Hinge downBalanced over midfoot, bar 2.7 cm ahead
Side view
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Barbell single-leg Romanian deadlift

Standing on the right leg with a 40 kg barbell in both hands; the free leg extends back in line with the trunk as it hinges to about 78°. Shin angle solved to balance over one foot.

11°Ankle dorsiflexion
10°Knee flexion
6°Hip flexion
3°Trunk from vertical
6°Arm to trunk
0°Elbow flexion
9Ankle spacing, cm
50Hand spacing, cm
5Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load 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
18 / 313
Hip extensors
11 / 190
Knee flexors
43 / 252
Calves
92 / 100
Shoulder, per side
13 / 13

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

Hamstrings
100 pts
Glutes
100 pts
Lower back
64 pts

Effort and your quota

6.5/10 effort6.8fatigue per set

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

One hard set earns 200 legs points, 64 core points.

Prime movers

Hamstrings and gluteus maximus of the standing leg, gluteus medius, spinal erectors.

What to look for

  • Pivot at the hip like a see-saw.
  • Keep the bar level; hips stay square.
  • Back toe points at 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.