CommunityExerciseI need exercises that are done lying flat on back, my knees cannot take weight. Any suggestions? in Exercise I need exercises that are done lying flat on back, my knees cannot take weight. Any suggestions? Roberta T. Do straight leg raises, Prone straight leg raises, lying hamstring stretch with resistance band and standing qaudriceps stretch i think. Stop procrastinating. It's time to take charge of your life. Start today