The study looked at how to properly test the strength of large piles by applying loads in two directions. By analyzing 96 tests, researchers found that the maximum test load didn't reach the total load applied in both directions. To make sure a pile can handle its intended load, the upward or downward load should be at least double the design load. It's safer to increase the load capacity by at least double the maximum upward or downward load to confirm the design load.