The Effects of Different Stretch Amplitudes on Electromyographic Activity During Drop Jumps

2008 ◽  
Vol 22 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Jenq-Dong Lin ◽  
Yu Liu ◽  
Jenq-Charng Lin ◽  
Feng-Jen Tsai ◽  
Chun-Yu Chao
Keyword(s):  
Electromyographic Activity ◽  
Drop Jumps

scholarly journals Muscle in Variable Gravity: “I Do Not Know Where I Am, But I Know What to Do”

2021 ◽  
Vol 12 ◽  
Author(s):  
Elena Monti ◽  
Janice Waldvogel ◽  
Ramona Ritzmann ◽  
Kathrin Freyler ◽  
Kirsten Albracht ◽  
...  
Keyword(s):  
Sarcomere Length ◽  
Joint Angle ◽  
Parabolic Flight ◽  
Published Data ◽  
Electromyographic Activity ◽  
Gravity Level ◽  
Muscle Fascicle ◽  
Drop Jumps ◽  
Variable Gravity ◽  
Sarcomere Number

Purpose: Fascicle and sarcomere lengths are important predictors of muscle mechanical performance. However, their regulation during stretch-shortening cycle (SSC) activities in usual and challenging conditions is poorly understood. In this study, we aimed to investigate muscle fascicle and sarcomere behavior during drop jumps (a common SSC activity) in conditions of variable gravity.Methods: Fifteen volunteers performed repeated drop jumps in 1 g, hypo-gravity (0 to 1 g), and hyper-gravity (1 to 2 g) during a parabolic flight. Gastrocnemius medialis (GM) electromyographic activity and fascicle length (Lf) were measured at drop-off, ground contact (GC), minimum ankle joint angle (MAJ), and push-off. GM sarcomere number was estimated by dividing Lf, measured by ultrasound at rest, by published data on GM sarcomere length, and measured in vivo at the same joint angle. Changes in sarcomere length were estimated by dividing GM Lf in each jump phase by sarcomere number calculated individually. The sarcomere force-generating capacity in each jump phase was estimated from the sarcomere length-tension relationship previously reported in the literature.Results: The results showed that, regardless of the gravity level, GM sarcomeres operated in the ascending portion of their length-tension relationship in all the jump phases. Interestingly, although in hypo-gravity and hyper-gravity during the braking phase (GC-MAJ) GM fascicles and sarcomeres experienced a stretch (as opposed to the quasi-isometric behavior in 1 g), at MAJ they reached similar lengths as in 1 g, allowing sarcomeres to develop about the 70% of their maximum force.Conclusion: The observed fascicle behavior during drop jumping seems useful for anchoring the tendon, enabling storage of elastic energy and its release in the subsequent push-off phase for effectively re-bouncing in all gravity levels, suggesting that an innate neuromuscular wisdom enables to perform SSC movements also in challenging conditions.

257. Electromyographic Activity of Forearm Flexors and Extensor Muscles from Typing on Negatively Sloped Computer Keyboards

2000 ◽  
Author(s):  
R. Marklin ◽  
G. Simoneau ◽  
D. Cahaya
Keyword(s):  
Electromyographic Activity ◽  
Extensor Muscles

scholarly journals Changes in electromyographic activity, mechanical power, and relaxation rates following inspiratory ribcage muscle fatigue

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Antonio Sarmento ◽  
Guilherme Fregonezi ◽  
Maria Lira ◽  
Layana Marques ◽  
Francesca Pennati ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Low Frequency ◽  
Mechanical Power ◽  
Electromyographic Activity ◽  
Median Frequency ◽  
Relaxation Rates ◽  
Shortening Velocity ◽  
Inspiratory Muscles ◽  
Underlying Mechanisms

AbstractMuscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here, simultaneous measurements of pressure, volume, and ribcage inspiratory muscle activity were performed non-invasively during fatigue (inspiratory threshold valve set at 70% of maximal inspiratory pressure) and recovery to verify if inspiratory ribcage muscle fatigue (1) leads to slowing of contraction and relaxation properties of ribcage muscles and (2) alters median frequency and high-to-low frequency ratio (H/L). During the fatigue protocol, sternocleidomastoid showed the fastest decrease in median frequency and slowest decrease in H/L. Fatigue was also characterized by a reduction in the relative power of the high-frequency and increase of the low-frequency. During recovery, changes in mechanical power were due to changes in shortening velocity with long-lasting reduction in pressure generation, and slowing of relaxation [i.e., tau (τ), half-relaxation time (½RT), and maximum relaxation rate (MRR)] was observed with no significant changes in contractile properties. Recovery of median frequency was faster than H/L, and relaxation rates correlated with shortening velocity and mechanical power of inspiratory ribcage muscles; however, with different time courses. Time constant of the inspiratory ribcage muscles during fatigue and recovery is not uniform (i.e., different inspiratory muscles may have different underlying mechanisms of fatigue), and MRR, ½RT, and τ are not only useful predictors of inspiratory ribcage muscle recovery but may also share common underlying mechanisms with shortening velocity.

Effects of attaching elastic bands to the waist and heels on drop jumps

2021 ◽  
pp. 1-25
Author(s):  
Hsien-Te Peng ◽  
Chen-Yi Song ◽  
Zong-Rong Chen ◽  
Chien-Ting Lai ◽  
Chin-Yi Gu ◽  
...  
Keyword(s):  
Elastic Bands ◽  
Drop Jumps

scholarly journals Measuring implanted patient response to tone pips

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Juan M. Cornejo ◽  
Agar K. Quintana ◽  
Nohra E. Beltran ◽  
Pilar Granados
Keyword(s):  
Auditory Nerve ◽  
Dynamic Range ◽  
Test Procedure ◽  
Electrical Potential ◽  
Electrical Current ◽  
Intensity Level ◽  
Electromyographic Activity ◽  
Variable Intensity ◽  
Electrode Current ◽  
Auditory Behavior

Abstract Background An electrical potential not previously reported—electrical cochlear response (ECR)—observed only in implanted patients is described. Its amplitude and growth slope are a measurement of the stimulation achieved by a tone pip on the auditory nerve. The stimulation and recording system constructed for this purpose, the features of this potential obtained in a group of 43 children, and its possible clinical use are described. The ECR is obtained by averaging the EEG epochs acquired each time the cochlear implant (CI) processes a tone pip of known frequency and intensity when the patient is sleeping and using the CI in everyday mode. The ECR is sensitive to tone pip intensity level, microphone sensitivity, sound processor gain, dynamic range of electrical current, and responsiveness to electrical current of the auditory nerve portion involved with the electrode under test. It allows individual evaluation of intracochlear electrodes by choosing, one at the time, the central frequency of the electrode as the test tone pip frequency, so the ECR measurement due to a variable intensity tone pip allows to establish the suitability of the dynamic range of the electrode current. Results There is a difference in ECR measurements when patients are grouped based on their auditory behavior. The ECR slope and amplitude for the Sensitive group is 0.2 μV/dBHL and 10 μV at 50 dBHL compared with 0.04 μV/dBHL and 3 μV at 50dBHL for the Inconsistent group. The clinical cases show that adjusting the dynamic range of current based on the ECR improved the patient’s auditory behavior. Conclusions ECR can be recorded regardless of the artifact due to the electromyographic activity of the patient and the functioning of the CI. Its amplitude and growth slope versus the intensity of the stimulus differs between electrodes. The relationship between minimum ECR detection intensity level and auditory threshold suggests the possibility of estimating patient auditory thresholds this way. ECR does not depend on the subject’s age, cooperation, or health status. It can be obtained at any time after implant surgery and the test procedure is the same regardless of device manufacturer.

scholarly journals Is Skeletal Muscle Dysfunction a Limiting Factor of Exercise Functional Capacity in Patients with Sickle Cell Disease?

2021 ◽  
Vol 10 (11) ◽  
pp. 2250
Author(s):  
Etienne Gouraud ◽  
Philippe Connes ◽  
Alexandra Gauthier-Vasserot ◽  
Camille Faes ◽  
Salima Merazga ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sickle Cell Disease ◽  
Muscle Fatigue ◽  
Sickle Cell ◽  
Functional Capacity ◽  
Muscle Dysfunction ◽  
Electromyographic Activity ◽  
Cell Disease ◽  
Step Frequency ◽  
Hemoglobin C

Patients with sickle cell disease (SCD) have reduced functional capacity due to anemia and cardio–respiratory abnormalities. Recent studies also suggest the presence of muscle dysfunction. However, the interaction between exercise capacity and muscle function is currently unknown in SCD. The aim of this study was to explore how muscle dysfunction may explain the reduced functional capacity. Nineteen African healthy subjects (AA), and 24 sickle cell anemia (SS) and 18 sickle cell hemoglobin C (SC) patients were recruited. Maximal isometric torque (Tmax) was measured before and after a self-paced 6-min walk test (6-MWT). Electromyographic activity of the Vastus Lateralis was recorded. The 6-MWT distance was reduced in SS (p < 0.05) and SC (p < 0.01) patients compared to AA subjects. However, Tmax and root mean square value were not modified by the 6-MWT, showing no skeletal muscle fatigue in all groups. In a multiple linear regression model, genotype, step frequency and hematocrit were independent predictors of the 6-MWT distance in SCD patients. Our results suggest that the 6-MWT performance might be primarily explained by anemia and the self-paced step frequency in SCD patients attempting to limit metabolic cost and fatigue, which could explain the absence of muscle fatigue.

scholarly journals Effects of Functional Electrical Stimulation Cycling of Different Duration on Viscoelastic and Electromyographic Properties of the Knee in Patients with Spinal Cord Injury

2020 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Antonino Casabona ◽  
Maria Stella Valle ◽  
Claudio Dominante ◽  
Luca Laudani ◽  
Maria Pia Onesta ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Electrical Stimulation ◽  
Functional Electrical Stimulation ◽  
Muscle Activity ◽  
Response Times ◽  
Electromyographic Activity ◽  
Functional Changes ◽  
Pendulum Test ◽  
Cord Injury

The benefits of functional electrical stimulation during cycling (FES-cycling) have been ascertained following spinal cord injury. The instrumented pendulum test was applied to chronic paraplegic patients to investigate the effects of FES-cycling of different duration (20-min vs. 40-min) on biomechanical and electromyographic characterization of knee mobility. Seven adults with post-traumatic paraplegia attended two FES-cycling sessions, a 20-min and a 40-min one, in a random order. Knee angular excursion, stiffness and viscosity were measured using the pendulum test before and after each session. Surface electromyographic activity was recorded from the rectus femoris (RF) and biceps femoris (BF) muscles. FES-cycling led to reduced excursion (p < 0.001) and increased stiffness (p = 0.005) of the knee, which was more evident after the 20-min than 40-min session. Noteworthy, biomechanical changes were associated with an increase of muscle activity and changes in latency of muscle activity only for 20-min, with anticipated response times for RF (p < 0.001) and delayed responses for BF (p = 0.033). These results indicate that significant functional changes in knee mobility can be achieved by FES-cycling for 20 min, as evaluated by the pendulum test in patients with chronic paraplegia. The observed muscle behaviour suggests modulatory effects of exercise on spinal network aimed to partially restore automatic neuronal processes.

scholarly journals Effects of Attentional Focus on Motor Performance and Physiology in a Slow-Motion Violin Bow-Control Task: Evidence for the Constrained Action Hypothesis in Bowed String Technique

2021 ◽  
pp. 002242942110347
Author(s):  
Emma Allingham ◽  
Clemens Wöllner
Keyword(s):  
Music Education ◽  
Motor Performance ◽  
Body Movement ◽  
Music Performance ◽  
Arm Movement ◽  
Slow Motion ◽  
Attentional Focus ◽  
Electromyographic Activity ◽  
Constrained Action Hypothesis ◽  
Conscious Thinking

The constrained action hypothesis states that focusing attention on action outcomes rather than body movement improves motor performance. Dexterity of motor control is key to successful music performance, making this a highly relevant topic to music education. We investigated effects of focus of attention (FOA) on motor skill performance and EMG muscle activity in a violin bowing task among experienced and novice upper strings players. Following a pedagogically informed exercise, participants attempted to produce single oscillations of the string at a time under three FOA: internal (on arm movement), external (on sound produced), and somatic (on string resistance). Experienced players’ number of bow slips was significantly reduced under somatic focus relative to internal, although number of successful oscillations was not affected. Triceps electromyographic activity was also significantly lower in somatic compared to internal foci for both expertise groups, consistent with physiological understandings of FOA effects. Participants’ reported thoughts during the experiment provided insight into whether aspects of constrained action may be evident in performers’ conscious thinking. These results provide novel support for the constrained action hypothesis in violin bow control, suggesting a somatic FOA as a promising performance-enhancing strategy for bowed string technique.

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