scholarly journals PO-166 Neuromuscular Fatigue after maximal Concentric and Eccentric Contractions of Knee Extensor

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Shenpeng Xu ◽  
Ying Wang ◽  
Wan Chen
Keyword(s):  
Electrical Stimulation ◽  
Knee Flexion ◽  
Low Frequency ◽  
Knee Extensor ◽  
Knee Extension ◽  
Neuromuscular Fatigue ◽  
Peripheral Fatigue ◽  
Concentric Exercise ◽  
Significant Difference ◽  
Low Frequency Fatigue

Objective The aim of this study was to investigate after different maximal contractions concentric and eccentric would cause different neuromuscular fatigue of knee extensor.  Methods Ten healthy young men(21≤age≤24) who were not adapted by electrical stimulation were the subjects.The subjects were asked to arrive at the laboratory in three weeks at the same time of every week to avoid the effects of biological rhythms.Each subject performed three group maximal contractions on the ISOMED2000 isokinetic muscle tester according to the requirements.The subjects performed the same neuromuscular function test before and after exercise.The centripetal motion scheme:3*30,M1(knee flexion)-CON,M2(knee extension)-CON.angular velocity is 60 °,interval 30s in each group.Centrifugal motion scheme:3*30,M1(knee flexion)-ECC,M2(knee extension)-ECC.angular velocity is 60 °,interval 30s in each group.  Results The decrease rate of peak torque after concentric exercise was 55.93±13.20%, which was significantly higher than that after centrifugal exercise (20.06 ±11.06%, P < 0.01)The total work of the concentric movement was 8737.20±1543.43J, which was significantly smaller than that of the centrifugal exercise group (14312.20±2978.31J, P < 0. 01).The decline rate of MVC in concentric exercise was 24.89 ±10.54 and that in centrifugal exercise was 19.32±9.90,there was no significant difference between the two groups. Double Twitch induced a very significant decrease in PT-SSR RFD-SSN RHD-SS (P<0.01).There was no significant difference in VA decline rate.PAP decreased from 142.82±14.55% to 125.23±11.36 after concentric exercise, and after eccentric exercise PAP decreased from 141.1215.72% to 126.02 ±10.45.  Conclusions The neuromuscular fatigue caused by two kinds of exercise. Peripheral fatigue accounted for 39.19% after concentric exercise and 23.59% after centrifugal exercise,but there was little difference in the degree of central fatigue.All of them showed low frequency fatigue, and the low frequency fatigue after centrifugal exercise was more obvious. Key World:Neuromuscular fatigue; Electrical stimulation; High-frequency fatigue; Low-frequency fatigue; PAP.

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.

scholarly journals Post-Activation Potentiation and Fatigue in Quadriceps Femoral Muscle after a 5 s Maximal Voluntary Isometric Contraction

2018 ◽  
Vol 1 (68) ◽  
Author(s):  
Nerijus Masiulis ◽  
Albertas Skurvydas ◽  
Sigitas Kamandulis ◽  
Audrius Sniečkus ◽  
Marius Brazaitis ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Isometric Exercise ◽  
Low Frequency ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Simultaneous Occurrence ◽  
Contraction Force ◽  
Maximal Voluntary Isometric Contraction ◽  
Low Frequency Fatigue

Following an acute physical exercise, both post-activation potentiation and fatigue of the neuromuscular apparatus may occur. The voluntary recruitment of motor units occurs with frequencies that elicit incompletely fused tetanic contractions and these frequencies are most susceptible for post-activation potentiation as well as low-frequency fatigue. Therefore, the goal of the present study was to investigate which of the processes post-activation potentiation or low-frequency fatigue will be prevalent after 5 s maximal voluntary contraction (MVC). Eight healthy untrained men (age 24—35 years, mass 81.2 ± 5.1 kg) performed maximal sustained isometric knee extension for 5 s at a knee angle of 90 degrees. The contractile properties of quadriceps muscle evoked by electrical stimulation at 1, 7, 10, 15, 20, 50 Hz and 100 Hz, were recorded before and immediately after the exercise and 3, 5, and 10 min following the exercise. The rest interval between muscle electrical stimulation was 3 s. A significant raise of force evoked by 1—15 Hz stimulation was observed immediately after the 5 s MVC exercise (p < 0.01). Later in recovery (at 10 min) the contraction force at 15 Hz and 20 Hz significantly decreased (p < 0.05). Tetanic force at 50 Hz and 100 Hz demonstrated a significant decrease immediately after the exercise and remained depressed up to 3 min (p < 0.01). The ratio of 20 / 50 Hz recorded immediately after the 5 s MVC increased significantly (p < 0.05), however 10 min after the exercise there was a significant decrease compared to its initial level (p < 0.05). The simultaneous occurrence of post-activation potentiation at low stimulation frequencies and suppressed forces at high stimulation frequencies suggests that potentiation and fatigue mechanisms were acting concurrently. Moreover, when post-activation potentiation is lost (in 10 min after the 5 s MVC exercise), the contraction force at low stimulation frequencies decreases resulting in significant low-frequency fatigue.Keywords: isometric exercise, electrical stimulation, low-frequency fatigue, recovery.

Twelve- to Thirteen-Year-Old Boys Are More Resistant to Low-Frequency Fatigue than Young Men

2005 ◽  
Vol 17 (4) ◽  
pp. 399-409 ◽  
Author(s):  
Vytautas Streckis ◽  
Albertas Skurvydas ◽  
Aivaras Ratkevicius
Keyword(s):  
Low Frequency ◽  
Knee Extensor ◽  
Ground Reaction Forces ◽  
Extensor Muscles ◽  
Significant Difference ◽  
Drop Jumps ◽  
Generating Capacity ◽  
Reaction Forces ◽  
Low Frequency Fatigue ◽  
Knee Extensor Muscles

The aim of this study was to compare low-frequency fatigue (LFF) after 100 drop jumps in boys (age = 12.7 ± 0.7 years, mean ± SD) and men (age = 25.6 ± 1.7 years). The force-generating-capacity test (FGCT) of knee extensor muscles was performed before the exercise, as well as 3 and 20 min after the exercise. Before exercise, men were stronger than boys, but twitch time characteristics did not differ between the groups. The 20:50 Hz torque ratio was similar in boys and men as well (0.71 ± 0.08 and 0.73 ± 0.08, respectively). After exercise, at 20 min of recovery, the 20:50 Hz ratio was depressed to 48.9 ± 11.6% of initial in men and to 74.5 ± 10.0% of initial in boys (p < .05). There was no significant difference between boys and men in ground-reaction forces of drop jumps when the values were normalized to body mass. It is argued that intrinsic differences in the muscle-tendon complex are responsible for less severe LFF in boys compared with men.

scholarly journals Self-Managed Strength Training for Active Duty Military With a Knee Injury: A Randomized Controlled Pilot Trial

2019 ◽  
Vol 184 (7-8) ◽  
pp. e174-e183 ◽  
Author(s):  
Laura A Talbot, Col, USAFR (Ret.) ◽  
Emily Brede ◽  
Marquita N Price ◽  
Pilar d Zuber ◽  
E Jeffrey Metter
Keyword(s):  
Knee Flexion ◽  
Knee Injuries ◽  
Knee Extensor ◽  
Knee Extension ◽  
Active Duty ◽  
Group Differences ◽  
Significant Group ◽  
Active Duty Military ◽  
Significant Difference ◽  
Injured Knee

Abstract Introduction Knee injuries among active duty military are one of the most frequent musculoskeletal injuries and are often caused by exercise or intense physical activity or combat training. These injuries pose a threat to force readiness. Our objective was to assess feasibility (including recruitment and retention rates) of three self-managed strengthening strategies for knee injuries and determine if they resulted in improvements in lower extremity strength, function, pain, and activity compared to usual physical therapy (PT) in military members. Methods A pilot study using a randomized controlled trial was conducted at three outpatient military medical treatment facilities. After baseline testing, 78 active duty military members with a knee injury were randomized to 1–4 trial arms: (1) neuromuscular electrical stimulation (NMES) applied to the quadriceps muscle; (2) graduated strength walking using a weighted vest (WALK); (3) combined NMES with strength walking (COMBO); (4) usual PT alone. All groups received usual PT. The primary outcome was the rates of change in knee extensor and flexor strength over 18 weeks. Secondary outcomes explored the rates of change in functional performance, pain, and activities of daily living scale (ADLS). The primary analysis for the endpoints used repeated measures, linear mixed-effects models. This study was approved by Institutional Review Boards at all facilities. Results The randomized sample (N = 78) included 19 participants in the PT-only, 20 in the WALK, 19 in the NMES and 20 in the COMBO groups. At baseline, there were no group differences. Fifty of the participants completed the 18-week study. The completers and non-completers differed at baseline on injury mechanism, with more completers injured during sports (45% vs 29%), and more non-completers during military training (36% vs 18%). Also, they differed in uninjured knee extension (completers 28% weaker), and uninjured knee flexion (completers 22% weaker). Adherence for self-reported daily step logs showed that the WALK group was 15% below goal and COMBO group 6% below goal. The 300 PV muscle stimulator showed the NMES group completed 34% of recommended stimulation sessions and the COMBO group 30%. Knee extension strength in the injured knee found only the COMBO group having a statistically higher improvement compared to PT-only (Change over 18 weeks: 10.6 kg in COMBO; 2.1 kg in PT-only). For the injured knee flexion changes, only the COMBO showed significant difference from PT-only (Change over 18 weeks: 7.5 kg in COMBO; −0.2 kg in PT-only). Similarly, for the uninjured knee, only the COMBO showed significant difference from PT-only in knee extension (Change over 18 weeks: 14.7 Kg in COMBO; 2.7 kg in PT-only) and knee flexion (Change over 18 weeks: 6.5 kg in COMBO; −0.2 kg in PT-only). Overall pain improved during the study for all groups with no significant group differences. Similarly, function and ADLS significantly improved over 18 weeks, with no significant group differences. Conclusions Knee extensor strength improvements in the COMBO group were significantly higher compared to usual PT. Pain, functional measures, and ADLS all improved during the study with no group differences. Further research is required to confirm these findings.

Effects of chronic low-frequency electrical stimulation of human knee extensor muscles exposed to static passive stretching

2006 ◽  
Vol 32 (1) ◽  
pp. 74-80 ◽  
Author(s):  
B. S. Shenkman ◽  
E. V. Lyubaeva ◽  
D. V. Popov ◽  
A. I. Netreba ◽  
O. S. Tarasova ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Low Frequency ◽  
Knee Extensor ◽  
Human Knee ◽  
Passive Stretching ◽  
Extensor Muscles ◽  
Knee Extensor Muscles ◽  
Stimulation Of

Central and peripheral contributions to neuromuscular fatigue induced by a 24-h treadmill run

2010 ◽  
Vol 108 (5) ◽  
pp. 1224-1233 ◽  
Author(s):  
Vincent Martin ◽  
Hugo Kerhervé ◽  
Laurent A. Messonnier ◽  
Jean-Claude Banfi ◽  
André Geyssant ◽  
...  
Keyword(s):  
Compound Muscle Action Potential ◽  
Vastus Lateralis ◽  
Low Frequency ◽  
Force Production ◽  
Neuromuscular Fatigue ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Function Evaluation ◽  
Central Component ◽  
Low Frequency Fatigue

This experiment investigated the fatigue induced by a 24-h running exercise (24TR) and particularly aimed at testing the hypothesis that the central component would be the main mechanism responsible for neuromuscular fatigue. Neuromuscular function evaluation was performed before, every 4 h during, and at the end of the 24TR on 12 experienced ultramarathon runners. It consisted of a determination of the maximal voluntary contractions (MVC) of the knee extensors (KE) and plantar flexors (PF), the maximal voluntary activation (%VA) of the KE and PF, and the maximal compound muscle action potential amplitude (Mmax) on the soleus and vastus lateralis. Tetanic stimulations also were delivered to evaluate the presence of low-frequency fatigue and the KE maximal muscle force production ability. Strength loss occurred throughout the exercise, with large changes observed after 24TR in MVC for both the KE and PF muscles (−40.9 ± 17.0 and −30.3 ± 12.5%, respectively; P < 0.001) together with marked reductions of %VA (−33.0 ± 21.8 and −14.8 ± 18.9%, respectively; P < 0.001). A reduction of Mmax amplitude was observed only on soleus, and no low-frequency fatigue was observed for any muscle group. Finally, KE maximal force production ability was reduced to a moderate extent at the end of the 24TR (−10.2%; P < 0.001), but these alterations were highly variable ( ± 15.7%). These results suggest that central factors are mainly responsible for the large maximal muscle torque reduction after ultraendurance running, especially on the KE muscles. Neural drive reduction may have contributed to the relative preservation of peripheral function and also affected the evolution of the running speed during the 24TR.

scholarly journals Low-Frequency Fatigue at Different Muscle Length Following Intermittent Eccentric Drop Jumps in 12—14 Year-Old Boys

2018 ◽  
Vol 3 (57) ◽  
Author(s):  
Vytautas Streckis ◽  
Giedrius Gorianovas ◽  
Birutė Miseckaitė ◽  
Valerija Streckienė ◽  
Ronaldas Endrijaitis ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Eccentric Exercise ◽  
Mechanical Damage ◽  
Low Frequency ◽  
Muscle Length ◽  
Contraction Force ◽  
Low Frequencies ◽  
Drop Jumps ◽  
Low Frequency Fatigue ◽  
Initial Force

Low frequency fatigue (LFF) in 12—14 year-old adolescent boys (n = 10) doing 75 eccentric jumps performed every20 s from a platform 80 cm high was investigated.Thus the aim of this study was to find out if LFF manifests itself in the muscles of boys aged 12—14 years doing 75 dropjumps performed every 20 s at angles of 90˚ and 135˚ from a platform 80 cm high. The results of the research have shownthat doing 75 eccentric jumps performed every 20 s calls forth LFF in the muscles of boys that is particularly strong anddisappears more slowly at a shorter length of the muscle exercised. Thus, the hypothesis as to the sarcomeric origin ofLFF in the muscles of boys and men has been confirmed. Besides, the muscles of men of mature age are more resistantto LFF than those of boys. This fact, as well as a more acute pain brought about in the muscles of boys, indicates thatthe muscles of boys are less resistant to mechanical damage than those of men of mature age.It is maintained that as a result of the eccentric exercise performed, some portion of the weak sarcomeres gets tornand then the strong sarcomeres, i.e. the ones that develop contraction force have to work at a shorter muscle length.When muscle contraction length is short the sensitiveness of miofibrillas to Ca 2+  decreases. It is rather unexpectedthough that 24 h after the end of the exercise the force developed by electrostimulation at low frequencies (20 Hz) issmaller (p < 0.05), as compared to the initial force registered at a shorter muscle length. Since after the exercise therewas also a decrease in the force developed at a shorter muscle length in particular, the sarcomeres are believed tohave been damaged during eccentric exercise.Keywords: electrical stimulation, force, age, muscle damage, stretch-shortening exercise.

Kilohertz and Low-Frequency Electrical Stimulation With the Same Pulse Duration Have Similar Efficiency for Inducing Isometric Knee Extension Torque and Discomfort

2017 ◽  
Vol 96 (6) ◽  
pp. 388-394 ◽  
Author(s):  
Flávia Vanessa Medeiros ◽  
Martim Bottaro ◽  
Amilton Vieira ◽  
Tiago Pires Lucas ◽  
Karenina Arrais Modesto ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Pulse Duration ◽  
Low Frequency ◽  
Knee Extension ◽  
Isometric Knee Extension

scholarly journals Comparison of Recovery Strategies on Maximal Force-Generating Capacity and Electromyographic Activity Level of the Knee Extensor Muscles

2011 ◽  
Vol 46 (4) ◽  
pp. 386-394 ◽  
Author(s):  
Nidhal Zarrouk ◽  
Haithem Rebai ◽  
Abdelmoneem Yahia ◽  
Nizar Souissi ◽  
François Hug ◽  
...  
Keyword(s):  
Knee Extensor ◽  
Neuromuscular Fatigue ◽  
Activity Level ◽  
Knee Extensors ◽  
Emg Activity ◽  
Electromyographic Activity ◽  
Active Recovery ◽  
Concentric Exercise ◽  
Extensor Muscles ◽  
Knee Extensor Muscles

Context: With regard to intermittent training exercise, the effects of the mode of recovery on subsequent performance are equivocal. Objective: To compare the effects of 3 types of recovery intervention on peak torque (PT) and electromyographic (EMG) activity of the knee extensor muscles after fatiguing isokinetic intermittent concentric exercise. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Eight elite judo players (age = 18.4 ± 1.4 years, height = 180 ± 3 cm, mass = 77.0 ± 4.2 kg). Intervention(s): Participants completed 3 randomized sessions within 7 days. Each session consisted of 5 sets of 10 concentric knee extensions at 80% PT at 120°/s, with 3 minutes of recovery between sets. Recovery interventions were passive, active, and electromyostimulation. The PT and maximal EMG activity were recorded simultaneously while participants performed isokinetic dynamometer trials before and 3 minutes after the resistance exercise. Main Outcome Measure(s): The PT and maximal EMG activity from the knee extensors were quantified at isokinetic velocities of 60°/s, 120°/s, and 180°/s, with 5 repetitions at each velocity. Results: The reduction in PT observed after electromyo-stimulation was less than that seen after passive (P &lt; .001) or active recovery (P &lt; .001). The reduction in PT was less after passive recovery than after active recovery (P &lt; .001). The maximal EMG activity level observed after electromyostimulation was higher than that seen after active recovery (P &lt; .05). Conclusions: Electromyostimulation was an effective recovery tool in decreasing neuromuscular fatigue after high-intensity, intermittent isokinetic concentric exercise for the knee extensor muscles. Also, active recovery induced the greatest amount of neuromuscular fatigue.

Assessment of low-frequency fatigue with two methods of electrical stimulation

2004 ◽  
Vol 97 (5) ◽  
pp. 1923-1929 ◽  
Author(s):  
V. Martin ◽  
G. Y. Millet ◽  
A. Martin ◽  
G. Deley ◽  
G. Lattier
Keyword(s):  
Motor Nerve ◽  
Femoral Nerve ◽  
Low Frequency ◽  
Knee Extensor ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Significant Time ◽  
Activation Level ◽  
Voluntary Activation Level ◽  
Low Frequency Fatigue

The aim of this study was to compare the use of transcutaneous vs. motor nerve stimulation in the evaluation of low-frequency fatigue. Nine female and eleven male subjects, all physically active, performed a 30-min downhill run on a motorized treadmill. Knee extensor muscle contractile characteristics were measured before, immediately after (Post), and 30 min after the fatiguing exercise (Post30) by using single twitches and 0.5-s tetani at 20 Hz (P20) and 80 Hz (P80). The P20-to-P80 ratio was calculated. Electrical stimulations were randomly applied either maximally to the femoral nerve or via large surface electrodes (ES) at an intensity sufficient to evoke 50% of maximal voluntary contraction (MVC) during a 80-Hz tetanus. Voluntary activation level was also determined during isometric MVC by the twitch-interpolation technique. Knee extensor MVC and voluntary activation level decreased at all points in time postexercise ( P < 0.001). P20 and P80 displayed significant time × gender × stimulation method interactions ( P < 0.05 and P < 0.001, respectively). Both stimulation methods detected significant torque reductions at Post and Post30. Overall, ES tended to detect a greater impairment at Post in male and a lesser one in female subjects at both Post and Post30. Interestingly, the P20-P80 ratio relative decrease did not differ between the two methods of stimulation. The low-to-high frequency ratio only demonstrated a significant time effect ( P < 0.001). It can be concluded that low-frequency fatigue due to eccentric exercise appears to be accurately assessable by ES.

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