Is the Classification of Athletes Based on Force-Velocity Profiling from Countermovement Jumps Influenced by the Choice of Method?

PURPOSE Force-velocity (FV) profiling is a tool for classifying athletes as force- or velocity-deficient, allowing for tailored training prescriptions. However, profiling classification may vary depending on the measurement method used. This study compared FV profile variables derived from countermovement jumps (CMJs) using four approaches: the Flight-time method, a Kinetic method, and two Kinematic methods. METHODS Sixteen National-level female handball players completed CMJs with 0, 20, 40, 50, and 70 kg of additional mass. All jumps were recorded by a force plate and 3D motion capture system. For each jump, jump height, height of push-off (HPO), average force, and average velocity were estimated, and FV profiles were derived using each of the four methods. The two kinematic methods represented displacement of the center of mass of 1) the body and 2) the whole system (i.e., body + additional mass). A pre-measured HPO (Flight-time method) overestimated the HPO derived from kinetic and kinematics methods at low values and underestimated it at high values. RESULTS The Flight-time method underestimated average force by 7% compared to the kinetic method and overestimated it by 1-3% compared to the kinematic methods. Average velocity during push-off was lower when derived from the Flight-time method than all other methods, particularly at the highest velocities (~20%). The resultant FV profiles (slopes) differed systematically by 30-39% between methods, such that >80% of participants were classified differently (i.e., force-deficient, velocity-deficient, or balanced) depending on the method applied. CONCLUSIONS We question the practical use of the FV profiles based on the Flight-time method, as it could result in the misclassification of athletes.