Virasana
hold 60 s · beginner · move in slowly, hold, come out the same way
Take care: Sit higher (two blocks) if the knees hurt, and skip it with a knee injury or one that will not fold this far.
Virasana, sitting on a block: kneeling with the knees together and the feet just wider than the hips, tops of the feet down and toes pointing straight back, the hips lower onto a block between 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, 14 core points.
Quadriceps and tibialis anterior (stretched), spinal erectors (holding the spine tall), 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.