Eduardo Martinez-Valdes1,2,3, Dario Farina4, Francesco Negro5, Alessandro Del Vecchio4, Deborah Falla1. 1. Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UNITED KINGDOM. 2. Centro de Investigación en Fisiología del Ejercicio-CIFE, Facultad de Ciencias, Universidad Mayor, Santiago, CHILE. 3. Department of Sports Medicine and Sports Orthopaedics, University of Potsdam, Potsdam, GERMANY. 4. Department of Bioengineering, Imperial College London, Royal School of Mines, London, UNITED KINGDOM. 5. Department of Clinical and Experimental Sciences, Università degli Studi di Brescia, Brescia, ITALY.
Abstract
PURPOSE:Moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) are associated with different adjustments in motor output. Changes in motor unit (MU) peripheral properties may contribute to these adjustments, but this is yet to be elucidated. This study evaluated early changes in MU conduction velocity (MUCV) and MU action potential amplitude after 2 wk of either HIIT or MICT. METHODS:Sixteen men were assigned to either an MICT group or HIIT group (n = 8 each), and participated in six training sessions over 14 d. HIIT: 8 to 12 × 60-s intervals at 100% peak power output. Moderate-intensity continuous training: 90 to 120 min continuous cycling at ~65% V˙O2peak. Preintervention and postintervention, participants performed maximal voluntary contractions (MVC) and submaximal (10%, 30%, 50%, and 70% of MVC) isometric knee extensions while high-density EMG was recorded from the vastus medialis (VM) and vastus lateralis (VL) muscles. The high-density EMG was decomposed into individual MU by convolutive blind-source separation and tracked preintervention and postintervention. RESULTS: Both training interventions induced changes in MUCV, but these changes depended on the type of training (P < 0.001). The HIIT group showed higher values of MUCV after training at all torque levels (P < 0.05), MICT only displayed changes in MUCV at low torque levels (10%-30% MVC, P < 0.002). There were no changes in MU action potential amplitude for either group (P = 0.2). CONCLUSIONS: Two weeks of HIIT or MICT elicit differential changes in MUCV, likely due to the contrasting load and volume used in such training regimes. This new knowledge on the neuromuscular adaptations to training has implications for exercise prescription.
RCT Entities:
PURPOSE: Moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) are associated with different adjustments in motor output. Changes in motor unit (MU) peripheral properties may contribute to these adjustments, but this is yet to be elucidated. This study evaluated early changes in MU conduction velocity (MUCV) and MU action potential amplitude after 2 wk of either HIIT or MICT. METHODS: Sixteen men were assigned to either an MICT group or HIIT group (n = 8 each), and participated in six training sessions over 14 d. HIIT: 8 to 12 × 60-s intervals at 100% peak power output. Moderate-intensity continuous training: 90 to 120 min continuous cycling at ~65% V˙O2peak. Preintervention and postintervention, participants performed maximal voluntary contractions (MVC) and submaximal (10%, 30%, 50%, and 70% of MVC) isometric knee extensions while high-density EMG was recorded from the vastus medialis (VM) and vastus lateralis (VL) muscles. The high-density EMG was decomposed into individual MU by convolutive blind-source separation and tracked preintervention and postintervention. RESULTS: Both training interventions induced changes in MUCV, but these changes depended on the type of training (P < 0.001). The HIIT group showed higher values of MUCV after training at all torque levels (P < 0.05), MICT only displayed changes in MUCV at low torque levels (10%-30% MVC, P < 0.002). There were no changes in MU action potential amplitude for either group (P = 0.2). CONCLUSIONS: Two weeks of HIIT or MICT elicit differential changes in MUCV, likely due to the contrasting load and volume used in such training regimes. This new knowledge on the neuromuscular adaptations to training has implications for exercise prescription.
Authors: Altamash S Hassan; Edward H Kim; Obaid U Khurram; Mark Cummings; Christopher K Thompson; Laura Miller McPherson; C J Heckman; Julius P A Dewald; Francesco Negro Journal: Conf Proc IEEE Eng Med Biol Soc Date: 2019-07