The correct answer should be gymnastics. While the other mentioned sports could help him too, gymnastics is the most comprehensive one because it involves almost every muscle in the body to do various exercises, whereas biking would increase his leg muscle fitness most, but would not do much for the rest of his body.
Biomechanics is the term. Its studies the structure and function of biological systems.
It can compromise oxygen and nutrient delivery to muscles which can cause cramps.
Increase body and muscle temperature
extend a joint beyond its regular range of motion
