On your back with the other knee bent and that foot flat. The straight leg lifts from the floor until it is level with the bent knee, then lowers slowly. Shown on the right leg.
Bodyweight exercise: the load slider has no effect here; body mass comes from your limits.
Faults grow with knee bend and apply to lifts standing on the floor. The fault check flags a knee caving more than 10° inside the line of the toes and a load split beyond 60/40. Knee cave shows best in the front camera.
Femur changes keep standing height fixed by shortening or lengthening the torso. Longer femurs force more forward lean in any squat.
Prescription: 2 × 10 each leg. Follow it as written; it is not adjusted by your limits.
Rehab exercise: not scored and never pushed toward failure. Stop and check with your physio if it hurts.
Quadriceps (rectus femoris), hip flexors.
One 3D skeleton drives both views. Segment lengths and widths are Winter's anthropometric ratios of height; segment masses and centre-of-mass positions follow Dempster's data. For free-standing lifts the whole-body angle is found numerically so the combined centre of mass of lifter and load sits over the middle of the foot. Arms and legs use two-link inverse kinematics with a pole direction. Rep timing follows a minimum-jerk profile.
Balance is quasi-static, so ballistic lifts are shown slowed down. Cable pull and pad support forces are not modelled. The spine is one rigid segment and joints have no range-of-motion limits or muscle forces.