Muscle architecture of the rectus femoris and vastus lateralis in cyclists, runners, triathletes, and physically active individuals

The study aimed to compare measurements of fascicle length (FL), muscle thickness (MT), and pennation angle (PA) of the vastus lateralis (VL) and rectus femoris (RF) muscles of cyclists, runners, triathletes, and physically active individuals (control group). Forty volunteers (10 cyclists, 10 runners, 10 triathletes, and 10 physically active individuals) aged between 18 and 45 years participated in the study. FL, MT, and PA were measured by a B-mode ultrasound system with panoramic imaging. For RF, the variables were analyzed at 50% of its length. For VL, five positions along its length were analyzed (0%, 25%, 50%, 75%, and 100%), with 0% near the knee and 100% near the hip. FL, MT, and PA data from the RF were analyzed using a one-way ANOVA for comparison between groups, and data from the VL were analyzed using a two-way ANOVA (group vs. position). In case of significant interaction, the variables were compared between groups using Tukey's post-hoc test. All statistical analyses were performed considering p<0.05. No group interaction was observed for all RF variables. No group interactions were observed for all VL variables. However, there is a significant interaction between positions in the VL for MT and PA, with larger measurements observed at 0% and smaller measurements at 100%. We conclude that there are no differences in muscle architecture when comparing cyclists, runners, triathletes, and physically active individuals. However, the groups do show higher MT and PA values in the region near the knee (0%).