Author(s): RUSSO, G., FURESI SATTA, A., RONDINI, D., PENNINO, D., COLORETTI, V., FANTOZZI, S., SEMPRINI, G., Institution: UNIVERSITY OF TUSCIA, Country: ITALY, Abstract-ID: 2785

INTRODUCTION:
Technical actions such as cornering are key determinants of mountain bike (MTB) performance, yet they are rarely quantified with field-based measures. Wearable inertial sensors allow performance-relevant acceleration metrics to be collected in ecological tasks, comparing expert and less-expert MTB riders (Camomilla et al., 2015).
METHODS:
Thirteen youth MTB riders (12–18 y.o.; 8 expert and 5 non-expert) performed repeated turns on MTB terrain (left and right), completing three trials per turning direction. IMUs were mounted on the bike front (fork area), seat tube, and on the participant’s back.
A U-shaped turning test was used, consisting of a 10 m approach (start), a 180-degree turn around a semicircle with 9 m diameter, and a 10 m exit section (re-acceleration). The task was segmented into four phases: start, turn-entry, turn-exit, and re-acceleration. Mean horizontal acceleration (Acc-H) and Absolute peak horizontal acceleration (Hpeak-abs) were computed per phase. Linear mixed models tested fixed effects of turning phase, turning side, and expertise, with random intercepts for participants; turning side was included to account for unavoidable terrain-related variability between directions.
RESULTS:
Mean Acc-H differed across phases at all sensor locations (front, seat tube, participant: p < .001), with the same overall ordering across sensors: start > re-acceleration > turn-entry ≈ turn-exit (turn-entry vs. turn-exit: ns).
For peak acceleration, phase effects were present at the front and participant sensors (p<.0001), while the seat-tube showed no overall significant effects.
For both front and participant peaks, phase × direction interactions were significant (p<.01), reflecting that Right vs Left differences were phase-specific: at start, Right > Left (p<.05), whereas in re-acceleration, Left > Right (p<.05). For participant peaks, a slightly higher peaks in experts than non-experts was found (p = .05).
CONCLUSION:
Field-based IMU metrics captured clear phase-dependent changes in horizontal loading during MTB cornering across all sensor locations, and revealed phase-dependent left–right asymmetries that may reflect turning direction and terrain-related variability. No effects of expertise were detected on mean or peak horizontal acceleration. Expertise did not affect mean Acc-H, but showed a small effect on peak acceleration.

Camomilla, V., Bergamini, E., Fantozzi, S., & Vannozzi, G. (2018). Trends supporting the in-field use of wearable inertial sensors for sport performance evaluation: A systematic review. Sensors, 18(3), 873.