Jump and catchCentre of mass inside base of support
Side view
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Hang power snatch

A 40 kg bar on a snatch grip starts at the hips, hinges to just above the knees, then an explosive extension sends it overhead to be caught locked out in a quarter squat. Legs keyframed, trunk lean solved for balance every frame.

3°Ankle dorsiflexion
2°Knee flexion
5°Hip flexion
1°Trunk from vertical
34°Arm to trunk
2°Elbow flexion
32Ankle spacing, cm
110Hand spacing, cm
-4Knee outside ankle, cm
–Knee cave, ° inside toe line
50 / 50Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 40 kg. Balance and joint demand re-solve as you change it.

Lower back
12 / 229
Hip extensors
6 / 140
Knee extensors
17 / 43
Calves
35 / 35
Shoulder, per side
77 / 83
Elbow, per side
36 / 61

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

Glutes
100 pts
Quads
82 pts
Hamstrings
64 pts
Upper back
46 pts
Shoulders
35 pts
Calves and shins
35 pts

Effort and your quota

8.5/10 effort8.9fatigue per set

Your quota per set: 10 reps at 40 kg, stopping 2 reps short of failure.

One hard set earns 271 legs points, 35 push points, 46 pull points.

Prime movers

Gluteus maximus, quadriceps, hamstrings, trapezius, deltoids, calves.

What to look for

  • Bar brushes the hips at the jump.
  • Pull the elbows high, then punch under.
  • Lock out overhead with the bar over the back of the neck.
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.