Open, eccentric
Side view
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Dumbbell fly

Flat bench, 14 kg dumbbells, elbows fixed at a slight 18° bend. Arms open from vertical to about 72° of abduction in the trunk frame.

-15°Ankle dorsiflexion
79°Knee flexion
39°Hip flexion
87°Trunk from vertical
90°Arm to trunk
18°Elbow flexion
60Ankle spacing, cm
52Hand spacing, cm
6Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 14 kg each hand. Balance and joint demand re-solve as you change it.

Shoulder, per side
15 / 97
Elbow, per side
14 / 47

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

Chest
100 pts
Shoulders
82 pts

Effort and your quota

3/10 effort3.1fatigue per set

Your quota per set: 10 reps at 14 kg each hand, stopping 2 reps short of failure.

One hard set earns 182 push points.

Prime movers

Pectoralis major, anterior deltoid.

What to look for

  • Elbow angle stays fixed; bending more turns it into a press.
  • Stop where the stretch is strong, not where the dumbbells touch the floor.
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.