14. Lisa does curl-ups every morning to develop her abdominal muscle, what principle does Lisa apply? a. Overload principle c. Principle of Specificity b. Principle of Progression d. Principle of Reversibility 15. Principle of physical activity and FITT principle are important in designing your fitness plan. This is done a. to ensure a safety fitness program. b. to develop a specific target muscle development. to engage in moderate to vigorous physical activities. d. to achieve the optimum fitness development and reduces the risk of acquiring health problems.