ECSS Paris 2023: CP-BM05
INTRODUCTION: Maximal strength has been reported to improve running economy and is considered an important factor influencing long-distance running performance [1]. Muscle strength is closely associated with morphological characteristics, and maximal strength is generally proportional to muscle cross-sectional area (CSA), which is often used as an indicator of muscle strength. Previous studies have reported positive associations between quadriceps femoris CSA and sprint performance in long-distance runners [2]. However, increased muscle mass may increase lower-limb mass and moment of inertia, potentially disadvantaging leg swing during running. Although muscle morphology is thought to influence running kinematics and performance, the relationship between thigh muscle CSA and running kinematics remains unclear. Therefore, the purpose of this study was to investigate the relationship between the CSA of individual thigh muscles and lower-limb kinematics in long-distance runners. METHODS: Eight male long-distance runners participated in this study (height: 1.66 ± 0.05 m, weight: 53.6 ± 4.5 kg, 5000-m personal best time: 14’11’’0 ± 0’28’’2). CSA of each muscle was obtained from T1-weighted spin-echo axial images at 50% of the right thigh length using magnetic resonance imaging. Running kinematics were obtained by recording treadmill running at 20 km/h from the left sagittal plane. Joint angles, angular velocities, and joint torques of the hip and knee were calculated from digitized body landmark coordinates. Pearson's correlation coefficients were used to analyze relationships between muscle CSA and 5000-m personal best times, kinematic variables, and joint torques. RESULTS: CSA in rectus femoris exhibited significant positive correlations with mean hip extension angular velocity (r=0.92, p<0.01) and maximum knee flexion torque during the flight phase (r=0.80, p<0.05). In contrast, CSA in semimembranosus exhibited a significant negative correlation with mean knee flexion angular velocity (r=-0.84, p<0.05). No significant correlations were observed between CSAs in other muscle and 5000-m personal best times, kinematic variables, or joint torques. CONCLUSION: In long-distance runners, morphological characteristics of the rectus femoris and semimembranosus are associated with hip and knee joint angular velocities during running and knee joint torque during the flight phase. 1. Støren et al., Med Sci Sports Exerc, 2008. 2. Ando et al., J Hum Kinet, 2022.
Read CV Haruka TAKAHASHIECSS Paris 2023: CP-BM05
INTRODUCTION: Percussive massage therapy (PMT) has become more common in clinical settings and among the general population. Although initial findings suggest that PMT may increase muscle strength, the mechanisms underlying these effects are unclear. The purpose of this study was to investigate the acute effects of PMT on gastrocnemius muscle architecture, which is a key determinant of muscle function. METHODS: The study included 43 healthy young participants (21 females, 22 males; age: 20.30±1.79 years, body height: 172.23±9.03 cm, body weight: 65.37±10.94 kg, body mass index: 21.91±2.24 kg/m²). Participants were randomly assigned to either the PMT group (N=23; 12 females, 11 males) or the control group (N=20; 9 females, 11 males). B-mode ultrasonography was used to investigate the architectural characteristics of the gastrocnemius lateralis and gastrocnemius medialis muscles, including pennation angle, muscle thickness, and fiber length parameters. Participants in the PMT group underwent a percussive massage intervention using the Hypervolt Go 2 device at 2750 ppm. The intervention was applied sequentially to each gastrocnemius muscle group for 8 minutes per side. Participants in the control group rested for an equivalent duration. Muscle architecture assessments were repeated bilaterally immediately after the intervention or rest period. Statistical analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA). RESULTS: The PMT and control groups were comparable in terms of baseline sociodemographic characteristics and muscle architectural parameters (p > 0.05). There were no significant differences between pre- and post-intervention measurements in the dominant or non-dominant limbs of either group (p > 0.05). CONCLUSION: Applying PMT to the gastrocnemius lateralis and gastrocnemius medialis muscles of healthy young individuals does not cause significant acute changes in the architectural characteristics of these muscles. These results suggest that the acute effects of PMT may be neuromuscular rather than structural. Future research could focus on the effects of repeated or long-term PMT applications on muscle structure.
Read CV Beyzanur İnanECSS Paris 2023: CP-BM05
INTRODUCTION: Changes in joint angle alter passive tension applied to the muscle-tendon unit and its surrounding connective tissues. When the muscle-tendon unit is elongated by changes in joint angle, both muscle and deep fascia stiffness increase [1, 2]. This angle-dependent increase in stiffness reflects changes in tissue loading and could be involved in force transmission within the musculoskeletal system. Although the stiffness of muscle and deep fascia has been reported to differ across regions within the quadriceps femoris [3, 4], it remains unclear how the stiffness of these regions varies with to changes in joint angle. Clarifying whether stiffness changes differ across anatomical regions may help to better understand how the quadriceps femoris distributes mechanical load during passive elongation. Here, we examined region-specific changes in deep fascia stiffness within the quadriceps femoris at different knee flexion angles. METHODS: Shear wave elastography was used to measure shear wave velocity (SWV) of muscle and deep fascia as an index of stiffness in 25 healthy males. The SWV was measured under passive conditions in the proximal and distal regions of the rectus femoris, vastus lateralis, and vastus medialis at knee flexion angles of 0 (full extension), 45, and 90 deg. In addition, we measured SWV in the medial and lateral regions of the vastus lateralis. Linear mixed-effects models were used to test the effects of region, knee flexion angle, and their interaction. RESULTS: Muscle SWV increased with knee flexion angle in all examined regions of the rectus femoris, vastus lateralis, and vastus medialis (all p < 0.001). A significant interaction between region and knee flexion angle was found for the SWV of deep fascia (p < 0.01). The deep fascia SWV increased with knee flexion angle in most regions (p < 0.001), whereas no significant change in deep fascia SWV was detected in the proximal-lateral region of the vastus lateralis across the tested angles (p = 0.998). CONCLUSION: Across the quadriceps femoris, the muscle stiffness increased consistently with knee flexion angle, whereas the deep fascia stiffness changed differently between regions. The mechanisms underlying these regional differences may be related to regional variations in fascial microstructure, such as differences in collagen fiber organization and multilayered structure [5]. Such region-dependent stiffness changes suggest complexity of local mechanical loading within the vastus lateralis, and may be relevant when considering region-specific effects of stretching. REFERENCE: [1] Chen B. et al., Sci Rep, 2020 [2] Chanel B. et al., Translational Sports Med, 2025. [3] Kodesho T. et al., Eur J Appl Physiol, 2021. [4] Otsuka S. et al., J Biomech, 2020 [5] Otsuka S. et al., J Biomech, 2018
Read CV Satoshi MikataECSS Paris 2023: CP-BM05