There was a black bodybuilder back in the 80's named JJ Marsh. He had enormous shredded quads. He mentioned his thighs really took off when he started training legs three times a week. I thought I would give it a try and train legs 3 times a week (10 sets of 10 on squats) to see what would happen. Well, it worked and my weak point became my strong point. I no longer train quads 3 times a week because it's brutally hard but I would recommend a hard gainer to give it a try for a month or so. Be sure to take in plenty of calories. This was back in the early 90's when I experimented with this routine, but I recall putting on around 4" on my thighs in under a year, with just squats and lying hamstring curls.