CMJ fatigue checks: average two jumps during squats, take the best after
In short
In 13 trained men, averaging two countermovement jumps was more sensitive to fatigue during squat training than taking the best jump. After the session, acceptable reliability required the best of two jumps and at least 10 minutes of rest. Jump height reached its lowest point 30–40 minutes after training, so the 10-minute measurement rule does not establish recovery.
A jump check needs a scoring rule as well as a stopwatch. During squats, the average of two countermovement jumps picked up fatigue more sensitively. After the session, the useful combination was at least 10 minutes of rest and the best of two. Researchers compared jump height with the pre-exercise baseline.
Why average the jumps between sets?
Thirteen trained men completed five sets of fixed-repetition squats, five sets stopped by a velocity-loss threshold, and a control condition in randomized, counterbalanced order. Two CMJs were recorded at baseline and immediately after each set. Average scores were lower than maximum scores, revealing fatigue more sensitively, with greater reductions in the final two sets. Within-session reliability was acceptable: CV ≤5.29%, ICC ≥0.745. CV describes measurement variability; ICC describes consistency across repeated measurements.
Can a jump immediately after training show recovery?
The researchers also tested eight timepoints between 5 and 60 minutes after training. ICC was low in the early 0–15-minute window; acceptable reliability was achieved only with maximum scores from 10 minutes onward (CV ≤7.29%, ICC ≥0.750). One good jump immediately after the last set is a weak basis for declaring yourself recovered.
Does resting 10 minutes mean you can lift heavy again?
Jump height actually bottomed out 30–40 minutes after training. Ten minutes marks a measurement recommendation, not a return of strength. The study did not establish a CMJ cutoff that predicts success on the next heavy set or estimates a squat 1RM.
Keep the jump score, timing, and scoring method alongside your fairlift workout notes. A between-set average below your usual baseline can prompt a reassessment before another heavy set. For Big Three records and the Muscle Index, testing 1RM with little fatigue and consistent conditions makes comparisons more useful. See how fatigue changes maximum load for the related testing problem.
This was a small study of 13 trained men. The same reliability figures cannot be assumed for women or beginners, and a CMJ score alone cannot determine whether a heavy attempt is safe.
Frequently asked questions
How many CMJs should I perform between squat sets, and which score should I use?
Perform two CMJs and use their average height for a more sensitive check of within-session fatigue. In 13 trained men, within-session reliability was CV ≤5.29% and ICC ≥0.745.
When should I measure CMJ after training, and which score should I use?
Wait at least 10 minutes and use the best of two jumps. That combination achieved acceptable reliability (CV ≤7.29%, ICC ≥0.750), but waiting 10 minutes does not establish recovery.
When was jump height lowest after squats?
Across eight assessments between 5 and 60 minutes after training, CMJ height was lowest at 30–40 minutes. The largest measured fatigue response was therefore delayed beyond the end of the session.
Can CMJ results determine when to attempt a Big Three 1RM?
CMJ can help track fatigue, but this study did not validate a jump threshold for attempting a 1RM. Interpret Big Three records logged in fairlift alongside fatigue and testing conditions.
Source: PubMed