Kenny Kroxdale lifts and sells equipment. Check out his thoughts.
"45 Degree Hip/Back Extension
This provides some good information on the 45 Degree Hip/Back Extension.
It’s essentially a Good Morning performed from a different angle.
Bell Shaped Strength Curve Training
The 45 Degree Hip/Back Extension has a “Bell Shaped Strength Curve”. That means it is easy at the beginning and end of the movement.
It is hard in the middle part of he movement. As he stated in the video, this works the mid range knee area of a Deadlift.
90 Degree/Parallel Hip/Back Extension
This essentially is a Good Morning from a different angle, as well.
“Descending Strength Curve Training”
The 90 Degree Hip/Back Extension has a “Descending Strength Curve”. That means it is easy at the beginning and middle part of the movement; hard at the end/lockout.
It works the top end/lockout of a Deadlift.
Good Morning Hip/Back Extension
Another version of a Hip/Back Extension from a different angle.
The Ascending Strength Curve
The Good Morning has an “Ascending Shaped Strength Curve”. That means it is hard in the bottom position and easier at the middle and top part of the movement.
Good Morning increase strength and power off the floor of a Deadlift.
Choose The Right Tool For The Job
Each of these Hip/Back Extension Exercises elicits a different training effect.
- 45 Degree Hip/Back Extension for increasing Mid Range Strength; knee area of the Deadlift.
- 90 Degree Hip/Back Extension for increasing Top End/Lockout of the Deadlift.
- Good Morning Hip/Back Extension for increasing strength and power off the floor of he Deadlift
Kenny Croxdale"