Fatigue and muscle–tendon stiffness after stretch–shortening cycle and isometric exercise

2006 ◽  
Vol 31 (5) ◽  
pp. 565-572 ◽  
Author(s):  
Hechmi Toumi ◽  
Georges Poumarat ◽  
Thomas M. Best ◽  
Alain Martin ◽  
John Fairclough ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Isometric Exercise ◽  
Isometric Contractions ◽  
Jump Performance ◽  
Tendon Stiffness ◽  
Before And After ◽  
Drop Jumps ◽  
Stretch Shortening Cycle ◽  
Knee Muscle

The purpose of the present study was to compare vertical jump performance after 2 different fatigue protocols. In the first protocol, subjects performed consecutive sets of 10 repetitions of stretch–shortening cycle (SSC) contractions. In the second protocol, successive sets of 10 repetitions of isometric contractions were performed for 10 s with the knee at 90° of flexion. The exercises were stopped when the subjects failed to reach 50% of their maximum voluntary isometric contractions. Maximal isometric force and maximal concentric power were assessed by performing supine leg presses, squat jumps, and drop jumps. Surface EMG was used to determine changes in muscle activation before and after fatigue. In both groups, the fatigue exercises reduced voluntary isometric force, maximal concentric power, and drop jump performance. Kinematic data showed a decrease in knee muscle–tendon stiffness accompanied by a lengthened ground contact time. EMG analysis showed that the squat and drop jumps were performed similarly before and after the fatigue exercise for both groups. Although it was expected that the stiffness would decrease more after SSC than after isometric fatigue (as a result of a greater alteration of the reflex sensitivity SSC), our results showed that both protocols had a similar effect on knee muscle stiffness during jumping exercises. Both fatigue protocols induced muscle fatigue, and the decrease in jump performance was linked to a decrease in the strength and stiffness of the knee extensor muscles.

Residual force depression following muscle shortening is exaggerated by prior eccentric drop jump exercise

2013 ◽  
Vol 115 (8) ◽  
pp. 1191-1195 ◽  
Author(s):  
Gintare Dargeviciute ◽  
Nerijus Masiulis ◽  
Sigitas Kamandulis ◽  
Albertas Skurvydas ◽  
Håkan Westerblad
Keyword(s):  
Isometric Force ◽  
Knee Extensor ◽  
Mechanical Work ◽  
Muscle Performance ◽  
Eccentric Contractions ◽  
Force Depression ◽  
Jump Exercise ◽  
Before And After ◽  
Drop Jumps ◽  
Residual Force

We studied the relation between two common force modifications in skeletal muscle: the prolonged force depression induced by unaccustomed eccentric contractions, and the residual force depression (rFD) observed immediately after active shortening. We hypothesized that rFD originates from distortion within the sarcomeres and the extent of rFD: 1) correlates to the force and work performed during the shortening steps, which depend on sarcomeric integrity; and 2) is increased by sarcomeric disorganization induced by eccentric contractions. Nine healthy untrained men (mean age 26 yr) participated in the study. rFD was studied in electrically stimulated knee extensor muscles. rFD was defined as the reduction in isometric torque after active shortening compared with the torque in a purely isometric contraction. Eccentric contractions were performed as 50 repeated drop jumps with active deceleration to 90° knee angle, immediately followed by a maximal upward jump. rFD was assessed before and 5 min to 72 h after drop jumps. The series of drop jumps caused a prolonged force depression, which was about two times larger at 20-Hz than at 50-Hz stimulation. There was a significant correlation between increasing rFD and increasing mechanical work performed during active shortening both before and after drop jumps. In addition, a given rFD was obtained at a markedly lower mechanical work after drop jumps. In conclusion, the extent of rFD correlates to the mechanical work performed during active shortening. A series of eccentric contractions causes a prolonged reduction of isometric force. In addition, eccentric contractions exaggerate rFD, which further decreases muscle performance during dynamic contractions.

scholarly journals Time to failure and neuromuscular response to intermittent isometric exercise at different levels of vascular occlusion: a randomized crossover study

2017 ◽  
Vol 6 (1) ◽  
pp. 55-70 ◽  
Author(s):  
Mikhail Santos Cerqueira ◽  
Rafael Pereira ◽  
Taciano Rocha ◽  
Gabriel Mesquita ◽  
Cláudia Regina Oliveira de Paiva Lima ◽  
...  
Keyword(s):  
Isometric Force ◽  
Isometric Exercise ◽  
Vascular Occlusion ◽  
Median Frequency ◽  
Time To Failure ◽  
Isometric Handgrip ◽  
Total Occlusion ◽  
Emg Signal ◽  
Before And After ◽  
Force Reduction

Objectives: The purpose this study was investigate the effects of different vascular occlusion levels (total occlusion (TO), partial occlusion (PO) or free flow (FF)) during intermittent isometric handgrip exercise (IIHE) on the time to failure (TF) and the recovery of the maximum voluntary isometric force (MVIF), median frequency (EMGFmed) and peak of EMG signal (EMGpeak) after failure.  Methods: Thirteen healthy men (21 ± 1.71 year) carried out an IIHE until the failure at 45% of MVIF with TO, PO or FF. Occlusion pressure was determined previously to the exercise. The MVIF, EMGFmed and EMGpeak were measured before and after exercise. Results: TF (in seconds) was significantly different (p < 0.05) among all investigated conditions: TO (150 ± 68), PO (390 ± 210) and FF (510 ± 240). The MVIF was lower immediately after IIHE, remaining lower eleven minutes after failure in all cases (p <0.05), when compared to pre exercise. There was a greater force reduction (p <0.05) one minute after the failure in the PO (-45.8%) and FF (-39.9%) conditions, when compared to TO (-28.1%). Only the PO condition caused lower MVIF (p <0.05) than in the OT, eleven minutes after the task failure. PO caused a greater reduction in EMGFmed compared TO and greater increase in EMGpeak, when compared to TO and FF (p <0.05). Conclusions: TO during IIHE lead to a lower time to failure, but a faster MVIF recovery, while the PO seems to be associated to a slower neuromuscular recovery, when compared to other conditions.

scholarly journals Relationship between force and stiffness in muscle fibers after stretch

2005 ◽  
Vol 99 (5) ◽  
pp. 1769-1775 ◽  
Author(s):  
Dilson E. Rassier ◽  
Walter Herzog
Keyword(s):  
Fiber Length ◽  
Muscle Activation ◽  
Isometric Force ◽  
Ringer Solution ◽  
Isometric Contractions ◽  
Force Enhancement ◽  
Weakly Bound ◽  
Length Relationship ◽  
Cross Bridges ◽  
The Relationship

The purpose of this study was to evaluate the relationship between force and stiffness after stretch of activated fibers, while simultaneously changing contractility by interfering with the cross-bridge kinetics and muscle activation. Single fibers dissected from lumbrical muscles of frogs were placed at a length 20% longer than the plateau of the force-length relationship, activated, and stretched by 5 and 10% of fiber length (speed: 40% fiber length/s). Experiments were conducted with maximal and submaximal stimulation in Ringer solution and with the addition of 2 and 5 mM of the myosin inhibitor 2,3-butanedione monoxime (BDM) to the solution. The steady-state force after stretch of an activated fiber was higher than the isometric force produced at the corresponding length in all conditions investigated. Lowering the frequency of stimulation decreased the force and stiffness during isometric contractions, but it did not change force enhancement and stiffness enhancement after stretch. Administration of BDM decreased the force and stiffness during isometric contractions, but it increased the force enhancement and stiffness enhancement after stretch. The relationship between force enhancement and stiffness suggests that the increase in force after stretch may be caused by an increase in the proportion of cross bridges attached to actin. Because BDM places cross bridges in a weakly bound, pre-powerstroke state, our results further suggest that force enhancement is partially associated with a recruitment of weakly bound cross bridges into a strongly bound state.

scholarly journals Residual Force Enhancement Is Present in Consecutive Post-Stretch Isometric Contractions of the Hamstrings during a Training Simulation

2021 ◽  
Vol 18 (3) ◽  
pp. 1154
Author(s):  
Neil D. Chapman ◽  
John W. Whitting ◽  
Suzanne Broadbent ◽  
Zachary J. Crowley-McHattan ◽  
Rudi Meir
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Training Stimulus ◽  
Knee Extension ◽  
Voluntary Activation ◽  
Isometric Contractions ◽  
Force Enhancement ◽  
Residual Force ◽  
Residual Force Enhancement ◽  
Training Simulation

Residual force enhancement (rFE) is observed when isometric force following an active stretch is elevated compared to an isometric contraction at corresponding muscle lengths. Acute rFE has been confirmed in vivo in upper and lower limb muscles. However, it is uncertain whether rFE persists using multiple, consecutive contractions as per a training simulation. Using the knee flexors, 10 recreationally active participants (seven males, three females; age 31.00 years ± 8.43 years) performed baseline isometric contractions at 150° knee flexion (180° representing terminal knee extension) of 50% maximal voluntary activation of semitendinosus. Participants performed post-stretch isometric (PS-ISO) contractions (three sets of 10 repetitions) starting at 90° knee extension with a joint rotation of 60° at 60°·s−1 at 50% maximal voluntary activation of semitendinosus. Baseline isometric torque and muscle activation were compared to PS-ISO torque and muscle activation across all 30 repetitions. Significant rFE was noted in all repetitions (37.8–77.74%), with no difference in torque between repetitions or sets. There was no difference in activation of semitendinosus or biceps femoris long-head between baseline and PS-ISO contractions in all repetitions (ST; baseline ISO = 0.095–1.000 ± 0.036–0.039 Mv, PS-ISO = 0.094–0.098 ± 0.033–0.038 and BFlh; baseline ISO = 0.068–0.075 ± 0.031–0.038 Mv). This is the first investigation to observe rFE during multiple, consecutive submaximal PS-ISO contractions. PS-ISO contractions have the potential to be used as a training stimulus.

Kinetics, kinematics, and knee muscle activation during sit to stand transition in unilateral and bilateral knee osteoarthritis

2021 ◽  
Vol 86 ◽  
pp. 38-44
Author(s):  
Marina Petrella ◽  
Luiz Fernando A. Selistre ◽  
Paula R.M.S. Serrão ◽  
Giovanna C. Lessi ◽  
Glaucia H. Gonçalves ◽  
...  
Keyword(s):  
Knee Osteoarthritis ◽  
Muscle Activation ◽  
Bilateral Knee ◽  
Sit To Stand ◽  
Knee Muscle

scholarly journals Effects of Short-Term Plyometric Training on Agility, Jump and Repeated Sprint Performance in Female Soccer Players

2021 ◽  
Vol 18 (5) ◽  
pp. 2274
Author(s):  
Marcin Maciejczyk ◽  
Renata Błyszczuk ◽  
Aleksander Drwal ◽  
Beata Nowak ◽  
Marek Strzała
Keyword(s):  
Physical Performance ◽  
Sprint Performance ◽  
Soccer Players ◽  
Plyometric Training ◽  
Countermovement Jump ◽  
Short Term ◽  
Jump Performance ◽  
Squat Jump ◽  
Repeated Sprint ◽  
Before And After

The aim of the study was to determine the effects of short-term (4 weeks, twice a week: 8 sessions) plyometric training on agility, jump, and repeated sprint performance in female soccer players. The study comprised 17 females performing this sports discipline. The players were randomly divided into two groups: with plyometric training (PLY) and the control (CON). All players followed the same training program, but the PLY group also performed plyometric exercises. Tests used to evaluate physical performance were carried out immediately before and after PLY. After implementing the short PLY training, significant improvement in jump performance (squat jump: p = 0.04, ES = 0.48, countermovement jump: p = 0.009, ES = 0.42) and agility (p = 0.003, ES = 0.7) was noted in the PLY group. In the CON group, no significant (p > 0.05) changes in physical performance were observed. In contrast, PLY did not improve repeated sprint performance (p > 0.05) among female soccer players. In our research, it was shown that PLY can also be effective when performed for only 4 weeks instead of the 6–12 weeks typically applied.

Postactivation Potentiation of Force Is Independent of H-Reflex Excitability

2008 ◽  
Vol 3 (2) ◽  
pp. 219-231 ◽  
Author(s):  
Matthew J. Hodgson ◽  
David Docherty ◽  
E. Paul Zehr
Keyword(s):  
Isometric Force ◽  
Plantar Flexion ◽  
Force Production ◽  
H Reflex ◽  
Postactivation Potentiation ◽  
Neural Excitability ◽  
Reflex Excitability ◽  
Before And After ◽  
History Of ◽  
A Minor

The contractile history of muscle can potentiate electrically evoked force production. A link to voluntary force production, related in part to an increase in reflex excitability, has been suggested.Purpose:Our purpose was to quantify the effect of postactivation potentiation on voluntary force production and spinal H-reflex excitability during explosive plantar fexion actions.Methods:Plantar flexor twitch torque, soleus H-reflex amplitudes, and the rate of force development of explosive plantar fexion were measured before and after 4 separate conditioning trials (3 × 5 s maximal contractions).Results:Twitch torque and rate of force production during voluntary explosive plantar flexion were significantly increased (P < .05) while H-reflex amplitudes remained unchanged. Although twitch torque was significantly higher after conditioning, leading to a small increase in the rate of voluntary force production, this was unrelated to changes in reflex excitability.Conclusion:We conclude that postactivation potentiation may result in a minor increase in the rate of voluntary isometric force production that is unrelated to neural excitability.

Metabolic heat production during fatigue from voluntary repetitive isometric contractions in humans

1996 ◽  
Vol 81 (3) ◽  
pp. 1323-1330 ◽  
Author(s):  
E. Saugen ◽  
N. K. Vollestad
Keyword(s):  
Energy Cost ◽  
Isometric Force ◽  
Recovery Period ◽  
Isometric Exercise ◽  
Muscle Mechanics ◽  
Force Production ◽  
Cellular Level ◽  
Voluntary Contraction ◽  
O2 Uptake ◽  
Postexercise Recovery

The effect of repetitive isometric knee extensions on the energy cost of contraction was examined. The rate of temperature rise (dT/dt) was determined in test contractions at 30 and 50% of maximal voluntary contraction (MVC) force before and during 30% MVC repetitive isometric exercise (RIE) to exhaustion and regularly in a 30-min postexercise recovery period (n = 9). Pulmonary O2 uptake and muscle temperature (Tmus) were determined at regular intervals. During the 30% MVC test contractions, dT/dt was 5.6 +/- 0.6 mK/s in unfatigued muscle, increasing linearly by 68% during exercise. In the 50% MVC test contractions, dT/dt rose by 84% from 9.8 +/- 1.1 mK/s. dT/dt determined during test contractions at both force levels did not decrease significantly throughout the 30-min postexercise recovery period. The rise in dT/dt was paralleled by 76% increased in O2 uptake. In contrast, Tmus rose initially and then leveled off. The present data indicate that RIE induced a gradual rise in the rate of energy turnover associated with isometric force production. Neither increased Tmus nor recruitment of less economic type II fibers can fully explain the increased energy cost. We suggest that energetic changes may occur at the cellular level and argue that this may be associated with the changes in muscle mechanics occurring during fatigue from submaximal voluntary RIE.

scholarly journals Early effects of eccentric contractions on muscle glucose uptake

2019 ◽  
Vol 126 (2) ◽  
pp. 376-385 ◽  
Author(s):  
Ole Emil Andersen ◽  
Ole Bækgaard Nielsen ◽  
Kristian Overgaard
Keyword(s):  
Glucose Uptake ◽  
Eccentric Exercise ◽  
Muscle Activation ◽  
Eccentric Contractions ◽  
Isometric Contractions ◽  
Uptake Rates ◽  
Length Changes ◽  
Early Effects ◽  
Insulin Responsiveness ◽  
Isolated Rat

Muscle-damaging eccentric exercise impairs muscle glucose uptake several hours to days after exercise. Little, however, is known about the acute effects of eccentric exercise on contraction- and insulin-induced glucose uptake. This study compares glucose uptake rates in the first hours following eccentric, concentric, and isometric contractions with and without insulin present. Isolated rat extensor digitorum longus muscles were exposed to either an eccentric, concentric, or isometric contraction protocol, and muscle contractions were induced by electric stimulation that was identical between contraction protocols. In eccentric and concentric modes, length changes of 0.6 or 1.2 mm were used during contractions. Both contraction- and insulin-induced glucose uptake were assessed immediately and 2 h after contractions. Glucose uptake increased significantly following all modes of contraction and was higher after eccentric contractions with a stretch of 1.2 mm compared with the remaining contraction groups when assessed immediately after contractions [eccentric (1.2 mm) > eccentric (0.6 mm), concentric (1.2 mm), concentric (0.6 mm), isometric > rest; P < 0.05]. After 2 h, contraction-induced glucose uptake was still higher than noncontracting levels, but with no difference between contraction modes. The presence of insulin increased glucose uptake markedly, but this response was blunted by, respectively, 39–51% and 29–36% ( P < 0.05) immediately and 2 h after eccentric contractions stretched 1.2 mm compared with concentric and isometric contractions. The contrasting early effects of eccentric contractions on contraction- and insulin-induced glucose uptake suggest that glucose uptake is impaired acutely following eccentric exercise because of reduced insulin responsiveness.NEW & NOTEWORTHY This study shows that, in isolated rat muscle, muscle-damaging eccentric contractions result in a transient increase in contraction-induced glucose uptake compared with isometric and concentric contractions induced by identical muscle activation protocols. Furthermore, our results demonstrate that, in contrast, the insulin-stimulated glucose uptake is impaired immediately following muscle-damaging eccentric contractions.

Muscle Activity Before and After Subacromial Injection

2021 ◽  
pp. 1-7
Author(s):  
Lucas Ettinger ◽  
Matthew Shaprio ◽  
Andrew Karduna
Keyword(s):  
Rotator Cuff ◽  
Muscle Activation ◽  
Rotator Cuff Tears ◽  
Subacromial Impingement ◽  
Upper Trapezius ◽  
Subacromial Injection ◽  
Shoulder Muscle ◽  
Shoulder Muscles ◽  
Before And After ◽  
Arm Elevation

Context: Shoulder muscle activation in patients with subacromial impingement is highly cited and variable in the literature. Differences between studies could be due to artifacts introduced by normalization practices in the presence of pain. Ultimately, this lack of knowledge pertaining to pathogenesis limits the clinical treatment and restoration of muscular function. Design: A total of 21 patients with stage 2 subacromial impingement and 21 matched controls were recruited for EMG testing of their affected shoulder during an arm elevation task. The patients were tested before and after receiving an injection to their subacromial bursa. Methods: The EMG from 7 shoulder muscles were measured before and after treatment during humeral motion in the scapular plane. Results: Our findings indicate an increase in anterior deltoid, middle deltoid, and upper trapezius activity following the injection; further, this trend extended to the controls. The control subjects had a greater activation of the latissimus dorsi at peak arm elevation when compared with the patient group postinjection. Conclusions: Our results indicate that a reduction in subacromial pain is associated with changes in shoulder muscle recruitment, primarily of the deltoid. This change in deltoid activity may lend evidence to rotator cuff function in patients without rotator cuff tears.

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