This article includes the upper leg only. I have not described training or anatomy of the calf area. Maybe next time!
The Anatomy Of The Legs
The legs are composed of numerous muscles including the quadriceps (rectus femoris, rectus medialis, rectus lateralis, and rectus intermedialis). These muscles extend the knee and (rectus femoris only) help to flex the hip.
The legs also are made up of the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus). These muscles help to flex the knee joint. Also included in the leg group are the adductor muscles, the abductor muscles, the glutes, gracillus, and sartorius.
Training The Legs
For me personally, training legs is very difficult not because of the amount of weight you must use, the pain in the muscles after and during a workout, or because of the time spent in the gym. They are difficult because there are so many ways you can train them according to if you are trying to gain mass, strength, definition, or separation.
First, let me go through a few terms that I use in my training program.
Super Sets: Similar to circuit training in that you are stacking two or more exercises back-to-back without a break. Super sets are great for really bringing out detail in the legs. An example of this would be doing lunges x 15, hack squats x 15, and extensions x 15.
Drop Sets: Consecutive sets on one exercise using decreasing amounts of weight without rest between sets. For example, I would do leg extensions as follows: 230x10, 190x10, 150x10. That is one set.
Leg Extensions: 12, 10,8, 6* -
Smith Machine Squats: 12, 10, 8, 6 - View Exercise
Hack Squats: 12, 10, 8 - View Exercise
Lunges or Step-Ups: 3x15 - View Exercise
Seated Leg Curls (double legged): 12, 10, 8, 6 - View Exercise
Prone Dumbbell Leg Curls: 12, 10, 8 - View Exercise - Shown On Machine
Stiff-legged Dead Lifts: 12, 10, 8 - View Exercise
* (Ascending weight => decreasing reps)
Leg Extensions (warm-up only): 3x15
Leg Press: 12, 10, 8, 6 - View Exercise
Single Leg Extensions: 12, 10, 8, 6
Sissy Squats: 3 x 12
Single Leg Curls: 12, 10, 8, 6
Stiff-legged Dead Lifts: 12, 10, 8
Leg Extensions (Drop Sets): 10=>10=>10 x 3 sets
Super Set (Squats w/ Sissy Squats w/ Lunges): 10=>15=>1 minute x 3 sets
Double Leg Curls: 12, 10, 8, 6
Dumbbell Leg Curls: 12, 10, 8, 6
Stiff-legged Dead Lifts: 12, 10, 8
Double Leg Curls (Drop Sets): 8=>8=>8 x 4 sets
Stiff-legged Dead Lifts: 4 sets x 8 reps
Single Leg Extensions: 4 sets x 8 reps
Smith Squats: 4 sets x 8 reps
Hack Squats: 4 sets x 8 reps
As you can see, there is almost an unlimited variation in the way that you can train your legs. The first 3 workouts I described are more of a contest-season type workout because you are doing supersets and drop sets almost every workout. Also, there are a higher number of repetitions. The final workout I described is more what I do in the off-season for mass. Each set I increase the weight and try to get the same number of repetitions, which is not always very easy. You will need to start with a little lighter weight on the first set. Also, you can do a range of 6-8 reps just in case you fatigue on the last set.
There are numerous other exercises and equipment you can use. This just happens to be what I have available at the "gym" I workout at. If you have all the nice hammer strength equipment feel free to try it out.
Hopefully, this article will help to get you on the right track to building your legs up. This is by no means "the way" to do it, but simply a direction to take. Every body responds differently to varying weight, repetitions, and rest periods. I have to play with every factor when getting my body ready for a show or when trying to put on size during the off-season.