Answer;
increase the intensity of their workouts
Teenagers who score below the health standard in a specific fitness component may need to increase the intensity of their workouts.
Explanation;
Exercise intensity is how hard one should exercise to improve fitness. All exercise should be hard enough to demand more effort than usual.
Frequency of exercise refers to how often one should exercise to improve a component of physical fitness. Refers to the fact that exercise must be performed regular if you are to reach and maintain an adequate level of physical fitness.