Marjaryasana-Bitilasana
8 reps · beginner
Take care: Put a blanket under the knees if they are tender, and come onto the fists or forearms if the wrists hurt.
Marjaryasana-Bitilasana, on hands and knees: knees under the hips, hands under the shoulders, arms straight. Breathing in (cow) the belly sinks and the head lifts to look forward; breathing out (cat) the back rounds up toward the ceiling and the chin tucks toward the chest. The spine bends about 40° each way, the lower back most in cow and the upper back most in cat.
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.
8 slow, controlled reps. 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: 30 push points, 8 arms points, 64 core points.
Spinal erectors, rectus abdominis and obliques (moving the spine), serratus anterior, deltoids and triceps (holding the arms), neck flexors and extensors.
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.