Increased cross-education of muscle strength and reduced corticospinal inhibition following eccentric strength training

Kidgell, Dawson; Frazer, Ashlyn K.; Rantalainen, Timo; Ruotsalainen, Ilona; Ahtiainen, Juha P.; Avela, Janne; Howatson, Glyn

doi:10.1016/j.neuroscience.2015.05.057

Cited by 98 publications

(103 citation statements)

References 43 publications

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“…31 Using a transcranial magnetic stimulation method, unilateral training protocols were shown to reduce intracortical inhibition and silent period duration as well as increase corticospinal excitability. 32,33 The physiologic bases for these changes are not understood, but our data support the view that there is bidirectional communication between the central brain areas and yoked and agonist-antagonist muscle pairs. As indicated, it is important to remember that resistance exercise resulted in increased muscle expression of IGF-1.…”

Section: Discussionsupporting

confidence: 63%

Improvement of Eye Alignment in Adult Strabismic Monkeys by Sustained IGF-1 Treatment

McLoon

Christiansen

Ghose

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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PurposeThe goal of this study was to determine if continuous application of insulin-like growth factor-1 (IGF-1) could improve eye alignment of adult strabismic nonhuman primates and to assess possible mechanisms of effect.MethodsA continuous release pellet of IGF-1 was placed on one medial rectus muscle in two adult nonhuman primates (M1, M2) rendered exotropic by the alternating monocular occlusion method during the first months of life. Eye alignment and eye movements were recorded for 3 months, after which M1 was euthanized, and the lateral and medial rectus muscles were removed for morphometric analysis of fiber size, nerve, and neuromuscular density.ResultsMonkey 1 showed a 40% reduction in strabismus angle, a reduction of exotropia of approximately 11° to 14° after 3 months. Monkey 2 showed a 15% improvement, with a reduction of its exotropia by approximately 3°. The treated medial rectus muscle of M1 showed increased mean myofiber cross-sectional areas. Increases in myofiber size also were seen in the contralateral medial rectus and lateral rectus muscles. Similarly, nerve density increased in the contralateral medial rectus and yoked lateral rectus.ConclusionsThis study demonstrates that in adult nonhuman primates with a sensory-induced exotropia in infancy, continuous IGF-1 treatment improves eye alignment, resulting in muscle fiber enlargement and altered innervational density that includes the untreated muscles. This supports the view that there is sufficient plasticity in the adult ocular motor system to allow continuous IGF-1 treatment over months to produce improvement in eye alignment in early-onset strabismus.

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Section: Discussionsupporting

confidence: 63%

Improvement of Eye Alignment in Adult Strabismic Monkeys by Sustained IGF-1 Treatment

McLoon

Christiansen

Ghose

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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“…It is well documented that resistance training of one limb increases muscle strength of the other limb, which is known as the cross‐educational effect . A similar phenomenon is observed for eccentric exercise‐induced muscle damage such that the initial bout of eccentric exercise of one limb attenuated the magnitude of muscle damage of the contralateral homologous muscle .…”

Section: Introductionmentioning

confidence: 72%

“…The possible mechanisms of the protection conferred by 2MVIC on 30MVEC of the contralateral arm have not been explored, but some speculations could be made. It is well documented that resistance training of one limb increases muscle strength of the homologous muscle of the opposite limb, which is known as the cross‐education effect . Diffusion of impulses between hemispheres, co‐activation via bilateral corticospinal pathways, learning in coordination, and afferent modulation have been described as potential candidates for the cross‐education effect .…”

Section: Discussionmentioning

confidence: 99%

“…It seems possible that neural factors and/or systemic effect contributed to the CL‐RBE. Kidgell et al showed that eccentric training modulated corticospinal excitability and inhibition of the untrained limb to a greater extent than concentric training. It may be that one bout of 2MVIC also modulated corticospinal excitability during 30MVEC of the contralateral limb.…”

Section: Discussionmentioning

confidence: 99%

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Muscle damage protective effect by two maximal isometric contractions on maximal eccentric exercise of the elbow flexors of the contralateral arm

Chen

Lin

Chen

et al. 2018

Scandinavian Med Sci Sports

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Muscle damage after 30 maximal eccentric contractions of the elbow flexors (30MVEC) is reduced when the same exercise is performed by the opposite arm, and when two maximal voluntary isometric contractions at a long muscle length (2MVIC) are performed prior to 30MVEC by the same arm. This study investigated the hypothesis that 2MVIC would attenuate muscle damage after 30MVEC performed by the opposite arm. Untrained young (20-25 years) men were placed into 1 of 4 experimental groups that performed 2MVIC at 1 (1d), 2 (2d), 4 (4d), or 7 days (7d) before 30MVEC by the opposite arm, or one control group that performed 30MVEC only (n = 13/group). Changes in indirect muscle damage markers after 30MVEC were compared among the groups by mixed-design two-way ANOVA. Maximal voluntary concentric contraction torque, range of motion, plasma creatine kinase activity, and muscle soreness did not change significantly after 2MVIC. Changes in these variables after 30MVEC were smaller (P < .05) for 1d (eg, peak soreness: 45 ± 21 mm) and 2d groups (46 ± 20 mm) than control group (66 ± 18 mm), without significant differences between 1d and 2d groups. No significant differences in the changes were found among 4d, 7d, and control groups, except for soreness showing smaller (P < .05) increases for 4d group (54 ± 19 mm) than 7d (62 ± 17 mm) and control groups. These results supported the hypothesis and showed that muscle damage induced by 30MVEC was reduced by 2MVIC performed 1-2 days prior to 30MVIC by the contralateral arm.

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“…While conventional exercise is not considered to be an approach to motor priming, in non-disabled individuals, some studies have concluded that resistance training is associated with increased CSE (26, 31), and with greater twitch forces of the cortically evoked motor response (32). This may suggest that changes in CSE are similar for skill training and strength training (26).…”

Section: Introductionmentioning

confidence: 99%

Priming for Improved Hand Strength in Persons with Chronic Tetraplegia: A Comparison of Priming-Augmented Functional Task Practice, Priming Alone, and Conventional Exercise Training

et al. 2017

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Many everyday tasks cannot be accomplished without adequate grip strength, and corticomotor drive to the spinal motoneurons is a key determinant of grip strength. In persons with tetraplegia, damage to spinal pathways limits transmission of signals from motor cortex to spinal motoneurons. Corticomotor priming, which increases descending drive, should increase corticospinal transmission through the remaining spinal pathways resulting in increased grip strength. Since the motor and somatosensory cortices share reciprocal connections, corticomotor priming may also have potential to influence somatosensory function. The purpose of this study was to assess changes in grip (precision, power) force and tactile sensation associated with two different corticomotor priming approaches and a conventional training approach and to determine whether baseline values can predict responsiveness to training. Participants with chronic (≥1 year) tetraplegia (n = 49) were randomized to one of two corticomotor priming approaches: functional task practice plus peripheral nerve somatosensory stimulation (FTP + PNSS) or PNSS alone, or to conventional exercise training (CET). To assess whether baseline corticospinal excitability (CSE) is predictive of responsiveness to training, in a subset of participants, we assessed pre-intervention CSE of the thenar muscles. Participants were trained 2 h daily, 5 days/week for 4 weeks. Thirty-seven participants completed the study. Following intervention, significant improvements in precision grip force were observed in both the stronger and weaker hand in the FTP + PNSS group (effect size: 0.51, p = 0.04 and 0.54, p = 0.03, respectively), and significant improvements in weak hand precision grip force were associated with both PNSS and CET (effect size: 0.54, p = 0.03 and 0.75, p = 0.02, respectively). No significant changes were observed in power grip force or somatosensory scores in any group. Across all groups, responsiveness to training as measured by change in weak hand power grip force was correlated with baseline force. Change in precision grip strength was correlated with measures of baseline CSE. These findings indicate that corticomotor priming with FTP + PNSS had the greatest influence on precision grip strength in both the stronger and weaker hand; however, both PNSS and CET were associated with improved precision grip strength in the weaker hand. Responsiveness to training may be associated with baseline CSE.

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Increased cross-education of muscle strength and reduced corticospinal inhibition following eccentric strength training

Cited by 98 publications

References 43 publications

Improvement of Eye Alignment in Adult Strabismic Monkeys by Sustained IGF-1 Treatment

Improvement of Eye Alignment in Adult Strabismic Monkeys by Sustained IGF-1 Treatment

Muscle damage protective effect by two maximal isometric contractions on maximal eccentric exercise of the elbow flexors of the contralateral arm

Priming for Improved Hand Strength in Persons with Chronic Tetraplegia: A Comparison of Priming-Augmented Functional Task Practice, Priming Alone, and Conventional Exercise Training

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