Hinge downBalanced over midfoot
Side view
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Dumbbell stiff-leg deadlift

Take care: Loads the lower back: keep it flat and stop short of where it rounds.

22 kg dumbbell in each hand in front of the thighs, knees nearly straight (5° to 10°) while the trunk hinges to about 74°. The shins re-balance so the whole system stays over midfoot.

6°Ankle dorsiflexion
5°Knee flexion
3°Hip flexion
3°Trunk from vertical
3°Arm to trunk
0°Elbow flexion
24Ankle spacing, cm
40Hand 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: 22 kg each hand. Balance and joint demand re-solve as you change it.

Lower back
19 / 325
Hip extensors
11 / 196
Knee flexors
17 / 105
Calves
45 / 45

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
Forearms and grip
46 pts

Effort and your quota

6.5/10 effort6.8fatigue per set

Your quota per set: 10 reps at 22 kg each hand, stopping 2 reps short of failure.

One hard set earns 182 legs points, 23 arms points, 64 core points.

Prime movers

Hamstrings, gluteus maximus, spinal erectors, grip.

What to look for

  • Keep the knees soft but almost straight.
  • Let the dumbbells hang straight down from the shoulders.
  • Stop when the back starts to round.
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.