I'm no expert...
But I know what you're talking about. The hormone you're talking about is GH(growth hormone), and it's got some connection to raised testosterone levels(which is obviously good, unless you're a chick.)
If you haven't been working out your legs m8, tomorrow is going to be too late to start, START NOW!
Alot of people(misread perhaps?) think that working out your legs isn't good for aesthetics(big lower body, smaller upper body or something), this is wrong...wrong wrong WRNG!
Working your legs in a gym is an excellent way to get fit, here's why:
1. Legs(especially upper) are the largest muscle group in the body, meaning that when you work them, they burn the most calories..yada yada yada, you know where this point is going.
2. Sure, your legs will get abit more muscular(really a bad thing), but as long as you treat them as just another muscle group to work out, they are one of your most powerful weapons.
3. As stated, they raise testosterone levels after a workout essentially because of their size, and the effort it takes your body to repair them, by releasing GH.
4. My favourite. Leg workouts benefit your entire body as far as getting chiseled goes, because of your legs size, as a muscle group; they eat up heaps of calories.
You asked for some workouts for da legs? here's afew that'll do the trick:
1.Leg press - its #1 for a reason m8
2. Leg curls - ...
3. Leg extensions - ...
4. Squats? - not too sure about this one, its a full body exercise, but its a hella workout on the flippers.
Do yourself a favour.
1. Take a pic of yourself in a mirror before you start
2. Incorporate those exercises into a solid weekly routine
3. Continue for AT MOST 2 months
4. Take a pic of yourself 60 days from now.
5. Compare.