Chop downBalanced over midfoot
Side view
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Dumbbell woodchop

Take care: Twisting under load: go light, keep the back long, and skip it if your lower back is sore.

Wide stance with one 8 kg dumbbell held by its ends in both hands; it travels from high over the right shoulder to low outside the left knee as the trunk turns, bends forward and the knees bend. The pelvis shifts front to back to stay balanced.

3°Ankle dorsiflexion
4°Knee flexion
9°Hip flexion
4°Trunk from vertical
105°Arm to trunk
91°Elbow flexion
40Ankle spacing, cm
12Hand spacing, cm
-5Knee outside ankle, cm
–Knee cave, ° inside toe line
42 / 58Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 8 kg. Balance and joint demand re-solve as you change it.

Lower back
31 / 129
Hip extensors
17 / 78
Knee flexors
18 / 21
Calves
31 / 41
Shoulder, per side
38 / 38
Elbow, per side
24 / 29

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
Glutes
64 pts
Shoulders
46 pts
Quads
35 pts

Effort and your quota

5/10 effort5.2fatigue per set

Your quota per set: 10 reps at 8 kg, stopping 2 reps short of failure.

One hard set earns 99 legs points, 46 push points, 100 core points.

Prime movers

Obliques, rectus abdominis, gluteus maximus, deltoids, quadriceps.

What to look for

  • Turn from the trunk and hips; the arms just follow.
  • Pivot on the back foot as you chop down.
  • Keep the back long; bend the knees to reach low.
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.