Biomechanics, Volume 4, Issue 2 (June 2024) – 4 articles

Throwing performance is a critical aspect of sports, particularly in overhead activities, necessitating reliable assessment methods. This study explores the test–retest reliability of throwing performance metrics measured by the 1080 Sprint, a robotic device integrating linear position technology and an electric motor. Specifically focusing on professional volleyball athletes with scapular dyskinesis, the study draws data from a previously published investigation on the impact of mirror cross exercise. Thirty-nine athletes were recruited, aged 21.9 ± 3.6 years, height 1.79 ± 0.3 m weight 68.5 ± 19.8 kg, and body mass index 21.3 ± 3.2 kg/m², meeting stringent inclusion criteria. One-sample t-tests indicated no statistically significant differences between test–retest trials. The study revealed excellent reliability of the 1080 Sprint, with intraclass correlation coefficient (ICC) values exceeding 0.99 for all metrics, including speed, force, and power. The standard error of measurement (SEM) calculation revealed that the Sprint 1080 motorized resistance device demonstrates high precision in measuring throwing performance. Bland and Altman plots indicated minimal systematic bias across all metrics, encompassing speed, force, and power. The provision of the minimum detectable change (MDC) for each variable of the Sprint 1080 motorized resistance device offers coaches a valuable tool to identify performance improvements in volleyball athletes. In conclusion, the present study shows that the 1080 Sprint is valid and reliable for measuring throwing performance in volleyball athletes for monitoring purposes. Full article

Lower extremity joint kinetic factors are thought to modulate walk-to-run transition (WRT) and run-to-walk transition (RWT). This study aimed to investigate joint stiffness and energetic patterns during the WRT and RWT processes and identify whether gait transitions occur within a single step or not. Ten healthy subjects participated in treadmill WRT (1.8–2.4 m/s) and RWT (2.4–1.8 m/s) tests. We investigated two steps before transition (S–2, S–1), two steps after transition (S1, S2) and the transition step (S0). We found significant differences between S2 and S–2 for ankle joint stiffness during WRT and RWT (p < 0.001); for hip joint stiffness, we found significant differences between S1 and S–1 during WRT and RWT (p ≤ 0.001). Additionally, stance phase mechanical energy generation was observed to transfer from proximal to distal joints at S0 during WRT, and from distal to proximal at S0 during RWT. Transition step ankle kinematic and kinetic patterns were similar to the target locomotion task gait format in both WRT and RWT. Moreover, RWT required longer adaptation time compared with WRT. These findings indicate that WRT and RWT were modulated before and after the actual transitions, not within a single step. Redistribution of joint mechanical work generation was related to gait transition triggers, which modulate the WRT and RWT processes. Full article

This study investigates the sagittal plane dynamics of the foot, particularly the metatarsophalangeal (MTP) joint and medial longitudinal arch (MLA) movements, in relation to obesity and foot health. The kinematics of the MTP and arch joints were measured in 17 individuals with class 2–3 obesity (BMI > 35 kg/m²) and 10 normal-weight individuals (BMI ≤ 24.9 kg/m²) using marker-based tracking. Analysis was conducted during heel lifting while seated and during walking at self-selected speeds. The results indicated that obese participants exhibited 20.92% greater MTP joint dorsiflexion at the end of the push-off phase and 19.84% greater MLA compression during the stance phase compared to normal-weight controls. However, no significant differences were found in the kinematic joint coupling ratio. While these findings reveal the different biomechanical behaviors of the MTP joint and MLA in obese compared to normal-weight individuals, it is important to interpret the implications of these differences with caution. This study identifies specific biomechanical variations that could be further explored to understand their potential impact on foot health in obese populations. Full article

This narrative review aims to provide a comprehensive overview of the scientific literature on wheelchair badminton and its distinctive aspects, encompassing abilities and disabilities, propulsion technique, and the use of a racket. The relatively young history of wheelchair badminton is reflected in the scarcity of scientific studies within this domain, highlighting the need for further investigation. The review systematically covers existing articles on wheelchair badminton, offering a nearly exhaustive compilation of knowledge in this area. Findings suggest that athletes with abdominal capacities engage in more intense matches with a higher frequency of offensive shots compared to athletes with little or no abdominal capacities. Moreover, backward propulsion induces higher cardiorespiratory responses, overall intensity of effort, physiological stress, metabolic load, and rating of perceived exertion, particularly at high imposed rolling resistance or speeds, and makes it difficult to generate sufficient forces on the handrim, requiring adjustments in the kinematics of propulsion techniques, particularly at high rolling resistances or speeds, potentially leading to performance decrements. The use of a badminton racket further increases generated forces while decreasing the efficiency of propulsion and modifying the propulsion technique with shorter and quicker pushes, potentially impacting performance. Further research is imperative to explore additional perspectives, address existing gaps, and expand the scope of study within the wheelchair badminton domain. This narrative review serves as a foundation for future investigations, emphasizing the necessity of continued research to enhance our understanding of wheelchair badminton. Full article