Halasana
hold 30 s · advanced · move in slowly, hold, come out the same way
Take care: Learn it from a teacher, with a folded blanket under the shoulders; skip it with a neck or lower-back injury, high blood pressure, glaucoma or a heart condition, and during pregnancy.
Halasana: from shoulder stand, the straight legs lower over the head until the tucked toes rest on the mat behind it; the hands leave the back and the arms stretch along the mat behind the back, palms down. The hips stay high over the shoulders; the head stays on the mat facing up. The leg angle is solved so the toes just reach the floor.
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.
Hold for 30 seconds: move into the pose slowly, breathe steadily, and come out the way you went in. Yoga is practised for control, balance and mobility, never to failure, so this does not change with your limits.
Level: advanced. One round counts like light conditioning work: 41 legs points, 12 push points, 12 pull points, 12 arms points, 31 core points.
Hamstrings, calves and spinal erectors (stretched), rectus abdominis, hip flexors, triceps and posterior deltoid (pressing the arms down); neck and upper back stretched.
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.