Since I’m from the country that this type of squat is named after, I’ll tell you something. This squat was popularized in America in the late 1980s, when the assistant coach of the Bulgarian national weightlifting team, Angel Spasov, visited the USA and talked about the best training methods for Bulgarian weightlifters. The interest in the Bulgarian system is very high, because the Bulgarian weightlifters win dozens of medals at the world championships and the Olympic Games.
According to Angel Spasov’s explanations, the Bulgarian weightlifters have completely removed neck barbell squats from their training program, replacing them with bench press repetitions and split squats with the rear leg raised. Spasov published an article co-authored with Terry Todd titled “The Bulgarian Leg Training Secret” in which he also recommends this pattern over traditional squats.
Myth and reality
The late Ivan Abadjiev - the most decorated and legendary former head coach of the national barbell team of Bulgaria - subsequently denied the claims of his assistant. During a seminar in 2011, Abadjiev claimed that national weightlifters never used this technique in their training and never stopped squatting with neck weights.
The idea of introducing them was proposed only by Angel Spasov, but Abadjiev did not accept it, as he doubted how effectively they would affect the main goal of the team. Abadjiev’s program focuses on a small number of exercises that the coach believes are most important for honing Olympic sport-specific skills.
However, the assistant coach took the opportunity to promote his idea during the workshop in the USA. And apparently he succeeded, because the exercise has gained popularity and undeniably gives its benefits.