Rate of fatigue during repeated submaximal contractions of human quadriceps muscle

1991 ◽  
Vol 69 (10) ◽  
pp. 1410-1415 ◽  
Author(s):  
T. Dolmage ◽  
E. Cafarelli
Keyword(s):  
Vastus Lateralis ◽  
Close Relation ◽  
Quadriceps Muscle ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Vastus Lateralis Muscle ◽  
Relaxation Rates ◽  
Twitch Characteristics ◽  
Rate Of Decline ◽  
Force Time

Our purpose was to determine the effect of eight different combinations of contraction intensity, duration, and rest on the rate of fatigue in vastus lateralis muscle. A single combination consisted of contractions at 30 or 70% maximal voluntary contraction (MVC), held for 3 or 7 s with 3- or 7-s rest intervals. Contractions were repeated until the subject could not hold the force for the requisite duration. At regular intervals during each experiment, a brief MVC, a single twitch, and the response to eight stimulation pulses at 50 Hz were elicited. The rate of fatigue was the rate of decline of MVC calculated from regression analysis. Mean rate of fatigue (n = 8) ranged from 0.3 to 25% MVC/min and was closely related (r = 0.98) to the product of the relative force and the duty cycle. Force from 50 Hz stimulation fell linearly and in parallel with MVC. Twitch force was first potentiated and then fell twice as fast as 50 Hz stimulation and MVC (p < 0.05). Differentiated twitch contraction and relaxation rates were higher at potentiation and lower at the limit of endurance, compared with control values (p < 0.05). The maximal electromyogram decreased 25% and the submaximal EMG increased to maximal by the end of the protocol, indicating that the entire motor unit pool had been recruited. The close relation between rate of fatigue and the force × time product probably reflects the off-setting interaction of contraction amplitude, duration, and rest interval. This occurs despite the changes in twitch characteristics and the apparent recruitment of fast fatiguing motor units.Key words: fatigue, surface EMG, limit of endurance, force × time product, twitch interpolation.

scholarly journals Neuromuscular fatigue during a long-duration cycling exercise

2002 ◽  
Vol 92 (4) ◽  
pp. 1487-1493 ◽  
Author(s):  
Romuald Lepers ◽  
Nicola A. Maffiuletti ◽  
Ludovic Rochette ◽  
Julien Brugniaux ◽  
Guillaume Y. Millet
Keyword(s):  
Time Course ◽  
Muscle Activation ◽  
Mechanical Response ◽  
Vastus Lateralis ◽  
Quadriceps Muscle ◽  
Voluntary Contraction ◽  
Vastus Lateralis Muscle ◽  
Electromyographic Activity ◽  
Cycling Exercise ◽  
M Wave

The effects of prolonged cycling on neuromuscular parameters were studied in nine endurance-trained subjects during a 5-h exercise sustained at 55% of the maximal aerobic power. Torque during maximal voluntary contraction (MVC) of the quadriceps muscle decreased progressively throughout the exercise ( P < 0.01) and was 18% less at the end of exercise compared with the preexercise value. Peak twitch torque, contraction time, and total area of mechanical response decreased significantly ( P < 0.05) after the first hour of exercise. In contrast, changes in M-wave characteristics were significant only after the fourth hour of the exercise. Significant reductions ( P < 0.05) in electromyographic activity normalized to the M wave occurred after the first hour for the vastus lateralis muscle but only at the end of the exercise for the vastus medialis muscle. Muscle activation level, assessed by the twitch interpolation technique, decreased by 8% ( P < 0.05) at the end of the exercise. The results suggest that the time course is such that the contractile properties are significantly altered after the first hour, whereas excitability and central drive are more impaired toward the latter stages of the 5-h cycling exercise.

Intent-Related Differences in Surface EMG of Maximum Eccentric and Concentric Contractions

2003 ◽  
Vol 19 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Mark D. Grabiner ◽  
Tammy M. Owings
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Eccentric Contraction ◽  
Surface Emg ◽  
Vastus Lateralis Muscle ◽  
Concentric Contractions ◽  
Concentric Contraction ◽  
Contraction Condition ◽  
The Difference

For this study it was hypothesized that when participants intended to perform a maximum voluntary concentric (or eccentric) contraction but had an eccentric (or concentric) contraction imposed upon them, the initial EMG measured during the isometric phase preceding the onset of the dynamometer motion would reflect the intended contraction condition. The surface EMG of the vastus lateralis muscle was measured in 24 participants performing isokinetic concentric and eccentric maximum voluntary knee extensor contractions. The contractions were initiated from rest and from the same knee flexion angle and required the same level of external force to trigger the onset of dynamometer motion. Vastus lateralis EMG were quantified during the isometric phase preceding the onset of the dynamometer motion. When participants intended to perform a concentric contraction but had an eccentric contraction imposed upon them, the initial EMG resembled that of a concentric contraction. When they intended to perform an eccentric contraction but had a concentric contraction imposed upon them, the initial EMG resembled that of an eccentric contraction. Overall, the difference between concentric and eccentric contractions observed during the period of theinitialmuscle activation implies that descending signals include information that distinguishes between eccentric and concentric contractions.

Alternate muscle activity observed between knee extensor synergists during low-level sustained contractions

2002 ◽  
Vol 93 (2) ◽  
pp. 675-684 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara ◽  
Kei Masani ◽  
Hiroaki Kanehisa ◽  
Tetsuo Fukunaga
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Force Production ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Low Level ◽  
Integrated Emg

To determine quantitatively the features of alternate muscle activity between knee extensor synergists during low-level prolonged contraction, a surface electromyogram (EMG) was recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) in 11 subjects during isometric knee extension exercise at 2.5% of maximal voluntary contraction (MVC) for 60 min ( experiment 1). Furthermore, to examine the relation between alternate muscle activity and contraction levels, six of the subjects also performed sustained knee extension at 5.0, 7.5, and 10.0% of MVC ( experiment 2). Alternate muscle activity among the three muscles was assessed by quantitative analysis on the basis of the rate of integrated EMG sequences. In experiment 1, the number of alternations was significantly higher between RF and either VL or VM than between VL and VM. Moreover, the frequency of alternate muscle activity increased with time. In experiment 2, alternating muscle activity was found during contractions at 2.5 and 5.0% of MVC, although not at 7.5 and 10.0% of MVC, and the number of alternations was higher at 2.5 than at 5.0% of MVC. Thus the findings of the present study demonstrated that alternate muscle activity in the quadriceps muscle 1) appears only between biarticular RF muscle and monoarticular vasti muscles (VL and VM), and its frequency of alternations progressively increases with time, and 2) emerges under sustained contraction with force production levels ≤5.0% of MVC.

scholarly journals Damaging eccentric exercise attenuates disuse induced declines in daily myofibrillar protein synthesis and transiently prevents muscle atrophy in healthy men.

2021 ◽  
Author(s):  
Tom S. O. Jameson ◽  
Sean P Kilroe ◽  
Jonathan Fulford ◽  
Doaa Reda Abdelrahman ◽  
Andrew John Murton ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Eccentric Exercise ◽  
Vastus Lateralis ◽  
Quadriceps Muscle ◽  
Quadriceps Strength ◽  
Myofibrillar Protein ◽  
Muscle Volume ◽  
Vastus Lateralis Muscle ◽  
Deuterated Water ◽  
Myofibrillar Protein Synthesis

Introduction: Short-term disuse leads to muscle loss driven by lowered daily myofibrillar protein synthesis (MyoPS). However, disuse commonly results from muscle damage, and its influence on muscle deconditioning during disuse is unknown. Methods: 21 males (20±1 y, BMI=24±1 kg·m-2 (±SEM)) underwent 7 days of unilateral leg immobilization immediately preceded by 300 bilateral, maximal, muscle-damaging eccentric quadriceps contractions (DAM; n=10) or no exercise (CON; n=11). Participants ingested deuterated water and underwent temporal bilateral thigh MRI scans and vastus lateralis muscle biopsies of immobilized (IMM) and non-immobilized (N-IMM) legs. Results: N-IMM quadriceps muscle volume remained unchanged throughout in both groups. IMM quadriceps muscle volume declined after 2 days by 1.7±0.5% in CON (P=0.031; and by 1.3±0.6% when corrected to N-IMM; P=0.06) but did not change in DAM, and declined equivalently in CON (by 6.4±1.1% [5.0±1.6% when corrected to N-IMM]) and DAM (by 2.6±1.8% [4.0±1.9% when corrected to N-IMM]) after 7 days. Immobilization began to decrease MyoPS compared with N-IMM in both groups after 2 days (P=0.109), albeit with higher MyoPS rates in DAM compared with CON (P=0.035). Frank suppression of MyoPS was observed between days 2-7 in CON (IMM=1.04±0.12, N-IMM=1.86±0.10%·d-1; P=0.002) but not DAM (IMM=1.49±0.29, N-IMM=1.90±0.30%·d-1; P>0.05). Declines in MyoPS and quadriceps volume after 7 days correlated positively in CON (R2=0.403; P=0.035) but negatively in DAM (R2=0.483; P=0.037). Quadriceps strength declined following immobilization in both groups, but to a greater extent in DAM. Conclusion: Prior muscle damaging eccentric exercise increases MyoPS and prevents loss of quadriceps muscle volume after 2 (but not 7) days of disuse.

Motor Unit Interpulse Intervals During High Force Contractions

Motor Control ◽  
2016 ◽  
Vol 20 (1) ◽  
pp. 70-86 ◽  
Author(s):  
Matt S. Stock ◽  
Brennan J. Thompson
Keyword(s):  
Motor Unit ◽  
Polynomial Regression ◽  
Vastus Lateralis ◽  
Motor Units ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Emg Signal ◽  
Coefficients Of Variation ◽  
Low Threshold ◽  
The Relationship

We examined the means, medians, and variability for motor-unit interpulse intervals (IPIs) during voluntary, high force contractions. Eight men (mean age = 22 years) attempted to perform isometric contractions at 90% of their maximal voluntary contraction force while bipolar surface electromyographic (EMG) signals were detected from the vastus lateralis and vastus medialis muscles. Surface EMG signal decomposition was used to determine the recruitment thresholds and IPIs of motor units that demonstrated accuracy levels ≥ 96.0%. Motor units with high recruitment thresholds demonstrated longer mean IPIs, but the coefficients of variation were similar across all recruitment thresholds. Polynomial regression analyses indicated that for both muscles, the relationship between the means and standard deviations of the IPIs was linear. The majority of IPI histograms were positively skewed. Although low-threshold motor units were associated with shorter IPIs, the variability among motor units with differing recruitment thresholds was comparable.

Human neuromuscular fatigue is associated with altered Na+-K+-ATPase activity following isometric exercise

2002 ◽  
Vol 92 (4) ◽  
pp. 1585-1593 ◽  
Author(s):  
J. R. Fowles ◽  
H. J. Green ◽  
R. Tupling ◽  
S. O'Brien ◽  
B. D. Roy
Keyword(s):  
Atpase Activity ◽  
Maximal Voluntary Contraction ◽  
Vastus Lateralis ◽  
Isometric Exercise ◽  
Voluntary Contraction ◽  
Neuromuscular Fatigue ◽  
Vastus Lateralis Muscle ◽  
M Wave ◽  
Leg Extension ◽  
Muscle Action Potential

The purpose of this study was to investigate the hypothesis that reductions in Na+-K+- ATPase activity are associated with neuromuscular fatigue following isometric exercise. In control (Con) and exercised (Ex) legs, force and electromyogram were measured in 14 volunteers [age, 23.4 ± 0.7 (SE) yr] before and immediately after (PST0), 1 h after (PST1), and 4 h after (PST4) isometric, single-leg extension exercise at ∼60% of maximal voluntary contraction for 30 min using a 0.5 duty cycle (5-s contraction, 5-s rest). Tissue was obtained from vastus lateralis muscle before exercise in Con and after exercise in both the Con (PST0) and Ex legs (PST0, PST1, PST4), for the measurements of Na+-K+-ATPase activity, as determined by the 3- O-methylfluorescein phosphatase (3- O-MFPase) assay. Voluntary (maximal voluntary contraction) and elicited (10, 20, 50, 100 Hz) force was reduced 30–55% ( P < 0.05) at PST0 and did not recover by PST4. Muscle action potential (M-wave) amplitude and area (measured in the vastus medialis) and 3- O-MFPase activity at PST0-Ex were less than that at PST0-Con ( P < 0.05) by 37, 25, and 38%, respectively. M-wave area at PST1-Ex was also less than that at PST1-Con ( P < 0.05). Changes in 3- O-MFPase activity correlated to changes in M-wave area across all time points ( r = 0.38, P < 0.05, n= 45). These results demonstrate that Na+-K+- ATPase activity is reduced by sustained isometric exercise in humans from that in a matched Con leg and that this reduction in Na+-K+-ATPase activity is associated with loss of excitability as indicated by M-wave alterations.

Behavior of coactive muscles during fatigue

1993 ◽  
Vol 74 (1) ◽  
pp. 170-175 ◽  
Author(s):  
J. A. Psek ◽  
E. Cafarelli
Keyword(s):  
Time Course ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Close Correlation ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Emg Activity ◽  
Short Period ◽  
Force Time ◽  
Knee Flexors

Coactivation is antagonist muscle activity that occurs during voluntary contraction. Recently, we showed that the extent of coactivity in the knee flexors decreases after a short period of resistance training of the knee extensors (8). The purpose of the present experiment was to study the time course of coactivation in the knee flexors during fatigue of the knee extensors. Ten male subjects performed repeated submaximal static leg extensions in a low-intensity long-duration and a high-intensity short-duration fatigue protocol until they could no longer produce the required force [time limit of endurance (Tlim)]. Maximal voluntary contraction (MVC), submaximal force, and surface electromyographic (EMG) activity were measured periodically. Vastus lateralis EMG increased progressively during fatigue of the extensor muscles (P < 0.05), resulting in a 38% change from control at Tlim. Biceps femoris EMG, which was our measure of coactivation, also increased by approximately 60% at Tlim in each protocol (P < 0.05). These observations lead us to conclude that a small but significant force loss during repeated static contractions to Tlim is due to an increase in antagonist activity. Moreover, the close correlation between the antagonist and agonist EMG supports the notion of a "common drive" to both motoneuron pools (10).

Mechanical load increases muscle IGF-I and androgen receptor mRNA concentrations in humans

2001 ◽  
Vol 280 (3) ◽  
pp. E383-E390 ◽  
Author(s):  
Marcas M. Bamman ◽  
James R. Shipp ◽  
Jie Jiang ◽  
Barbara A. Gower ◽  
Gary R. Hunter ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Mechanical Load ◽  
Vastus Lateralis ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Creatine Kinase Activity ◽  
Total Testosterone ◽  
Vastus Lateralis Muscle ◽  
Mrna Concentration ◽  
Igf I

The mechanism(s) of load-induced muscle hypertrophy is as yet unclear, but increasing evidence suggests a role for locally expressed insulin-like growth factor I (IGF-I). We investigated the effects of concentric (CON) vs. eccentric (ECC) loading on muscle IGF-I mRNA concentration. We hypothesized a greater IGF-I response after ECC compared with CON. Ten healthy subjects (24.4 ± 0.7 yr, 174.5 ± 2.6 cm, 70.9 ± 4.3 kg) completed eight sets of eight CON or ECC squats separated by 6–10 days. IGF-I, IGF binding protein-4 (IGFBP-4), and androgen receptor (AR) mRNA concentrations were determined in vastus lateralis muscle by RT-PCR before and 48 h after ECC and CON. Serum total testosterone (TT) and IGF-I were measured serially across 48 h, and serum creatine kinase activity (CK), isometric maximum voluntary contraction (MVC), and soreness were determined at 48 h. IGF-I mRNA concentration increased 62% and IGFBP-4 mRNA concentration decreased 57% after ECC ( P < 0.05). Changes after CON were similar but not significant ( P = 0.06–0.12). AR mRNA concentration increased ( P < 0.05) after ECC (63%) and CON (102%). Serum TT and IGF-I showed little change. MVC fell 10% and CK rose 183% after ECC ( P < 0.05). Perceived soreness was higher ( P < 0.01) after ECC compared with CON. Results indicate that a single bout of mechanical loading in humans alters activity of the muscle IGF-I system, and the enhanced response to ECC suggests that IGF-I may somehow modulate tissue regeneration after mechanical damage.

Determining the Force-Length-Velocity Relations of the Quadriceps Muscles: I. Anatomical and Geometric Parameters

1999 ◽  
Vol 15 (2) ◽  
pp. 182-190 ◽  
Author(s):  
John W. Chow ◽  
Warren G. Darling ◽  
James C. Ehrhardt
Keyword(s):  
Magnetic Resonance ◽  
Knee Flexion ◽  
Vastus Lateralis ◽  
Quadriceps Muscle ◽  
Vastus Lateralis Muscle ◽  
Moment Arm ◽  
Anatomical Position ◽  
Moment Arms ◽  
Effective Moment

The purpose of this study was to determine the coordinates of the origin and insertion, muscle volumes, lengths, lines of action, and effective moment arm of the quadriceps muscles in vivo using magnetic resonance imaging (MRI) and radiography for a pilot study involving musculoskeletal modeling. Two magnetic resonance scans were performed, and axial images were obtained for the left thigh of a female subject in the anatomical position to measure muscle volume, coordinates of the origin and insertion, and muscle belly length at the anatomical position of each quadriceps muscle. Six knee radiographs were used to determine the effective moment arm of the quadriceps force at different knee flexion angles. A combination of MRI and radiography data was used to compute the muscle lengths at different knee flexion angles. The coordinates of the vastus lateralis, muscle volumes of individual quadriceps muscles, and effective moment arms were clearly different from the corresponding values from cadaver data reported in the literature. These comparisons demonstrate the advantages of using personalized muscle parameters instead of those collected from cadavers and dry-bone specimens.

Medial and Lateral Quadriceps Muscle Activity during Weight-Bearing Knee Extension Exercise

1998 ◽  
Vol 7 (4) ◽  
pp. 248-257 ◽  
Author(s):  
Gilbert M. Willett ◽  
Jason B. Paladino ◽  
Kory M. Barr ◽  
Jill N. Korta ◽  
Gregory M. Karst
Keyword(s):  
Vastus Lateralis ◽  
Weight Bearing ◽  
Quadriceps Muscle ◽  
Surface Emg ◽  
Knee Extension ◽  
Emg Activity ◽  
Exercise Condition ◽  
Elastic Resistance ◽  
Activity Performance ◽  
History Of

The purpose of this study was to determine the effect of weight-bearing terminal knee extension (WBKE) on normalized mean electromyographic (EMG) activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) and the VMO/VL ratio. Sixteen subjects with no history of knee dysfunction participated. Surface EMG data were recorded from the VMO and VL of subjects' test legs as they performed the WBKE exercise under four conditions, three involving elastic resistance and one involving no elastic resistance. EMG data were normalized relative to a maximal isometric quadriceps contraction, and overall mean VMO and VL activity and the VMO/VL ratio were determined for all conditions. The three conditions utilizing elastic resistance showed higher mean VMO and VL activity than the no-resistance condition. The VMO/ VL ratio was not significantly altered during any exercise condition as compared to maximal, quadriceps setting exercise. WBKE against elastic resistance was superior to the same exercise without resistance for generating mean VMO and VL activity. Performance of the WBKE, regardless of the position of lower extremity rotation, does not selectively activate the VMO apart from, or to a greater degree than, the VL.

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