Final answer:
-All of the above. Athletes take nutritional substances to enhance muscle hypertrophy, speed up recovery, and control body water.
Step-by-step explanation:
Athletes take nutritional substances for a variety of reasons including enhancing muscle hypertrophy, speeding up recovery, and controlling body water. These substances can help athletes increase their performance and improve their overall physical fitness. However, it should be noted that the use of certain synthetic hormones and performance-enhancing drugs is illegal and banned in many professional sports due to their potential health risks.