Right knee
Side view
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A-skip

A running drill: skipping on the spot, driving one knee to hip height with the toes pulled up while the other foot gives a small hop off the ball of the foot, the opposite arm driving forward. Momentum is ignored, so no balance check.

3°Ankle dorsiflexion
53°Knee flexion
34°Hip flexion
3°Trunk from vertical
35°Arm to trunk
90°Elbow flexion
21Ankle spacing, cm
45Hand spacing, cm
1Knee 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
100 pts
Calves and shins
82 pts
Glutes
64 pts
Quads
46 pts

Effort and your quota

6/10 effort6fatigue per set

Your quota per set: 30 s hard, stopping 2 reps short of failure.

One hard set earns 167 legs points, 100 core points.

Prime movers

Hip flexors, calves, gluteus maximus, quadriceps, abdominals.

What to look for

  • Knee up to hip height, toes pulled up.
  • Small, springy hop on the ball of the other foot.
  • Opposite arm drives forward; stay tall.
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.