Press, concentricBalanced over midfoot
Side view
Drag to orbit, pinch or scroll to zoom

Alternating dumbbell shoulder press

Standing with 16 kg dumbbells at the shoulders; the right one presses overhead while the left waits at the shoulder, then they swap. The hips shift to keep the load split even.

3°Ankle dorsiflexion
2°Knee flexion
5°Hip flexion
3°Trunk from vertical
45°Arm to trunk
154°Elbow flexion
32Ankle spacing, cm
60Hand 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: 16 kg each hand. Balance and joint demand re-solve as you change it.

Lower back
37 / 37
Hip extensors
20 / 20
Knee flexors
26 / 26
Calves
40 / 40
Shoulder, per side
25 / 25
Elbow, per side
20 / 41

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
Abs and core
64 pts
Upper back
46 pts

Effort and your quota

4/10 effort4.2fatigue per set

Your quota per set: 10 reps at 16 kg each hand, stopping 2 reps short of failure.

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

Prime movers

Anterior and lateral deltoid, triceps, obliques, upper trapezius.

What to look for

  • Stay tall; do not lean away from the pressing arm.
  • Keep the waiting dumbbell still at the shoulder.
  • Finish with the biceps by the ear.
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.