scholarly journals Vision fine-tunes preparation for landing in the cane toad, Rhinella marina

2018 ◽  
Vol 14 (9) ◽  
pp. 20180397 ◽  
Author(s):  
Laura J. Ekstrom ◽  
Chris Panzini ◽  
Gary B. Gillis
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Fine Tuning ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Impact Forces ◽  
Before And After ◽  
The Impact

In toad hopping, the hindlimbs generate the propulsive force for take-off while the forelimbs resist the impact forces associated with landing. Preparing to perform a safe landing, in which impact forces are managed appropriately, likely involves the integration of multiple types of sensory feedback. In toads, vestibular and/or proprioceptive feedback is critical for coordinated landing; however, the role of vision remains unclear. To clarify this, we compare pre-landing forelimb muscle activation patterns before and after removing vision. Specifically, we recorded EMG activity from two antagonistic forelimb muscles, the anconeus and coracoradialis, which demonstrate distance-dependent onset timing and recruitment intensity, respectively. Toads were first recorded hopping normally and then again after their optic nerves were severed to remove visual feedback. When blind, toads exhibited hop kinematics and pre-landing muscle activity similar to when sighted. However, distance-dependent relationships for muscle activity patterns were more variable, if present at all. This study demonstrates that blind toads are still able to perform coordinated landings, reinforcing the importance of proprioceptive and/or vestibular feedback during hopping. But the increased variability in distance-dependent activity patterns indicates that vision is more responsible for fine-tuning the motor control strategy for landing.

scholarly journals Changes in Locomotor Muscle Activity After Treadmill Training in Subjects With Incomplete Spinal Cord Injury

2009 ◽  
Vol 101 (2) ◽  
pp. 969-979 ◽  
Author(s):  
Monica A. Gorassini ◽  
Jonathan A. Norton ◽  
Jennifer Nevett-Duchcherer ◽  
Francois D. Roy ◽  
Jaynie F. Yang
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Treadmill Training ◽  
Emg Activity ◽  
Incomplete Spinal Cord Injury ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Cord Injury

Intensive treadmill training after incomplete spinal cord injury can improve functional walking abilities. To determine the changes in muscle activation patterns that are associated with improvements in walking, we measured the electromyography (EMG) of leg muscles in 17 individuals with incomplete spinal cord injury during similar walking conditions both before and after training. Specific differences were observed between subjects that eventually gained functional improvements in overground walking (responders), compared with subjects where treadmill training was ineffective (nonresponders). Although both groups developed a more regular and less clonic EMG pattern on the treadmill, it was only the tibialis anterior and hamstring muscles in the responders that displayed increases in EMG activation. Likewise, only the responders demonstrated decreases in burst duration and cocontraction of proximal (hamstrings and quadriceps) muscle activity. Surprisingly, the proximal muscle activity in the responders, unlike nonresponders, was three- to fourfold greater than that in uninjured control subjects walking at similar speeds and level of body weight support, suggesting that the ability to modify muscle activation patterns after injury may predict the ability of subjects to further compensate in response to motor training. In summary, increases in the amount and decreases in the duration of EMG activity of specific muscles are associated with functional recovery of walking skills after treadmill training in subjects that are able to modify muscle activity patterns following incomplete spinal cord injury.

More than a footwedge: Golf-specific footwear alters muscle activation patterns during standing balance

2020 ◽  
pp. 175433712093826
Author(s):  
Samuel J Wilson ◽  
Jacob R Gdovin ◽  
Charles C Williams ◽  
Paul T Donahue ◽  
James G Mouser ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Standing Balance ◽  
Medial Gastrocnemius ◽  
Extrinsic Factors ◽  
Activation Patterns ◽  
Intrinsic Factors ◽  
Muscle Activation Patterns

Within a golf swing, one aspect that stands out in each phase is the ability to maintain balance. Previous reports suggest that extrinsic factors, such as footwear, and intrinsic factors, such as muscular exertion level, have detrimental effects on human postural control. However, no studies have examined the effects of modern golf footwear on muscle activity of the lower extremity. Thus, the purpose of this study was to examine differences in muscle activity when walking for extended durations in golf footwear. Participants were tested for balance prior to walking sessions and then every 60 min until the 240th minute in three types of golf footwear; dress shoes, tennis shoes, and casual shoes, and barefoot. Mean muscle activity during balance testing of the vastus medialis, semitendinosus, tibialis anterior, and medial gastrocnemius was examined using a 4 × 5 repeated measures analysis of variance to identify differences within time and footwear types. Increases in muscle activity were observed after the second hour. Footwear differences were observed in the dress shoe and tennis shoe style relative to the casual style, and primarily attributed to the increased sole/midsole thickness, and increased mass of the dress shoe. These results suggest that golf footwear characteristics may alter muscle activity patterns during standing balance.

scholarly journals A Comparison of Muscle Activity in Concentric and Counter Movement Maximum Bench Press

2013 ◽  
Vol 38 ◽  
pp. 63-71 ◽  
Author(s):  
Roland van den Tillaar ◽  
Gertjan Ettema
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Bench Press ◽  
Body Height ◽  
Emg Activity ◽  
Activation Patterns ◽  
Repetition Maximum ◽  
Muscle Activation Patterns ◽  
Free Weight ◽  
Muscle Actions

Abstract The purpose of this study was to compare the kinematics and muscle activation patterns of regular free-weight bench press (counter movement) with pure concentric lifts in the ascending phase of a successful one repetition maximum (1-RM) attempt in the bench press. Our aim was to evaluate if diminishing potentiation could be the cause of the sticking region. Since diminishing potentiation cannot occur in pure concentric lifts, the occurrence of a sticking region in this type of muscle actions would support the hypothesis that the sticking region is due to a poor mechanical position. Eleven male participants (age 21.9 ~ 1.7 yrs, body mass 80.7 ~ 10.9 kg, body height 1.79 ~ 0.07 m) conducted 1-RM lifts in counter movement and in pure concentric bench presses in which kinematics and EMG activity were measured. In both conditions, a sticking region occurred. However, the start of the sticking region was different between the two bench presses. In addition, in four of six muscles, the muscle activity was higher in the counter movement bench press compared to the concentric one. Considering the findings of the muscle activity of six muscles during the maximal lifts it was concluded that the diminishing effect of force potentiation, which occurs in the counter movement bench press, in combination with a delayed muscle activation unlikely explains the existence of the sticking region in a 1-RM bench press. Most likely, the sticking region is the result of a poor mechanical force position.

scholarly journals Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

2021 ◽  
Vol 18 (3) ◽  
pp. 1366
Author(s):  
Roland van den Tillaar ◽  
Eirik Lindset Kristiansen ◽  
Stian Larsen
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Knee Extensors ◽  
Force Output ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Prime Movers ◽  
Almost All ◽  
Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

Development of an Apparatus for Bilateral Rhythmical Training of Arm Movement Via Linear and Elliptical Trajectories of Various Directions

2014 ◽  
Vol 8 (3) ◽  
Author(s):  
Zlatko Matjačić ◽  
Matjaž Zadravec ◽  
Jakob Oblak
Keyword(s):  
Muscle Activation ◽  
Arm Movement ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Arm Cycling ◽  
Arm Reaching ◽  
Direction Of Movement ◽  
Muscle Groups ◽  
Neurologically Intact

Clinical rehabilitation of individuals with various neurological disorders requires a significant number of movement repetitions in order to improve coordination and restoration of appropriate muscle activation patterns. Arm reaching movement is frequently practiced via motorized arm cycling ergometers where the trajectory of movement is circular thus providing means for practicing a single and rather nonfunctional set of muscle activation patterns, which is a significant limitation. We have developed a novel mechanism that in the combination with an existing arm ergometer device enables nine different movement modalities/trajectories ranging from purely circular trajectory to four elliptical and four linear trajectories where the direction of movement may be varied. The main objective of this study was to test a hypothesis stating that different movement modalities facilitate differences in muscle activation patterns as a result of varying shape and direction of movement. Muscle activation patterns in all movement modalities were assessed in a group of neurologically intact individuals in the form of recording the electromyographic (EMG) activity of four selected muscle groups of the shoulder and the elbow. Statistical analysis of the root mean square (RMS) values of resulting EMG signals have shown that muscle activation patterns corresponding to each of the nine movement modalities significantly differ in order to accommodate to variation of the trajectories shape and direction. Further, we assessed muscle activation patterns following the same protocol in a selected clinical case of hemiparesis. These results have shown the ability of the selected case subject to produce different muscle activation patterns as a response to different movement modalities which show some resemblance to those assessed in the group of neurologically intact individuals. The results of the study indicate that the developed device may significantly extend the scope of strength and coordination training in stroke rehabilitation which is in current clinical rehabilitation practice done through arm cycling.

Muscle Activity as a Releasing Factor for Pain in the Shoulder and Neck

Cephalalgia ◽  
1999 ◽  
Vol 19 (25_suppl) ◽  
pp. 1-8 ◽  
Author(s):  
RH Westgaard
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Experimental Situation ◽  
Activity Patterns ◽  
Trapezius Muscle ◽  
Emg Activity ◽  
Occupational Setting ◽  
Autonomic Activation ◽  
Pain Symptoms ◽  
Vocational Studies

In this review, the evidence for trapezius muscle activity as a releasing factor for shoulder and neck pain is considered, mainly on the basis of studies in our laboratory. Two lines of evidence are produced, (i) vocational studies in an occupational setting, where muscle activity pattern is recorded by surface EMG and a clinical examination of the shoulder region of the subjects performed; and (ii) laboratory studies where muscle activity patterns and pain development are recorded in an experimental situation with mental stress and minimal physical activity. The vocational studies demonstrate pain development in the shoulder and neck despite very low muscle activity recorded, making it very difficult to assume muscular involvement for all cases with such complaints. However, the hypothesis of pain development through overexertion of a subpopulation of low-threshold motor units also makes it difficult to draw a firm negative conclusion. The laboratory experiments, on the other hand, show that trapezius activity patterns in response to stress have many features that would be expected if muscle activation induces pain symptoms. It is further noted that the trapezius is the only muscle with activity patterns that show these features. Possibly, we observe the effects of parallel physiological phenomena, e.g., a systemic autonomic activation that induces pain symptoms and also facilitates the motor response of some muscles. Evidence of autonomic activation of trapezius is presented by the observation of low-level, rhythmic EMG activity during sleep. However, this is not firm evidence for the above hypothesis, which at present best serves as a basis for further experimentation.

Neural Drive to Muscles in Stuttering

1989 ◽  
Vol 32 (2) ◽  
pp. 252-264 ◽  
Author(s):  
Anne Smith
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Cross Correlation ◽  
Frequency Range ◽  
Neural Drive ◽  
Activation Patterns ◽  
Fluent Speech ◽  
Muscle Activation Patterns ◽  
Cross Correlation Analysis ◽  
Cross Correlations

EMG recordings were made from muscles of the jaw, lip, and neck during speech of 10 stutterers and 10 nonstutterers. One-second records of disfluent behaviors of stutterers and of fluent speech of the normal speakers were analyzed by computing cross correlations between all possible muscle pairs and spectra for each muscle channel. The cross correlation analysis indicated that for both the disfluent behavior of stutterers and the fluent speech of nonstutterers, jaw muscles (including antagonistic pairs), lip muscles, and neck muscles tend to be coactivated. Thus, no dramatic differences in muscle activation patterns were revealed in the correlational analysis. In contrast, spectral analysis revealed differences between muscle activity during disfluent behavior and fluent speech. During disfluencies the muscles of 6 of the stutterers showed large, rhythmic oscillations in the frequency range of 5 to 12 Hz. Large oscillations were not observed in this frequency range in the muscle activity of normal speakers. The oscillations in muscle activity during disfluencies generally occurred at the same frequency in the various muscle systems studied. These results suggest that diverse muscles are subject to common oscillatory synaptic drive during disfluent behaviors and that this drive is disruptive to speech production. A reasonable speculation is that the disruptive oscillatory drive is produced by tremorogenic mechanisms.

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