A conceptual field-based framework for lower-upper body kinetic chain assessment in the tennis serve using IMUs and portable force plates: measurement coverage, new performance indices, and applied implications.

Understanding the tennis serve requires an integrated view of how forces generated at the ground are transmitted through the lower limbs, trunk, and upper extremities to the racket. Despite this, most wearable-sensor research has focused predominantly on upper-body kinematics, with leg drive and ground reaction forces remaining largely unexplored in field-based settings. This conceptual paper proposes a practical, on-court framework that combines wearable inertial measurement units (IMUs) with a portable force plate to capture key lower-upper body components of the kinetic chain during the tennis serve. Building on established proximal-to-distal sequencing principles, two novel indices-the Kinetic Chain Efficiency Index and the Lower-Upper Coupling Ratio-are introduced to characterize lower-upper body coordination. In addition, a Measurement Coverage Index is presented to explicitly define which biomechanical components of the serve are accessible with this measurement configuration. By synthesizing existing literature and highlighting key methodological gaps, the paper outlines a conceptually grounded pathway for integrating lower-body mechanics into tennis biomechanics without reliance on laboratory-based motion capture. Practical implications for coaching and strength and conditioning are discussed, including potential applications in performance profiling, serve consistency, and the identification of kinetic-chain patterns that may be relevant to mechanical inefficiency or injury-related loading. Overall, the framework situates a more integrated biomechanical assessment within a realistic field environment and provides a structured basis for future research and applied tennis practice.