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.

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.

Changes in EMG power spectrum (high-to-low ratio) with force fatigue in humans

1982 ◽  
Vol 53 (5) ◽  
pp. 1094-1099 ◽  
Author(s):  
J. Moxham ◽  
R. H. Edwards ◽  
M. Aubier ◽  
A. De Troyer ◽  
G. Farkas ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Power Spectrum ◽  
Low Frequency ◽  
Normal Subjects ◽  
Quadriceps Muscle ◽  
Force Response ◽  
Low Frequencies ◽  
Emg Power Spectrum ◽  
Low Frequency Fatigue

During and following high-load fatiguing voluntary contractions, the force response of skeletal muscle to electrical stimulation is altered so that the frequency-force curve is moved to the right. Fatiguing contractions also result in a shift to the left of the electromyographic (EMG) power spectrum. In the quadriceps muscle and the diaphragm of normal subjects the change in the force response to electrical stimulation has been correlated with the EMG changes. After repeated submaximal contractions in the quadriceps and diaphragm, the forces produced by electrical stimulation at low frequencies were reduced, indicating low-frequency fatigue. This type of fatigue persisted for several hours but did not result in any change in the EMG high-to-low ratio. Low-frequency fatigue is probably an important aspect of the failure of skeletal muscle to generate adequate force, and the EMG high-to-low ratio may not recognize this type of fatigue.

Role of intracellular calcium and metabolites in low-frequency fatigue of mouse skeletal muscle

1997 ◽  
Vol 272 (2) ◽  
pp. C550-C559 ◽  
Author(s):  
E. R. Chin ◽  
C. D. Balnave ◽  
D. G. Allen
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Low Frequency ◽  
Single Muscle ◽  
Low Frequencies ◽  
Time Integral ◽  
Metabolic Component ◽  
Dependent Component ◽  
Low Frequency Fatigue

We have examined the extent to which prolonged reductions in low-frequency force (i.e., low-frequency fatigue) result from increases in intracellular free Ca2+ concentration ([Ca2+]i) and alterations in muscle metabolites. Force and [Ca2+]i were measured in mammalian single muscle fibers in response to short, intermediate, and long series of tetani that elevated the [Ca2+]i-time integral to 5, 17, and 29 microM x s, respectively. Only the intermediate and long series resulted in prolonged (>60 x min) reductions in Ca2+ release and low-frequency fatigue. When fibers recovered from the long series of tetani without glucose, Ca2+ release was reduced to a greater extent and force was reduced at high and low frequencies. These findings indicate that the decrease in sarcoplasmic reticulum Ca2+ release associated with fatigue has at least two components: 1) a metabolic component, which, in the presence of glucose, recovers within 1 h, and 2) a component dependent on the elevation of the [Ca2+]i-time integral, which recovers more slowly. It is this Ca2+-dependent component that is primarily responsible for low-frequency fatigue.

scholarly journals Low-Frequency Fatigue as an Indicator of Eccentric Exercise-Induced Muscle Injury: The Role of Vitamin E

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Antonios Kyparos ◽  
Michalis G. Nikolaidis ◽  
Konstantina Dipla ◽  
Andreas Zafeiridis ◽  
Vassilis Paschalis ◽  
...  
Keyword(s):  
Vitamin E ◽  
Eccentric Exercise ◽  
Muscle Injury ◽  
Low Frequency ◽  
Low Frequency Fatigue ◽  
Exercise Induced

Low-frequency depression of tension in the cat gastrocnemius muscle after eccentric exercise

2004 ◽  
Vol 97 (4) ◽  
pp. 1195-1202 ◽  
Author(s):  
S. Parikh ◽  
D. L. Morgan ◽  
J. E. Gregory ◽  
U. Proske
Keyword(s):  
Eccentric Exercise ◽  
Muscle Activation ◽  
Low Frequency ◽  
Muscle Length ◽  
Isometric Tension ◽  
Medial Gastrocnemius ◽  
Eccentric Contractions ◽  
Optimum Length ◽  
Length Dependence ◽  
Before And After

Subjecting a muscle to a series of eccentric contractions in which the contracting muscle is lengthened results in a number of changes in its mechanical properties. These include a fall in isometric tension that is particularly pronounced during low-frequency stimulation, a phenomenon known as low-frequency depression (LFD). Reports of LFD have not taken into account the shift in optimum length for active tension generation to longer muscle lengths that takes place after eccentric contractions. Given the length dependence of the stimulation frequency-tension curve, we tested the hypothesis that the change in this relationship after eccentric exercise is due to the shift in optimum length. We measured LFD by recording tension in response to a linearly increasing rate of stimulation of the nerve to medial gastrocnemius of anesthetized cats, over the range 0–100 pulses per second. Tension responses were measured before and after 50 eccentric contractions consisting of 6-mm stretches starting at 3 mm below optimum length and finishing at 3 mm above it. An index of LFD was derived from the tension responses to ramp stimulation. It was found that LFD after the eccentric contractions was partly, but not entirely, due to changes in the muscle's optimum length. An additional factor was the effect of fatigue. These observations led to the conclusion that the muscle length dependence of LFD was reduced by eccentric contractions. All of this means that after eccentric exercise the tension deficit at low rates of muscle activation is likely to be less severe than first thought.

Low-frequency fatigue and neuromuscular performance after exercise-induced damage to elbow flexor muscles

2008 ◽  
Vol 105 (4) ◽  
pp. 1146-1155 ◽  
Author(s):  
James M. Dundon ◽  
John Cirillo ◽  
John G. Semmler
Keyword(s):  
Eccentric Exercise ◽  
Biceps Brachii ◽  
Maximum Voluntary Contraction ◽  
Low Frequency ◽  
Elbow Flexor ◽  
Triceps Brachii ◽  
Force Fluctuations ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
Low Frequency Fatigue

The purpose of this study was to quantify the association between low-frequency fatigue (LFF) and the increase in EMG and force fluctuations after eccentric exercise of elbow flexor muscles. Ten subjects performed two tasks involving voluntary isometric contractions of elbow flexors: a maximum voluntary contraction (MVC) and a constant-force task at five submaximal target forces (5, 10, 20, 40, 60% MVC) while EMG was recorded from biceps and triceps brachii. A third task involved electrical stimulation of biceps brachii at 12 frequencies (1–100 Hz). These tasks were performed before, after, and 2 h and 24 h after concentric or eccentric exercise. MVC force declined after eccentric exercise (34% decline) and remained depressed 24 h later (22% decline), whereas the reduced force following concentric exercise (32%) was recovered 2 h later. Biceps brachii EMG and force fluctuations during the submaximal voluntary contractions increased after eccentric exercise (both ∼2× greater) with the greatest effect at low forces. LFF was equivalent immediately after both types of exercise (50–60% reduction in 20:100 Hz force) with a slower recovery following eccentric exercise. A significant association was found between the change in LFF and EMG ( r2values up to 0.52), with the strongest correlations observed at low forces (20% MVC) and at 2 h after exercise. In contrast, there were no significant associations between LFF and force fluctuations during voluntary or electrically evoked contractions, suggesting that other physiological factors located within the muscle are likely to be playing a major role in the impaired motor performance after eccentric exercise.

scholarly journals Factors in fatigue during intermittent electrical stimulation of human skeletal muscle

2002 ◽  
Vol 93 (2) ◽  
pp. 469-478 ◽  
Author(s):  
David W. Russ ◽  
Krista Vandenborne ◽  
Stuart A. Binder-Macleod
Keyword(s):  
Electrical Stimulation ◽  
Low Frequency ◽  
Metabolic Cost ◽  
Peak Force ◽  
Medial Gastrocnemius ◽  
Single Frequency ◽  
High Frequency Stimulation ◽  
Frequency Stimulation ◽  
Low Frequency Fatigue ◽  
Force Time

During an electrically elicited isometric contraction, the metabolic cost of attaining is greater than of maintaining force. Thus fatigue produced during such stimulation may not simply be a function of the force-time integral (FTI), as previously suggested. The goal of the present study was to evaluate fatigue produced in human medial gastrocnemius by intermittent, isometric electrical stimulation with trains of different frequencies (20, 40, or 80 Hz) and durations (300, 600, or 1,200 ms) that produced different peak forces and FTIs. Each subject ( n = 10) participated in a total of six sessions. During each session, subjects received a pre- and postfatigue testing protocol and a different, 150-train fatiguing protocol. Each fatiguing protocol used only a single frequency and duration. The fatigue produced by the different protocols was correlated to the initial peak force of the fatiguing protocols ( r 2= 0.74–0.85) but not to the initial or total FTI. All of the protocols tested produced a proportionately greater impairment of force in response to low- vs. high-frequency stimulation (i.e., low-frequency fatigue). There was no effect of protocol on low-frequency fatigue, suggesting that all the protocols produced comparable levels of impairment in excitation-contraction coupling. These results suggest that, for brief stimulated contractions, peak force is a better predictor of fatigue than FTI, possibly because of the different metabolic demands of attaining and maintaining force.

scholarly journals Postfatigue potentiation of the paralyzed soleus muscle: evidence for adaptation with long-term electrical stimulation training

2006 ◽  
Vol 101 (2) ◽  
pp. 556-565 ◽  
Author(s):  
Richard K. Shields ◽  
Shauna Dudley-Javoroski ◽  
Andrew E. Littmann
Keyword(s):  
Electrical Stimulation ◽  
Soleus Muscle ◽  
Neuromuscular Electrical Stimulation ◽  
Low Frequency ◽  
Home Based ◽  
Early Implementation ◽  
Cord Injury ◽  
Low Frequency Fatigue ◽  
Output Behavior

Understanding the torque output behavior of paralyzed muscle has important implications for the use of functional neuromuscular electrical stimulation systems. Postfatigue potentiation is an augmentation of peak muscle torque during repetitive activation after a fatigue protocol. The purposes of this study were 1) to quantify postfatigue potentiation in the acutely and chronically paralyzed soleus and 2) to determine the effect of long-term soleus electrical stimulation training on the potentiation characteristics of recently paralyzed soleus muscle. Five subjects with chronic paralysis (>2 yr) demonstrated significant postfatigue potentiation during a repetitive soleus activation protocol that induced low-frequency fatigue. Ten subjects with acute paralysis (<6 mo) demonstrated no torque potentiation in response to repetitive stimulation. Seven of these acute subjects completed 2 yr of home-based isometric soleus electrical stimulation training of one limb (compliance = 83%; 8,300 contractions/wk). With the early implementation of electrically stimulated training, potentiation characteristics of trained soleus muscles were preserved as in the acute postinjury state. In contrast, untrained limbs showed marked postfatigue potentiation at 2 yr after spinal cord injury (SCI). A single acute SCI subject who was followed longitudinally developed potentiation characteristics very similar to the untrained limbs of the training subjects. The results of the present investigation support that postfatigue potentiation is a characteristic of fast-fatigable muscle and can be prevented by timely neuromuscular electrical stimulation training. Potentiation is an important consideration in the design of functional electrical stimulation control systems for people with SCI.

Intracellular calcium concentration during low-frequency fatigue in isolated single fibers of mouse skeletal muscle

1993 ◽  
Vol 75 (1) ◽  
pp. 382-388 ◽  
Author(s):  
H. Westerblad ◽  
S. Duty ◽  
D. G. Allen
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Low Frequency ◽  
Intracellular Calcium Concentration ◽  
Low Frequencies ◽  
Single Fibers ◽  
Control Comparison ◽  
Low Frequency Fatigue ◽  
Tetanic Tension

Low-frequency fatigue is a form of muscle fatigue that follows intense muscle activity and is characterized by reduced tetanic tension at low frequencies of stimulation while tetanic tension at high stimulus frequencies is close to normal. The present experiments were performed on isolated single fibers of mouse in which tension and intracellular calcium concentration ([Ca2+]i) were measured. Fatigue was produced by intermittent short tetani continued until tension had declined to 30% of control. Comparison of low- (30- and 50-Hz) and high- (100-Hz) frequency tetani under control conditions and after 30 min of recovery from fatigue showed that low-frequency fatigue was present. During low-frequency fatigue, tetanic [Ca2+]i was substantially reduced at all stimulus frequencies but there was no change in Ca2+ sensitivity or maximum Ca(2+)-activated tension. One possible cause of the reduced tetanic [Ca2+]i is failure of conduction of the action potential in the T tubule, leading to reduced [Ca2+]i in the center of the fiber. However, imaging of [Ca2+]i across the fiber during low-frequency fatigue did not show any such gradient, suggesting that Ca2+ release is uniform across the fiber. Another possible mechanism is that changes in the Ca2+ pumping ability of the sarcoplasmic reticulum might affect tetanic [Ca2+]i. Measurements of the sarcoplasmic reticulum pump function showed a small slowing of Ca2+ uptake rate during low-frequency fatigue, which is unlikely to cause the reduced tetanic [Ca2+]i. In conclusion, the immediate cause of low-frequency fatigue appears to be a reduced tetanic [Ca2+]i, which is probably a consequence of a reduced Ca2+ release from the sarcoplasmic reticulum.

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