ECSS Paris 2023: CP-BM18
INTRODUCTION: The deadlift is the last discipline of powerlifting and is crucial for competition success. The International Powerlifting Federation (IPF) allows two techniques, the sumo (SDL) and conventional (CDL) [1]. This study aims to investigate differences in muscle forces during preferred and non-preferred deadlifts. We hypothesised that those performing their preferred deadlift technique would require lower hip extensors, hip flexors, hip adductors, and knee extensors muscle forces compared to the non-preferred technique. METHODS: Two national-level powerlifters (1 female), active members of the Austrian Powerlifting Federation, were recruited for this study. Individual one-repetition maximum was self-estimated (e1RM) according to the athlete’s information in previous training sessions. The female athlete was using the sumo deadlift as the preferred technique (57.6kg; e1RM: 120kg; 20y; 4y of strength training experience). The male athlete was executing the conventional deadlift as the preferred technique (98kg; e1RM: 290kg; 27y; 8y of strength training experience). After an individual warm-up, each participant performed four sets of one repetition at 80% of preferred e1RM both in the preferred and non-preferred techniques. Lifts were performed following the rules of the IPF [1]. Joint kinematics were calculated using a Vicon motion capture system with 12 infrared cameras. Ground-reaction forces were captured with two Kistler forces plates and used to compute joint moments and muscle forces in OpenSim 4.5 [2,3]. Forces for each muscle group were calculated (hip extensors (HE), hip adductors (HAd), and knee extensors (KE)) and time-varying waveforms were used to estimate significant differences using paired t-tests via statistical parametric mapping. RESULTS: Results indicate that during the preferred SDL, HE and KE muscle forces were lower compared to the non-preferred lift. The athlete who prefers CDL, lifts with higher KE and HE muscle forces, compared to his non-preferred technique. No significant differences in HE between the SDL and CDL were observed. In both participants KE muscle forces during the CDL were significantly higher than those during SDL, independently of the athlete’s preference. The HAd muscle forces were also significantly larger during CDL compared to the SDL for both athletes. CONCLUSION: The results of this preliminary study contradict our initial hypothesis, suggesting the preferred deadlift technique cannot be explained by lower muscle forces compared to the non-preferred technique. We suggest that athletes with lower muscle force capabilities in the HE and KE should use the SDL. However, when the goal is to train the HE and KE, the CDL is recommended. References: 1. International Powerlifting Federation. (2025). powerlifting.sport/rules/codes/info/technical-rules 2. Delp et al. (2007). 10.1109/TBME.2007.901024 3. Rajagopal et al. (2016). 10.1109/TBME.2016.2586891
Read CV Marcel HackerECSS Paris 2023: CP-BM18
INTRODUCTION: The Copenhagen adductor exercise (CAE) is effective for improving hip adductor muscle strength. However, CAE variations have been proposed that may increase or decrease loading of these muscles. Specifically, CAE may be performed with the support at the knee, ankle, or between these joints (MID). This study aimed to determine hip and knee loading for these CAE variations. METHODS: Twenty-four participants (13 women) performed three repetitions of each CAE variation using their right lower limb. Reflective markers were used to model the pelvis and right lower limbs. A wooden support was placed on a force platform and the force acting on the lower limb was calculated. Sagittal, frontal, and transverse plane hip and knee net joint moments (NJM) were calculated. RESULTS: The hip adductor NJM was 0.93 ± 0.16 Nm/kg for knee, 1.36 ± 0.21 Nm/kg for MID, and 1.54 ± 0.23 Nm/kg for ankle support placements. The sagittal hip NJM was an extensor moment (knee: -0.17 ± 0.23 Nm/kg; MID: -0.28 ± 0.32 Nm/kg; ankle: -0.38 ± 0.40 Nm/kg). Both hip adductor and extensor NJM were greatest for the ankle and smallest for the knee (P < 0.005) support. Hip sagittal plane NJM was significantly correlated with thigh transverse plane orientation for all variations (R2 = 0.94-0.96; P < 0.001). There was a knee abductor (-0.12 ± 0.03 Nm/kg) and knee extensor (0.08 ± 0.04 Nm/kg) NJM for the knee support. The other variations had knee adductor (MID: 0.44 ± 0.09 Nm/kg; ankle: 0.73 ± 0.14 Nm/kg) and flexor (MID: -0.16 ± 0.01 Nm/kg; ankle: -0.43 ± 0.21 Nm/kg) NJM. Knee frontal and sagittal NJM were different between each condition (P < 0.005). Knee sagittal plane NJM was significantly correlated with leg transverse plane orientation for all variations (R2 = 0.80-0.87; P < 0.001). CONCLUSION: Hip adductor loading increased as the CAE support location was moved from the knee to the ankle. Most participants had a hip extensor NJM, however some utilized a hip flexor NJM. The correlations between thigh transverse plane rotation and hip sagittal plane NJM demonstrated that a more medially rotated thigh had hip flexor NJM while less medial thigh rotation resulted in a hip extensor NJM. Most hip adductor muscles are hip flexors while the ischiocondylar head of adductor magnus is a hip extensor. Therefore, these muscles may act synergistically to generate the hip adductor NJM while neutralizing the flexor and extensor actions. Changing thigh transverse plane rotation may alter this load sharing to favour those adductors that are flexors or extensors. CAE variations with the support distal to the knee had internal knee adductor and flexor NJM, which are equivalent to external knee abduction and extension moments. This combination of external moments may place stress on the anterior cruciate and medial collateral ligaments. As support location for the CAE moves distally, hip and knee moments increase. Consequently, potential stress on the knee ligaments should be considered when attempting to increase hip muscle loading.
Read CV Loren ChiuECSS Paris 2023: CP-BM18
INTRODUCTION: Due to sport profile, rowing is classified into sweep rowing (single oar) and scull rowing (double oar) (1). Athletes have to repeat the rowing movement throughout the race, during the race load will accumulate continuously (2), it will affect particular muscle groups’ muscle mechanical properties and promoting injury risk (3). Rowers may have bilateral muscle asymmetry due to specific technical factors. Many studies have pointed out that changes in muscle mechanical properties, such as muscle tone and stiffness, are related to sports performance and injuries (4,5). The purpose of this study was to investigate the differences in bilateral muscle mechanical properties between the dominant side and the non-dominant side of sweep and sculls rowers before and after the 2000-meter time trial test of water rowing. METHODS: Six male sweep rowers (SW, n=6) and 6 male sculls rowers (SC, n=6) were recruited for this study. The handheld MyotonPRO device was used to collect muscle tone (frequency) and stiffness data of the posterior deltoid (PD) and vastus medialis (VM) (dominant and non-dominant sides) before and after the 2000-meter time trial test of water rowing. Two-way mixed-design analysis of variance was used to analyze differences in muscle tone (frequency) and stiffness between dominant and non-dominant at pre- and post-rowing time-trial. RESULTS: The results of the mixed-design two-way ANOVA showed that in the sweep group, the muscle tone (frequency) of the non-dominant side PD (F = 5.06; p = 0.048) and VM (F = 5.89; p = 0.036), as well as the dominant side PD (F = 10.45; p = 0.009) and VM (F = 6.08; p = 0.033) were significantly increased after the 2000-meter time trial test. On the other hand, the muscle stiffness of the non-dominant side PD (F = 6.12; p = 0.033) and VM (F = 5.14; p = 0.047), as well as the dominant side PD (F = 5.42; p = 0.042) and VM (F = 9.26; p = 0.012) were significantly increased after the 2000-meter time trial test. In the sculls groups, the muscle tone (frequency) of the non-dominant side PD (F = 4.40; p = 0.062) and VM (F = 3.47; p = 0.092), as well as the dominant side PD (F = 4.00; p = 0.074) and VM (F = 2.69; p = 0.132) showed no significant increase after the 2000-meter time trial test. On the other hand, the muscle stiffness of the non-dominant side PD (F = 0.67; p = 0.431) and VM (F = 2.75; p = 0.128), as well as the dominant side PD (F = 2.03; p = 0.185) and VM (F = 3.42; p = 0.094) showed no significant increase after the 2000-meter time trial test. CONCLUSION: After a high-intensity, high-load 2000-meter water rowing time trial, PD and VM in the sweep group showed an increase in muscle tone and stiffness, as well as symmetrical changes in bilateral muscle mechanical properties.
Read CV Chun-Hao ChangECSS Paris 2023: CP-BM18