Author(s): KALINA, T., KADLECÍKOVÁ, E., NOVÁK, V., Institution: MASARYK UNIVERSITY, Country: CZECH REPUBLIC, Abstract-ID: 2510

INTRODUCTION:
The aim of this exploratory pilot study was to examine the association between functional and strength asymmetries assessed under laboratory conditions and biomechanical asymmetries in running measured in the field. Specifically, the study sought to determine whether asymmetries identified during laboratory-based screening are reflected in stride kinematics during overground running.
METHODS:
Eight trained endurance runners (6 men, 2 women; mean age 23.15 years) participated in this exploratory pilot investigation. Inclusion criteria required completion of a 10 km race under 60 minutes within the previous 12 months. Data collection was conducted in two phases. In the field assessment, participants completed two 1-km runs on a standard 400 m track under alternating pacing and terrain conditions (flat, slight incline, slight decline). Bilateral biomechanical data were recorded using Stryd Next Gen Duo foot pods. The analyzed parameters included ground contact time (GCT), leg spring stiffness (LSS), vertical oscillation (VO), and impact load ratio (ILR). Inter-limb asymmetry indices were calculated for each variable. In the laboratory assessment, functional asymmetry was evaluated using selected Functional Movement Screen subtests (hurdle step, inline lunge, active straight-leg raise) and the Y-Balance Test Lower Quarter to assess dynamic stability. Lower-limb strength and explosiveness were measured using K-delta force plates during bilateral counter-movement jumps and single-leg counter-movement jumps, from which asymmetry indices were derived. Associations between laboratory- and field-based asymmetries were examined using correlation analysis, with statistical significance set at p < 0.05.
RESULTS:
Correlation analysis revealed no statistically significant associations (p > 0.05) between asymmetries identified in functional screening or bilateral strength performance and inter-limb asymmetries in running biomechanics. No significant differences in running parameters were observed between athletes classified as symmetrical or asymmetrical based on functional screening scores. Similarly, retrospective grouping based on running asymmetry did not reveal systematic differences in laboratory-based functional measures. The only statistically significant association was a strong negative correlation between asymmetry in single-leg counter-movement jump performance and asymmetry in ground contact time (r = −0.756, p = 0.030), indicating that greater unilateral differences in explosive strength were associated with greater inter-limb differences in ground contact time during running.
CONCLUSION:
Laboratory-based functional asymmetries in endurance runners do not consistently correlate with running biomechanics, except for a link between unilateral jump and ground contact time. Given the small sample, these preliminary results suggest that valid athlete assessment requires combining lab screenings with sport-specific monitoring under ecologically valid conditions.