Changes in motor unit behavior following isometric fatigue of the first dorsal interosseous muscle

McManus, Lara; Hu, Xiaogang; Rymer, William Z.; Lowery, Madeleine M.; Suresh, Nina L.

doi:10.1152/jn.00146.2015

Cited by 52 publications

(57 citation statements)

References 51 publications

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“…It is know that shifts in median frequency of the EMG signal, towards low frequencies, provides an indirect measure of metabolic and ionic state of active muscles [42,43], and is related to reductions in the muscle fiber conduction velocity [44]. Our results indicate that EMGFmed returns to baseline levels 5 minutes after exercise with vascular occlusion carried out to failure.…”

Section: Median Frequency Of the Emg Signalmentioning

confidence: 55%

“…McManus et al [44] demonstrated an increase in the amplitude of EMG signal over a period of recovery after exercise carried out to the task failure with free blood flow, indicating the recruitment of larger motor units to compensate for the force reduction capacity in fatigued muscle. In our study, however, this possible additional recruitment of motor units was not converted into an increase in force generation capacity in the PO condition, probably due to fatigue of the type I muscle fiber, since the oxygen availability was partially preserved in this condition.…”

Section: Emg Peakmentioning

confidence: 99%

“…In our study, however, this possible additional recruitment of motor units was not converted into an increase in force generation capacity in the PO condition, probably due to fatigue of the type I muscle fiber, since the oxygen availability was partially preserved in this condition. Additionally, synchronization of motor units can also contribute to an increase in the amplitude of the EMG signal after the failure [44,49].…”

Section: Emg Peakmentioning

confidence: 99%

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

Cerqueira

Pereira

Rocha

et al. 2017

Int J Appl Exerc Physiol

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ABSTRACT:Objectives: The purpose this study was to 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 task 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 was significantly different (p < 0.05) among all investigated conditions: TO (150 ± 68s), PO (390 ± 210s) and FF (510 ± 240s). 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 induced lower MVIF (p <0.05) than in the TO, eleven minutes after the task failure. PO induced 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.

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Section: Median Frequency Of the Emg Signalmentioning

confidence: 55%

Section: Emg Peakmentioning

confidence: 99%

Section: Emg Peakmentioning

confidence: 99%

See 1 more Smart Citation

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

Cerqueira

Pereira

Rocha

et al. 2017

Int J Appl Exerc Physiol

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“…Furthermore, unlike at higher contractile intensities, the opportunity for changes in recruitment and de-recruitment of MUs is much greater in fatiguing submaximal tasks, which can have an impact on discharge rates. However, relatively few studies have assessed concurrently the interaction between recruitment and rate coding during fatiguing tasks (61). Finally, interpretations of fatigue-related changes in MU output in many studies cited here have necessarily been directed by findings obtained from single MUs, but from a functional aspect the system utilizes groups of concurrently activated MUs.…”

Section: Changes In the Neuromuscular Pathway With Fatiguing Exercisementioning

confidence: 99%

Neural Contributions to Muscle Fatigue

Taylor

Amann

Duchateau

et al. 2016

Medicine &Amp; Science in Sports &Amp; Exercise

375

198

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During exercise, there is a progressive reduction in the ability to produce muscle forces. Processes within the nervous system, as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue, and impairment of homeostasis can contribute to impairment of performance during exercise. This review discusses some of the neural changes that accompany exercise and the development of fatigue. The role of brain monoaminergic neurotransmitter systems in whole-body endurance performance is discussed, particularly with regard to exercise in hot environments. Next, fatigue-related alterations in the neuromuscular pathway are discussed in terms of changes in motor unit firing, motoneuron excitability and motor cortical excitability. These changes have mostly been investigated during single-limb isometric contractions. Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue are discussed. These afferents have roles in cardiovascular and respiratory responses to exercise, and in impairment of exercise performance through interaction with the motor pathway, as well as providing sensations of muscle discomfort. Thus, changes at all levels of the nervous system including the brain, spinal cord, motor output, sensory input and autonomic function occur during exercise and fatigue. The mix of influences and the importance of their contribution varies with the type of exercise being performed.

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“…; McManus et al. ). It has been suggested that grouping MU data in this way misrepresents MU firing behavior (De Luca and Contessa ; Hu et al.…”

Section: Introductionmentioning

confidence: 97%

Effects of fatiguing, submaximal high- versus low-torque isometric exercise on motor unit recruitment and firing behavior

et al. 2018

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The purpose of this investigation was to evaluate the effects of repeated, high‐ (HT: 70% MVIC) versus low‐torque (LT: 30% MVIC) isometric exercise performed to failure on motor unit (MU) recruitment and firing behavior of the vastus lateralis. Eighteen resistance‐trained males (23.1 ± 3.8 years) completed familiarization, followed by separate experimental sessions in which they completed either HT or LT exercise to failure in random order. LT exercise resulted in a greater time to task failure and a more dramatic decline in the muscle's force capacity, but the total work completed was similar for HT and LT exercise. An examination of the firing trains from 4670 MUs recorded during exercise revealed that firing rates generally increased during HT and LT exercise, but were higher during HT than LT exercise. Furthermore, recruitment thresholds (RT) did not significantly change during HT exercise, whereas the RT of the smallest MUs increased and the RT for the moderate to large MUs decreased during LT exercise. Both HT and LT exercise resulted in the recruitment of additional higher threshold MUs in order to maintain torque production. However, throughout exercise, HT required the recruitment of larger MUs than did LT exercise. In a few cases, however, MUs were recruited by individuals during LT exercise that were similar in size and original (pre) RT to those detected during HT exercise. Thus, the ability to achieve full MU recruitment during LT exercise may be dependent on the subject. Consequently, our data emphasize the task and subject dependency of muscle fatigue.

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Changes in motor unit behavior following isometric fatigue of the first dorsal interosseous muscle

Cited by 52 publications

References 51 publications

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

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

Neural Contributions to Muscle Fatigue

Effects of fatiguing, submaximal high- versus low-torque isometric exercise on motor unit recruitment and firing behavior

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