Velocity Profiling for Jumpers: Using Load-Velocity Curves to Diagnose the Real Weakness Behind Your Jump

Two jumpers with identical 70 cm vertical jumps can produce that 70 cm in completely different ways. One pushes hard and slow; the other rebounds light and fast. Their training prescriptions should be the opposite of each other. The force-dominant jumper needs to develop velocity; the velocity-dominant jumper needs to develop force. Yet jump height alone cannot tell you which jumper you are. The diagnostic tool that does is the load-velocity profile, and its more refined cousin the force-velocity (F-V) curve.

Samozino and Morin (2016) showed quantitatively that vertical jump performance is determined not by a single variable like maximum strength but by the shape of the force-velocity profile. Athletes with the same jump height have different paths to improvement depending on where their balance between theoretical maximum force (F0) and theoretical maximum velocity (V0) sits. This guide walks through the procedure to build a load-velocity profile with an 800Hz IMU, the criteria to diagnose a jumper's weakness, and the prescriptions that target each weakness. Combined with the reactive strength index, it forms the most complete framework for jumper evaluation.

The force-velocity curve describes how the force a muscle produces declines as contraction velocity rises. Heavy loads (high force) move slowly; light loads (low force) move fast. The two endpoints are theoretical extremes: F0 is the force at zero velocity, V0 is the velocity at zero force. Jump height is proportional to the product of F0 and V0 (power, P) but is also shaped by their balance (the F0/V0 ratio).

Over 90% of jumpers tilt toward force-deficit or velocity-deficit; well-balanced is rare. The diagnostic task is to measure this ratio precisely with IMU data.

A load-velocity profile is built from mean velocity at 4-6 jump squat loads. The standard protocol: bodyweight countermovement jump, 20 kg jump squat, 40 kg, 60 kg, 80 kg, 100 kg (depending on capacity). Three reps at each load, recording the fastest. The 800Hz IMU automatically yields take-off and mean velocity for each jump.

Plotted on a load (x-axis) by velocity (y-axis) plane, the data form a near-perfect line. The y-intercept is V0; the load-axis intercept (converted to bodyweight + added load) is F0. The slope determines the F0/V0 ratio. Plotting the same athlete's squat jump test data alongside reveals the contribution of the stretch-shortening cycle.

Diagnosis dictates opposite prescriptions. Force-deficit jumpers train slow, heavy work at 80-95% 1RM for 1-3 reps (squat, deadlift, trap bar deadlift) twice or three times per week. The target is a 5-10 kg increase in back squat 1RM over 6-8 weeks. Velocity-deficit jumpers do the opposite: explosive jump squats at 30-50% 1RM, box jumps, and depth jumps two or three times per week. The target is a 0.2-0.4 m/s increase in V0.

Well-balanced jumpers benefit from block periodization that alternates the two regions: a 4-week force block followed by a 4-week velocity block, finishing with a velocity block before the season for sport specificity. The most common mistake is reflexively prescribing the force-deficit program to a well-balanced jumper. A well-balanced profile is already developed across the range; loading only one side breaks the balance.

Velocity profiling reveals its full value when used as a season-long tracking tool, not a one-off assessment. The recommended re-test interval is every 4 weeks. Weekly is too noisy; 8+ weeks risks missing adaptation. Test on the same weekday, after the same warm-up, at the same time of day for consistency.

Samozino and Morin (2016) reported that 12 weeks of targeted training improved force-deficit jumpers by 8% on average and velocity-deficit jumpers by 11%, while a uniformly trained control group improved only 3%. Equal training time, three to four times the efficiency. Including velocity profiling as a core item in the athlete testing battery is now standard practice in modern jump coaching.