scholarly journals Modularity of Endpoint Force Patterns Evoked Using Intraspinal Microstimulation in Treadmill Trained and/or Neurotrophin-Treated Chronic Spinal Cats

2009 ◽  
Vol 101 (3) ◽  
pp. 1309-1320 ◽  
Author(s):  
Vanessa S. Boyce ◽  
Michel A. Lemay
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Motor Output ◽  
Medial Gastrocnemius ◽  
Lumbar Spinal Cord ◽  
Intraspinal Microstimulation ◽  
Hindlimb Muscles ◽  
Spinal Motor ◽  
Lumbar Spinal

Chronic spinal cats with neurotrophin-secreting fibroblasts (NTF) transplants recover locomotor function. To ascertain possible mechanisms, intraspinal microstimulation was used to examine the lumbar spinal cord motor output of four groups of chronic spinal cats: untrained cats with unmodified-fibroblasts graft (Op-control) or NTF graft and locomotor-trained cats with unmodified-fibroblasts graft (Trained) or NTF graft (Combination). Forces generated via intraspinal microstimulation at different hindlimb positions were recorded and interpolated, generating representations of force patterns at the paw. Electromyographs (EMGs) of hindlimb muscles, medial gastrocnemius, tibialis anterior, vastus lateralis, and biceps femoris posterior, were also collected to examine relationships between activated muscles and force pattern types. The same four force pattern types obtained in spinal-intact cats were found in chronic spinal cats. Proportions of force patterns in spinal cats differed significantly from those in intact cats, but no significant differences in proportions were observed among individual spinal groups (Op-control, NTF, Trained, and Combination). However, the proportions of force patterns differed significantly between trained (Trained and Combination) and untrained groups (Op-control and NTF). Thus the frequency of expression of some response types was modified by injury and to a lesser extent by training. Force pattern laminar distribution differed in spinal cats compared with intact, with more responses obtained dorsally (0–1,000 μm) and fewer ventrally (3,200–5,200 μm). EMG analysis demonstrated that muscle activity highly predicted some force pattern types and was independent of hindlimb position. We conclude that spinal motor output modularity is preserved after injury.

scholarly journals The effect of perturbation magnitude on lower limb muscle activity during reactive stepping using functional data analysis

2020 ◽  
Author(s):  
Tyler M. Saumur ◽  
Jacqueline Nestico ◽  
George Mochizuki ◽  
Stephen D. Perry ◽  
Avril Mansfield ◽  
...  
Keyword(s):  
Data Analysis ◽  
Functional Data Analysis ◽  
Functional Data ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Limb Muscle ◽  
Perturbation Magnitude ◽  
Reactive Stepping

AbstractThis study aimed to determine the effect of perturbation magnitude on stance and stepping limb muscle activation during reactive stepping using functional data analysis. Nineteen healthy, young adults responded to 6 small and 6 large perturbations using an anterior lean-and-release system, evoking a single reactive step. Muscle activity from surface electromyography was compared between the two conditions for medial gastrocnemius, biceps femoris, tibialis anterior, and vastus lateralis of the stance and stepping limb using functional data analysis. Stance limb medial gastrocnemius and biceps femoris activation increased in the large compared to small perturbation condition immediately prior to foot-off and at foot contact. In the stepping limb, significant increases in medial gastrocnemius, biceps femoris, and tibialis anterior activity occurred immediately prior to foot-off during the large perturbations. Similar to the stance limb, medial gastrocnemius and biceps femoris activity significantly increased during and following foot contact in the large, compared to small, perturbation condition. Lastly, vastus lateralis activity significantly increased for large, compared to small, perturbations during foot-off and immediately following foot contact. These findings highlight lower limb muscle activity modulation associated with perturbation magnitude throughout reactive stepping and the additional benefit of implementing functional data analysis to study reactive balance control.

Arm movements can increase leg muscle activity during submaximal recumbent stepping in neurologically intact individuals

2013 ◽  
Vol 115 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Digna de Kam ◽  
Hennie Rijken ◽  
Toos Manintveld ◽  
Bart Nienhuis ◽  
Volker Dietz ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Weight Bearing ◽  
Arm Movements ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Vastus Lateralis Muscle ◽  
Rehabilitation Programs ◽  
Cord Injury ◽  
Leg Muscle

Facilitation of leg muscle activity by active arm movements during locomotor tasks could be beneficial during gait rehabilitation after spinal cord injury. The present study explored the effects of arm movements on leg muscle activity during submaximal recumbent stepping. Healthy subjects exercised on a recumbent stepping machine both with and without arm movements. Activity of five leg muscles was recorded and compared for stepping with and without arm movements. To determine which arm movements are optimal for leg muscle facilitation, subjects were instructed to step with 1) mechanically coupled vs. decoupled arm and leg movements, 2) synchronous vs. asynchronous arm movements, and 3) at 50 vs. 70 RPM. Leg muscle activity was increased by active arm movements in all muscles, except the vastus lateralis muscle. Activity of other extensors (soleus, medial gastrocnemius, and biceps femoris) was primarily increased during the extension phase, whereas activity of flexors (tibialis anterior) was also increased during the flexion phase. Facilitation was more or less consistent for both frequencies and for synchronous and asynchronous movements. For coupled arm movements, facilitation tended to be diminished or absent. The observed facilitation in the present study is probably of neuromuscular rather than biomechanical origin, since the arms are probably hardly involved in postural control or weight-bearing during recumbent stepping. Further studies in patients should explore the possibility to integrate neuromuscular facilitation in rehabilitation programs.

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.

Control of abdominal and expiratory intercostal muscle activity during vomiting: role of ventral respiratory group expiratory neurons

1987 ◽  
Vol 57 (6) ◽  
pp. 1854-1866 ◽  
Author(s):  
A. D. Miller ◽  
L. K. Tan ◽  
I. Suzuki
Keyword(s):  
Muscle Activity ◽  
Discharge Rate ◽  
Abdominal Muscle ◽  
Lumbar Spinal Cord ◽  
Abdominal Muscles ◽  
Ventral Respiratory Group ◽  
Before And After ◽  
The One ◽  
Lumbar Spinal

The role of ventral respiratory group (VRG) expiratory (E) neurons in the control of abdominal and internal intercostal (expiratory) muscle activity during vomiting was examined in decerebrate cats by recording from these neurons during fictive vomiting in paralyzed animals and comparing abdominal muscle activity during vomiting before and after sectioning the axons of these descending neurons. Fictive vomiting was defined by a series of bursts of coactivation of abdominal and phrenic nerves elicited by either subdiaphragmatic vagus nerve stimulation or emetic drugs. Such coordinated activity would be expected to produce vomiting if the animals were not paralyzed. Data were recorded from 27 VRG E neurons that were antidromically activated from the lower thoracic (T13) or lumbar spinal cord. During fictive vomiting, almost two-thirds of these neurons (17/27) were mainly active in between periods of abdominal and phrenic nerve coactivation, when the internal intercostal motoneurons are known to be active. This group of neurons was termed INT neurons. INT neurons were subdivided according to whether they were active between every burst of phrenic and abdominal nerve coactivation (INTa neurons, n = 10) or only between some bursts (INTb neurons, n = 7). Another one-third of the VRG E neurons had normal or increased levels of activity when the abdominal nerves were active during fictive vomiting (ABD neurons). The one remaining neuron was mainly silent throughout fictive vomiting. ABD neurons were indistinguishable from INT neurons on the basis of their location in the VRG, type of firing pattern (ramp versus step ramp), conduction velocity, or extent of projection in the lumbar cord. However, INTa neurons had a significantly higher discharge rate during respiration than either ABD or INTb neurons. Abdominal muscle EMG and nerve activity were recorded from six unparalyzed cats before and after cutting the axons of VRG E neurons as they cross the midline between C1 and the obex. The lesions abolished or almost eliminated expiratory modulation of abdominal muscle activity. In contrast, the abdominal muscles were always active during vomiting; however, the amplitude of postlesion abdominal activity varied from approximately 70-100% of prelesion values in three cats to 60-70% of normal in a fourth animal to only approximately 20% of prelesion values in two other cats.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Lower Extremity Muscle Activity During a Women's Overhand Lacrosse Shot

2014 ◽  
Vol 41 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Brianna M. Millard ◽  
John A. Mercer
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Body Height ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Discrete Events ◽  
Warm Up ◽  
Lower Extremity Muscle ◽  
One Year

AbstractThe purpose of this study was to describe lower extremity muscle activity during the lacrosse shot. Participants (n=5 females, age 22±2 years, body height 162.6±15.2 cm, body mass 63.7±23.6 kg) were free from injury and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG) leads to measure muscle activity of the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (GA). Participants completed five trials of a warm-up speed shot (Slow) and a game speed shot (Fast). Video analysis was used to identify the discrete events defining specific movement phases. Full-wave rectified data were averaged per muscle per phase (Crank Back Minor, Crank Back Major, Stick Acceleration, Stick Deceleration). Average EMG per muscle was analyzed using a 4 (Phase) x 2 (Speed) ANOVA. BF was greater during Fast vs. Slow for all phases (p<0.05), while TA was not influenced by either Phase or Speed (p>0.05). RF and GA were each influenced by the interaction of Phase and Speed (p<0.05) with GA being greater during Fast vs. Slow shots during all phases and RF greater during Crank Back Minor and Major as well as Stick Deceleration (p<0.05) but only tended to be greater during Stick Acceleration (p=0.076) for Fast vs. Slow. The greater muscle activity (BF, RF, GA) during Fast vs. Slow shots may have been related to a faster approach speed and/or need to create a stiff lower extremity to allow for faster upper extremity movements.

scholarly journals Leg Muscle Activity and Perception of Effort before and after Four Short Sessions of Submaximal Eccentric Cycling

2020 ◽  
Vol 17 (21) ◽  
pp. 7702
Author(s):  
Pierre Clos ◽  
Romuald Lepers
Keyword(s):  
Muscle Activity ◽  
Peak Power ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Peak Power Output ◽  
Leg Muscles ◽  
Perception Of Effort ◽  
Before And After ◽  
Power Outputs

Background: This study tested muscle activity (EMG) and perception of effort in eccentric (ECC) and concentric (CON) cycling before and after four sessions of both. Methods: Twelve volunteers naïve to ECC cycling attended the laboratory six times. On day 1, they performed a CON cycling peak power output (PPO) test. They then carried-out four sessions comprising two sets of 1 to 1.5-min cycling bouts at 5 intensities (30, 45, 60, 75, and 90% PPO) in ECC and CON cycling. On day 2 and day 6 (two weeks apart), EMG root mean square of the vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF), and soleus (SOL) muscles, was averaged from 15 to 30 s within each 1-min bout and perception of effort was asked after 45 s. Results: Before the four cycling sessions, while VL EMG was lower in ECC than CON cycling, most variables were not different. Afterwards, ECC cycling exhibited lower RF EMG at 75 and 90% PPO (all p < 0.02), lower VL and BF EMG at all exercise intensities (all p < 0.02), and inferior SOL EMG (all p < 0.04) except at 45% PPO (p = 0.07). Perception of effort was lower in ECC cycling at all exercise intensities (all p < 0.03) but 60% PPO (p = 0.11). Conclusions: After four short sessions of ECC cycling, the activity of four leg muscles and perception of effort became lower in ECC than in CON cycling at most of five power outputs, while they were similar before.

scholarly journals Neuromuscular Alterations After Ankle Sprains: An Animal Model to Establish Causal Links After Injury

2016 ◽  
Vol 51 (10) ◽  
pp. 797-805 ◽  
Author(s):  
Lindsey K. Lepley ◽  
Patrick O. McKeon ◽  
Shane G. Fitzpatrick ◽  
Catherine L. Beckemeyer ◽  
Timothy L. Uhl ◽  
...  
Keyword(s):  
Ankle Sprain ◽  
Muscle Activity ◽  
Tibialis Anterior ◽  
Vastus Lateralis ◽  
Onset Time ◽  
Biceps Femoris ◽  
Sample Entropy ◽  
Ankle Ligaments ◽  
Lateral Ankle ◽  
Lateral Ankle Ligaments

Context: The mechanisms that contribute to the development of chronic ankle instability are not understood. Investigators have developed a hypothetical model in which neuromuscular alterations that stem from damaged ankle ligaments are thought to affect periarticular and proximal muscle activity. However, the retrospective nature of these studies does not allow a causal link to be established. Objective: To assess temporal alterations in the activity of 2 periarticular muscles of the rat ankle and 2 proximal muscles of the rat hind limb after an ankle sprain. Design: Controlled laboratory study. Setting: Laboratory. Patients or Other Participants: Five healthy adult male Long Evans rats (age = 16 weeks, mass = 400.0 ± 13.5 g). Intervention(s): Indwelling fine-wire electromyography (EMG) electrodes were implanted surgically into the biceps femoris, medial gastrocnemius, vastus lateralis, and tibialis anterior muscles of the rats. We recorded baseline EMG measurements while the rats walked on a motor-driven treadmill and then induced a closed lateral ankle sprain by overextending the lateral ankle ligaments. After ankle sprain, the rats were placed on the treadmill every 24 hours for 7 days, and we recorded postsprain EMG data. Main Outcome Measure(s): Onset time of muscle activity, phase duration, sample entropy, and minimal detectable change (MDC) were assessed and compared with baseline using 2-tailed dependent t tests. Results: Compared with baseline, delayed onset time of muscle activity was exhibited in the biceps femoris (baseline = −16.7 ± 54.0 milliseconds [ms]) on day 0 (5.2 ± 64.1 ms; t4 = −4.655, P = .043) and tibialis anterior (baseline = 307.0 ± 64.2 ms) muscles on day 3 (362.5 ± 55.9 ms; t4 = −5.427, P = .03) and day 6 (357.3 ± 39.6 ms; t4 = −3.802, P = .02). Longer phase durations were observed for the vastus lateralis (baseline = 321.9 ± 92.6 ms) on day 3 (401.3 ± 101.2 ms; t3 = −4.001, P = .03), day 4 (404.1 ± 93.0 ms; t3 = −3.320, P = .048), and day 5 (364.6 ± 105.2 ms; t3 = −3.963, P = .03) and for the tibialis anterior (baseline = 103.9 ± 16.4 ms) on day 4 (154.9 ± 7.8 ms; t3 = −4.331, P = .050) and day 6 (141.9 ± 16.2 ms; t3 = −3.441, P = .03). After sprain, greater sample entropy was found for the vastus lateralis (baseline = 0.7 ± 0.3) on day 6 (0.9 ± 0.4; t4 = −3.481, P = .03) and day 7 (0.9 ± 0.3; t4 = −2.637, P = .050) and for the tibialis anterior (baseline = 0.6 ± 0.4) on day 4 (0.9 ± 0.5; t4 = −3.224, P = .03). The MDC analysis revealed increased sample entropy values for the vastus lateralis and tibialis anterior. Conclusions: Manually inducing an ankle sprain in a rat by overextending the lateral ankle ligaments altered the complexity of muscle-activation patterns, and the alterations exceeded the MDC of the baseline data.

scholarly journals Focusing on Increasing Velocity during Heavy Resistance Knee Flexion Exercise Boosts Hamstring Muscle Activity in Chronic Stroke Patients

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Jonas Vinstrup ◽  
Joaquin Calatayud ◽  
Markus D. Jakobsen ◽  
Emil Sundstrup ◽  
Lars L. Andersen
Keyword(s):  
Muscle Strength ◽  
Muscle Activity ◽  
High Speed ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Maximum Load ◽  
Chronic Stroke ◽  
Stroke Patients ◽  
Speed Condition ◽  
Contraction Speed

Background. Muscle strength is markedly reduced in stroke patients, which has negative implications for functional capacity and work ability. Different types of feedback during strength training exercises may alter neuromuscular activity and functional gains.Objective. To compare levels of muscle activity during conditions of blindfolding and intended high contraction speed with a normal condition of high-intensity knee flexions.Methods. Eighteen patients performed unilateral machine knee flexions with a 10-repetition maximum load. Surface electromyography (EMG) was recorded from the quadrics and hamstring muscles and normalized to maximal EMG (nEMG) of the nonparetic limb.Results. For the paretic leg, the speed condition showed higher values of muscle activity compared with the normal and blindfolded conditions for both biceps femoris and semitendinosus. Likewise, the speed condition showed higher co-contraction values compared with the normal and blindfolded conditions for the vastus lateralis. No differences were observed between exercise conditions for the nonparetic leg.Conclusion. Chronic stroke patients are capable of performing heavy resistance training with intended high speed of contraction. Focusing on speed during the concentric phase elicited higher levels of muscle activity of the hamstrings compared to normal and blindfolded conditions, which may have implications for regaining fast muscle strength in stroke survivors.

Effect of Absolute and Relative Loading on Muscle Activity During Stable and Unstable Squatting

2010 ◽  
Vol 5 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Jeffrey M. McBride ◽  
Tony R. Larkin ◽  
Andrea M. Dayne ◽  
Tracie L. Haines ◽  
Tyler J. Kirby
Keyword(s):  
Body Mass ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Force Plate ◽  
Rest Period ◽  
Biceps Femoris ◽  
Erector Spinae ◽  
Repetition Maximum ◽  
Maximum Test ◽  
Significant Difference

Purpose:The purpose of this investigation was to determine the effect of stable and unstable conditions on one repetition maximum strength and muscle activity during dynamic squatting using absolute and relative loading.Methods:Ten recreationally weight-trained males participated in this study (age = 24.1 ± 2.0 y, height = 178.0 ± 5.6 cm, body mass = 83.7 ± 13.4 kg, 1RM/body mass = 1.53 ± 0.31), which involved two laboratory sessions separated by 1 wk. Linear position transducers were used to track bar displacement while subjects stood on a force plate for all trials. Vastus lateralis (VL), biceps femoris (BF) and erector spinae (L1) muscle activity (average integrated EMG [IEMG]) was also recorded during all trials. During the frst session subjects complete a one repetition maximum test in a stable dynamic squat (S1RM = 128.0 ± 31.4 kg) and an unstable dynamic squat (U1RM = 83.8 ± 17.3 kg) in a randomized order with a 30-min rest period between conditions. The second session consisted of the performance of three trials each for 12 different conditions (unstable and stable squats using three different absolute loads [six conditions] and unstable and stable squats using three different relative loads [six conditions]).Results:Results revealed a statistically significant difference between S1RM and U1RM values (P < .05). The stable trials resulted in the same or a significantly higher value for VL, BF and L1 muscle activity in comparison with the unstable trials for all twelve conditions.Conclusions:Unstable squatting is of equal or less (depending on the loading condition) benefit to improving or maximizing muscle activity during resistance exercise.

Sign in / Sign up

Export Citation Format

Share Document