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Title of the item:

Effects of Different Velocity Loss Thresholds on Passive Contractile Properties and Muscle Oxygenation in the Squat Exercise Using Free Weights.

Title :
Effects of Different Velocity Loss Thresholds on Passive Contractile Properties and Muscle Oxygenation in the Squat Exercise Using Free Weights.
Authors :
Muñoz-López A; Department of Human Motricity and Sports Performance, University of Seville, Spain; MOVE-IT Research Group and Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain; Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital, University of Cádiz, Cádiz, Spain; Department of Sport, CEU Cardenal Spinola University, Spain; and Department of Physical Education and Sport, University of Sevilla, Spain.
Marín-Galindo A
Corral-Pérez J
Costilla M
Sánchez-Sixto A
Sañudo B
Casals C
Ponce-González JG
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Source :
Journal of strength and conditioning research [J Strength Cond Res] 2021 May 04. Date of Electronic Publication: 2021 May 04.
Publication Model :
Ahead of Print
Publication Type :
Journal Article
Language :
English
Imprint Name(s) :
Original Publication: Champaign, IL : Human Kinetics Pub., c1993-
Entry Date(s) :
Date Created: 20210611 Latest Revision: 20210611
Update Code :
20210914
DOI :
10.1519/JSC.0000000000004048
PMID :
34115697
Academic Journal
Abstract: Muñoz-López, A, Marín-Galindo, A, Corral-Pérez, J, Costilla, M, Sánchez-Sixto, A, Sañudo, B, Casals, C, and Ponce-González, JG. Effects of different velocity loss thresholds on passive contractile properties and muscle oxygenation in the squat exercise using free weights. J Strength Cond Res XX(X): 000-000, 2021-The current study assessed the impact between different velocity loss thresholds on changes in the muscle contractile properties and muscle oxygenation after a single resistance training (RT) session. Thirty physically active men participated in a crossover study performing 3 sets of the squat exercise at a lifted speed of ≈0.75 m·s -1, with 2 different velocity loss thresholds: 20% (VL20) vs 40% (VL40) in a randomized order. Contractile properties of the knee extensor muscles were tested using tensiomyography. In addition, muscle oxygenation was continuously measured from baseline until the end of the exercise session. The vastus lateralis showed a significant moment by condition interaction in time delay (p = 0.044), muscle displacement (p = 0.001), and contraction velocity (p = 0.007), with greater reductions in VL40. In both trainings, oxygenated hemoglobin and tissue oxygen index decreased, whereas deoxygenated hemoglobin increased (moment as the main effect, p < 0.05), but without a moment by condition interaction. VL40 showed a lower deoxygenation slope in set 1 (-0.468%·s-1, p = 0.001) and set 3 (-0.474%·s-1, p = 0.037) as well as higher losses in set 1 (-41.50%, p = 0.003), set 2 (-41.84%, p = 0.002), and set 3 (-62.51%, p < 0.001), compared with VL20. No differences were found in the recovery period between conditions. In conclusion, during the RT program design, coaches and athletes should consider that VL40 produces higher mechanical and neuromuscular impairments than VL20, which seems to be necessary for hypertrophy to occur; however, VL40 also produces a longer period of lower oxygen supply than VL20, which can induce fast-to-slow muscle fiber transition.
(Copyright © 2021 by the National Strength & Conditioning Association.)

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