Correct sequence of events when you are unexpectedly hit by an angry duck. (Health/science) PLEASE HELP

Aresearcher is interested in the effect of exercise on stamina in elderly patients. the patients are randomly assigned to be in a high-exercise or low-exercise training program. at the end of the program, their stamina is measured by seeing how long they can walk comfortably on a treadmill. identify the independent variable. identify the dependent variable and explain how it was measure.