Heterogeneity of rectus femoris muscle architectural adaptations after two different 14-week resistance training
Thiago T Matta1, Francisco X M B Nascimento, Igor A Fernandes
1Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; School of Physical Education and Sports, Laboratory of Biomechanics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Purpose:
This study aimed to determine the architectural changes of rectus femoris muscle at distinctive sites of the thigh length after two different 14-week resistance training programmes.
Methods:
Thirty-five untrained men were randomly allocated into three different groups: conventional resistance training (n = 12), isokinetic training (n = 12) and control (n = 11). Rectus femoris cross-sectional area, thickness and fascicle angle at two specific thigh sites (30% and 50% of the length) were assessed before and after 14 weeks of unilateral knee extension exercise or control. The isometric peak torque of the knee extensors was estimated as a muscle strength index.
Results:
Conventional (30% = 47·4% versus 50% = 14·4%) and isokinetic (30% = 31·8% versus 50% = 11·4%) training induced significant increases on thickness at both rectus femoris sites. While conventional training resulted in substantial increments on cross-sectional area (30% = 62·1%, 50% = 19·5%), isokinetic training provoked a significant increase only at the distal site (50% = 64·7%). The isometric peak torque increased (22·4 and 29·6%, for conventional and isokinetic groups, respectively) after training independently of the training mode, although no significant changes were observed for any dependent variable in the control group.
Conclusions:
In general, the training modes resulted in similar changes on rectus femoris architecture, whereas their magnitude depended on the thigh site.
