well i started losing my hair when i was really fit, lifting a lot of weight, on my peak when it comes to mass and ripped like fu*k.... this might have been due to high DHT levels as a result of soo much weight training....
on the other hand i have heard, cardio decreases DHT levels so might contribute to at least slowing down hairloss....
i do a lot more cardio now... dont think it really grows hair but i do feel a lot fresher and quicker....