8 reps · beginner
The first fundamental of contemporary pilates: lying on the back with the knees bent, the feet flat and hip-width apart and the arms long by the sides. Breathing out, the deep abdominals draw in and the pelvis tilts so the small natural arch of the lower back presses gently into the mat (imprint); breathing in, the pelvis returns to neutral and the arch comes back (release).
Bodyweight: no weights. Joint demand below is your own body's weight in this position.
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.
8 slow, controlled reps. Pilates is practised for control, balance and mobility, never to failure, so this does not change with your limits.
Level: beginner. One round counts like light conditioning work: 51 core points.
Transversus abdominis, rectus abdominis and internal obliques (tilting the pelvis), pelvic floor; spinal erectors released.
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.