Assessment of muscle architecture of the biceps femoris and vastus lateralis by ultrasound after a chronic stretching program.
OBJECTIVE
To evaluate the chronic effects of a static stretching program on the muscle architecture of biceps femoris (BF) and vastus lateralis (VL) muscles in ultrasound (US) images.


METHODS
Randomized controlled longitudinal trial.


METHODS
Biomechanics Laboratory of Physical Education School of the Army, Rio de Janeiro, Brazil.


METHODS
The study included 24 healthy and physically active male volunteers (19.05 ± 1.40 years, 1.73 ± 0.07 m, and 73.15 ± 8.33 kg), randomly allocated to 1 of 2 groups: stretching group (SG, n = 12) and control group (n = 12).


METHODS
The SG was submitted to 3 sets of 30 seconds of static stretching 3 times a week during 8 weeks.


METHODS
Ultrasound equipment (7.5 MHz) was used for the evaluation of BF and VL muscle architecture variables (pennation angle, fiber length, muscle thickness, and fascicle displacement) before and after training. Knee range of motion (ROM) and isometric flexion and extension torque (TQ) were also measured.


RESULTS
There were no significant changes in muscle architecture, TQ, and maximum knee flexion angle (P > 0.05). However, maximum knee extension angle (MEA) increased significantly in the SG (pretraining: 159.37 ± 7.27 degrees and posttraining: 168.9 ± 3.7 degrees; P < 0.05).


CONCLUSIONS
Volume or intensity (or both) of the stretching protocol was insufficient to cause structural changes in the VL and BF muscles. The increase in MEA could not be explained by muscle architecture changes.


CONCLUSIONS
To describe changes in the VL and BF muscle tendon unit using US after a long-term stretching program to identify which structures are responsible for ROM increase.
*Biomedical Engineering Program, COPPE/Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; and †School of Physical Education and Sports, Department of Biosciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Kelly M M
KM
e Lima
Simone P
SP
Carneiro
Daniel de S
Dde S
Alves
Carolina C
CC
Peixinho
Liliam F
LF
de Oliveira
D000293:Adolescent; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000000981:diagnostic imaging*; D053580:Muscle Strength / Q000502:physiology; D052580:Muscle Stretching Exercises / Q000379:methods*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D009929:Organ Size; D052097:Quadriceps Muscle / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D016059:Range of Motion, Articular / Q000502:physiology; D013848:Thigh; D014463:Ultrasonography; D055815:Young Adult