- Using your dominant hand, count the number of times you can completely stretch a rubber band be- tween the thumb and pinky finger in 20 seconds. Be sure to stretch the rubber band as far as possible each time and do not take a break in between trials. Explain the actions that were occurring at the cellular level to produce this movement. Include sources of energy and any possible effect of muscle fatigue. Hypothesize what would happen if blood flow was restricted to the hand when this experiment is per- formed.