ECSS Paris 2023: CP-BM12
INTRODUCTION: Working with heterogeneous sensor data can substantially improve movement analysis by providing richer biomechanical detail[1]. A persistent obstacle in such setups is temporal misalignment between data streams[2]. Even small offsets can affect outcomes and worsen biomechanical predictions. Current approaches typically (i) rely on explicit synchronization actions or identifiable shared events to align sensor signals[2] or (ii) use hardware-based synchronization via a master device and wireless protocols[1]. However, controlled synchronization actions are often impractical in field or laboratory settings due to missing or mistimed actions, while hardware solutions are not consistently available across systems. Consequently, reliable post-hoc synchronization remains crucial for accurate analyses. METHODS: In this work, we adapt the Nearest Advocate algorithm (NAd)[3], an event-based time delay estimation method originally developed for multi-sensor event time series, to sport science. Raw pressure measurements were preprocessed using a Butterworth low-pass filter, followed by a temporal differentiation, half-wave rectification, and moving-average smoothing to enhance heel-strike features. Heel-strike events were then identified via peak detection with the minimum peak distance constrained by a maximum expected step frequency of 300 spm. Experiments were conducted using 40 instrumented treadmill pressure signals as reference, recorded across multiple speeds and incline conditions per run. For controlled evaluation with known time delays, clones of these signals were generated that are temporally shifted and noise-contaminated, with additive noise levels up to 10% of peak pressure. The experiments comprised: (i) estimation of randomized time delays, (ii) estimation of randomized time delays under systematically missing steps (removal of every second step to simulate one-sided pressure signals), and (iii) visual and statistical assessment of alignment between these treadmill recordings and corresponding pressure insole (PI) data. RESULTS: NAd accurately recovered (i) randomized time delays (RMSE = 0.81 ms ± 0.80 ms; MAE = 0.16 ms), with (ii) moderate degradation when every second step was removed (RMSE = 1.79 ms ± 1.78 ms; MAE = 0.67 ms). For real data, (iii) the temporally corrected (one-sided) PI-signals aligned clearly with treadmill recordings, yielding low post-alignment residual errors (RMSE = 0.24 ms), while estimated global device offsets were ~0.75 s (right) and ~0.74 s (left) with substantial between-trial variability (SD = 1.14 s). CONCLUSION: These experiments indicate that NAd enables millisecond-level post-hoc time delay correction of heterogeneous sensor signals, without requiring dedicated synchronization actions or additional hardware. This enables practical synchronization in cross-device measurement setups and supports more reliable downstream data analysis. [1] Verdel 2023 [2] Bannach 2009 [3] Schranz 2024
Read CV Christina HalmichECSS Paris 2023: CP-BM12
INTRODUCTION: Anterior cruciate ligament (ACL) rupture frequently results in long-term functional deficits, despite surgical reconstruction and extensive rehabilitation. Altered postural control may be a contributing factor to these deficits. Time to stabilization (TTS) is an established method for assessing dynamic postural control. However, evidence following ACL reconstruction remains limited. Therefore, the aim was to assess the dynamic postural control following ACL reconstruction. METHODS: In this cross-sectional study, 24 individuals twelve months following an ACL reconstruction using a quadriceps tendon graft and 24 matched healthy controls were assessed. Participants performed single-leg hops for distance with subsequent landing on a force plate to calculate TTS. Linear mixed models examined group and limb effects. RESULTS: In this cross-sectional study, 24 individuals twelve months following an ACL reconstruction using a quadriceps tendon graft and 24 matched healthy controls were assessed. Participants performed single-leg hops for distance with subsequent landing on a force plate to calculate TTS. Linear mixed models examined group and limb effects. Results: Jump distance was significantly lower in the ACL-involved limb compared to the contralateral limb and both limbs of controls (p < 0.03). TTS was shorter in the ACL-involved limb versus the non-involved limb (estimate = -0.69, SE = 0.19, p = 0.001), with no significant differences between groups (p = 0.21). CONCLUSION: Twelve months following ACL reconstruction, dynamic stabilization during landing appears preserved or even improved in the involved limb. However, the possibility of an influence of the jumping distance cannot be discounted. These findings challenge assumptions of persistent postural deficits following reconstruction and highlight the need for further research.
Read CV Aglaja BuschECSS Paris 2023: CP-BM12
INTRODUCTION: Posture is an automatic and unconscious condition regulated by the Tonic Postural System (TPS), which integrates multisensory afferent inputs to maintain balance and guide movements (1). Given the key role of plantar proprioception in postural control, this study investigated whether plantar proprioceptive stimulation leads to changes on dynamic balance and ankle joint range of motion (ROM). We hypothesized that such stimulation might improve dynamic balance but not induce changes in ankle joint ROM. METHODS: Twenty physically active young adults (mean age: 22.9 1.36 years, height: 169.3 8.84 cm, weight: 64.2 10.44 kg) were randomly assigned to an experimental group (EG, n=10) or a control group (CG, n=10). The EG performed a session of plantar proprioceptive stimulation involving walking on a 2-meter reflexology mat (3x1-minute with 30-second rest among series) and balance exercises on proprioceptive pads, while the CG rested in a supine position for an equivalent period of time (i.e., 14 minutes). Dynamic balance was assessed using the Y-Balance Test (YBT) and ankle joint ROM (i.e., dorsiflexion and plantar flexion) was measured using an inertial sensor (Beyond, Motustech). Assessments were conducted before (T0) and immediately after (T1) the intervention. RESULTS: The EG showed significant improvement in YBT from T0 (mean right: 88.1 12.96 cm; mean left: 88.7 13.57 cm) to T1 (mean right: 93.9 13.15 cm; mean left: 95.6 11.61 cm) for both right (p=0.005) and left stance legs (p=0.004). No significant changes were observed in ankle joint ROM in either group (p>0.05) for both feet. CONCLUSION: Plantar proprioceptive stimulation effectively enhanced dynamic balance and not affect ankle joint ROM. These results support neurosensorial and motor control adaptations rather than mechanical modifications. Proprioceptive plantar stimulation represents an effective strategy to improve dynamic balance in a short time without affecting ankle joint ROM. References 1. Carini F, Mazzola M, Fici C, Palmeri S, Messina M, Damiani P, et al. Posture and posturology, anatomical and physiological profiles: overview and current state of art. Acta Biomed. 2017;88(1):11-6.
Read CV Alberto CanzoneECSS Paris 2023: CP-BM12