The topography of hypertrophy: how muscle architecture changes with strength training

Download files
Access & Terms of Use
open access
Copyright: Eguchi, Junya
Altmetric
Abstract
Background. Progressive resistance training (PRT) changes skeletal muscle architecture. The effects of training on muscle architecture have been difficult to study in detail with conventional methods such as ultrasound imaging, which is usually limited to two-dimensions and is prone to projection errors. In this study, diffusion tensor imaging (DTI; a magnetic resonance imaging (MRI) technique) was used to investigate three-dimensional changes in the architecture of four knee extensor muscles following PRT. We also compared ultrasound measurements of muscle architecture with DTI measurements. Methods. Eleven healthy young adults completed eight weeks of PRT of the quadriceps muscles (leg press and leg extension). From anatomical MRI and DTI scans of the upper leg, mean fascicle lengths, pennation angles, muscle volume and physiological cross-sectional area (PCSA) were obtained from the rectus femoris (RF), vastus lateralis (VL), vastus intermedius (VI) and vastus medialis (VM) muscles before and after training. Mean fascicle length and pennation angle of VL, and anatomical cross-sectional area (ACSA) of VL, VM and RF were obtained using ultrasound. Results. Mean isometric strength increased by 12±14% (p<0.05). Volume increased (p<0.01) in all muscles, ranging from 11% in VI to 14% in VL. Fascicle length increased (p<0.01) by 13±14% (mean±SD) in VM, by 19±14% in VI and by 22±22% in RF, and did not change significantly in VL (p=0.84). PCSA increased in VL (13±17% increase, p<0.05) but not in other muscles. Pennation angles and summed PCSA did not change significantly. Isometric strength change did not correlate significantly with summed PCSA change (r=0.25; p=0.06). Mean ACSA measurements were larger for MRI than ultrasound. Ultrasound and DTI/MRI measurement comparisons of VL fascicle length and pennation angle showed weak negative and positive correlations, respectively. Discussion. This is the first DTI-based study to measure training-induced changes in muscle architecture. The data corroborate previous findings made with ultrasound that fascicles increase in length following PRT. Muscle volume increased by a similar amount to fascicle length. Surprisingly, the lack of PCSA increase meant that PCSA
Persistent link to this record
Link to Publisher Version
Link to Open Access Version
Additional Link
Author(s)
Eguchi, Junya
Supervisor(s)
Herbert, Rob
Bolsterlee, Bart
Thom, Jeanette
Creator(s)
Editor(s)
Translator(s)
Curator(s)
Designer(s)
Arranger(s)
Composer(s)
Recordist(s)
Conference Proceedings Editor(s)
Other Contributor(s)
Corporate/Industry Contributor(s)
Publication Year
2018
Resource Type
Thesis
Degree Type
Masters Thesis
UNSW Faculty
Files
download public version.pdf 2.09 MB Adobe Portable Document Format
Related dataset(s)