Holding dumbbells at maximum weight for 3 seconds is tiresome. So this is extreme version of high intensity training when one always do exercises to the point of failure.<p>It is surprising that doing just one repetition works. A typical recommendation with high intensity training is to select weight so one can do 5-12 repetitions to the point of failure. The actual number depends on goal (strength or muscle size), genetics etc. I guess the college students where not trained previously so this worked.