Press, concentric
Side view
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Dumbbell Z press

Sitting on the floor with the legs straight out, 12 kg dumbbells pressed from the shoulders to overhead. With no back support and no legs to help, the trunk has to hold itself upright.

-5°Ankle dorsiflexion
3°Knee flexion
89°Hip flexion
0°Trunk from vertical
46°Arm to trunk
154°Elbow flexion
17Ankle spacing, cm
60Hand spacing, cm
0Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 12 kg each hand. Balance and joint demand re-solve as you change it.

Shoulder, per side
20 / 20
Elbow, per side
16 / 32

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

Shoulders
100 pts
Triceps
82 pts
Upper back
64 pts
Abs and core
46 pts

Effort and your quota

4/10 effort4.2fatigue per set

Your quota per set: 10 reps at 12 kg each hand, stopping 2 reps short of failure.

One hard set earns 182 push points, 64 pull points, 82 arms points, 46 core points.

Prime movers

Deltoids, triceps, upper back, abdominals.

What to look for

  • Sit tall on the sit bones; no leaning back.
  • Press straight up over the shoulders.
  • Keep the legs long and the ribs down.
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.