Early motor unit conduction velocity changes to high-intensity interval training versus continuous training

  • 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 x 60-s intervals at 100% peak power output. Moderate-intensity continuous training: 90 to 120 min continuous cycling at similar to 65% VO2peak. 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 byPurpose 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 x 60-s intervals at 100% peak power output. Moderate-intensity continuous training: 90 to 120 min continuous cycling at similar to 65% VO2peak. 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.show moreshow less

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Author details:Eduaro Andrés Martinez-ValdesORCiDGND, Dario Farina, Francesco NegroORCiD, Alessandro Del VecchioORCiD, Deborah Falla
DOI:https://doi.org/10.1249/MSS.0000000000001705
ISSN:0195-9131
ISSN:1530-0315
Pubmed ID:http://www.ncbi.nlm.nih.gov/pubmed?term=29975302
Title of parent work (English):Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Publisher:Lippincott Williams & Wilkins
Place of publishing:Philadelphia
Publication type:Article
Language:English
Year of first publication:2018
Completion year:2018
Release date:2021/07/19
Tag:Action potential; Amplitude; Conduction velocity; Endurance training; High-intensity interval training; Motor unit
Volume:50
Issue:11
Number of pages:12
First page:2339
Last Page:2350
Organizational units:Humanwissenschaftliche Fakultät / Strukturbereich Kognitionswissenschaften / Department Sport- und Gesundheitswissenschaften
DDC classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit