Acute passive stretching alters the mechanical properties of human plantar flexors and the optimal angle for maximal voluntary contraction

2004 ◽  
Vol 93 (5-6) ◽  
pp. 614-623 ◽  
Author(s):  
Derek E. Weir ◽  
Jill Tingley ◽  
Geoffrey C. B. Elder
Keyword(s):  
Mechanical Properties ◽  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Plantar Flexors ◽  
Optimal Angle ◽  
Passive Stretching

scholarly journals Exercise tolerance during muscle contractions below and above the critical torque in different muscle groups

2018 ◽  
Vol 43 (2) ◽  
pp. 174-179 ◽  
Author(s):  
Leonardo Henrique Perinotto Abdalla ◽  
Benedito Sérgio Denadai ◽  
Natália Menezes Bassan ◽  
Camila Coelho Greco
Keyword(s):  
Exercise Intensity ◽  
Maximal Voluntary Contraction ◽  
Exercise Tolerance ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Isometric Contractions ◽  
Plantar Flexors ◽  
Significant Difference ◽  
Muscle Groups

The objective of this study was to test the hypotheses that end-test torque (ET) (expressed as % maximal voluntary contraction; MVC) is higher for plantar flexors (PF) than knee extensors (KE) muscles, whereas impulse above ET (IET) is higher for KE than PF. Thus, we expected that exercise tolerance would be longer for KE than PF only during the exercise performed above ET. After the determination of MVC, 40 men performed two 5-min all-out tests to determine ET and IET. Eleven participants performed a further 4 intermittent isometric tests, to exhaustion, at ET + 5% and ET – 5%, and 1 test for KE at the exercise intensity (%MVC) corresponding to ET + 5% of PF. The IET (7243.2 ± 1942.9 vs. 3357.4 ± 1132.3 N·m·s) and ET (84.4 ± 24.8 vs. 73.9 ± 19.5 N·m) were significantly lower in PF compared with KE. The exercise tolerance was significantly longer for PF (300.7 ± 156.7 s) than KE (156.7 ± 104.3 s) at similar %MVC (∼60%), and significantly shorter for PF (300.7 ± 156.7 s) than KE (697.0 ± 243.7 s) at ET + 5% condition. However, no significant difference was observed for ET – 5% condition (KE = 1030.2 ± 495.4 s vs. PF = 1028.3 ± 514.4 s). Thus, the limit of tolerance during submaximal isometric contractions is influenced by absolute MVC only during exercise performed above ET, which seems to be explained by differences on both ET (expressed as %MVC) and IET values.

Factors Affecting Force Loss With Prolonged Stretching

2001 ◽  
Vol 26 (3) ◽  
pp. 262-272 ◽  
Author(s):  
David G. Behm ◽  
Duane C. Button ◽  
Jeremy C. Butt
Keyword(s):  
Maximal Voluntary Contraction ◽  
Muscle Activation ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Control Group ◽  
Tetanic Force ◽  
Factors Affecting ◽  
Passive Stretching ◽  
Interpolated Twitch Technique ◽  
Muscle Compliance

The purpose of this study was to investigate factors underlying the force loss occurring after prolonged, static, passive stretching. Subjects were tested before and 5-10 min following 20 min of static, passive stretching of the quadriceps (N = 12) or a similar period of no stretch (control, N = 6). Measurements included isometric maximal voluntary contraction (MVC) force, surface integrated electromyographic (iEMG) activity of the quadriceps and hamstrings, evoked contractile properties (twitch and tetanic force), and quadriceps inactivation as measured by the interpolated twitch technique (ITT). Following stretching, there was a significant 12% decrement in MVC with no significant changes in the control group. Muscle inactivation as measured by the ITT and iEMG increased by 2.8% and 20.2%, respectively. While twitch forces significantly decreased 11.7%, there was no change in tetanic force post-stretch. Although possible increases in muscle compliance affected twitch force, a lack of tetanic force change would suggest that post-stretch force decrements are more affected by muscle inactivation than changes in muscle elasticity. Key Words: antagonist, electromyography, maximum voluntary contraction, muscle activation, twitch, tetanus

Wide-pulse-width, high-frequency neuromuscular stimulation: implications for functional electrical stimulation

2006 ◽  
Vol 101 (1) ◽  
pp. 228-240 ◽  
Author(s):  
Evan R. L. Baldwin ◽  
Piotr M. Klakowicz ◽  
David F. Collins
Keyword(s):  
Electrical Stimulation ◽  
Nerve Stimulation ◽  
Maximal Voluntary Contraction ◽  
Neuromuscular Electrical Stimulation ◽  
Initial Step ◽  
Voluntary Contraction ◽  
Triceps Surae ◽  
Muscle Stimulation ◽  
Plantar Flexors ◽  
Wrist Flexors

Electrical stimulation (1-ms pulses, 100 Hz) produces more torque than expected from motor axon activation (extra contractions). This experiment investigates the most effective method of delivering this stimulation for neuromuscular electrical stimulation. Surface stimulation (1-ms pulses; 20 Hz for 2 s, 100 Hz for 2 s, 20 Hz for 3 s) was delivered to triceps surae and wrist flexors (muscle stimulation) and to median and tibial nerves (nerve stimulation) at two intensities. Contractions were evaluated for amplitude, consistency, and stability. Surface electromyograph was collected to assess how H-reflexes and M-waves contribute. In the triceps surae, muscle stimulation produced the largest absolute contractions (23% maximal voluntary contraction), evoked the largest extra contractions as torque increased by 412% after the 100-Hz stimulation, and was more consistent and stable compared with tibial nerve stimulation. Absolute and extra contraction amplitude, consistency, and stability of evoked wrist flexor torques were similar between stimulation types: torques reached 11% maximal voluntary contraction, and extra contractions increased torque by 161%. Extra contractions were 10 times larger in plantar flexors compared with wrist flexors with muscle stimulation but were similar with nerve stimulation. For triceps surae, H reflexes were 3.4 times larger than M waves during nerve stimulation, yet M waves were 15 times larger than H reflexes during muscle stimulation. M waves in the wrist flexors were larger than H reflexes during nerve (8.5 times) and muscle (18.5 times) stimulation. This is an initial step toward utilizing extra contractions for neuromuscular electrical stimulation and the first to demonstrate their presence in the wrist flexors.

Failed Excitability of Spinal Motoneurons Induced by Prolonged Running Exercise

2007 ◽  
Vol 97 (1) ◽  
pp. 596-603 ◽  
Author(s):  
S. Racinais ◽  
O. Girard ◽  
J. P. Micallef ◽  
S. Perrey
Keyword(s):  
Maximal Voluntary Contraction ◽  
Ventilatory Threshold ◽  
Central Fatigue ◽  
Voluntary Contraction ◽  
H Reflex ◽  
Spinal Motoneurons ◽  
Plantar Flexors ◽  
M Wave ◽  
V Wave ◽  
First Time

The main purpose of this study was to investigate the modulations in H-reflex and V-wave responses (spinal loop properties) induced by prolonged locomotion activities. The second purpose was to compare the development of central fatigue between continuous and intermittent running modes. Eleven males randomly performed two 90-min running exercises either continuously (CONT, first ventilatory threshold) or intermittently (INT, 150 s at a velocity 20% higher than that during CONT/30 s of recovery). Neuromuscular tests of the plantar flexors [including M-wave and H-reflex at rest and M-wave and V-wave during maximal voluntary contraction (MVC)] were performed before and 5 and 30 min after the running exercises. During MVC, the torque significantly decreased ( P < 0.05) from preexercise to 5 and 30 min postexercise (−11 and −9%, respectively), as did the RMS/M ratio (−11 and −13%, respectively) and the V/M ratio (−19 and −37%, respectively) for the soleus muscle. At rest, the H/M ratio also decreased significantly ( P < 0.001) from preexercise to 5 and 30 min postexercise (−61 and −55%, respectively). Last, no difference in the alteration of spinal loop properties was noted between CONT and INT. In conclusion, the results regarding H-reflex and V-wave suggest for the first time a modulation in spinal loop properties after prolonged running.

scholarly journals Mechanical Responses of the Human Triceps Surae after Passive "Stretching" Training of the Plantarflexors in Conditions Modulating Weightlessness

2010 ◽  
Vol 24 (1) ◽  
pp. 19-34 ◽  
Author(s):  
Yuri Koryak
Keyword(s):  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Triceps Surae ◽  
Time To Peak ◽  
Passive Stretching ◽  
Muscle Stretching ◽  
Human Triceps Surae ◽  
Isometric Twitch ◽  
Passive Muscle ◽  
Tetanic Tension

Mechanical Responses of the Human Triceps Surae after Passive "Stretching" Training of the Plantarflexors in Conditions Modulating WeightlessnessThe effect of a 60-day 6° head-down tilt of bed rest with and without prolonged passive muscle "stretching" training on the mechanical properties of the human triceps surae muscle was studied in 13 healthy male subjects. One group (n = 6; mean age 30.8 ± 3.1 years) underwent a 60-day head-down tilt, and a second group (n = 7; mean age 30.4 ± 1.2 years) underwent head-down tilt with prolonged passive muscle stretching. Head-down tilt without prolonged passive muscle "stretching" training showed maximal voluntary contraction declined by 34 % (p < 0.05) and the electrically evoked tetanic tension at 150 impulses·s-1and isometric twitch contraction reduced by 17 % (p < 0.02) and 18 % (p < 0.05), respectively. Time-to-peak tension, and half-relaxation time of the twitch slightly decreased by 3% (p > 0.05), and 7 %, respectively, but total contraction time slightly increased. The difference between electrically evoked tetanic tension and the maximal voluntary contraction expressed as a percentage of electrically evoked tetanic tension (referred to as force deficiency), has also been calculated. The force deficiency increased by 61 % (p < 0.001). After head-down tilt with prolonged passive muscle "stretching" training, the time-to-peak tension did not change, and half-relaxation time of the twitch decreased. In addition, there was a 14 % lengthening in the total duration of the twitch. The results of prolonged passive muscle "stretching" training demonstrated a clear deterioration of voluntarily and electrically induced muscle contractions. Passive "stretching" training caused a decrease by 29 % (p < 0.05) in the maximal voluntary contraction. The isometric twitch contraction, and electrically evoked tetanic tension both showed reductions by 17 %, and by 19 % (p < 0.05), respectively. The force deficiency decreased significantly by 21 % (p < 0.02). The rate of rise of electrically evoked tetanic tension and feature of voluntary contractions significantly reduced during head-down tilt with prolonged passive muscle "stretching" training. These basic experimental findings concluded that prolonged passive "stretching" training of a single muscle did not prevent a reserve of neuromuscular function.

scholarly journals Corticospinal excitability of the biceps brachii is shoulder position dependent

2017 ◽  
Vol 118 (6) ◽  
pp. 3242-3251 ◽  
Author(s):  
Brandon Wayne Collins ◽  
Edward W. J. Cadigan ◽  
Lucas Stefanelli ◽  
Duane C. Button
Keyword(s):  
Evoked Potentials ◽  
Maximal Voluntary Contraction ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Voluntary Contraction ◽  
Corticospinal Excitability ◽  
State Dependent ◽  
Shoulder Flexion ◽  
Erb’S Point ◽  
Shoulder Position

The purpose of this study was to examine the effect of shoulder position on corticospinal excitability (CSE) of the biceps brachii during rest and a 10% maximal voluntary contraction (MVC). Participants ( n = 9) completed two experimental sessions with four conditions: 1) rest, 0° shoulder flexion; 2) 10% MVC, 0° shoulder flexion; 3) rest, 90° shoulder flexion; and 4) 10% MVC, 90° shoulder flexion. Transcranial magnetic, transmastoid electrical, and Erb’s point stimulation were used to induce motor-evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), and maximal muscle compound potentials (Mmax), respectively, in the biceps brachii in each condition. At rest, MEP, CMEP, and Mmax amplitudes increased ( P < 0.01) by 509.7 ± 118.3%, 113.3 ± 28.3%, and 155.1 ± 47.9%, respectively, at 90° compared with 0°. At 10% MVC, MEP amplitudes did not differ ( P = 0.08), but CMEP and Mmax amplitudes increased ( P < 0.05) by 32.3 ± 10.5% and 127.9 ± 26.1%, respectively, at 90° compared with 0°. MEP/Mmax increased ( P < 0.01) by 224.0 ± 99.1% at rest and decreased ( P < 0.05) by 51.3 ± 6.7% at 10% MVC at 90° compared with 0°. CMEP/Mmax was not different ( P = 0.22) at rest but decreased ( P < 0.01) at 10% MVC by 33.6 ± 6.1% at 90° compared with 0°. EMG increased ( P < 0.001) by 8.3 ± 2.0% at rest and decreased ( P < 0.001) by 21.4 ± 4.4% at 10% MVC at 90° compared with 0°. In conclusion, CSE of the biceps brachii was dependent on shoulder position, and the pattern of change was altered within the state in which it was measured. The position-dependent changes in Mmax amplitude, EMG, and CSE itself all contribute to the overall change in CSE of the biceps brachii. NEW & NOTEWORTHY We demonstrate that when the shoulder is placed into two common positions for determining elbow flexor force and activation, corticospinal excitability (CSE) of the biceps brachii is both shoulder position and state dependent. At rest, when the shoulder is flexed from 0° to 90°, supraspinal factors predominantly alter CSE, whereas during a slight contraction, spinal factors predominantly alter CSE. Finally, the normalization techniques frequently used by researchers to investigate CSE may under- and overestimate CSE when shoulder position is changed.

Nonuniform strain of human soleus aponeurosis-tendon complex during submaximal voluntary contractions in vivo

2003 ◽  
Vol 95 (2) ◽  
pp. 829-837 ◽  
Author(s):  
Taija Finni ◽  
John A. Hodgson ◽  
Alex M. Lai ◽  
V. Reggie Edgerton ◽  
Shantanu Sinha
Keyword(s):  
Achilles Tendon ◽  
Maximal Voluntary Contraction ◽  
Three Dimensional ◽  
Motor Units ◽  
Magnetic Resonance Images ◽  
Voluntary Contraction ◽  
Force Transmission ◽  
Voluntary Contractions ◽  
Nonuniform Strain

The distribution of strain along the soleus aponeurosis tendon was examined during voluntary contractions in vivo. Eight subjects performed cyclic isometric contractions (20 and 40% of maximal voluntary contraction). Displacement and strain in the apparent Achilles tendon and in the aponeurosis were calculated from cine phase-contrast magnetic resonance images acquired with a field of view of 32 cm. The apparent Achilles tendon lengthened 2.8 and 4.7% in 20 and 40% maximal voluntary contraction, respectively. The midregion of the aponeurosis, below the gastrocnemius insertion, lengthened 1.2 and 2.2%, but the distal aponeurosis shortened 2.1 and 2.5%, respectively. There was considerable variation in the three-dimensional anatomy of the aponeurosis and muscle-tendon junction. We suggest that the nonuniformity in aponeurosis strain within an individual was due to the presence of active and passive motor units along the length of the muscle, causing variable force along the measurement site. Force transmission along intrasoleus connective tissue may also be a significant source of nonuniform strain in the aponeurosis.

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