Uttanasana
hold 30 s · beginner · move in slowly, hold, come out the same way
Take care: Bend the knees generously and come up slowly with a rounded back if your lower back is sore; rise slowly if you get light-headed.
Uttanasana, with the knees bent as much as the back needs. Feet hip-width; from standing the body folds forward from the hips until the trunk hangs down over the thighs and the hands come to the mat just in front of the feet (blocks under them if the floor is far). The knees soften to about 20° so the spine can stay long; the hips are solved back over the heels so the centre of mass stays 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 30 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: 27 legs points, 7 core points.
Hamstrings (stretched), calves (stretched), spinal erectors (stretched), gluteus maximus (stretched), quadriceps (holding).
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.