title: Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training.
abstract: One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion.
authors.affiliation: Physical Education Post-Graduation Program, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.|Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Thiago Torres
authors.initials: TT
authors.lastname: Matta
authors.affiliation: Physical Education Post-Graduation Program, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.|Army Physical Education School, Rio de Janeiro, RJ, Brazil.
authors.forename: Francisco Xavier
authors.initials: FX
authors.lastname: Nascimento
authors.affiliation: Centre for Exercise and Sports Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, WA, Australia.
authors.forename: Gabriel S
authors.initials: GS
authors.lastname: Trajano
authors.affiliation: Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Roberto
authors.initials: R
authors.lastname: Simão
authors.affiliation: Kinesiology and Sports Studies Department, Eastern Illinois University, Charleston, IL, USA.
authors.forename: Jeffrey Michael
authors.initials: JM
authors.lastname: Willardson
authors.affiliation: Physical Education Post-Graduation Program, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.|Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Liliam Fernandes
authors.initials: LF
authors.lastname: Oliveira
mesh_terms: D000222:Adaptation, Physiological; D001938:Brazil; D006801:Humans; D006984:Hypertrophy; D007537:Isometric Contraction; D008297:Male; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D013997:Time Factors; D019415:Torque; D016896:Treatment Outcome; D014463:Ultrasonography; D055815:Young Adult
keywords: dynamometer; muscle mass; muscle thickness; performance; strength training; ultrasound