He also has an explanation to his method…
" In this test, three repetitions were performed with 185lbs plus band tension provided by orange “Micro-Mini” bands (15-20lbs of tension) and there was a 2-minute rest and then three repetitions were performed with just 185lbs and no band tension. I picked power cleans from high block since they are a very short duration lift and are very explosive, band tension is different since it pulls you in the direction of where the band is anchored so doing full lifts can be very difficult.
As expected, barbell acceleration and velocity had higher peaks when there was no band tension. The band tension adds additional force to the barbell that must be overcome by the lifter to make the lift. An interesting aspect of the acceleration is that with band tension, the acceleration of the barbell peaks again at the same time as velocity peaks. Without band tension, there is no peak in this area. It is interesting because acceleration of the barbell is directly related with the force applied to the barbell.
The clean with the bands only went up 72cm and without band tension the height was 77cm, keep in mind the maximum velocity difference was only 0.07m/s so the difference in height should only be 1.8cm but in reality it is 5cm because of the band tension. With the bands, the lift lasted 0.5839s. When the bands were removed, the lift lasted 0.5339s.
The duration from the start of the lift to the maximum velocity is 0.3003s for the banded, and 0.2669s for the lift without banded. Duration of the lift from maximum velocity to receiving bar is 0.3670s for bands, 0.2670s without bands. A particularly interesting area in the acceleration graph is from 0.2002s - 0.3336s since the difference in the acceleration is equal. Therefore it becomes possible to determine the average of this difference and it tells you how much acceleration the bands put on the barbell.
After some simple math the difference is 3m/s^2 (which also happens to be the difference in maximum accelerations of both), so the apparent downward acceleration of the barbell with band tension is around -12.81m/s^2 compared to the regular downward acceleration of gravity, -9.81m/s^2. By taking into account the apparent downward acceleration of the bar and band tension, one can compare the force output of either lift.
Zero acceleration equals zero force for F=ma, so for a regular barbell -9.81m/s^2 means that the barbell is falling at freefall at -100% of force, so 9.81m/s^2 would be 100% force. With the bands we have determined free fall speed to be about -12.81m/s^2 and 100% force to be 12.81m/s^2. So we can now calculate the maximum force outputs of either lift with some interpolation.
For the lift with band tension, the maximum force applied to the barbell was 157.60% of barbell weight (weight = mass*gravity + band tension) and the maximum force applied to the barbell without bands was 236.16% of barbell weight. So the next test would be if doing a regular lift without bands generates that same amount of force, if it is less then 236.16% of barbell weight, then it would show that the training effect of using bands leads to a short-term increase in maximum force output. "
