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Bear plank

On hands and toes with the knees hovering about 5 cm off the floor, hips and knees at 90°. Static hold.

0°Ankle dorsiflexion
112°Knee flexion
82°Hip flexion
82°Trunk from vertical
84°Arm to trunk
2°Elbow flexion
17Ankle spacing, cm
40Hand spacing, cm
0Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load left / right, %
0Pelvis drop, cm

Load and joint demand

Bodyweight exercise: the load slider has no effect here; body mass comes from your limits.

No gravity-based joint demand to show for this exercise.

Faults

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.

Body

Femur changes keep standing height fixed by shortening or lengthening the torso. Longer femurs force more forward lean in any squat.

Muscles worked

Abs and core
60 pts
Quads
38 pts
Shoulders
28 pts

Effort and your quota

4/10 effort4fatigue per set

Your quota per set: hold 34 s, stopping 2 reps short of failure.

One hard set earns 38 legs points, 28 push points, 60 core points.

Prime movers

Transversus abdominis, rectus abdominis, quadriceps, deltoids.

What to look for

  • Knees just off the floor, back flat.
  • Breathe without letting the hips rise.
How the model works, and its limits

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.