Rowing, as it creates a rhythmic cycle of strength enduring it.
Answer:
They are at higher risk because of hormones. During adolescence, you go through different hormonal changes, including sexual ones. These sexual changes may result in developing different urges such as masturbation. However, the problem comes with a lack of proper sexual education and how most of their knowledge on sex is based off of myths perpetuated by peers. So it's really a lack of education on sexual reproduction and the transmission of diseases.
Rowing helps develop muscle endurance. Hope this helps