Bhujangasana
hold 20 s · beginner · move in slowly, hold, come out the same way
Take care: Lift only as far as is comfortable for the lower back; skip it with a back injury that bending backward aggravates, and during pregnancy.
Bhujangasana. Lying face down, legs straight back with the tops of the feet on the mat, hands under the shoulders. The chest lifts about 30° by extending the spine while the pelvis and legs stay down; the elbows stay bent and close to the ribs.
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: 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: 22 legs points, 16 pull points, 39 core points.
Spinal erectors, multifidus, gluteus maximus, rhomboids and lower trapezius; abdominals and hip flexors 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.