Momentum-based load prescriptions: applications to jump squat training

Velocity-based training is often applied to ballistic exercises, like the barbell jump squat, to improve vertical jump performance. However, determining the ideal training load based on velocity data remains difficult, as load prescriptions tend to be limited to subjective velocity loss thresholds, velocity ranges, or both. Using data from jump squats performed with 0%, 15%, 30%, 45%, and 60% of the 1-repetition maximum squat, we explored subjective and objective methods to determine the ideal training load. Specifically, we explored takeoff velocity and a related metric only recently discussed in the literature, system momentum (i.e., takeoff velocity multiplied by the mass of the athlete-load system). At the group level, an ideal training load could not be revealed objectively using takeoff velocity. With individual participants, the process remained challenging using takeoff velocity. Conversely, an ideal training load could be revealed easily and objectively using system momentum at the group average and individual participant levels. System momentum at takeoff is well-suited to assist practitioners seeking to identify appropriate training loads for jump squat training, and potentially other ballistic exercises. We suggest a pivot from velocity to system momentum when seeking to objectively establish training loads for the jump squat and related exercises.