scholarly journals Variations in Muscle Activity of Vastus Lateralis and Gastrocnemius Lateralis with Increasing Draft Load

2014 ◽  
Vol 46 ◽  
pp. 38-39 ◽  
Author(s):  
T Crook ◽  
E Hodson-Tole ◽  
A Wilson
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Gastrocnemius Lateralis

scholarly journals Using a Back Exoskeleton During Industrial and Functional Tasks—Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial

2021 ◽  
pp. 001872082110072
Author(s):  
Tessy Luger ◽  
Mona Bär ◽  
Robert Seibt ◽  
Monika A. Rieger ◽  
Benjamin Steinhilber
Keyword(s):  
Heart Rate ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Erector Spinae ◽  
Stair Climbing ◽  
Trunk Flexion ◽  
User Friendliness ◽  
Timed Up And Go ◽  
System Usability Scale ◽  
Task Accomplishment

Objective To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton. Background Back-support exoskeletons have the potential to reduce work-related physical demands. Methods Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS. Results During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm. Conclusion Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable. Application These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

Force fluctuations are modulated by alternate muscle activity of knee extensor synergists during low-level sustained contraction

2004 ◽  
Vol 97 (6) ◽  
pp. 2121-2131 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara ◽  
Kei Masani ◽  
Tetsuo Fukunaga
Keyword(s):  
Correlation Coefficient ◽  
Muscle Activity ◽  
High Frequency ◽  
Vastus Lateralis ◽  
Frequency Component ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
High Frequency Component ◽  
Knee Extensors ◽  
Force Fluctuations

The study examined the hypothesis that altered synergistic activation of the knee extensors leads to cyclic modulation of the force fluctuations. To test this hypothesis, the force fluctuations were investigated during sustained knee extension at 2.5% of maximal voluntary contraction force for 60 min in 11 men. Surface electromyograms (EMG) were recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles. The SD of force and average EMG (AEMG) of each muscle were calculated for 30-s periods during alternate muscle activity. Power spectrum of force was calculated for the low- (≤3 Hz), middle- (4–6 Hz), and high-frequency (8–12 Hz) components. Alternate muscle activity was observed between RF and the set of VL and VM muscles. The SD of force was not constant but variable due to the alternate muscle activity. The SD was significantly greater during high RF activity compared with high VL and VM activity ( P < 0.05), and the correlation coefficient between the SD and AEMG was significantly greater in RF [0.736 (SD 0.095), P < 0.05] compared with VL and VM. Large changes were found in the high-frequency component. During high RF activity, the correlation coefficient between the SD and high-frequency component [0.832 (SD 0.087)] was significantly ( P < 0.05) greater compared with other frequency components. It is suggested that modulations in knee extension force fluctuations are caused by the unique muscle activity in RF during the alternate muscle activity, which augments the high-frequency component of the fluctuations.

Alternate muscle activity observed between knee extensor synergists during low-level sustained contractions

2002 ◽  
Vol 93 (2) ◽  
pp. 675-684 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara ◽  
Kei Masani ◽  
Hiroaki Kanehisa ◽  
Tetsuo Fukunaga
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Force Production ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Low Level ◽  
Integrated Emg

To determine quantitatively the features of alternate muscle activity between knee extensor synergists during low-level prolonged contraction, a surface electromyogram (EMG) was recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) in 11 subjects during isometric knee extension exercise at 2.5% of maximal voluntary contraction (MVC) for 60 min ( experiment 1). Furthermore, to examine the relation between alternate muscle activity and contraction levels, six of the subjects also performed sustained knee extension at 5.0, 7.5, and 10.0% of MVC ( experiment 2). Alternate muscle activity among the three muscles was assessed by quantitative analysis on the basis of the rate of integrated EMG sequences. In experiment 1, the number of alternations was significantly higher between RF and either VL or VM than between VL and VM. Moreover, the frequency of alternate muscle activity increased with time. In experiment 2, alternating muscle activity was found during contractions at 2.5 and 5.0% of MVC, although not at 7.5 and 10.0% of MVC, and the number of alternations was higher at 2.5 than at 5.0% of MVC. Thus the findings of the present study demonstrated that alternate muscle activity in the quadriceps muscle 1) appears only between biarticular RF muscle and monoarticular vasti muscles (VL and VM), and its frequency of alternations progressively increases with time, and 2) emerges under sustained contraction with force production levels ≤5.0% of MVC.

scholarly journals Effect of 4 Weeks of Anti-Gravity Treadmill Training on Isokinetic Muscle Strength and Muscle Activity in Adults Patients with a Femoral Fracture: A Randomized Controlled Trial

2020 ◽  
Vol 17 (22) ◽  
pp. 8572
Author(s):  
Pyeongon Kim ◽  
Haneul Lee ◽  
Wonho Choi ◽  
Sangmi Jung
Keyword(s):  
Hip Fracture ◽  
Muscle Strength ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Controlled Trial ◽  
Treadmill Training ◽  
Control Group ◽  
Isokinetic Muscle Strength ◽  
Gluteus Muscle ◽  
Before And After

This study aimed to identify the effect of anti-gravity treadmill training on isokinetic lower-limb muscle strength and muscle activities in patients surgically treated for a hip fracture. A total of 34 participants were randomly assigned into two groups: anti-gravity treadmill training group (n = 17) and control group (n = 17). The isokinetic muscle strength and endurance of hip flexor and extensor and the activities of the vastus lateralis (VL), vastus medialis (VM), gluteus maximus (GM), and gluteus medialis (Gm) muscles were measured before and after 4 weeks of the interventions. Significant improvements were observed in isokinetic muscle strength and endurance of hip flexors and extensors in both groups (p < 0.05); however, no significant differences were observed between the groups (p > 0.05) except for muscle strength of the hip extensor (d = 0.78, p = 0029). Statistically significant increases in the muscle activity of VL, VM, GM, and Gm were found before and after the intervention (p < 0.05), and significant differences in muscle activities of GM (d = 2.64, p < 0.001) and Gm (d = 2.59, p < 0.001) were observed between the groups. Our results indicate that both groups showed improvement in muscle strength, endurance, and activities after the intervention. Additionally, anti-gravity treadmill training improved significantly more muscle strength at 60°/s of the hip extensor and gluteus muscle activities than conventional therapy, which may be appropriate for patients with hip fracture surgery.

The frequency of alternate muscle activity is associated with the attenuation in muscle fatigue

2006 ◽  
Vol 101 (3) ◽  
pp. 715-720 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activity ◽  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Sustained Contraction ◽  
Low Level ◽  
Before And After

Alternate muscle activity between synergist muscles has been demonstrated during low-level sustained contractions [≤5% of maximal voluntary contraction (MVC) force]. To determine the functional significance of the alternate muscle activity, the association between the frequency of alternate muscle activity during a low-level sustained knee extension and the reduction in knee extension MVC force was studied. Forty-one healthy subjects performed a sustained knee extension at 2.5% MVC force for 1 h. Before and after the sustained knee extension, MVC force was measured. The surface electromyogram was recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles. The frequency of alternate muscle activity for RF-VL, RF-VM, and VL-VM pairs was determined during the sustained contraction. The frequency of alternate muscle activity ranged from 4 to 11 times/h for RF-VL (7.0 ± 2.0 times/h) and RF-VM (7.0 ± 1.9 times/h) pairs, but it was only 0 to 2 times/h for the VL-VM pair (0.5 ± 0.7 times/h). MVC force after the sustained contraction decreased by 14% ( P < 0.01) from 573.6 ± 145.2 N to 483.3 ± 130.5 N. The amount of reduction in MVC force was negatively correlated with the frequency of alternate muscle activity for the RF-VL and RF-VM pairs ( P < 0.001 and r = 0.65 for both) but not for the VL-VM pair. The results demonstrate that subjects with more frequent alternate muscle activity experience less muscle fatigue. We conclude that the alternate muscle activity between synergist muscles attenuates muscle fatigue.

Effect of vertical loading on energy cost and kinematics of running in trained male subjects

1995 ◽  
Vol 79 (6) ◽  
pp. 2078-2085 ◽  
Author(s):  
M. Bourdin ◽  
A. Belli ◽  
L. M. Arsac ◽  
C. Bosco ◽  
J. R. Lacour
Keyword(s):  
Energy Cost ◽  
Vastus Lateralis ◽  
Center Of Mass ◽  
The Body ◽  
Treadmill Running ◽  
Net Energy ◽  
Electromyographic Activity ◽  
External Work ◽  
Vertical Loading ◽  
Gastrocnemius Lateralis

This investigation examined, in a group of 10 trained male runners, the effect of vertical loading during level treadmill running at a velocity of 5 m/s. The net energy cost of running (Cr), the external work of the center of mass of the body (Wext; both expressed in J.kg-1.m-1), and the eccentric-to-concentric ratio (Ecc/Con) of integrated electromyographic activity for the vastus lateralis (VL) and gastrocnemius lateralis muscles were measured. It was observed that Wext and Ecc/Con for the VL could explain a large part of the interindividual variations in Cr. This result reinforces the hypothesis that Ecc/Con could be a good index of effectiveness in the stretch-shortening cycle. When the subjects ran with a vertical load of 9.3% of their body mass, Cr and Wext were significantly reduced (P < 0.01 and P < 0.05, respectively), whereas Ecc/Con for the VL and gastrocnemius lateralis remained unchanged. The variations in Cr and Wext due to vertical loading were significantly correlated (r = 0.75; P < 0.01). It was then concluded that the significant improvement of Cr observed with the added load was mainly due to the fact that Wext was significantly decreased.

Effects of surface grade on proximal hindlimb muscle strain and activation during rat locomotion

2002 ◽  
Vol 93 (5) ◽  
pp. 1731-1743 ◽  
Author(s):  
Gary B. Gillis ◽  
Andrew A. Biewener
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Muscle Strain ◽  
Activation Patterns ◽  
Rat Muscle ◽  
High Speeds ◽  
Hindlimb Muscle ◽  
Limb Muscles

Sonomicrometry and electromyography were used to determine how surface grade influences strain and activation patterns in the biceps femoris and vastus lateralis of the rat. Muscle activity is generally present during much of stance and is most intense on an incline, intermediate on the level, and lowest on a decline, where the biceps remains inactive except at high speeds. Biceps fascicles shorten during stance, with strains ranging from 0.07–0.30 depending on individual, gait, and grade. Shortening strains vary significantly among grades ( P = 0.05) and average 0.21, 0.16, and 0.14 for incline, level, and decline walking, respectively; similar trends are present during trotting and galloping. Vastus fascicles are stretched while active over the first half of stance on all grades, and then typically shorten over the second half of stance. Late-stance shortening is highest during galloping, averaging 0.14, 0.10, and 0.02 in the leading limb on incline, level, and decline surfaces, respectively. Our results suggest that modulation of strain and activation in these proximal limb muscles is important for accommodating different surface grades.

scholarly journals Characterization of kinesiological patterns of the frontal kick, mae-geri, in karate experts and non-karate practitioners

2014 ◽  
Vol 9 (1) ◽  
pp. 20 ◽  
Author(s):  
António M. VencesBrito ◽  
Marco A. Colaço Branco ◽  
Renato M. Cordeiro Fernandes ◽  
Mário A. Rodrigues Ferreira ◽  
Orlando J. S. M. Fernandes ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Neuromuscular Control ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Maximum Speed ◽  
Ballistic Performance ◽  
The Impact

Presently, coaches and researchers need to have a better comprehension of the kinesiological parameters that should be an important tool to support teaching methodologies and to improve skills performance in sports. The aim of this study was to (i) identify the kinematic and neuromuscular control patterns of the front kick (<em>mae-geri</em>) to a fixed target performed by 14 experienced karate practitioners, and (ii) compare it with the execution of 16 participants without any karate experience, allowing the use of those references in the analysis of the training and learning process. Results showed that the kinematic and neuromuscular activity during the kick performance occurs within 600 ms. Muscle activity and kinematic analysis demonstrated a sequence of activation bracing a proximal-to-distal direction, with the muscles presenting two distinct periods of activity (1, 2), where the karateka group has a greater intensity of activation – root mean square (RMS) and electromyography (EMG) peak – in the first period on <em>Rectus Femoris</em> (RF1) and  <em>Vastus Lateralis</em> (VL1) and a lower duration of co-contraction in both periods on <em>Rectus Femoris</em>-<em>Biceps Femoris</em> and <em>Vastus Lateralis</em>-<em>Biceps Femoris</em> (RF-BF; VL-BF). In the skill performance, the hip flexion, the knee extension and the ankle plantar flexion movements were executed with smaller difference in the range of action (ROA) in the karateka group, reflecting different positions of the segments. In conclusion, it was observed a general kinesiological pattern, which was similar in karateka and non-karateka practitioners. However, in the karateka group, the training induces a specialization in the muscle activity reflected in EMG and kinematic data, which leads to a better ballistic performance in the execution of the <em>mae-geri</em> kick, associated with a maximum speed of the distal segments, reached closer to the impact moment, possibly representing more power in the contact.

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