TENDON SLACK LENGTH AND ITS EFFECT ON MUSCLE FORCE-GENERATION CHARACTERISTICS

2011 ◽  
Vol 11 (02) ◽  
pp. 445-456 ◽  
Author(s):  
YOONSU NAM ◽  
HYUN WOO UHM
Keyword(s):  
Experimental Data ◽  
Critical Parameter ◽  
Muscle Force ◽  
Reference Data ◽  
Length Change ◽  
Knee Extension ◽  
Force Generation ◽  
Force Transfer ◽  
Tendon Force ◽  
Slack Length

Based on the force transfer relationship from muscle to tendon, a chart determining a normalized tendon force is developed. A sensitivity analysis verifies that the tendon slack length is the most critical parameter affecting the tendon force. Therefore, it may be claimed that the variation of this parameter from Delp's reference data will noticeably change the musculotendon characteristics of a subject. The effect of tendon slack length change on this characteristic was analyzed theoretically and checked by numerical results. An optimization algorithm was introduced, which searches the tendon slack lengths of quadriceps by minimizing the differences of calculated knee extension moment from experimental data.

Muscle Force Generation and Age: The Role of Sex Hormones

1993 ◽  
pp. 129-141 ◽  
Author(s):  
S. K. Phillips ◽  
J. L. Rowbury ◽  
S. A. Bruce ◽  
R. C. Woledge
Keyword(s):  
Sex Hormones ◽  
Muscle Force ◽  
Force Generation

scholarly journals Effect of Low-Frequency Vibration on Muscle Response under Different Neurointact Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Chaofei Zhang ◽  
Wenjun Wang ◽  
Dennis Anderson ◽  
Sishu Guan ◽  
Guofa Li ◽  
...  
Keyword(s):  
Stretch Reflex ◽  
Muscle Force ◽  
Low Frequency ◽  
Quantitative Relationship ◽  
Length Change ◽  
Whole Body ◽  
Sprague Dawley ◽  
Nonlinear Hysteresis ◽  
Low Frequency Vibration ◽  
Gastrocnemius Muscles

Stretch reflex is an important factor that influences the biomechanical response of the human body under whole-body vibration. However, there is a lack of quantitative evaluation at lower frequencies. Thus, the aim of this study was to investigate the effects of vibration on the stretch reflex and, in particular, to explore the quantitative relationship between dynamic muscle responses and low-frequency vibrations. The gastrocnemius muscle of 45 Sprague-Dawley rats was dissected. Sinusoidal vibrations of five discrete frequencies (2~16 Hz) with peak-to-peak amplitudes of 1 mm were applied to the gastrocnemius muscles with 2 mm or 3 mm prelengthening. Variables including dynamic muscle force, vibration acceleration, and displacement were recorded in two conditions, with and without the stretch reflex. Results showed that the dynamic muscle forces decreased by 20% on average for the 2 mm prelengthening group after the stretch reflex was blocked and by 24% for the 3 mm prelengthening group. Statistical analysis indicated that the amplitude of dynamic muscle force in the “with stretch reflex” condition was significantly larger than that in the “without stretch reflex” condition (p<0.001). The tension-length curve was found to be a nonlinear hysteresis loop that changed with frequency. The phase difference between the dynamic muscle force and the length change was affected significantly by vibration frequency (p<0.01), and the minimum frequency was 4–8 Hz. Experimental results of this study could benefit musculoskeletal model by providing a theoretical support to build a stretch reflex model for low-frequency vibration.

scholarly journals The Relationship between Walking Speed and Step Length in Older Aged Patients

Diseases ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 17 ◽  
Author(s):  
Yuji Morio ◽  
Kazuhiro Izawa ◽  
Yoshitsugu Omori ◽  
Hironobu Katata ◽  
Daisuke Ishiyama ◽  
...  
Keyword(s):  
Muscle Force ◽  
Walking Speed ◽  
Step Length ◽  
Knee Extension ◽  
Height Ratio ◽  
Roc Curve Analysis ◽  
Aged Patients ◽  
Speed Test ◽  
Slow Group ◽  
Fast Group

Compared with elderly people who have not experienced falls, those who have were reported to have a shortened step length, large fluctuations in their pace, and a slow walking speed. The purpose of this study was to elucidate the step length required to maintain a walking speed of 1.0 m/s in patients aged 75 years or older. We measured the 10 m maximum walking speed in patients aged 75 years or older and divided them into the following two groups: Those who could walk 1.0 m/s or faster (fast group) and those who could not (slow group). Step length was determined from the number of steps taken during the 10 m-maximum walking speed test, and the step length-to-height ratio was calculated. Isometric knee extension muscle force (kgf), modified functional reach (cm), and one-leg standing time (s) were also measured. We included 261 patients (average age: 82.1 years, 50.6% men) in this study. The fast group included 119 participants, and the slow group included 142 participants. In a regression logistic analysis, knee extension muscle force (p = 0.03) and step length-to-height ratio (p < 0.01) were determined as factors significantly related to the fast group. As a result of ROC curve analysis, a step length-to-height ratio of 31.0% could discriminate between the two walking speed groups. The results suggest that the step length-to-height ratio required to maintain a walking speed of 1.0 m/s is 31.0% in patients aged 75 years or older.

scholarly journals How muscle fiber lengths and velocities affect muscle force generation as humans walk and run at different speeds

2013 ◽  
Vol 216 (11) ◽  
pp. 2150-2160 ◽  
Author(s):  
E. M. Arnold ◽  
S. R. Hamner ◽  
A. Seth ◽  
M. Millard ◽  
S. L. Delp
Keyword(s):  
Muscle Fiber ◽  
Muscle Force ◽  
Force Generation

X-ray interferometry of the axial movement of myosin heads during muscle force generation initiated by T-Jump

2009 ◽  
Vol 43 (4) ◽  
pp. 632-642
Author(s):  
N. A. Koubassova ◽  
S. Y. Bershitsky ◽  
M. A. Ferenczi ◽  
P. Panine ◽  
T. Narayanan ◽  
...  
Keyword(s):  
Muscle Force ◽  
Force Generation ◽  
X Ray ◽  
Axial Movement

ASSESSMENT OF PARAMETER UNCERTAINTY IN RIGID MUSCULOSKELETAL SIMULATION USING A PROBABILISTIC APPROACH

2015 ◽  
Vol 18 (03) ◽  
pp. 1550013 ◽  
Author(s):  
Tien Tuan Dao ◽  
Marie-Christine Ho Ba Tho
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Parameter Uncertainty ◽  
Input Data ◽  
Muscle Force ◽  
Muscle Tension ◽  
Probabilistic Approach ◽  
Rectus Femoris ◽  
Joint Moment ◽  
Musculoskeletal Simulation

Experimental investigation coupled with numerical simulations is commonly used for solving multi-physical problems. In the field of biomechanics, in which the aim is to understand the mechanics of living system, the main difficulties are to provide experimental data reflecting the multi-physical behavior of the system of interest. These experimental data are used as input data for numerical simulations to quantify output responses through physical and/or biological laws expressed by constitutive mathematical equations. However, uncertainties on the experimentally available data exist from factors such as human variability and differences in protocols parameters and techniques. Thus, the true values of these data could never be experimentally measured. The objective of this study was to develop a modeling workflow to assess and account for the parameter uncertainty in rigid musculoskeletal simulation. A generic musculoskeletal model was used. Data uncertainties of the right thigh mass, physiological cross-sectional area (pCSA) and muscle tension coefficient of the rectus femoris were accounted to estimate their effect on the joint moment and muscle force computing, respectively. A guideline was developed to fuse data from multiple sources into a sample variation space leading to establish input data distribution. Uncertainty propagation was performed using Monte Carlo and most probable point methods. A high degree of sensitivity of 0.98 was noted for the effect of thigh mass uncertainty on the hip joint moment using inverse dynamics method. A strong deviation of rectus femoris muscle force (around 260 N) was found under effect of pCSA and muscle tension coefficient on the force estimation using static optimization method. Accounting parameter uncertainty into rigid musculoskeletal simulation plays an essential role in the evaluation of the confidence in the model outputs. Thus, simulation outcome may be computed and represented in a more reliable manner with a global range of plausible values.

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