Extensor ◽  
Foot Orthoses ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Peak Knee ◽  
Recreational Runners ◽  
Stiffness Characteristics

Commercially available foot orthoses are advocated for the treatment of chronic running injuries, such as patellofemoral pain, yet the mechanisms behind their effects are not well understood. This study aimed to examine the limb and joint stiffness characteristics when running with and without orthotics. Twelve recreational runners ran at 4.0 m/s. Limb stiffness was obtained using a spring-mass model of running by dividing the peak vertical ground reaction force (GRF) by the amount of limb compression. Knee and ankle joint stiffness’s were calculated by dividing the peak sagittal plane joint moment by the joint angular excursion. Differences between orthotic and non-orthotic running conditions were contrasted using paired samples t-tests. The results indicate that both peak knee extensor moment (orthotic = 2.74±0.57 and no-orthotic = 3.12±0.62 Nm/kg) and knee stiffness (orthotic = 5.56±1.08 and no-orthotic = 6.47±1.40 Nm/kg rad) were significantly larger when running without orthotics. This study may give further insight into the mechanical effects of commercially available foot orthoses. The current investigation provides some evidence to suggest that orthoses may be able to improve patellofemoral pathologies in recreational runners although further investigation is required.

scholarly journals Predictive simulation of post-stroke gait with functional electrical stimulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gilmar F. Santos ◽  
Eike Jakubowitz ◽  
Nicolas Pronost ◽  
Thomas Bonis ◽  
Christof Hurschler
Keyword(s):  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Inverse Dynamics ◽  
Knee Extensor ◽  
Treatment Programs ◽  
Knee Extensors ◽  
Drop Foot ◽  
Stroke Patients ◽  
Post Stroke ◽  
Knee Hyperextension

AbstractPost-stroke patients present various gait abnormalities such as drop foot, stiff-knee gait (SKG), and knee hyperextension. Functional electrical stimulation (FES) improves drop foot gait although the mechanistic basis for this effect is not well understood. To answer this question, we evaluated the gait of a post-stroke patient walking with and without FES by inverse dynamics analysis and compared the results to an optimal control framework. The effect of FES and cause-effect relationship of changes in knee and ankle muscle strength were investigated; personalized muscle–tendon parameters allowed the prediction of pathologic gait. We also predicted healthy gait patterns at different speeds to simulate the subject walking without impairment. The passive moment of the knee played an important role in the estimation of muscle force with knee hyperextension, which was decreased during FES and knee extensor strengthening. Weakening the knee extensors and strengthening the flexors improved SKG. During FES, weak ankle plantarflexors and strong ankle dorsiflexors resulted in increased ankle dorsiflexion, which reduced drop foot. FES also improved gait speed and reduced circumduction. These findings provide insight into compensatory strategies adopted by post-stroke patients that can guide the design of individualized rehabilitation and treatment programs.

scholarly journals Predictive Simulation of Post-Stroke Gait and Effects of Functional Electrical Stimulation: A Case Report

2021 ◽  
Author(s):  
Gilmar F. Santos ◽  
Eike Jakubowitz ◽  
Nicolas Pronost ◽  
Thomas Bonis ◽  
Christof Hurschler
Keyword(s):  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Inverse Dynamics ◽  
Knee Extensor ◽  
Treatment Programs ◽  
Knee Extensors ◽  
Drop Foot ◽  
Stroke Patients ◽  
Post Stroke ◽  
Knee Hyperextension

Abstract Post-stroke patients present various gait abnormalities such as drop foot, stiff-knee gait (SKG), and knee hyperextension. Functional electrical stimulation (FES) improves drop foot gait although the mechanistic basis for this effect is not well understood. To answer this question, we evaluated the gait of a post-stroke patient walking with and without FES by inverse dynamics analysis and compared the results to an optimal control framework. The effect of FES and cause-effect relationship of changes in knee and ankle muscle strength were investigated; personalized muscle-tendon parameters allowed the prediction of pathologic gait. We also predicted healthy gait patterns at different speeds to simulate the subject walking without impairment. The passive moment of the knee played an important role in the estimation of muscle force with knee hyperextension, which was decreased during FES and knee extensor strengthening. Weakening the knee extensors and strengthening the flexors improved SKG. During FES, weak ankle plantarflexors and strong ankle dorsiflexors resulted in increased ankle dorsiflexion, which reduced drop foot. FES also improved gait speed and reduced circumduction. These findings provide insight into compensatory strategies adopted by post-stroke patients that can guide the design of individualized rehabilitation and treatment programs.

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

2016 ◽  
Vol 51 (7) ◽  
pp. 519-524 ◽  
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 &lt; .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.

scholarly journals The Prognostic Factors and Required Degree Influencing the Activities of Daily Living and Gait in Brain Impairment Patients with Hemiplegia

Disabilities ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 187-201
Author(s):  
Seungsu Kim ◽  
Jihye Park ◽  
Young Jin Ko
Keyword(s):  
Hip Joint ◽  
Gait Cycle ◽  
Knee Extensor ◽  
Knee Extensors ◽  
Knee Extensor Strength ◽  
Chi Squared ◽  
The Difference ◽  
Grade 3 ◽  
The One ◽  
Significant Factors

To improve the independence of brain impairment patients in ADL, we sought to identify influential parameters from information commonly collected in hospitals, prioritize the factors, and specify the degree to which those factors are necessary. In total, 64 patients with hemiplegia, who had been admitted to the one of the authors, were examined using various evaluation tools. Afterwards, we checked the difference between the capable group and the incapable group with an independent t-test or chi-squared test to determine the significant factors, and we prioritized the significant factors with Spearman’s rho test. The degree of their necessity was determined with the ROC curve. Standing balancing ability and hip joint and knee extensor strength are necessary in most ADL except for eating. In order to independently perform most ADL except eating and one gait cycle, the strength of the knee extensor and hip flexor was required to exceed grade 3 on the MRC scale. However, one gait cycle was possible even if the strength of the hip joint and knee extensors rated lower than 3 on the MRC scale. Additionally, upper limb motor recovery was required up to the distal parts in the order of bathing, dressing, and grooming.

Comparison of In-the-Ear and Over-the-Ear Hearing Aid Fittings

1986 ◽  
Vol 51 (4) ◽  
pp. 362-369 ◽  
Author(s):  
Donna M. Risberg ◽  
Robyn M. Cox
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Comparative Evaluation ◽  
Speech Intelligibility ◽  
Hearing Aid ◽  
Hearing Aid Fitting ◽  
The Difference ◽  
Functional Gain ◽  
The Relationship

A custom in-the-ear (ITE) hearing aid fitting was compared to two over-the-ear (OTE) hearing aid fittings for each of 9 subjects with mild to moderately severe hearing losses. Speech intelligibility via the three instruments was compared using the Speech Intelligibility Rating (SIR) test. The relationship between functional gain and coupler gain was compared for the ITE and the higher rated OTE instruments. The difference in input received at the microphone locations of the two types of hearing aids was measured for 10 different subjects and compared to the functional gain data. It was concluded that (a) for persons with mild to moderately severe hearing losses, appropriately adjusted custom ITE fittings typically yield speech intelligibility that is equal to the better OTE fitting identified in a comparative evaluation; and (b) gain prescriptions for ITE hearing aids should be adjusted to account for the high-frequency emphasis associated with in-the-concha microphone placement.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

Klein with Lacan: A Study on the Reception of Lacanian Ideas in Uruguay and Its Effects on Clinical Practices (1955–82)

2020 ◽  
Vol 22 (3) ◽  
pp. 341-361
Author(s):  
Gonzalo Grau-Pérez ◽  
J. Guillermo Milán
Keyword(s):  
Clinical Practice ◽  
Clinical Material ◽  
Clinical Practices ◽  
Before And After ◽  
The Difference ◽  
The 1960S ◽  
The Relationship ◽  
Discursive Approach ◽  
The Way ◽  
Clinical Cases

In Uruguay, Lacanian ideas arrived in the 1960s, into a context of Kleinian hegemony. Adopting a discursive approach, this study researched the initial reception of these ideas and its effects on clinical practices. We gathered a corpus of discursive data from clinical cases and theoretical-doctrinal articles (from the 1960s, 1970s and 1980s). In order to examine the effects of Lacanian ideas, we analysed the difference in the way of interpreting the clinical material before and after Lacan's reception. The results of this research illuminate some epistemological problems of psychoanalysis, especially the relationship between theory and clinical practice.

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