Changes in motor unit discharge patterns following strength training

Kim, Edward H.; Hassan, Altamash S.; Heckman, C. J.

doi:10.1113/jp278137

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…The hypothesis of mechanical-induced structural changes are confirmed by the results of a variety of animal studies [ 40 ], showing significant increases in muscle mass, the muscle cross-sectional area and the fiber cross-sectional area due to chronic stretching interventions: “It is Stretch that causes the Hypertrophy of Muscle” ([ 41 ] p. 93). However, increased MSt in the first weeks of training are commonly related to neuronal aspects [ 42 , 43 ], while morphological changes might be of minor relevance. The measured contralateral force transfer can also be seen as confirmation of the inclusion of neuronal aspects in the stretching-induced MSt increases.…”

Section: Discussionmentioning

confidence: 99%

Influence of One Hour versus Two Hours of Daily Static Stretching for Six Weeks Using a Calf-Muscle-Stretching Orthosis on Maximal Strength

Warneke

Keiner

Hillebrecht

et al. 2022

IJERPH

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Rebuilding strength capacity is of crucial importance in rehabilitation since significant atrophy due to immobilization after injury and/or surgery can be assumed. To increase maximal strength (MSt), strength training is commonly used. The literature regarding animal studies show that long-lasting static stretching (LStr) interventions can also produce significant improvements in MSt with a dose–response relationship, with stretching times ranging from 30 min to 24 h per day; however, there is limited evidence in human studies. Consequently, the aim of this study is to investigate the dose–response relationship of long-lasting static stretching on MSt. A total of 70 active participants (f = 30, m = 39; age: 27.4 ± 4.4 years; height: 175.8 ± 2.1 cm; and weight: 79.5 ± 5.9 kg) were divided into three groups: IG1 and IG2 both performed unilateral stretching continuously for one (IG1) or two hours (IG2), respectively, per day for six weeks, while the CG served as the non-intervened control. MSt was determined in the plantar flexors in the intervened as well as in the non-intervened control leg to investigate the contralateral force transfer. Two-way ANOVA showed significant interaction effects for MSt in the intervened leg (ƞ 2 = 0.325, p < 0.001) and in the contralateral control leg (ƞ 2 = 0.123, p = 0.009), dependent upon stretching time. From this, it can be hypothesized that stretching duration had an influence on MSt increases, but both durations were sufficient to induce significant enhancements in MSt. Thus, possible applications in rehabilitation can be assumed, e.g., if no strength training can be performed, atrophy could instead be reduced by performing long-lasting static stretch training.

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Section: Discussionmentioning

confidence: 99%

Influence of One Hour versus Two Hours of Daily Static Stretching for Six Weeks Using a Calf-Muscle-Stretching Orthosis on Maximal Strength

Warneke

Keiner

Hillebrecht

et al. 2022

IJERPH

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“…Offering a potential explanation for improvements in FORCE CoV with RET, 4 weeks of isometric strength training which significantly increased muscle strength also increased MU FR (+3 ± 2.5 pps) during the plateau phase of submaximal muscle contractions and decreased in the MU recruitment threshold (Del Vecchio et al, 2019). Similarly, an increase in MU FR during the plateau phase of trapezoidal dorsiflexor contractions was observed following strength training (Kim et al, 2019), with conduction of ballistic muscle contractions leading to earlier activation of MUs and increased MU FR in the dorsiflexor muscles post-training (Van Cutsem et al, 1998). Despite RET proving to be mostly an effective training mechanism to improve FORCE CoV , RET may not be accessible to all individuals due to its higher intensity, which may pose physical limitations for older individuals (Barry & Carson, 2004) and those who are injured or present with disability.…”

Section: Introductionmentioning

confidence: 86%

Training‐induced improvements in knee extensor force accuracy are associated with reduced vastus lateralis motor unit firing variability

Ely

Jones

Inns

et al. 2022

Experimental Physiology

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“…Motoneuron afterhyperpolarisation duration has been shown to decrease following short-term resistance training (Christie and Kamen 2010 ), which might indicate increased flow of positive charged ions onto the motoneurons and thus increased probability of action potential generation, possibly as a result of increased monoaminergic drive. Furthermore, in the study by Del Vecchio et al ( 2019 ) recruitment threshold of motor units were found to be decreased, but no changes were noted in derecruitment threshold relative to force produced, suggesting the hysteresis of motor unit recruitment had changed as a result of resistance training (Kim et al 2019a ). However, the lack of changes in the motoneuron input–output relationship (the relationship between motor unit discharge rate and force production) cast doubt that increased neuromodulatory input contributed to increased force production following short-term resistance training (Del Vecchio et al 2019 ).…”

Section: High-density Surface Electromyography: Potential For Source mentioning

confidence: 99%

The knowns and unknowns of neural adaptations to resistance training

et al. 2020

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The initial increases in force production with resistance training are thought to be primarily underpinned by neural adaptations. This notion is firmly supported by evidence displaying motor unit adaptations following resistance training; however, the precise locus of neural adaptation remains elusive. The purpose of this review is to clarify and critically discuss the literature concerning the site(s) of putative neural adaptations to short-term resistance training. The proliferation of studies employing non-invasive stimulation techniques to investigate evoked responses have yielded variable results, but generally support the notion that resistance training alters intracortical inhibition. Nevertheless, methodological inconsistencies and the limitations of techniques, e.g. limited relation to behavioural outcomes and the inability to measure volitional muscle activity, preclude firm conclusions. Much of the literature has focused on the corticospinal tract; however, preliminary research in non-human primates suggests reticulospinal tract is a potential substrate for neural adaptations to resistance training, though human data is lacking due to methodological constraints. Recent advances in technology have provided substantial evidence of adaptations within a large motor unit population following resistance training. However, their activity represents the transformation of afferent and efferent inputs, making it challenging to establish the source of adaptation. Whilst much has been learned about the nature of neural adaptations to resistance training, the puzzle remains to be solved. Additional analyses of motoneuron firing during different training regimes or coupling with other methodologies (e.g., electroencephalography) may facilitate the estimation of the site(s) of neural adaptations to resistance training in the future.

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Changes in motor unit discharge patterns following strength training

Cited by 6 publications

References 5 publications

Influence of One Hour versus Two Hours of Daily Static Stretching for Six Weeks Using a Calf-Muscle-Stretching Orthosis on Maximal Strength

Influence of One Hour versus Two Hours of Daily Static Stretching for Six Weeks Using a Calf-Muscle-Stretching Orthosis on Maximal Strength

Training‐induced improvements in knee extensor force accuracy are associated with reduced vastus lateralis motor unit firing variability

The knowns and unknowns of neural adaptations to resistance training

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