The assessment of leg asymmetries is gaining scientific interest due to its potential impact on performance and injury development. Athletes around puberty exhibit increased gait variability due to a non-established running pattern. This study aims to describe the asymmetries in the spatiotemporal running parameters in developmentally aged athletes. Forty athletes under 14 (U14) (22 females and 18 males) were assessed running on a treadmill at constant speeds of 12 and 14 km·h⁻¹ for 3 min. Step length, step frequency, along with contact (CT) and flight time, both in absolute values and as a percentage of step time, were recorded using a RunScribe sensor attached to the laces of each shoe. U14 runners exhibited high bilateral symmetry in the spatiotemporal parameters of running, with mean asymmetry values (1–5.7%) lower than the intra-limb coefficient of variation (1.7–9.6%). Furthermore, bilateral asymmetries did not vary between the two speeds. An individual-based interpretation of asymmetries identified subjects with consistent asymmetries at both speeds, particularly in terms of CT and contact ratio (%, CT/step time). This study confirms the high symmetry of pubertal runners and paves the way for the application of portable running assessment technology to detect asymmetries on an individual basis.

The evaluation of gait biomechanics using portable inertial measurement units (IMUs) offers real-time feedback and has become a crucial tool for detecting gait disorders. However, many of these devices have not yet been fully validated. The aim of this study was to assess the concurrent validity and relative reliability of the RunScribe™ system for measuring spatiotemporal gait parameters during walking. A total of 460 participants (age: 36 ± 13 years; height: 173 ± 9 cm; body mass: 70 ± 13 kg) were asked to walk on a treadmill at 5 km·h⁻¹. Spatiotemporal parameters of step frequency (SF), step length (SL), step time (ST), contact time (CT), swing time (SwT), stride time (StT), stride length (StL) and normalized stride length (StL%) were measured through RunScribe™ and OptoGait™ systems. Bland–Altman analysis indicated small systematic biases and random errors for all variables. Pearson correlation analysis showed strong correlations (0.70–0.94) between systems. The intraclass correlation coefficient supports these results, except for contact time (ICC = 0.64) and swing time (ICC = 0.34). The paired t-test showed small differences in SL, StL and StL% (≤0.25) and large in CT and SwT (1.2 and 2.2, respectively), with no differences for the rest of the variables. This study confirms the accuracy of the RunScribe™ system for assessing spatiotemporal parameters during walking, potentially reducing the barriers to continuous gait monitoring and early detection of gait issues.

This study compared the biomechanical profiles of elite and recreational distance runners across five measurement domains using wearable inertial sensors across treadmill speeds of 10–15 km/h. A total of 104 runners (52 elite; 52 recreational) were assessed using RunScribe sensors during an incremental treadmill protocol. Twenty‐three variables spanning spatiotemporal parameters, stiffness and force, impact loading, foot kinematics and vertical dynamics were recorded at each speed. Elite runners were matched 1:1 with recreational runners by sex, age, height, and body mass. For each variable, a linear mixed‐effects model (LMM) was fitted to within‐pair differences with pair‐level random intercepts and speed slopes, and speed and within‐pair body mass and age imbalances as fixed effects. FDR correction (Benjamini–Hochberg) was applied to the 23 group‐effect and 23 interaction tests independently. Twelve of 23 variables (52.2%) showed a significant group effect, and six (26.1%) a significant group×speed interaction after FDR correction. Elite runners showed shorter contact time ( d _z = −0.73 to −0.53), higher flight ratio ( d _z = +0.52 to +0.66) and a more anterior footstrike pattern at initial contact ( d _z = +0.58 to +0.67). RunScribe‐estimated vertical GRF rate and leg stiffness were also higher than in recreational runners ( d _z = +0.48 to +0.75, and + 0.51 to +0.62, respectively). Step frequency and step length showed no overall group difference. Significant group×speed interactions revealed that, for most affected variables, values changed more steeply with speed in recreational runners. These findings describe a distinct mechanical profile in elite runners across the six evaluated submaximal speeds.

En los últimos cuarenta años la popularidad de salir a correr o hacer running se ha incrementado notablemente. Su popularidad y el gran número de lesiones hace que el running sea la actividad física más estudiada por el área de la biomecánica. En la práctica clínica, se utilizan principalmente software de análisis de movimiento 2D para analizar la cinemática. Younext Direct Motion Capture® (Podoactiva S.L., Huesca) es un software que analiza los parámetros cinemáticos durante la carrera en el plano sagital. El objetivo general de este estudio fue determinar la fiabilidad y repetibilidad de la cinemática angular de la rodilla y del tobillo de la carrera en el plano sagital en población sana utilizando Younext Direct Motion Capture®. Estudio piloto observacional de concordancia. 8 sujetos (5 varones y 3 mujeres) fueron filmados mientras corrían en una cinta de correr, obteniendo tres grabaciones del ciclo de la carrera de cada participante en la primera sesión. Se realizó una segunda sesión de grabaciones a los 7 días del primer registro para volver a grabar siguiendo el mismo protocolo. Se calculó el coeficiente de correlación intraclase (ICC) para determinar la fiabilidad intra-sesión e inter-sesión del software a la hora de medir la cinemática de la rodilla y del tobillo. Se obtuvo una fiabilidad intra-sesión e inter-sesión casi perfectas (ICC> 0,81) tanto para tobillo como para rodilla. Este estudio demostró que el software Younext Direct Motion Capture® es fiable para analizar la cinemática angular de la rodilla y del tobillo de la carrera en población adulta sana.

Background: Fascial thickening in plantar fasciitis is well established on ultrasound, whereas the abductor digiti minimi (AddV), the imaging target of Baxter neuropathy, remains poorly characterized. We quantified plantar fascia, AddV and posterior chain with a dual design: within-subject (affected vs. contralateral foot) and between-group (patients vs. controls). Methods: A cross-sectional study was conducted in 18 patients with plantar fasciitis and 20 healthy controls. Thickness, cross-sectional area (CSA), echo-intensity, pennation angle and 35 texture variables were analyzed with Wilcoxon signed-rank, Mann–Whitney U, Cohen’s d, Spearman’s ρ and Benjamini–Hochberg correction. Results: AddV CSA was lower in the affected than in the contralateral foot (median 85.8 vs. 99.2 mm²; p = 0.038, unadjusted; d_z = −0.34), but did not differ from controls (92.9 ± 22.8 vs. 92.1 ± 22.5 mm2; p = 0.917). Within the affected foot, AddV CSA correlated inversely with fascia CSA (ρ = −0.62; p = 0.018, unadjusted). The fascia was thicker, larger and more hypoechoic in cases than in controls (thickness 4.99 vs. 3.07 mm; CSA 59.94 vs. 25.28 mm²; both p < 0.001, d > 2) and than contralaterally. Conclusions: Dual-design ultrasound suggests a small AddV asymmetry and an inverse AddV–fascia relationship that emerge only within subjects, even without overt Baxter neuropathy. These exploratory findings require confirmation before intrinsic-muscle assessment can be recommended in the sonographic evaluation of plantar fasciitis.