Knee strength testing stayed reliable a week apart

Repeating a standardized knee strength test one week later produced highly reliable measurements. The study, published October 1, 2026, compared peak torque measured with the Biodex System 4. It asked whether a measurement could be repeated consistently. It did not test whether a training program increased strength over that week.

Who repeated which strength test?

Fifteen healthy, physically active adults aged 21–34 took part: seven women and eight men. Researchers assessed concentric knee extension and flexion of the dominant leg at two angular velocities in two sessions spaced one week apart. Torque describes the turning effect of force at a joint; it is not a load lifted on a barbell. The device controls angular velocity, so changing from the slower to the faster condition changes the task being assessed.

Does reliability make every small increase real?

Peak torque did not differ significantly between sessions. High ICCs and the reported CV range support consistency under these test conditions. They do not establish a universal rule that an improvement above 4.2% must be real for every individual. A coefficient of variation is not the same statistic as a smallest detectable change. Likewise, a non-significant session difference does not mean every participant recorded identical values. The ICC estimates also have uncertainty, reflected in confidence intervals spanning 0.78–1.00 across conditions.

What makes a training record comparable?

1. Compare records from the same exercise, equipment and range of motion.
2. Keep conditions such as testing speed and position attached to the result rather than pooling different tasks.
3. Check a small one-session increase against another record collected under the same conditions.

These are editorial suggestions for interpreting a log, not a training prescription tested in the study. In fairlift, record the load and repetitions actually performed. The Muscle Index calculator requires Big Three 1RMs, so knee torque should never be converted into a pretend kilogram maximum for entry. For evidence about barbell records, read the separate powerlifting 1RM measurement study. Reliability belongs to the test and its conditions; a stable laboratory knee test cannot supply the measurement error for your squat, bench press or deadlift.