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Ski erg

On a ski machine: both handles pulled from overhead down past the hips as the hips hinge and the knees bend, then the arms rise as the body stands tall again. The machine is drawn behind as scenery; the handles hang on cords from its top.

8°Ankle dorsiflexion
6°Knee flexion
7°Hip flexion
2°Trunk from vertical
143°Arm to trunk
76°Elbow flexion
30Ankle spacing, cm
40Hand spacing, cm
-3Knee 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

Lats
100 pts
Triceps
82 pts
Abs and core
64 pts
Glutes
46 pts
Hamstrings
35 pts

Effort and your quota

5/10 effort5fatigue per set

Your quota per set: 60 s hard, stopping 2 reps short of failure.

One hard set earns 81 legs points, 82 push points, 100 pull points, 82 arms points, 64 core points.

Prime movers

Latissimus dorsi, triceps, abdominals, gluteus maximus, hamstrings.

What to look for

  • Start tall with the arms up, then crunch down: hips back, arms driving to the thighs.
  • Finish with the hands past the hips, then stand up and reach again.
  • The legs and the trunk give the power; the arms finish it.
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.