Early motor unit conduction velocity changes to high-intensity interval training versus continuous training
File(s)
Accepted version
Author(s)
Martinez-Valdes, Eduardo
Farina, Dario
Negro, Francesco
Del Vecchio, Alessandro
Falla, Deborah
Type
Journal Article
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.
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.
Date Issued
2018-11-01
Date Acceptance
2018-06-01
Citation
Medicine and Science in Sports and Exercise, 2018, 50 (11), pp.2339-2350
ISSN
0195-9131
Publisher
Lippincott, Williams & Wilkins
Start Page
2339
End Page
2350
Journal / Book Title
Medicine and Science in Sports and Exercise
Volume
50
Issue
11
Copyright Statement
© 2018 by the American College of Sports Medicine. This is a non-final version of an article published in final form in Medicine & Science in Sports & Exercise: November 2018 - Volume 50 - Issue 11 - p2339–2350, https://dx.doi.org/10.1249/MSS.0000000000001705
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000447560400019&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Life Sciences & Biomedicine
Sport Sciences
MOTOR UNIT
CONDUCTION VELOCITY
AMPLITUDE
ACTION POTENTIAL
HIGH-INTENSITY INTERVAL TRAINING
ENDURANCE TRAINING
HUMAN SKELETAL-MUSCLE
NA+-K+-ATPASE
LOW-VOLUME
EXERCISE PERFORMANCE
GLYCOGEN DEPLETION
SURFACE EMG
CONTRACTIONS
ADAPTATIONS
ENDURANCE
STRENGTH
Publication Status
Published
Date Publish Online
2018-11