%0 Journal Article
%A Pareja Blanco, Fernando
%A Rodríguez Rosell, David
%A Sanchez-Medina, L.
%A Sanchis-Moysi, J.
%A Dorado, C.
%A Mora Custodio, Ricardo
%A Yáñez García, Juan Manuel
%A Morales-Alamo, D.
%A Perez-Suarez, I.
%A Calbet, J. A. L.
%A González Badillo, Juan José
%T Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations
%D 2017
%U https://hdl.handle.net/10433/22396
%X 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.
%K Muscle strength
%K Training to failure
%K Muscle hypertrophy
%K Fiber type
%K Magnetic resonance imaging
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