Author(s): JIANG, Z., LI, M., HAUTIER, C., ZHANG, Q., Institution: SHANGHAI UNIVERSITY OF SPORT, Country: CHINA, Abstract-ID: 613

INTRODUCTION:
The assessment of Force-Velocity (F-V) profiles is crucial for optimizing rowing performance. However, constructing accurate F-V profiles requires precise measurement of handle force and velocity. Currently, the gold standard for velocity measurement is optical motion capture systems (Mocap), which prevents the routine application of F-V testing in daily training. Thus, deriving velocity from IMU data to construct Force-Velocity profiles offers a more practical solution for daily training environments. This study aimed to validate the concurrent validity, reliability, and sensitivity of a custom IMU-embedded force gauge for assessing rowing kinematics and F-V profiles against a Mocap system.
METHODS:
Twenty-five experienced male rowers performed maximal trials on a Concept2 ergometer across 5 resistance settings (2 sets of 20 strokes). A custom sensor unit, integrating a force gauge and an IMU, was attached between the handle and the chain. Simultaneously, marker-based Mocap data (Qualisys) were collected. Raw IMU data were processed using a custom-developed algorithm to compute stroke kinematics (e.g., Velocity, Distance) and derive F-V profiles via linear regression using peak force and peak velocity values. Statistical analysis included Linear Mixed-Effects Models, Intraclass Correlation Coefficient (ICC), Bland-Altman analysis, and Minimal Detectable Change (MDC).
RESULTS:
The results demonstrated excellent agreement with the Mocap system for all assessed kinematic parameters. For example, Peak Drive Velocity showed a negligible bias of -0.01 m/s (ICC = 0.988, MDC=0.08 m/s, RMSE = 0.05 m/s, LOA: -0.10 to 0.08 m/s) and Drive Distance showed a bias of -0.01 m (ICC = 0.979, MDC=0.07 m, RMSE = 0.04 m, LOA: -0.08 to 0.06 m). Regarding the F-V profile, the derived parameters exhibited high concurrent validity. Theoretical Maximal Power (Pmax) showed the highest agreement, with a bias of only 0.24% (2133.1 ± 755.4 vs. 2130.6 ± 722.2 W; ICC = 0.988, LOA: -236.6 to 231.6 W). Theoretical Maximal Force (F0) (ICC = 0.967, Bias = 2.1%) and Velocity (V0) (ICC = 0.956, Bias = -1.5%) also demonstrated strong correlations with no significant differences between methods (p > 0.05).
CONCLUSION:
The IMU-embedded force gauge, driven by the custom processing algorithm, provides valid and sensitive measures of both rowing kinematics and F-V profiles. Given the negligible bias and high reliability, this portable system offers a robust stand-alone solution, allowing coaches and scientists to accurately monitor rowers' mechanical characteristics and technical metrics in daily training environments.