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Scientific Programme

Biomechanics & Motor control

OP-BM17 - Running I

Date: 04.07.2024, Time: 13:45 - 15:00, Lecture room: Boisdale 2

Description

Chair TBA

Chair

TBA
TBA
TBA

ECSS Paris 2023: OP-BM17

Speaker A Qin Zhang

Speaker A

Qin Zhang
Shanghai University of Sport, School Of Athletic Performance
China
"Correlation between isokinetic lower-limb joint strength and joint stiffness in recreational runners"

INTRODUCTION: Stiffness, originally derived from "Hooks Law," is defined as the ratio between the external force and the deformation displacement applied to a spring system, reflecting the systems elastic performance and its ability to accumulate elastic potential energy. In running, higher lower-limb stiffness is beneficial for the storage and release of elastic energy, thus improving running economy. Knee and ankle joint stiffness are considered determining factors of lower-limb stiffness. Meanwhile, during the ground contact phase of running, the muscles around the knee and ankle joints contract synergistically to produce force and regulate the joint stiffness. Therefore, joint muscle strength may play an important role in regulating joint stiffness. This study aims to explore the correlation between isokinetic knee and ankle joint strength and knee and ankle joint stiffness in recreational runners. METHODS: Thirty-four male runners were recruited to measure knee and ankle joint stiffness at running speeds of 10 and 12 km·h-1 by the Vicon 3D motion capture system and the Kistler 3D force platforms mounted below the treadmill belt. The isokinetic strength test and training system was used to measure isokinetic knee and ankle joint concentric and eccentric peak torque (PT) at the velocities of 60 and 180°·s-1. Pearson correlations, with the Benjamini–Hochberg correction procedure, were used to analyze the correlation between isokinetic knee joint PT and knee joint stiffness, and the correlation between isokinetic ankle joint PT and ankle joint stiffness. RESULTS: For knee joint, the knee flexor eccentric PT at 60°/s (P<0.001, r=0.614; P<0.001, r=0.592) and 180°/s (P<0.001, r=0.582; P<0.01, r=0.558) was highly positively correlated with knee stiffness at 10 and 12 km·h-1. The knee flexor concentric PT at 60°·s-1 (P<0.05, r=0.417; P<0.05, r=0.404) and 180°·s-1 (P<0.05, r=0.440; P<0.05, r=0.396) was moderately positively correlated with knee stiffness at 10 and 12 km·h-1. For ankle joint, the ankle dorsiflexor eccentric PT at 60°·s-1 (P<0.05, r=0.460; P<0.05, r=0.523) was positively correlated with ankle joint stiffness at 10 and 12 km·h-1. CONCLUSION: knee and ankle stiffness during running may be associated with greater knee flexor and ankle dorsiflexor strength, which would inform muscle strength modulation of lower-limb joint stiffness to improve running performance.

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ECSS Paris 2023: OP-BM17

Speaker B Nichola Renwick

Speaker B

Nichola Renwick
University of Portsmouth, Research Group in Breast Health
United Kingdom
"EVALUATING THE EFFECTIVENESS OF SPORTS BRAS DURING RUNNING THROUGH DISCRETE AND CONTINUOUS MEASURES OF BREAST KINEMATICS "

INTRODUCTION: Breast biomechanics research is largely focused on reporting discrete measures of nipple displacement during various activities. Evaluating breast movement continuously across the gait cycle may provide insight into when and for how long across the gait cycle sports bras are effective at reducing breast kinematics which may more closely correlate with changes in perceived breast support and pain. This study aims to compare discrete and continuous breast kinematic variables and to assess their relationship with perceived breast support and pain. METHODS: Thirty-six females (mode bra size 34D) ran on a treadmill bare-breasted and in a sports bra. Electromagnetic sensors captured nipple motion and calculated it relative to a torso reference system (1); gait cycles were identified from right foot contact. Participants rated perceived breast support and pain (scale 0 to 10). Nipple displacement was reported as range of motion (ROM), peak values and breast movement reduction (2); nipple velocity and acceleration were calculated as first and second derivatives of nipple position and reported as peak values; these discrete values were calculated over ten gait cycles and averaged. Data were checked for normality using Shapiro-Wilk tests; Wilcoxon signed-rank or paired samples t-test compared between breast support conditions. Time histories for relative nipple position (normalised and non-normalised), velocity and acceleration were averaged across ten gait cycles for each participant and compared between breast support conditions using one-dimensional statistical parametric mapping (SPM) (3). Spearman’s rho correlation coefficients assessed the relationship between breast support and pain with kinematic variables. RESULTS: Nipple displacement, velocity and acceleration were significantly reduced in sports bra running compared to bare-breasted running for all discrete variables except peak lateral displacement (p=0.156). SPM identified multiple points across the gait cycle where the sports bra reduced breast movement; superior-inferior normalised displacement was reduced for the largest duration of the gait cycle (87%). Median score for breast support in the bra condition was 8. Median scores for perceived breast pain were 5 and 0 for bare-breasted and bra running, respectively. The strongest relationship with perceived support was reported for superior-inferior ROM (r=0.857; p=<0.001); strongest relationship with breast pain was reported for anterior-posterior peak negative acceleration (r=0.715; p=<0.001). CONCLUSION: Discrete measures of breast kinematics have a stronger relationship to perceived breast pain and support compared to continuous measures but continuous measures can identify when during the gait cycle a sports bra is most effective at reducing breast movement. REFERENCES: 1) Mills et al., J, Biomech, 2016 2) Norris et al., Ergonomics, 2021 3) Pataky, J, Biomech, 2010

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ECSS Paris 2023: OP-BM17

Speaker C Bas Van Hooren

Speaker C

Bas Van Hooren
Maastricht University, Nutrition and Movement Sciences
Netherlands
"The relationship between running biomechanics and running economy: A systematic review and meta-analysis of observational studies"

INTRODUCTION: Running biomechanics are considered an important determinant of running economy (RE). However, studies examining associations between running biomechanics and RE report inconsistent findings. The objective of this review is therefore to determine associations between running biomechanics and RE and explore potential causes of inconsistency. METHODS: Three databases were searched and monitored until April 2023. Observational studies were included if they 1) examined associations between running biomechanics and RE, or 2) compared running biomechanics between groups differing in RE, or 3) compared RE between groups differing in running biomechanics during level, constant-speed, and submaximal running in healthy humans (18-65 years). Risk of bias was assessed using a modified tool for observational studies and considered in the results interpretation using GRADE. Meta-analyses were performed when ≥2 studies reported on the same outcome. Meta-regressions were used to explore heterogeneity with speed, coefficient of variation of height, mass and age as continuous outcomes, and standardization of running shoes, oxygen versus energetic cost, and correction for resting oxygen or energy cost as categorical outcomes. RESULTS: Fifty-one studies (n=1115 participants) were included. Most spatiotemporal outcomes showed trivial and non-significant associations with RE: contact time r = -0.02 (95% confidence interval [CI], -0.15 to 0.12); flight time r = 0.11 (-0.09 to 0.32); stride time r = 0.01 (-0.8 to 0.50); duty factor r = -0.06 (-0.18 to 0.06); stride length r = 0.12 (-0.15 to 0.38), swing time r = 0.12 (-0.13 to 0.36)). A higher cadence showed a small significant association with a lower oxygen/energy cost (r = -0.20 (-0.35 to -0.05). A smaller vertical displacement and higher vertical and leg stiffness showed significant moderate associations with lower oxygen/energy cost (r = 0.35, = -0.31, = -0.28, respectively). Ankle, knee, and hip angles at initial contact, midstance or toe-off as well as their range of motion, peak vertical ground reaction force, mechanical work variables and electromyographic activation were not significantly associated with RE, although potentially relevant trends were observed for some outcomes. CONCLUSION: Overall, our findings show that biomechanical variables can explain 4-12% of the variance in running economy when considered in isolation, with this magnitude potentially increasing when combining different variables. Moreover, we also show that some biomechanical variables often considered relevant to RE (e.g., contact time) are not overall associated with RE when assessed at a similar speed for all runners. Nevertheless, optimal performance may require optimization of running biomechanics beyond simply minimizing energy cost, thus suggesting that components not significantly associated with RE may still be relevant from a performance or injury preventative perspective

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ECSS Paris 2023: OP-BM17