The Velocity-Based Warm-Up Protocol: An IMU-Driven Activation System

The job of a warm-up is to deliver the nervous system to the start line of the main set ready to perform. Yet most warm-ups are still a fixed routine—"5 min bike, dynamic mobility, an empty bar set"—that ignores the lifter's state on that particular day. The result: warm-ups that are sometimes insufficient (raising injury risk in the main set) and sometimes excessive (sapping output).

Velocity-based warm-up solves this with measurement. Tracking warm-up barbell or body velocity with an 800Hz IMU produces objective evidence of whether the nervous system has reached "main-set ready." Jovanović & Flanagan (2014) showed that warm-up velocity progression correlates strongly with main-set readiness, and the approach has since become standard in many elite environments.

This guide presents a five-stage velocity-based warm-up protocol, defines movement-specific velocity targets for jumps, squats, deadlifts, bench presses, and Olympic lifts, and provides a readiness decision framework. It is a quantitative layer on top of the principles laid out in our how to warm up before heavy lifting guide.

The traditional warm-up's flaw is its dependence on "feel." The same routine produces very different neuromuscular states depending on sleep, nutrition, fatigue, and ambient temperature. One day the empty bar moves at 0.95 m/s; another, the same lift comes in at 0.78 m/s. That gap is decisive for the safety and quality of the main set.

Velocity is a direct readout of neuromuscular state. If velocity at a given load runs 5-10% below baseline, activation is incomplete and additional work is warranted. 5-10% above baseline is a "good day," and a small bump in volume or intensity is reasonable. This is what daily autoregulation looks like in practice.

The second benefit is longitudinal tracking. Watching warm-up velocity at a fixed load drift over time exposes chronic fatigue, overtraining, and rehab progress earlier than subjective measures. This extends the principles of our autoregulated velocity training guide into the warm-up.

The protocol has five stages, each gated by an IMU metric. Total time is typically 15-25 minutes.

Stage 1: General activation (5 min). Bike, row, brisk walk—anything that brings heart rate to 100-120 bpm. No IMU measurement.

Stage 2: Dynamic mobility (5-7 min). Walkout squat, inchworm, world's greatest stretch. Reference our hip mobility assessment guide.

Stage 3: CNS activation (3-5 min). Three CMJs or five medicine-ball slams. Key IMU metric: jump height or peak acceleration. Reach 90% of baseline before moving on.

Stage 4: Movement-specific warm-up sets (5-8 min). Progressive load on the main movement: empty bar → 40% → 60% → 80% 1RM. Measure velocity each step. Reference movement-specific guides such as our power clean technique piece.

Stage 5: Readiness check (1-2 min). Verify the last warm-up set hits the velocity target and that rep-to-rep CV is under 5%. If yes, proceed to the main set.

Velocity targets depend on load (%1RM) and lift. The table below lists recommended mean propulsive velocity (MPV) ranges for Stage 4. Baseline is the lifter's personal average measured fresh.

If actual velocity is more than 5% below target, activation is incomplete. Add 1-2 warm-up sets or drop the main-set load by 5-10%. If velocity runs 5%+ above target, it's a "good day"—small bumps in load or volume are reasonable. See our 1RM calculation methods guide for load math.

Stage 5's job is the binary call: am I cleared to run the planned main set? Synthesize three data points.

1. Warm-up velocity progression. Velocity should fall predictably as load rises. If velocity at 60% 1RM is essentially the same as 80% 1RM, the system is not registering the load—do not main-set.

2. CNS activation indicator. The Stage 3 jump height should be at or above 90% of baseline. 80-90% means "proceed but reduce volume/intensity 5-10%." Below 80% means hold or convert to a light activation session.

3. Bilateral asymmetry. If asymmetry runs above 1.5x baseline during the warm-up, injury risk is elevated. Add unilateral activation work to bring up the weak side and re-test. Pair with our single-leg hop test data.

Synthesize the three into a green/yellow/red call. In elite environments this evaluation is increasingly automated session-to-session.

The most common failure is warm-up velocity that never reaches target. Causes vary—poor sleep, low fueling, chronic fatigue, cold gym. Short term: extend the warm-up by 5-10 min or drop the main-set load by 10-15%. If the pattern persists 3+ days, treat it as a recovery deficit—add a rest day or pull intensity back for a week.

Second is normal warm-up velocity that collapses in the main set. Usually this is overlong rest between the last warm-up set and the first work set, allowing activation to dissipate. Keep that gap to 3-5 minutes. As covered in our why form breaks down on heavy sets piece, lost activation is a frequent driver of form failure.

Third is chronic bilateral asymmetry. Warm-ups can mask only so much; chronic asymmetry above 15% needs a dedicated correction block. See the asymmetry section of our why my squat isn't getting stronger guide.

Finally, do not let the data crowd out the athlete. Velocity is a decision-support tool, not the goal. Combined with the lifter's subjective input, the system is more powerful than either alone.