Muscle Mechanical Work Adaptations With Increasing Walking Speed

2007 ◽  
Author(s):  
Richard R. Neptune ◽  
Kotaro Sasaki ◽  
Steven A. Kautz
Keyword(s):  
Muscle Force ◽  
Walking Speed ◽  
Center Of Mass ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Task Demands ◽  
Plantar Flexor ◽  
Vertical Support ◽  
Increased Activity ◽  
Body Support

Recent modeling studies of walking at self-selected speeds have identified how individual muscles work in synergy to satisfy the task demands including body support, forward propulsion and swing initiation (e.g. [1, 6]). These analyses revealed that young adults walking at a self-selected speed utilize a distribution of hip and knee extensor muscle force in early stance and ankle plantar flexor and rectus femoris force in late stance to provide support and forward propulsion [6]. However, how these muscles’ putative contributions to these functional tasks change with walking speed is not well understood. Intuitively, increasing walking speed would necessitate an increase in activity for muscles that contribute to forward propulsion. However, increasing walking speed is also associated with longer stride lengths (e.g., [2]), which may require increased activity from those muscles contributing to swing initiation, and increased activity from those muscles contributing to vertical support because the vertical excursion of the body’s center of mass increases.

scholarly journals The Relationships Among Sagittal-Plane Lower Extremity Moments: Implications for Landing Strategy in Anterior Cruciate Ligament Injury Prevention

2009 ◽  
Vol 44 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Yohei Shimokochi ◽  
Sae Yong Lee ◽  
Sandra J. Shultz ◽  
Randy J. Schmitz
Keyword(s):  
Anterior Cruciate Ligament ◽  
Lower Extremity ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Cruciate Ligament ◽  
Center Of Mass ◽  
Knee Extensor ◽  
Whole Body ◽  
Plantar Flexor ◽  
Anterior Cruciate

Abstract Context: Excessive quadriceps contraction with insufficient hamstrings muscle cocontraction has been shown to be a possible contributing factor for noncontact anterior cruciate ligament (ACL) injuries. Assessing the relationships among lower extremity internal moments may provide some insight into avoiding muscle contraction patterns that increase ACL injury risk. Objective: To examine the relationships of knee-extensor moment with ankle plantar-flexor and hip-extensor moments and to examine the relationship between knee moment and center of pressure as a measure of neuromuscular response to center-of-mass position. Design: Cross-sectional study. Setting: Applied Neuromechanics Research Laboratory. Patients or Other Participants: Eighteen healthy, recreationally active women (age  =  22.3 ± 2.8 years, height  =  162.5 ± 8.1 cm, mass  =  57.8 ± 9.3 kg). Intervention(s): Participants performed a single-leg landing from a 45-cm box onto a force plate. Kinetic and kinematic data were collected. Main Outcome Measure(s): Pearson product moment correlation coefficients were calculated among the net peak knee-extensor moment (KEMpk), sagittal-plane ankle (AM) and hip (HM) net internal moments, and anterior-posterior center of pressure relative to foot center of mass at KEMpk (COP). Results: Lower KEMpk related to both greater AM (r  =  −0.942, P < .001) and HM (r  =  −0.657, P  =  .003). We also found that more anterior displacement of COP was related to greater AM (r  =  −0.750, P < .001) and lower KEMpk (r  =  0.618, P  =  .006). Conclusions: Our results suggest that participants who lean the whole body forward during landing may produce more plantar-flexor moment and less knee-extensor moment, possibly increasing hip-extensor moment and decreasing knee-extensor moment production. These results suggest that leaning forward may be a technique to decrease quadriceps contraction demand while increasing hamstrings cocontraction demand during a single-leg landing.

Simulation-Guided Stimulation for Paretic Ankle Muscles During Stroke Gait

2007 ◽  
Author(s):  
J. Higginson ◽  
T. Kesar ◽  
R. Perumal ◽  
S. Binder-Macleod
Keyword(s):  
Neuronal Damage ◽  
Center Of Mass ◽  
Knee Extensors ◽  
Muscle Coordination ◽  
Hemiparetic Gait ◽  
Ankle Muscles ◽  
Vertical Support ◽  
The Brain ◽  
The U.S

Stroke is the leading cause of long-term adult disability in the U.S. Neuronal damage in the brain results in impaired muscle coordination which induces asymmetric and abnormal walking patterns. Muscle-actuated forward dynamic simulation of walking patterns of healthy young adults has elucidated unique and synergistic roles of the uniarticular and biarticular plantarflexors. Neptune and colleagues (2001) reported that soleus delivers energy to the trunk, gastrocnemius accelerates the leg forward, and both contribute significantly to vertical support of the center of mass [1]. In a simulation of post-stroke hemiparetic gait, Higginson et al. (2006) observed that non-paretic muscles mimicked the function of healthy muscles, while paretic ankle plantarflexor function was limited and required supplemental effort by hip and knee extensors [2].

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 Fatigue reduces the complexity of knee extensor torque during fatiguing sustained isometric contractions

2018 ◽  
Author(s):  
Jamie Pethick ◽  
Mark Burnley ◽  
Samantha Lee Winter
Keyword(s):  
Temporal Structure ◽  
Femoral Nerve ◽  
Knee Extensor ◽  
Approximate Entropy ◽  
Task Demands ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Fluctuation Analysis ◽  
Isometric Contractions ◽  
Scaling Exponent

The temporal structure, or complexity, of muscle torque output reflects the adaptability of motor control to changes in task demands. This complexity is reduced by neuromuscular fatigue during intermittent isometric contractions. We tested the hypothesis that sustained fatiguing isometric contractions would result in a similar loss of complexity. To that end, nine healthy participants performed, on separate days, sustained isometric contractions of the knee extensors at 20% MVC to task failure and at 100% MVC for 60 seconds. Torque and surface EMG signals were sampled continuously. Complexity and fractal scaling were quantified by calculating approximate entropy (ApEn) and the detrended fluctuation analysis (DFA) α scaling exponent. Global, central and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. Fatigue reduced the complexity of both submaximal (ApEn from 1.02 ± 0.06 to 0.41 ± 0.04, P < 0.05) and maximal contractions (ApEn from 0.34 ± 0.05 to 0.26 ± 0.04, P < 0.05; DFA α from 1.41 ± 0.04 to 1.52 ± 0.03, P < 0.05). The losses of complexity were accompanied by significant global, central and peripheral fatigue (all P < 0.05). These results demonstrate that a fatigue-induced loss of torque complexity is evident not only during fatiguing intermittent isometric contractions, but also during sustained fatiguing contractions.

Physical activity diminishes aging-related decline of physical and cognitive performance

2014 ◽  
Vol 155 (21) ◽  
pp. 817-821 ◽  
Author(s):  
Péter Apor ◽  
László Babai
Keyword(s):  
Quality Of Life ◽  
Physical Activity ◽  
Life Expectancy ◽  
Aging Process ◽  
Muscle Force ◽  
Walking Speed ◽  
Prognostic Impact ◽  
Elderly Persons ◽  
The Impact

Aging-related decline of muscle force, walking speed, locomotor coordination, aerobic capacity and endurance exert prognostic impact on life expectancy. Proper use of training may diminish the aging process and it may improve the quality of life of elderly persons. This paper provides a brief summary on the impact of training on aging-related decline of physical and cognitive functions. Orv. Hetil., 2014, 155(21), 817–821.

Knee angle-dependent oxygen consumption during isometric contractions of the knee extensors determined with near-infrared spectroscopy

2005 ◽  
Vol 99 (2) ◽  
pp. 579-586 ◽  
Author(s):  
C. J. de Ruiter ◽  
M. D. de Boer ◽  
M. Spanjaard ◽  
A. de Haan
Keyword(s):  
Oxygen Consumption ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extensors ◽  
Isometric Contractions ◽  
Knee Angle ◽  
Extensor Muscles ◽  
Knee Extensor Muscles

Fatigue resistance of knee extensor muscles is higher during voluntary isometric contractions at short compared with longer muscle lengths. In the present study we hypothesized that this would be due to lower energy consumption at short muscle lengths. Ten healthy male subjects performed isometric contractions with the knee extensor muscles at a 30, 60, and 90° knee angle (full extension = 0°). At each angle, muscle oxygen consumption (mV̇o2) of the rectus femoris, vastus lateralis, and vastus medialis muscle was obtained with near-infrared spectroscopy. mV̇o2 was measured during maximal isometric contractions and during contractions at 10, 30, and 50% of maximal torque capacity. During all contractions, blood flow to the muscle was occluded with a pressure cuff (450 mmHg). mV̇o2 significantly ( P < 0.05) increased with torque and at all torque levels, and for each of the three muscles mV̇o2 was significantly lower at 30° compared with 60° and 90° and mV̇o2 was similar ( P > 0.05) at 60° and 90°. Across all torque levels, average (± SD) mV̇o2 at the 30° angle for vastus medialis, rectus femoris, and vastus lateralis, respectively, was 70.0 ± 10.4, 72.2 ± 12.7, and 75.9 ± 8.0% of the average mV̇o2 obtained for each torque at 60 and 90°. In conclusion, oxygen consumption of the knee extensors was significantly lower during isometric contractions at the 30° than at the 60° and 90° knee angle, which probably contributes to the previously reported longer duration of sustained isometric contractions at relatively short muscle lengths.

Changes of gait characteristics in a child with femoral nerve injury: a 16-month follow-up case study

2016 ◽  
Vol 61 (3) ◽  
pp. 359-367 ◽  
Author(s):  
Seonhong Hwang ◽  
Jeong-Mee Park ◽  
Youngho Kim
Keyword(s):  
Stride Length ◽  
Stance Phase ◽  
Reaction Force ◽  
Femoral Nerve ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Step Length ◽  
Time Step ◽  
Major Function ◽  
Penetrating Wound

Abstract An 11-year-old child was able to walk independently even though he had injured his femoral nerve severely due to a penetrating wound in the medial thigh. In this study, gait analysis was conducted five times totally for 16 months to observe the characteristics of the gait parameters, which enabled him to walk independently. The cadence, walking speed, stride length, step length, stride time, step time, double limb support, and single limb support all improved after the third test (GA3). Insufficient knee flexion during the stance phase, that was the main problem of the subject, improved from 0.96° to the normal level of 17.01°. Although hip extension was also insufficient at the first test it subsequently improved and reached the normal range at the GA5. The peaks of the ground reaction force curve were low at the initial tests. However, these eventually improved and reached the reference values. The knee extensor moment during the stance phase increased markedly at the last test. Although the child lost his femoral nerve function, he was able to walk independently by compensating for the major function of the rectus femoris. In order to facilitate shock-absorption and move the feet forward, he reduced both gait speed and stride length, respectively. The results of this study are expected to provide insight into how clinicians set up their therapy goals, while considering compensations and changes over time.

scholarly journals The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5517 ◽  
Author(s):  
Dong Sun ◽  
Gusztáv Fekete ◽  
Qichang Mei ◽  
Yaodong Gu
Keyword(s):  
Lower Limb ◽  
Walking Speed ◽  
Sagittal Plane ◽  
External Rotation ◽  
Center Of Mass ◽  
Ground Reaction Forces ◽  
Joint Moments ◽  
Angle Variation ◽  
Foot Kinematics ◽  
Reaction Forces

Background Normative foot kinematic and kinetic data with different walking speeds will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects. Methods A total of 10 healthy male subjects participated in this study; they were asked to carry out walks at a self-selected speed. After measuring and averaging the results of NW, the subjects were asked to perform a 25% slower and 25% faster walk, respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX), and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01 m/s (SW), 1.34 m/s (NW), and 1.68 m/s (FW). Results Hindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion (DF) increased in FW, while hallux relative to forefoot (HX/FF) DF decreased. Increased peak eversion (EV) and peak external rotation (ER) in HF/TB were observed in FW with decreased peak supination (SP) in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW. Discussion Limited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF DF. Although small angle variation in HF/TB EV and FF/HF SP during FW may have profound effects for foot kinetics. Higher HF/TB ER contributed to the FF push-off the ground while the center of mass (COM) progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical COM height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response. The findings of foot kinematics, GRFs, and lower limb joint moments among healthy males may set a reference to distinguish abnormal and pathological gait patterns.

scholarly journals Child-adult differences in neuromuscular fatigue are muscle dependent

2018 ◽  
Vol 125 (4) ◽  
pp. 1246-1256 ◽  
Author(s):  
Enzo Piponnier ◽  
Vincent Martin ◽  
Bastien Bontemps ◽  
Emeric Chalchat ◽  
Valérie Julian ◽  
...  
Keyword(s):  
Near Infrared ◽  
Knee Extensor ◽  
Central Fatigue ◽  
Neuromuscular Fatigue ◽  
Muscle Group ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Plantar Flexor ◽  
Significant Difference ◽  
Lower Extent

The aim of the present study was to compare the development and etiology of neuromuscular fatigue of the knee extensor (KE) and plantar flexor (PF) muscles during repeated maximal voluntary isometric contractions (MVICs) between children and adults. Prepubertal boys ( n = 21; 9–11 yr) and men ( n = 24; 18–30 yr) performed two fatigue protocols consisting of a repetition of 5-s isometric MVIC of the KE or PF muscles interspersed with 5-s passive recovery periods until MVIC reached 60% of its initial value. The etiology of neuromuscular fatigue of the KE and PF muscles was investigated by means of noninvasive methods, such as the surface electromyography, single and doublet magnetic stimulation, twitch interpolation technique, and near-infrared spectroscopy. The number of repetitions performed was significantly lower in men (15.4 ± 3.8) than boys (38.7 ± 18.8) for the KE fatigue test. In contrast, no significant difference was found for the PF muscles between boys and men (12.1 ± 4.9 and 13.8 ± 4.9 repetitions, respectively). Boys displayed a lower reduction in potentiated twitch torque, low-frequency fatigue, and muscle oxygenation than men whatever the muscle group considered. In contrast, voluntary activation level and normalized electromyography data decreased to a greater extent in boys than men for both muscle groups. To conclude, boys experienced less peripheral and more central fatigue during repeated MVICs than men whatever the muscle group considered. However, child-adult differences in neuromuscular fatigue were muscle-dependent since boys fatigued similarly to men with the PF muscles and to a lower extent with the KE muscles. NEW & NOTEWORTHY Child-adult differences in neuromuscular fatigue during repeated maximal voluntary contractions are specific to the muscle group since children fatigue similarly to adults with the plantar flexor muscles and to a lower extent with the knee extensor muscles. Children experience less peripheral fatigue and more central fatigue than adults, regardless of the muscle group considered.

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