title: Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations.
abstract: We compared the effects of two resistance training (RT) programs only differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40) on muscle structural and functional adaptations. Twenty-two young males were randomly assigned to a VL20 (n = 12) or VL40 (n = 10) group. Subjects followed an 8-week velocity-based RT program using the squat exercise while monitoring repetition velocity. Pre- and post-training assessments included: magnetic resonance imaging, vastus lateralis biopsies for muscle cross-sectional area (CSA) and fiber type analyses, one-repetition maximum strength and full load-velocity squat profile, countermovement jump (CMJ), and 20-m sprint running. VL20 resulted in similar squat strength gains than VL40 and greater improvements in CMJ (9.5% vs 3.5%, P < 0.05), despite VL20 performing 40% fewer repetitions. Although both groups increased mean fiber CSA and whole quadriceps muscle volume, VL40 training elicited a greater hypertrophy of vastus lateralis and intermedius than VL20. Training resulted in a reduction of myosin heavy chain IIX percentage in VL40, whereas it was preserved in VL20. In conclusion, the progressive accumulation of muscle fatigue as indicated by a more pronounced repetition velocity loss appears as an important variable in the configuration of the resistance exercise stimulus as it influences functional and structural neuromuscular adaptations.
authors.affiliation: Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Pareja-Blanco
authors.affiliation: Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Rodríguez-Rosell
authors.affiliation: Studies, Research & Sports Medicine Center, Government of Navarre, Pamplona, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Sánchez-Medina
authors.affiliation: Department of Physical Education, Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.|Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Sanchis-Moysi
authors.affiliation: Department of Physical Education, Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.|Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Dorado
authors.affiliation: Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Mora-Custodio
authors.affiliation: Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Yáñez-García
authors.affiliation: Department of Physical Education, Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.|Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Morales-Alamo
authors.affiliation: Department of Physical Education, Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.|Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Pérez-Suárez
authors.affiliation: Department of Physical Education, Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.|Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria University, Las Palmas de Gran Canaria, Spain.
authors.forename: J A L
authors.initials: JAL
authors.lastname: Calbet
authors.affiliation: Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain.
authors.forename: J J
authors.initials: JJ
authors.lastname: González-Badillo
mesh_terms: D000222:Adaptation, Physiological; D054874:Athletic Performance / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D008297:Male; D018763:Muscle Fatigue; D053580:Muscle Strength / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D052097:Quadriceps Muscle / Q000502:physiology*; D055070:Resistance Training; D055815:Young Adult
chemical_list: D018995:Myosin Heavy Chains
keywords: Muscle strength; fiber type; magnetic resonance imaging; muscle hypertrophy; training to failure