D Colomer-Poveda1, S Romero-Arenas1, M Keller2, T Hortobágyi3, G Márquez4. 1. Department of Physical Education and Sport, Faculty of Sport, Catholic University of Murcia (UCAM), Murcia, Spain. 2. Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland. 3. Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen, Groningen, Netherlands. 4. Department of Physical Education and Sport, Faculty of Sport, Catholic University of Murcia (UCAM), Murcia, Spain. Electronic address: gmarquez@ucam.edu.
Abstract
OBJECTIVE: The increase in voluntary force of an untrained limb (i.e. Cross-education) after unilateral resistance training (RT) is believed to be a consequence of cortical adaptations. However, studies measuring neurophysiological adaptations with transcranial magnetic stimulation (TMS) found inconsistent results. One unexamined factor contributing to the conflicting data is the variation in the type and intensity of muscle contractions, fatigue, and the strategies of pacing the movement. Therefore, the purpose was to analyse how those unilateral RT variables affect the adaptations in ipsilateral M1 (iM1) and cross-education. METHODS: We performed a systematic literature review, with the following search terms with Boolean conjunctions: "Transcranial magnetic stimulation" AND "Ipsilateral cortex" AND "Resistance training". RESULTS: The 11 acute and 12 chronic studies included partially support the idea of increased cortical excitability and reduced intracortical inhibition in iM1, but the inconsistency between studies was high. CONCLUSIONS: Differences in type and intensity of contraction, fatigue, and strategies of pacing the movement contributed to the inconsistencies. The tentative conclusion is that high intensity eccentric or externally paced contractions are effective to increase iM1 excitability but cross-education can occur in the absence of such changes. Thus, the mechanism of the cross-education examined with TMS remains unclear.
OBJECTIVE: The increase in voluntary force of an untrained limb (i.e. Cross-education) after unilateral resistance training (RT) is believed to be a consequence of cortical adaptations. However, studies measuring neurophysiological adaptations with transcranial magnetic stimulation (TMS) found inconsistent results. One unexamined factor contributing to the conflicting data is the variation in the type and intensity of muscle contractions, fatigue, and the strategies of pacing the movement. Therefore, the purpose was to analyse how those unilateral RT variables affect the adaptations in ipsilateral M1 (iM1) and cross-education. METHODS: We performed a systematic literature review, with the following search terms with Boolean conjunctions: "Transcranial magnetic stimulation" AND "Ipsilateral cortex" AND "Resistance training". RESULTS: The 11 acute and 12 chronic studies included partially support the idea of increased cortical excitability and reduced intracortical inhibition in iM1, but the inconsistency between studies was high. CONCLUSIONS: Differences in type and intensity of contraction, fatigue, and strategies of pacing the movement contributed to the inconsistencies. The tentative conclusion is that high intensity eccentric or externally paced contractions are effective to increase iM1 excitability but cross-education can occur in the absence of such changes. Thus, the mechanism of the cross-education examined with TMS remains unclear.
Authors: A Manca; T Hortobágyi; T J Carroll; R M Enoka; J P Farthing; S C Gandevia; D J Kidgell; J L Taylor; F Deriu Journal: Sports Med Date: 2021-01 Impact factor: 11.136
Authors: Carlos Rodriguez-Lopez; Julian Alcazar; Jose Losa-Reyna; Noelia Maria Martin-Espinosa; Ivan Baltasar-Fernandez; Ignacio Ara; Robert Csapo; Luis M Alegre Journal: Front Physiol Date: 2021-02-18 Impact factor: 4.566