Curl, concentricBalanced over midfoot, bar 0.5 cm behind
Side view
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Cheat curl

Take care: Take care: the swing loads the lower back. Keep it small, the back flat, and skip it with a lower-back injury.

A heavier 40 kg barbell curl where a small hip drive from a slight forward lean starts the bar moving, then the bar is lowered slowly and strictly. An overload technique for strong lifters.

1°Ankle dorsiflexion
2°Knee flexion
15°Hip flexion
15°Trunk from vertical
4°Arm to trunk
10°Elbow flexion
30Ankle spacing, cm
43Hand spacing, cm
-3Knee 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
49 / 145
Hip extensors
33 / 71
Knee flexors
35 / 54
Calves
43 / 43
Shoulder, per side
19 / 84
Elbow, per side
4 / 69

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

Biceps
100 pts
Forearms and grip
64 pts
Lower back
23 pts

Effort and your quota

2/10 effort2.1fatigue per set

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

One hard set earns 60 pull points, 132 arms points, 23 core points.

Prime movers

Biceps brachii, brachialis, brachioradialis, spinal erectors (holding).

What to look for

  • A small hip drive, not a big swing.
  • Lower slowly with the body still.
  • Back stays flat throughout.
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.