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Publication . Article . 2021

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

Alejandro Muñoz-López; Alberto Marin-Galindo; Juan Corral-Pérez; Manuel Costilla; Alberto Sánchez-Sixto; Borja Sañudo; Cristina Casals; +1 Authors
Published: 04 May 2021 Journal: Journal of Strength and Conditioning Research, volume Publish Ahead of Print (issn: 1064-8011, Copyright policy )
Publisher: Ovid Technologies (Wolters Kluwer Health)
ABSTRACT Munoz-Lopez, A, Marin-Galindo, A, Corral-Perez, J, Costilla, M, Sanchez-Sixto, A, Sanudo, B, Casals, C, and Ponce-Gonzalez, 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.
Subjects by Vocabulary

Microsoft Academic Graph classification: Contraction velocity Chemistry Crossover study Cardiology medicine.medical_specialty medicine Muscle oxygenation Tensiomyography Deoxygenated Hemoglobin Muscle hypertrophy Squat Internal medicine Free weights


Physical Therapy, Sports Therapy and Rehabilitation, Orthopedics and Sports Medicine, General Medicine

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