StepCentre of mass inside base of support
Side view
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Waiter’s carry

One 12 kg dumbbell locked out overhead in the right hand, the left arm free, marching on the spot. The one-sided load overhead trains shoulder stability and resists a side bend.

4°Ankle dorsiflexion
2°Knee flexion
3°Hip flexion
4°Trunk from vertical
174°Arm to trunk
15°Elbow flexion
20Ankle spacing, cm
47Hand spacing, cm
-2Knee outside ankle, cm
–Knee cave, ° inside toe line
50 / 50Load left / right, %
0Pelvis drop, cm

Load and joint demand

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

Lower back
18 / 18
Hip extensors
10 / 10
Knee extensors
18 / 54
Calves
33 / 66

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
60 pts
Upper back
49 pts
Abs and core
28 pts
Triceps
21 pts

Effort and your quota

3.5/10 effort3.5fatigue per set

Your quota per set: carry 12 kg each hand for 42 s, stopping 2 reps short of failure.

One hard set earns 81 push points, 49 pull points, 21 arms points, 28 core points.

Prime movers

Deltoids, rotator cuff, upper trapezius, obliques, triceps.

What to look for

  • Lock the arm; biceps by the ear.
  • Keep the ribs down and the trunk upright.
  • Switch hands halfway.
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.