Which of the following factors occurred first in the development of exercise science in the 20th century? a) the establishment of the harvard fatigue laboratory. b) the formation of specific programs of study in colleges and universities to prepare professional physical education teachers and athletic coaches. c) the results of the kraus–weber physical fitness tests comparing children in the united states to children in europe. d) the development of programs in calisthenics and gymnastics as a way to improve fitness.