Skandasana
hold 20 s each side · intermediate · move in slowly, hold, come out the same way
Take care: Sit only as low as the bent knee stays comfortable and the heel stays down; keep the hands on the mat or a block with a sore knee or a groin strain.
Skandasana, the version most classes teach first. Feet about 125 cm apart across the mat, toes turned out a little; the weight shifts onto the right leg, whose knee bends deeply (about 115°) over the toes with the heel down, while the left leg stays straight with its foot flat. The trunk leans forward about 30° on a long spine and the palms press together in front of the chest, the elbows inside the knees. The pelvis is placed so the straight knee stays straight, the bent knee is solved and the body is solved over the feet.
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: 82 legs points, 12 core points.
Adductors and hamstrings of the straight leg (stretched), quadriceps and gluteus maximus of the bent leg, gluteus medius, calf of the bent leg (stretched), spinal erectors.
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.