The man, however, was the exact opposite.
A certain critical area of a man's body had a lower temperature compared to other parts, and was overly sensitive to high temperatures. Thus, if a man's cultivation technique involved scorching True Qi passing through several crucial points in the lower body, fertility would be impossible.
Li Nuo found several cultivation techniques that met the criteria, and indeed, he saw similar warnings in them.
Many things in this world are interconnected, and from the perspective of the Medical School, one could rationally explain matters related to the Martial Path.
From the Medical School's perspective alone, to address the issues with the Yuqing Heart Technique, one must start with the meridians.