Curl, concentric
Side view
Drag to orbit, pinch or scroll to zoom

Concentration curl

Seated and leaning forward, the right elbow braced against the inside of the right thigh; the arm hangs straight down and curls toward the shoulder.

-7°Ankle dorsiflexion
80°Knee flexion
116°Hip flexion
35°Trunk from vertical
38°Arm to trunk
10°Elbow flexion
48Ankle spacing, cm
56Hand spacing, cm
3Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load 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.

Shoulder, per side
14 / 45
Elbow, per side
10 / 43

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

Effort and your quota

1/10 effort1fatigue per set

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

One hard set earns 60 pull points, 100 arms points.

Prime movers

Biceps brachii, brachialis.

What to look for

  • The thigh fixes the elbow; nothing else moves.
  • Squeeze at the top.
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.