The percentage drop in barbell speed during a set, used to gauge fatigue and set effort.
Velocity loss (VL) is the percentage decrease in mean or peak concentric velocity between the fastest (usually first) and slowest repetitions of a resistance-training set, tracked via a linear position transducer, accelerometer, or camera-based velocity monitoring system. It is used within velocity-based training to prescribe or terminate sets at a target fatigue threshold (e.g., 10-20% VL) rather than relying on fixed repetition counts, on the premise that VL correlates with metabolic and neuromuscular fatigue and residual mechanical fitness loss. Optimal VL thresholds and their transfer to strength, power, or hypertrophy outcomes remain actively debated, and reliability depends heavily on the measurement device and exercise used.
This guide was auto-drafted and is pending editorial review.