Bulgarian Squat/Single Leg Split Squat

The exercise, which is widely known around the world as the Bulgarian squat. It's specific in that it runs on one leg while the other is extended backwards and leaning on support.

The movement is easy to perform when using only bodyweight. By adding additional weight (barbell, dumbbells) balancing becomes much more difficult, so this variation is recommended for more advanced fitness enthusiasts.

Involved muscles

Target

• Quadriceps

Synergists

• Gluteus Maximus
• Adductor Magnus
• Soleus

Dynamic Stabilizers

• Hamstrings
• Gastrocnemius

Stabilizers

• 
  
• Gluteus Medius
• Gluteus Minimus

Variations

According to the technique and available equipment

• Bodyweight - easy option to start learn and adapt to the movement;
• With dumbbells / weights - the easiest variation with which you can use to increase strength and muscle mass;
• Smith machine - this variation puts more stress on the long spinal muscles as stabilizers. I do not recommend this variation for people with lower back problems;
• With a short barbell - the hardest option, balance is almost impossible.I don't recommend performing this exercise with an olympic bar, as i said before balacing is almost impossible.
• With bands - the difficulty changes from low to high in the upper range of motion;

According to the type of support

• Stable (bench seat, 5-6 disk weights or even a dumbbell) - start with this.
• Unstable (Swiss ball) - a wonderful option for people aiming to improve their balance. Can be combined with dumbbells, all other options have risks and fewer benefits.

Method of execution

Preparation

• Stand with dumbbells grasped to sides facing away from bench. Extend leg back and place top of foot on bench.

Execution

• Squat down by flexing knee and hip of front leg until knee of rear leg is almost in contact with floor. Return to original standing position by extending hip and knee of forward leg and repeat. Continue with opposite leg.

Recommendations

• Avoid sudden movements, especially when descending;
• Do not hit your knee into the floor;
• Do not shake dumbbells;
• Do not bend, keep the body upright;
• While performing keep your whole foot on the ground, your weight should be evenly distributed;

Relevancy

Performed with weights the Bulgarian squat can contribute significantly to the increase of muscle mass in the upper sector of the thighs. In terms of functionality, performance of this type of squat can improve sprints and jumping length and height.

(sources:exrx.net)
(pictures:t-nation.com)