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Side view
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Jumping jack

Feet jump from together to wide while the arms sweep from the sides to overhead, with a small hop. Momentum is ignored, so no balance check.

4°Ankle dorsiflexion
2°Knee flexion
2°Hip flexion
0°Trunk from vertical
10°Arm to trunk
10°Elbow flexion
16Ankle spacing, cm
52Hand 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.

Shoulder, per side
3 / 12

N·m now / peak over the rep.

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

Calves and shins
35 pts
Adductors
29 pts
Glutes
29 pts
Shoulders
22 pts

Effort and your quota

6/10 effort6fatigue per set

Your quota per set: 58 reps at bodyweight, stopping 2 reps short of failure.

One hard set earns 82 legs points, 22 push points.

Prime movers

Calves, hip abductors and adductors, deltoids.

What to look for

  • Land softly on the balls of the feet.
  • The front camera shows the movement.
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.