Natarajasana
hold 20 s each side · intermediate · move in slowly, hold, come out the same way
Take care: Kick into the strap gently and stay more upright if the lower back pinches; skip it with a back injury that bending backward aggravates.
Natarajasana, with a strap. Standing on the right leg, the left knee bends and a strap looped round the left ankle is held in the left hand; the left foot kicks back and up into the strap while the trunk tips forward and the right arm reaches forward and up. The standing leg stays straight; the centre of mass is solved over the standing foot.
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 20 seconds on each side: 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: intermediate. One round counts like light conditioning work: 68 legs points, 7 push points, 33 core points.
Quadriceps and hip flexors of the lifted leg (stretched), gluteus maximus and hamstrings, spinal erectors, gluteus medius of the standing leg, pectoralis major and anterior deltoid (stretched), foot and ankle stabilisers.
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.