what is this leg excercise

[Mr I]

at about the 4.4min mark in the vid

Robert Burneika Trains Quads and Calves 3 Weeks out from the USAs

[mindstar]

those are a sissy squat variation

[Shibby]

Kind of a body weight front squat. More of an endurance agility exercise, not a mass builder. Now if you try the hamstring variation, it is very hard at first. You would lock your feet in with knees on the ground. Then keeping from your knees to your head in a straight line, lower your face towards (no hands of course) the ground and then pull yourself back up, staying in a straight line.

[Mr I]

Sounds like a great way to rip your hamstring