Sit up
Side view
Drag to orbit, pinch or scroll to zoom

Weighted sit-up

Knees bent, feet flat, a 10 kg dumbbell held across the chest. The trunk rises all the way from the floor to about 80°.

-32°Ankle dorsiflexion
110°Knee flexion
52°Hip flexion
90°Trunk from vertical
54°Arm to trunk
135°Elbow flexion
24Ankle spacing, cm
24Hand spacing, cm
2Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load left / right, %
0Pelvis drop, cm

Load and joint demand

Bodyweight exercise: the load slider has no effect here; body mass comes from your limits.

Shoulder, per side
22 / 32
Elbow, per side
34 / 35

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

Abs and core
100 pts

Effort and your quota

2/10 effort2fatigue per set

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

One hard set earns 100 core points.

Prime movers

Rectus abdominis, hip flexors, obliques.

What to look for

  • Keep the dumbbell tight to the chest.
  • Roll up smoothly; no jerking.
  • Lower under control.
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.