The Influence of Intermittent Fatigue Exercise on Early and Late Phases of Relaxation From Maximal Voluntary Contraction

1997 ◽  
Vol 22 (6) ◽  
pp. 573-584 ◽  
Author(s):  
Anna Jaskólska ◽  
Artur Jaskólski
Keyword(s):  
Relaxation Time ◽  
Relaxation Rate ◽  
Maximal Voluntary Contraction ◽  
Early Phase ◽  
Intermittent Exercise ◽  
Young Male ◽  
Voluntary Contraction ◽  
Hand Grip ◽  
Before And After ◽  
Late Relaxation Time

Twenty-two young male subjects were tested to estimate the behavior of the early and late phases of relaxation from a 3-s maximal voluntary contraction (MVC) under the influence of fatigue. Less demanding and more demanding protocols of intermittent hand grip exercise were used to fatigue muscle. Before and after fatigue, the early and late relaxation time, maximal relaxation rate, and half-relaxation time were measured. The results showed that during voluntary movement (a) the early phase of relaxation was independent of the mode of intermittent exercise and did not change significantly after fatigue; (b) the late relaxation time and absolute maximal relaxation rate were slower after both protocols, with the changes more pronounced following the more demanding protocol; and (c) the half-relaxation time and relative maximal relaxation rate were changed only in the more demanding protocol. It is concluded that unlike the relaxation following electrical stimulation of isolated muscle, the early phase of relaxation from voluntary contraction appears to be the most resistant to the type of intermittent fatiguing exercise used in the present study, whereas the late relaxation time was the most sensitive to this type of fatigue. Key words: hand grip exercise, late relaxation time, early relaxation time, half-relaxation time

Effect of caffeine on skeletal muscle function before and after fatigue

1983 ◽  
Vol 54 (5) ◽  
pp. 1303-1305 ◽  
Author(s):  
J. M. Lopes ◽  
M. Aubier ◽  
J. Jardim ◽  
J. V. Aranda ◽  
P. T. Macklem
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Relaxation Rate ◽  
Voluntary Contraction ◽  
Contractile Properties ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Muscle Contractile Properties ◽  
Before And After ◽  
Muscle Contractile

We studied the effect of caffeine on voluntary and electrically stimulated contractions of the adductor pollicis muscle in five adult volunteers. Caffeine (500 mg) was administered orally in a double-blind fashion. Electrical stimulation of the ulnar nerve was performed at 10, 20, 30, 50, and 100 Hz before and after a sustained voluntary contraction held at 50% of the maximal voluntary contraction (MVC). A brief tetanus at 30 Hz was also performed to calculate relaxation rate in the fresh muscle. Contractile properties, relaxation rate, and endurance were then assessed after caffeine and placebo, as well as the response of the fatigued muscle to different frequencies of stimulation. There was no difference in the maximal tension obtained with electrical stimulation (T100) or in the MVC between placebo and caffeine. The tensions developed with electrical stimulation at lower frequencies increased significantly with caffeine ingestion, shifting the frequency-force curve to the left, both before and after fatigue. Mean plasma caffeine concentration associated with these responses was 12.2 +/- 4.9 mg/l. We conclude that caffeine has a direct effect on skeletal muscle contractile properties both before and after fatigue as demonstrated by electrical stimulation.

Decrease in maximal voluntary contraction by tonic vibration applied to a single synergist muscle in humans

2000 ◽  
Vol 89 (4) ◽  
pp. 1420-1424 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara ◽  
Tetsuo Fukunaga
Keyword(s):  
Maximal Voluntary Contraction ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Vastus Medialis ◽  
Force Development ◽  
Ia Afferent ◽  
Before And After ◽  
Integrated Emg

The purpose of the study was to examine the effect of prolonged tonic vibration applied to a single synergist muscle on maximal voluntary contraction (MVC) and maximal rate of force development (dF/d t max). The knee extension MVC force and surface electromyogram (EMG) from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) during MVC were recorded before and after vibration of RF muscle at 30 Hz for 30 min. MVC, dF/d t max, and the integrated EMG (iEMG) of RF decreased significantly after prolonged tonic vibration in spite of no changes in iEMG of VL and VM. The present results indicate that MVC and dF/d t max may be influenced by the attenuated Ia afferent functions of a single synergist muscle.

scholarly journals Fatigue-induced adjustment in antagonist coactivation by old adults during a steadiness task

2016 ◽  
Vol 120 (9) ◽  
pp. 1039-1046 ◽  
Author(s):  
Christopher J. Arellano ◽  
David Caha ◽  
Joseph E. Hennessey ◽  
Ioannis G. Amiridis ◽  
Stéphane Baudry ◽  
...  
Keyword(s):  
Maximal Voluntary Contraction ◽  
Failure Time ◽  
Voluntary Contraction ◽  
Matching Task ◽  
Electromyographic Activity ◽  
Time To Failure ◽  
Old Adults ◽  
Before And After ◽  
Wrist Flexors ◽  
Maximal Voluntary Contraction Torque

The purpose of this study was to determine the adjustments in the level of coactivation during a steadiness task performed by young and old adults after the torque-generating capacity of the antagonist muscles was reduced by a fatiguing contraction. Torque steadiness (coefficient of variation) and electromyographic activity of the extensor and flexor carpi radialis muscles were measured as participants matched a wrist extensor target torque (10% maximum) before and after sustaining an isometric contraction (30% maximum) with wrist flexors to task failure. Time to failure was similar ( P = 0.631) for young (417 ± 121 s) and old (452 ± 174 s) adults. The reduction in maximal voluntary contraction torque (%initial) for the wrist flexors after the fatiguing contraction was greater ( P = 0.006) for young (32.5 ± 13.7%) than old (21.8 ± 6.6%) adults. Moreover, maximal voluntary contraction torque for the wrist extensors declined for old (−13.7 ± 12.7%; P = 0.030), but not young (−5.4 ± 13.8%; P = 0.167), adults. Torque steadiness during the matching task with the wrist extensors was similar before and after the fatiguing contraction for both groups, but the level of coactivation increased after the fatiguing contraction for old ( P = 0.049) but not young ( P = 0.137) adults and was twice the amplitude for old adults ( P = 0.002). These data reveal that old adults are able to adjust the amount of antagonist muscle activity independent of the agonist muscle during steady submaximal contractions.

Motor unit spike counts before and after maximal voluntary contraction

1990 ◽  
Vol 13 (12) ◽  
pp. 1146-1151 ◽  
Author(s):  
Judith L. Gooch ◽  
Bruce Y. Newton ◽  
Jack H. Petajan
Keyword(s):  
Motor Unit ◽  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Before And After ◽  
Unit Spike

The Performance of Female Young Adults in Perception of Efforts of Varied Nature and Magnitudes

1993 ◽  
Vol 37 (10) ◽  
pp. 793-797
Author(s):  
Shrawan Kumar ◽  
Maureen Simmonds ◽  
David Lechelt
Keyword(s):  
Young Adults ◽  
Statistical Analysis ◽  
Young Adult ◽  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Test Analysis ◽  
Hand Grip ◽  
Adult Females ◽  
Significant Difference ◽  
Entire Experiment

Ten normal young adult females performed maximal and graded exertions of the stoop lift, hand grip, and finger pinch. The levels of graded exertion required were 80%, 60%, 40% and 20% of maximal voluntary contraction (MVC). The sequence of all conditions were fully randomized. Each of the randomized conditions was tried three times in succession. The entire experiment was carried out on four different days at the same time of the day on Monday, Wednesday, Friday of one week and Friday of the next week. The data obtained were subjected to descriptive and statistical analysis with t-test, analysis of variance, and correlation and regression. There were significant differences in the efforts produced in three different activities (p<0.01). The levels of exertion from 20% to 80% were significantly different from each other (p<0.01). However, there were no significant differences between the three trials of any given condition and the exertions produced on four different days. The 80% and 60% of exertions were overestimated and 20% was underestimated compared to the objective values based on MVC (p<0.01). At 40% effort there was no significant difference between the objective level of exertion and subjectively gauged and produced effort. The reliability of perception among the female subjects was similar for finger pinch, hand grip, and stoop lift activities.

Enhancement of ADP-Induced Platelet Aggregation by Isometric Hand-Grip Excercise in Sclerotic Patients and its Prevention by EG-626, cAMPPDE Inhibitor

1975 ◽  
Author(s):  
T. Sano ◽  
T. Motomiya ◽  
H. Yamazaki ◽  
T. Shimamoto
Keyword(s):  
Platelet Aggregation ◽  
Cardiac Contractility ◽  
Systolic Time Intervals ◽  
Voluntary Contraction ◽  
Acute Stage ◽  
Camp Phosphodiesterase ◽  
Platelet Aggregability ◽  
Hand Grip ◽  
Before And After

We have reported an enhancement of ADP- and epinephrine-induced platelet aggregation in acute stage of thrombosis (TDH suppl. 60, 213, 1974). In such enhancement, a role of cyclic AMP in platelets is important. Recently Shimamoto and Hidaka found a potent cAMP phosphodiesterase inhibiting effect in a new synthetized drug, phthalazinol (EG 626). It inhibited primary and secondary aggregation in vitro in 1 ~ 5 μg/ml of final concentration. So we examined an effect of EG 626 on platelet aggregability induced by isometric hand-grip exercise. Isometric hand-grip exercise at 50% maxial voluntary contraction (Mod. Concept. Cardiovasc. Dis. 41, 11, 1972) was performed for 2 minutes, in 15 coronary herart disease, 13 cerebral artieriosclerotic disease, 15 essential hypertension and 15 control subjects. ADP-induced platelet aggregability was assessed before and after exercise by a new method (TDH 25, 524, 1971). Also heart rate, blood pressure and systolic time intervals were recorded. An enhancement of platelet aggregability to ADP by exercise was disclosed significantly (p < 0.01) in coronary and cerebral sclerotic patients. The enhancement was prevented when the patients were orally pretreated with EG 626, 300 mg 1.5 hours before exercise. PEP/ET value on the exercise was significantly (p < 0.05) reduced with EG 626 pretreatment, suggesting enhancement of cardiac contractility by EG626.

Force Perception before and after Maximal Voluntary Contraction

1993 ◽  
Vol 76 (2) ◽  
pp. 399-402 ◽  
Author(s):  
Judith L. Gooch ◽  
Jeffrey Randle
Keyword(s):  
Maximal Voluntary Contraction ◽  
Elbow Flexion ◽  
Voluntary Contraction ◽  
Low Level ◽  
Force Perception ◽  
Before And After ◽  
The Mean ◽  
Flexion Force

Capacity to match a low level of elbow flexion force maintained in the control arm was measured in the experimental arm in 16 subjects before and after maximal voluntary contraction (MVC). Prior to a 1-min. MVC, the mean force exerted by the experimental arm was 3.4 ± 1.0 kg when attempting to match the tension of a 2.3-kg weight in the control arm. After the MVC, the mean force exerted in the experimental arm was 4.4 ± 2.6 kg. The change in perception of force after a prolonged MVC as demonstrated in this study may be due to postcontraction potentiation of contraction, which has been demonstrated by others after a brief MVC.

Effects of Concentric and Eccentric Strength Training on Fatigue Induced by Concentric and Eccentric Exercises

2019 ◽  
Vol 14 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Eduardo Lusa Cadore ◽  
Miriam González-Izal ◽  
Rafael Grazioli ◽  
Igor Setuain ◽  
Ronei Silveira Pinto ◽  
...  
Keyword(s):  
Maximal Voluntary Contraction ◽  
Isometric Force ◽  
Vastus Lateralis ◽  
Voluntary Contraction ◽  
Eccentric Training ◽  
Echo Intensity ◽  
Rate Of Torque Development ◽  
Before And After ◽  
Torque Development ◽  
Similar Force

Purpose: To compare the concentric and eccentric training effects on fatigue induced by eccentric and concentric protocols. Methods: A total of 22 men and women (22 [3.6] y) were assigned to concentric (GCON, n = 11) or eccentric training (GECC, n = 11). The concentric (CON) and eccentric (ECC) protocols were composed of 4 sets of 20 knee-extension/flexion repetitions. Force losses were analyzed by comparing 10 repetitions’ mean torques during the protocols and by verifying the maximal voluntary contraction and rate of torque development before and after the protocols. Muscle damage was assessed using echo intensity of the vastus lateralis 48 h after the protocols. Training consisted of 6 wk of isokinetic exercise at 60°/s (concentric or eccentric) twice weekly. Results: Before training, both protocols resulted in dynamic and isometric force losses in GCON and GECC (P < .01), but the magnitude was greater after the CON protocol than after the ECC protocol (P < .001). After training, both GCON and GECC showed similar force decreases during the CON and ECC protocols (P < .01), and these changes were not different from the pretraining decreases. Regarding maximal voluntary contraction after training, GECC showed lower force decreases than GCON after ECC exercise (−13.7% vs −22.3%, respectively, P < .05), whereas GCON showed lower maximal voluntary contraction decreases after CON exercise compared with pretraining (−29.2%, P < .05). Losses in rate of torque development were similar after the protocols before and after the training regimens. No changes in echo intensity were observed after the protocols before and after training. Conclusion: Both interventions resulted in similar force decreases during fatigue protocols compared with those associated with pretraining.

Sternomastoid muscle twitch maximum relaxation rate: prolonged slowing with fatigue and post-tetanic acceleration

1991 ◽  
Vol 81 (5) ◽  
pp. 669-676 ◽  
Author(s):  
V. H. F. Mak ◽  
F. Chapman ◽  
C. James ◽  
S. G. Spiro
Keyword(s):  
Relaxation Rate ◽  
Maximal Voluntary Contraction ◽  
Time Course ◽  
Voluntary Contraction ◽  
Tetanic Stimulation ◽  
Sternomastoid Muscle ◽  
Twitch Contraction ◽  
Fresh State ◽  
Fatiguing Exercise ◽  
The Mean

1. The maximum rate of relaxation of stimulated twitches (twitch maximum relaxation rate) of the sternomastoid muscle was compared with its frequency-force curve (expressed as the ratio of force produced at a stimulation frequency of 20 Hz to that produced at 50 Hz, the 20:50 ratio) before and after fatiguing exercise of the sternomastoid muscle in 10 normal subjects. The mean (±) fresh state twitch maximum relaxation rate was 9.51 (± 0.64)% force loss/10 ms and the mean (± sem) 20:50 ratio was 73.4 (± 2.6)%. 2. The mean twitch maximum relaxation rate fell to 71.5 (± 2.2)% of the pre-fatigue value at 2 min after exercise, recovering to 73.1 (± 1.6)% by 5 min, 78.4 (± 2.34)% by 10 min and 80.6 (± 2.70)% by 60 min. The 20:50 ratio fell to 72.3 (± 3.56)% of pre-fatigue levels at 10 min after exercise and recovered to 78.8 (± 3.16)% by 60 min. There was no significant difference in the percentage falls between the two techniques. 3. Further studies were performed to determine the response of the twitch maximum relaxation rate to a prior brief tetanic stimulus or a brief maximal voluntary contraction of the muscle. Both tetanic stimulation and maximal voluntary contraction accelerated the twitch maximum relaxation rate to over 140% of the fresh state value. Both manoeuvres temporarily returned the slowed twitch maximum relaxation rate after fatiguing exercise back to the fresh state value. 4. The effect of fatiguing exercise on the time course of recovery of quadriceps twitch maximum relaxation rate was also studied in two subjects. The twitch maximum relaxation rate had not recovered to fresh state levels by 5 min after exercise in both subjects. At 10 min, one subject had recovered to the fresh state value, but the other had recovered to only 85% of the fresh state value. Both recovered to fresh state values by 1 h. 5. We conclude that the twitch maximum relaxation rate of the sternomastoid as measured from a twitch contraction has a prolonged time course of recovery after fatiguing exercise, and may follow the same time course of recovery as low-frequency fatigue. Tetanic stimulation and voluntary contractions may temporarily accelerate the relaxation rate, and therefore a distinction should be made between relaxation rates measured after a twitch contraction (twitch maximum relaxation rate) and those after tetanic stimulation or a maximum voluntary contraction (maximum relaxation rate).

Difference in aftereffects following prolonged Achilles tendon vibration on muscle activity during maximal voluntary contraction among plantar flexor synergists

2005 ◽  
Vol 98 (4) ◽  
pp. 1427-1433 ◽  
Author(s):  
Junichi Ushiyama ◽  
Kei Masani ◽  
Motoki Kouzaki ◽  
Hiroaki Kanehisa ◽  
Tetsuo Fukunaga
Keyword(s):  
Achilles Tendon ◽  
Muscle Activity ◽  
Maximal Voluntary Contraction ◽  
Plantar Flexion ◽  
Voluntary Contraction ◽  
High Threshold ◽  
Plantar Flexor ◽  
Afferent Activity ◽  
Ia Afferent ◽  
Before And After

It has been suggested that a suppression of maximal voluntary contraction (MVC) induced by prolonged vibration is due to an attenuation of Ia afferent activity. The purpose of the present study was to test the hypothesis that aftereffects following prolonged vibration on muscle activity during MVC differ among plantar flexor synergists owing to a supposed difference in muscle fiber composition. The plantar flexion MVC torque and surface electromyogram (EMG) of the medial head of gastrocnemius (MG), the lateral head of gastrocnemius (LG), and the soleus (Sol) were recorded in 13 subjects before and after prolonged vibration applied to the Achilles tendon at 100 Hz for 30 min. The maximal H reflexes and M waves were also determined from the three muscles, and the ratio between H reflexes and M waves (H/Mmax) was calculated before and after the vibration. The MVC torque was decreased by 16.6 ± 3.7% after the vibration ( P < 0.05; ANOVA). The H/Mmax also decreased for all three muscles, indicating that Ia afferent activity was successfully attenuated by the vibration in all plantar flexors. However, a reduction of EMG during MVC was observed only in MG (12.7 ± 4.0%) and LG (11.4 ± 3.9%) ( P < 0.05; ANOVA), not in Sol (3.4 ± 3.0%). These results demonstrated that prolonged vibration-induced MVC suppression was attributable mainly to the reduction of muscle activity in MG and LG, both of which have a larger proportion of fast-twitch muscle fibers than Sol. This finding suggests that Ia-afferent activity that reinforces the recruitment of high-threshold motor units is necessary to enhance force exertion during MVC.

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