Vajrasana
hold 60 s · beginner · move in slowly, hold, come out the same way
Take care: Sit on a block or a cushion between the heels if the knees or ankles hurt; skip it with a knee that will not fold this far.
Vajrasana, kneeling and sitting back on the heels: the knees together, the shins and the tops of the feet on the mat, the big toes close and the heels a little apart under the seat. From kneeling upright, the hips lower back onto the heels; the spine is upright and the hands rest on the thighs.
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 60 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: beginner. One round counts like light conditioning work: 18 legs points, 22 core points.
Quadriceps and tibialis anterior (stretched), ankle extensors (stretched), spinal erectors and deep core (holding the spine tall).
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.