Exercise guide
Knee/Hip Raise On Parallel Bars
The source title suggests a knee or hip raise, but the instructions describe a straight-leg raise performed on a vertical bench. The abdominals help control the pelvis while the hip flexors raise the extended legs and the forearms support the body.
Training context
Keeping the Supported Leg Raise Controlled
The back pad and forearm supports reduce the grip demand found in a hanging leg raise. Straight legs create a longer lever and make the exercise substantially harder than a bent-knee variation.
The legs do not need to reach parallel if doing so requires swinging or pulling the lower back away from the pad.
Technique overview
Raise the legs without creating momentum
Set the forearms on the pads, hold the handles, and press the back against the support. Raise the legs together through the highest controlled range, then lower slowly until they hang beneath the body. Use bent knees if the straight-leg version cannot be controlled.
Treat this as an overview and use a range, pace, and setup you can control.