Hinge downBalanced over midfoot, bar 0.8 cm ahead
Side view
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Stiff-leg deadlift

80 kg pulled from low shins with the knees nearly straight (5° to 12°). The shins re-balance so the whole system stays over midfoot.

6°Ankle dorsiflexion
5°Knee flexion
4°Hip flexion
3°Trunk from vertical
6°Arm to trunk
0°Elbow flexion
26Ankle spacing, cm
50Hand spacing, cm
-2Knee outside ankle, cm
–Knee cave, ° inside toe line
50 / 50Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 80 kg. Balance and joint demand re-solve as you change it.

Lower back
28 / 473
Hip extensors
16 / 280
Knee flexors
22 / 143
Calves
58 / 58
Shoulder, per side
25 / 25
Elbow, per side
12 / 12

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
82 pts
Lower back
64 pts

Effort and your quota

7/10 effort7.3fatigue per set

Your quota per set: 10 reps at 80 kg, stopping 2 reps short of failure.

One hard set earns 182 legs points, 64 core points.

Prime movers

Hamstrings, gluteus maximus, spinal erectors.

What to look for

  • Less knee bend than a Romanian deadlift, more hamstring stretch.
  • Keep the bar close; it hangs from the shoulders.
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.