Pennation Angle of the Quadricep Femoris Muscles in Resistance Trained Males vs. Non-Resistance Trained Males

Abstract

Pennation angle (PA) is the orientation at which muscle fibers attach to the deep aponeurosis within a muscle. PA is measured using in-vivo methods (ultrasound) which allows researchers to observe any angle discrepancies throughout different locations in the muscle. The quadriceps femoris (QF) is a muscle group used on a daily basis. Understanding the architecture of the QF is helpful for understanding and improving performance in sports or activities which relies on running, jumping, or explosive movements. Another reason to pursue our understanding of muscle architecture is examining potential for injury. Furthermore, asymmetrical strength of the quadriceps can lead to increased risk of injuries. However, limited research has looked at muscle architecture asymmetry as it relates to injury and function. PURPOSE: The aim of this study was to determine the magnitude of bilateral asymmetry for PA in the QF in resistance trained (RT) and non-resistance trained (NRT) males. METHODS: Thirty-eight males (22.97 ± 2.58 yrs., 180.22 ± 6.90cm, and 88.62 ± 14.88 kg) were recruited to participate in this study (25 were lower body RT and 13 were (NRT). The first visit consisted of protocol explanation and familiarization. The following visit consisted of PA assessment of the QF muscles using B-mode ultrasound. All PA measurements were taken in random order on both legs. Three images were taken and analyzed from the vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF) and vastus intermedius (VI). RESULTS: There was no significant group x leg effect for PA of the QF, [VM (p = 0.470), VL (p = 0.795), RF (p = 0.431), VI (p = 0.563)].Collapsing across groups revealed a non-significant effect on asymmetry as well (all p>0.05). The between leg percent differences were; VM 6.08% ± 3.65%, VL 4.84% ± 4.1%, RF 3.87% ± 4.0% and VI 3.53% ± 5.87%. CONCLUSION: This study revealed that PA angle in the QF muscles was not significantly different between RT and NRT in males.