Take care: Take care: this deliberately rounds the loaded spine. Start with an empty bar or a light plate, build range slowly, and skip it with a back injury or a disc problem.
Standing with a light 20 kg bar, the chin tucks and the back rounds forward one segment at a time as the bar slides down the legs, knees almost straight, then rolls back up the same way. A loaded stretch for the hamstrings and the back.
Load in the model: 20 kg. Balance and joint demand re-solve as you change it.
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.
Your quota per set: 10 reps at 20 kg, stopping 2 reps short of failure.
One hard set earns 94 legs points, 82 core points.
Hamstrings (stretched), spinal erectors, gluteus maximus.
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.