Simhasana
4 reps · beginner
Take care: Sit on a cushion between the heels if the knees or ankles hurt, or sit cross-legged instead.
Simhasana, sitting back on the heels (thunderbolt) with the knees a little apart: the hands press on the knees with the arms straight and the fingers spread, the trunk leans forward about 20°, and on a strong out-breath the mouth opens wide, the tongue reaches toward the chin and the gaze lifts.
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.
4 slow, controlled reps. Yoga 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: 4 legs points, 32 push points, 16 arms points, 12 core points.
Muscles of the face, jaw, tongue and throat; triceps and deltoids (pressing the knees), spinal erectors; quadriceps and ankle extensors (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.