Acute effects of 20-40% Velocity Loss Training on Leg Muscle Oxygenation During Back Squat

  1. Corral-Román, J 12
  2. Marín-Galindo, A. 12
  3. Costilla, M. 12
  4. Muñoz-López, A. 5
  5. Sánchez-Sixto, A. 4
  6. Sañudo, B. 3
  7. Casals-Vázquez, C. 12
  8. Ponce González, J.G. 12
  1. 1 MOVE-IT Research group and Department of Physical Education, Faculty of Education Sciences University of Cádiz, Cádiz, Spain.
  2. 2 Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital University of Cádiz, Spain.
  3. 3 Department of Physical Education and Sports, University of Seville, Seville, Spain.
  4. 4 Centro de Estudios Universitarios Cardenal Spínola CEU, Seville, Spain.
  5. 5 Department of Human Motor Skills and Sport Performance, University of Seville, Seville, Spain.
XII Simposio Internacional de Fuerza y Proyecto IronFEMME

Publisher: Universidad Politécnica de Madrid

ISBN: 978-84-09-16216-1

Year of publication: 2019

Pages: 99-100

Type: Conference paper


INTRODUCTION: Despite resistance training at different velocity loss (20% or 40%) obtained similar hypertrophy and squat strength gainsafter 8 weeks, the percentage of type IIX fibers is reduced in the RT program based on repetitions to failure (40%) (1). This fact could be explained by different muscle oxygenation. Therefore, the aim of this study was to describe the within-and-between-conditions differences in tissue oxygenation index (TOI) of two RT programs that only differed in the velocity loss in every set: 20% (20VL) or 40% (40VL). METHODS: 28 young men (21.8±2.3 yrs) were randomly allocated to 20VL or 40VL and performed three sets of back squat exercise. One week apart the order was reversed following a crossover design. Exercise intensity was set at 1 m·s-1, previously calculated with a progressive resistance test. TOI was measured before and continuously during the exercise in Vastus Lateralis (VL) and Vastus Medialis (VM) with a spatially resolved spectroscopy tissue oximeter (NIRO-200Nx). Differences within-and-between-conditions were determined through repeated measures ANOVA and Bonferroni post hoc (p<0.05). RESULTS: At 20VL, TOI was 76.5±4.6% and 76.0±5.6% at rest for VL and VM respectively. TOI decreased from the previous data to 45.3±16.4% and 46.9±12.9% during the first set, to 45.2±16.5% and 46.7±12.8% during the second, 44.8±18.1% and 47.3±13.3% during the third. TOI showed significant differences before and during the exercise (p<0.001) However, no significant differences were found between the sets. At 40VL, TOI was 75.5±4.8% and 75.8±3.3% at rest for VL and VM respectively. During exercise TOI dropped to 43.8±16.9% and 47.4±12% during the first set,to 43.6±16.2% and 46.7±12.8% during the second, 48.4±19.1% and 47.3±13.3% during the third. Similarly to 20VL, there were significant differences in TOI before and during the execution of the set (p<0.001), while no differences between sets were observed. No significant between-groups differences were found when the sets were compared. DISCUSSION: Our results showed a decrease in TOI during the exercise performance with both velocity loss protocols. Nevertheless, there were no significant differences between both conditions. Hence, variation in muscle fiber type distribution in 40VL RT could not be due to differences in muscle oxygenation during exercise compared to 20VL RT. REFERENCES: 1. Pareja Blanco F, RodríguezRosell D, Sánchez-Medina L, Sanchis-Moysi J, Dorado C, Mora-Custodio R, et al.Effects of velocity loss during resistance training on athletic performance,strength gains and muscle adaptations. Scand J Med Sci Sports. 2017;27(7):724–35.