Hamstring development has not always been necessary. Not long ago bodybuilders had done well in the development of their upper legs in both the front and rear; however, the importance of leg bicep formation for competition wasn't too popular.
Bodybuilders recently, such as Tom Platz, Robby Robinson and Sergio Oliva have made leg bicep formation essential to competition.
Not unlike the triceps, the leg biceps come into play for some poses. For example, in a side chest or triceps shot, the angle of the leg biceps is very prominent. For a shot that is from behind, great and defined rear deltoids, traps, and lats will not make up for a lack of leg bicep formation.
When viewing from the rear, the leg biceps need to be distinctly defined. In addition, ripped and muscular calves are important for the development of balance and muscularity of the back, shoulders and arms shown in maneuvers such as a rear double-biceps or rear lat spread.
These days, there are now more examples of striated and even cross-striated leg biceps, something that was extinct a decade to fifteen years passed. As with other sports, when something is new and spectacular, others join in to do the same thing or achieve similar results.
For the future, it looks like very muscular, striated, and vascular leg biceps will be the standard instead of a rarity in bodybuilding.
Once the legs get quite developed, they touch in the middle, even though usually, legs don't touch in the center because they are held separately away from each other.
In a side shot, well developed hamstrings and thighs become separated via a partition that is very visible to the judges and is a distinction of quality leg formation.
Hamstrings are particularly developed via Leg Curls. Leg Curls are performed both at a time, while lying on the stomach. Hamstring leg curls can also be done in isolation via a standing maneuver where one leg curls upwards at a time. Isolation techniques are useful when one side of the body or muscle is more developed than the other side.
Hamstring strength and development also occurs secondarily during exercises such as Squats and Lunges.
A good way to really stretch out your hamstrings comes from a couple lower-back exercises. Good mornings and Deadlifts also form the hamstrings and glutes. Methods that can aid in Hamstring development are shocking principles like the Stripping Method, partial and forced reps, and supersetting. The more you put into your hamstrings via heavy weight and shock methods, the more you'll get out of them.