Neuromuscular fatigue recovery following rapid and slow stretch–shortening cycle movements

2012 ◽  
Vol 37 (3) ◽  
pp. 437-447 ◽  
Author(s):  
Katie P. Wadden ◽  
Duane C. Button ◽  
Armin Kibele ◽  
David G. Behm
Keyword(s):  
Training Programs ◽  
Compound Action Potential ◽  
Neuromuscular Fatigue ◽  
Training Status ◽  
Condition Versus ◽  
Drop Jumps ◽  
Stretch Shortening Cycle ◽  
Underlying Mechanisms ◽  
Voluntary Contractions ◽  
Fatigue Recovery

The purpose of this study was to investigate underlying mechanisms and neuromuscular recovery patterns following rapid and slow stretch–shortening cycle (SSC) movements performed to fatigue. Fourteen (10 moderately trained (MT) and four highly trained (HT)) subjects completed rapid and slow SSC movements to fatigue. The rapid SSC movement consisted of continuous drop jumps from a 30 cm platform until a predetermined jump height was no longer maintained, and the slow SSC movement consisted of continuous squats to 90° of knee flexion at a load of 65% of subject’s one-repetition maximum until no further repetitions could be completed. Although blood lactate measures were significantly (p < 0.002) higher after the rapid SSC condition versus after the slow SSC condition, the recovery of neuromuscular properties (maximum voluntary contractions, twitch force, muscle compound action potential) following the two conditions to fatigue did not differ. The duration of the rapid SSC movement was dependent on the training status of the subject; HT subjects performed the rapid SSC longer (68.2%) than the MT subjects until fatigued. Thus, the neuromuscular fatigue recovery patterns were independent of the type of SSC movement, condition duration, and subject training status. Because rapid and slow SSC exercises induce similar fatigue patterns, training programs incorporating rapid SSC exercises can be developed similar to that prescribed in traditional slow SSC resistance training programs.

Neuromuscular fatigue after maximal stretch-shortening cycle exercise

1998 ◽  
Vol 84 (1) ◽  
pp. 344-350 ◽  
Author(s):  
V. Strojnik ◽  
P. V. Komi
Keyword(s):  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Peak Torque ◽  
Neuromuscular Fatigue ◽  
Cycle Exercise ◽  
Kinase Activation ◽  
Time To Peak ◽  
Single Twitch ◽  
Drop Jumps ◽  
Stretch Shortening Cycle

Strojnik, V., and P. V. Komi. Neuromuscular fatigue after maximal stretch-shortening cycle exercise. J. Appl. Physiol. 84(1): 344–350, 1998.—To examine some possible sites of fatigue during short-lasting maximally intensive stretch-shortening cycle exercise, drop jumps on an inclined sledge apparatus were analyzed. Twelve healthy volunteers performed jumps until they were unable to maintain jumping height >90% of their maximum. After the workout, the increases in the blood lactate concentration and serum creatine kinase activation were statistically significant ( P < 0.001 and P < 0.05, respectively) but rather small in physiological terms. The major changes after the workout were as follows: the single twitch was characterized by smaller peak torque ( P < 0.05) and shorter time to peak ( P < 0.05) and half-relaxation time ( P < 0.01). The double-twitch torque remained at the same level ( P > 0.05), but with a steeper maximal slope of torque rise ( P < 0.05); during 20- and 100-Hz stimulation the torque declined (both P < 0.01) and the maximal voluntary torque changed nonsignificantly but with a smaller maximal slope of torque rise ( P < 0.01) and a higher activation level ( P < 0.05), accompanied by an increased electromyogram amplitude. These findings indicate that the muscle response after the short-lasting consecutive maximum jumps on the sledge apparatus may involve two distinct mechanisms acting in opposite directions: 1) The contractile mechanism seems to be potentiated through a shorter Ca2+ transient and faster cross-bridge cycling, as implied by twitch changes. 2) High-frequency action potential propagation shows an impairment, which is suggested as the possible dominant reason for fatigue in exercise of this type.

scholarly journals Promoting recovery in daily life: study protocol for a randomized controlled trial

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Dorota Reis ◽  
Alexander Hart ◽  
Dirk Lehr ◽  
Malte Friese
Keyword(s):  
Training Programs ◽  
Controlled Trial ◽  
Online Training ◽  
Cognitive Behavioral ◽  
Main Mechanism ◽  
Work Related Stress ◽  
Work Related ◽  
Related Stress ◽  
Underlying Mechanisms

Abstract Background Work-related stress shows steadily increasing prevalence rates and has tangible consequences for individual workers, their organizations, and society as a whole. One mechanism that may help offset the negative outcomes of work-related stress on employees’ well-being is recovery. Recovery refers to the experience of unwinding from one's job when not at work. However, employees who experience high levels of work-related stress and are thus particularly in need of recovery tend to struggle to switch-off. Due to the detrimental effects of this prolonged and sustained mental representation of job stressors, interventions promoting recovery may contribute to improvements in employees' mental health. Methods In this randomized, waitlist controlled trial, we will investigate the effectiveness of two 6-week online training programs (cognitive behavioral and mindfulness-based). The sample will include employees working at least part-time during regular work hours. Besides the pre-post-follow-up assessments, the trial will include measurement bursts with the goal of examining the underlying mechanisms. We expect that both interventions will reduce work-related perseverative thinking (PT) compared with the waitlist control groups (primary outcome). Also, we expect that both interventions will result in similar improvements, but the underlying mechanisms will differ (process outcomes). In the cognitive-behavioral intervention group, we expect that the main mechanism responsible for lower PT levels will be an increase in recovery experiences across time. In the mindfulness-based group, we expect that the main mechanism responsible for lower PT levels will be an increase in facets of mindfulness across time. Discussion In the present study, we will investigate mechanisms underlying assumed changes in work-related PT in great detail. Besides evaluating the overall effectiveness of the two interventions in terms of pre-post-follow-up changes, we will look at the underlying processes at different levels—that is, within days, within weeks, across weeks, and between individuals. Accordingly, our study will offer a fine-grained approach to investigating potential determinants, mediators, and moderators of the processes that may, in the end, be responsible for work-related strain. From a public health perspective, if effective, the online training programs may offer valuable, low-threshold, and low-intensity interventions for a broad range of occupations. Trial registration German Clinical Trials Registration: DRKS00024933. Registered prospectively 7 April 2021. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00024933

Neuromuscular Fatigue in Individuals With Intellectual Disability: Comparison Between Sedentary Individuals and Athletes

Motor Control ◽  
2021 ◽  
Vol 25 (2) ◽  
pp. 264-282
Author(s):  
Rihab Borji ◽  
Firas Zghal ◽  
Nidhal Zarrouk ◽  
Sonia Sahli ◽  
Haithem Rebai
Keyword(s):  
Intellectual Disability ◽  
Recovery Period ◽  
Voluntary Contraction ◽  
Neuromuscular Fatigue ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Typical Development ◽  
Activation Level ◽  
Voluntary Activation Level ◽  
Voluntary Contractions

The authors explored neuromuscular fatigue in athletes with intellectual disability (AID) compared with sedentary individuals with intellectual disability (SID) and individuals with typical development. Force, voluntary activation level, potentiated resting twitch, and electromyography signals were assessed during isometric maximal voluntary contractions performed before and immediately after an isometric submaximal exhaustive contraction (15% isometric maximal voluntary contractions) and during recovery period. AID presented shorter time to task failure than SID (p < .05). The three groups presented similar isometric maximal voluntary contraction decline and recovery kinetic. Both groups with intellectual disability presented higher voluntary activation level and root mean square normalized to peak-to-peak M-wave amplitude declines (p < .05) compared with individuals with typical development. These declines were more pronounced in SID (p < .05) than in AID. The AID recovered their initial voluntary activation level later than controls, whereas SID did not. SID presented lower potentiated resting twitch decline compared with AID and controls with faster recovery (p < .05). AID presented attenuated central fatigue and accentuated peripheral fatigue compared with their sedentary counterparts, suggesting a neuromuscular profile close to that of individuals with typical development.

scholarly journals Test-retest reliability of electromyographic signal parameters used to evaluate neuromuscular fatigue in quadriceps femoris muscle

Kinesiology ◽  
2016 ◽  
Vol 48 (2) ◽  
pp. 174-181 ◽  
Author(s):  
Cristiano Rocha da Silva ◽  
Danilo de Oliveira Silva ◽  
Ronaldo Valdir Briani ◽  
Marcella Ferraz Pazzinatto ◽  
Deisi Ferrari ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Neuromuscular Fatigue ◽  
Median Frequency ◽  
Endurance Time ◽  
Retest Reliability ◽  
Emg Signal ◽  
Electromyographic Signal ◽  
Test Retest Reliability ◽  
Voluntary Contractions

The purpose of this study was to analyze the test-retest reliability of the median frequency (MDF) and root mean square (RMS) used to determine the onset of neuromuscular fatigue (NF) during sustained fatiguing contractions of the quadriceps. Eighteen healthy men were tested on two days, and electromyographic (EMG) signals were recorded from the vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) during sustained isometric contractions at 20 and 70% of maximum voluntary contractions (MVC) held until exhaustion. The reliability of endurance time was excellent at 20% MVC and poor at 70% MVC. EMG variables were evaluated: (1) at the beginning of the test; (2) at NF; and (3) at the end of the test. The NF time values presented poor reliability. The MDF has shown, in general, poor reliability at 20 and 70% MVC, whereas the RMS reliability presented better results for both loads, especially for RF, followed by the VM and VL muscles. The MDF and RMS values extracted from NF showed poor reliability at 20 and 70% MVC, which suggests caution in using these variables extracted from the EMG signal to determine the onset of NF.

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.

M-wave potentiation after voluntary contractions of different durations and intensities in the tibialis anterior

2015 ◽  
Vol 118 (8) ◽  
pp. 953-964 ◽  
Author(s):  
Javier Rodriguez-Falces ◽  
Jacques Duchateau ◽  
Yoshiho Muraoka ◽  
Stéphane Baudry
Keyword(s):  
Tibialis Anterior ◽  
Compound Action Potential ◽  
Pennation Angle ◽  
Second Phase ◽  
Median Frequency ◽  
Fascicle Length ◽  
M Wave ◽  
Muscle Fascicle ◽  
Phase Amplitude ◽  
Voluntary Contractions

The study was undertaken to provide insight into the mechanisms underlying the potentiation of the muscle compound action potential (M wave) after conditioning contractions. M waves were evoked in the tibialis anterior before and after isometric maximal voluntary contractions (MVC) of 1, 3, 6, 10, 30, and 60 s, and after 3-s contractions at 10, 30, 50, 70, 90, and 100% MVC. The amplitude, duration, and area of the first and second phases of the M wave, together with the median frequency (Fmedian) and muscle fiber conduction velocity (MFCV) were recorded. Furthermore, twitch force, muscle fascicle length, and pennation angle were measured at rest, before, and 1 s after the conditioning contractions. The results indicate that only the amplitude of the second phase of the M wave was significantly increased after conditioning contractions. The extent of this potentiation was similar for MVC durations ranging from 1 to 10 s and augmented progressively with contraction intensity from 30 to 70% MVC. After these conditioning contractions, the duration and area of the two M-wave phases decreased ( P < 0.05), whereas MFCV and Fmedian increased ( P < 0.05). For all of these parameters, the greatest changes occurred 1 s after the conditioning contraction. Changes in MFCV after the contractions were correlated with those in M-wave second-phase amplitude ( r2 = 0.42; P < 0.05) and Fmedian ( r2 = 0.53; P < 0.05). In contrast, fascicle length and pennation angle did not change after the conditioning contractions. It is concluded that the potentiation of the second phase of the M wave is mainly due to an increased MFCV.

scholarly journals A model for cognitively-based compassion training: theoretical underpinnings and proposed mechanisms

2019 ◽  
Author(s):  
Marcia Ash ◽  
Timothy Harrison ◽  
Melissa Pinto ◽  
Ralph DiClemente ◽  
Lobsang Tenzin Negi
Keyword(s):  
Health Behavior ◽  
Training Program ◽  
Interpersonal Skills ◽  
Training Programs ◽  
Belief Systems ◽  
Skill Development ◽  
Integrative Model ◽  
Social Wellbeing ◽  
Core Components ◽  
Underlying Mechanisms

AbstractAcross cultures and belief systems, compassion is widely considered to be beneficial for the development of personal and social wellbeing. Research indicates that compassion-training programs have broad health benefits, but how and why compassion-training programs are effective is still relatively unknown. This paper describes the theoretical underpinnings of a specific compassion-training program, CBCT® (Cognitively-Based Compassion Training), and proposes an integrative model that draws on existing health behavior constructs to identify CBCT’s core components and hypothesizes their directionality and interaction. The model includes two primary categories of skill development: (1) intrapersonal skills leading to greater resiliency, and (2) interpersonal skills leading to greater compassion. It is hypothesized that these two pathways are mutually reinforcing and both contribute to greater wellbeing. This model provides a foundation for theory-driven research on the underlying mechanisms in CBCT training. An understanding of CBCT’s mechanisms is a critical step towards optimizing and personalizing the intervention to meet the needs of specific populations.

Reproducible Measurement of Human Motoneuron Excitability With Magnetic Stimulation of the Corticospinal Tract

2009 ◽  
Vol 102 (1) ◽  
pp. 606-613 ◽  
Author(s):  
Peter G. Martin ◽  
Anna L. Hudson ◽  
Simon C. Gandevia ◽  
Janet L. Taylor
Keyword(s):  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials ◽  
Compound Action Potential ◽  
Maximal Response ◽  
Response Curves ◽  
Stimulus Response ◽  
Maximal Output ◽  
Voluntary Contractions ◽  
Stimulation Of

It is difficult to test responses of human motoneurons in a controlled way or to make longitudinal assessments of adaptive changes at the motoneuron level. These studies assessed the reliability of responses produced by magnetic stimulation of the corticospinal tract. Cervicomedullary motor evoked potentials (CMEPs) were recorded in the first dorsal interosseus (FDI) on 2 separate days. On each day, four sets of stimuli were delivered at the maximal output of the stimulator, with the final two sets ≥10 min after the initial sets. Sets of stimuli were also delivered at different stimulus intensities to obtain stimulus-response curves. In addition, on the second day, responses at different stimulus intensities were evoked during weak voluntary contractions. Responses were normalized to the maximal muscle compound action potential ( Mmax). CMEPs evoked in the relaxed FDI were small, even when stimulus intensity was maximal (3.6 ± 2.5% Mmax) but much larger during a weak contraction (e.g., 26.2 ± 10.2% Mmax). CMEPs evoked in the relaxed muscle at the maximal output of the stimulator were highly reproducible both within (ICC = 0.83, session 1; ICC = 0.87, session 2) and between sessions (ICC = 0.87). ICCs for parameters of the input-output curves, which included measures of motor threshold, slope, and maximal response size, ranged between 0.87 and 0.62. These results suggest that responses to magnetic stimulation of the corticospinal tract can be assessed in relaxation and contraction and can be reliably obtained for longitudinal studies of motoneuronal excitability.

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