The effects of exercise variation in muscle thickness, maximal strength and motivation in resistance trained men

Autoři: Eneko Baz-Valle aff001;  Brad J. Schoenfeld aff002;  Jon Torres-Unda aff003;  Jordan Santos-Concejero aff001;  Carlos Balsalobre-Fernández aff004
Působiště autorů: Department of Physical Education and Sport, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain aff001;  Health Sciences Department, Bronx, NY, United States of America aff002;  Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain aff003;  Department of Physical Education, Sport and Human Movement, Autonomous Univerisity of Madrid, Madrid, Spain aff004
Vyšlo v časopise: PLoS ONE 14(12)
Kategorie: Research Article



The objective of the present study was to compare the effects of a traditional resistance training program (fixed exercises and repetition ranges) to a resistance training program where exercises and repetition ranges were randomized on a session-by-session basis on markers of muscular adaptations and intrinsic motivation.


Twenty-one resistance trained men were randomized to perform an 8-week resistance training program using either a fixed exercise selection (CON) or having exercises randomly varied each session via a computerized app. Both groups performed 3 sets of 6 exercises, with training carried out 4 times per week.


Both conditions promoted large, statistically significant increases in the bench press and back-squat 1 repetition maximum without differences between groups. Muscle thickness (MT) measures for the individual quadriceps showed large, statistically significant increases in of the vastus lateralis and rectus femoris for both conditions, with no observed between-group differences. Although no between-group in MT were noted for the vastus intermedius, only the CON displayed significant increases from baseline. Participants in EXP showed a significant, moderate improvement in the intrinsic motivation to training, while participants in the CON group presented non-significant decreases in this variable.


Varying exercise selection had a positive effect on enhancing motivation to train in resistance-trained men, while eliciting similar improvements in muscular adaptations.

Klíčová slova:

Adipose tissue – Anthropometry – Exercise – Legs – Muscle analysis – Questionnaires – Strength training – Ultrasound imaging


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2019 Číslo 12
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