Recently, mostly in gym related activities and sport 12-3-30 method of doing cardio is getting popular. To simplify it is walking on treadmill with 12% incline, 3 miles per hour and for 30 minutes. It can be modified accordingly to needs. It would help to gather more users, focused more on strength, than on endurance.
It is better for heavy athletes than normal running and have similar cardiovascular benefits. I suggest to add Incline Walk to cover that activity. I am using stair-stepper for that, but it is not the same.