Hike backBalanced over midfoot
Side view
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Single-arm kettlebell swing

The kettlebell swing with a 16 kg bell in the right hand only; the left arm swings freely. Shown quasi-statically, without the momentum.

-3°Ankle dorsiflexion
12°Knee flexion
18°Hip flexion
2°Trunk from vertical
88°Arm to trunk
4°Elbow flexion
44Ankle spacing, cm
40Hand spacing, cm
-6Knee outside ankle, cm
–Knee cave, ° inside toe line
48 / 52Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 16 kg. Balance and joint demand re-solve as you change it.

Lower back
151 / 187
Hip extensors
76 / 103
Knee flexors
38 / 47
Calves
34 / 37
Shoulder, per side
12 / 115
Elbow, per side
3 / 55

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

Glutes
100 pts
Hamstrings
82 pts
Abs and core
64 pts
Forearms and grip
46 pts

Effort and your quota

6/10 effort6.3fatigue per set

Your quota per set: 10 reps at 16 kg, stopping 2 reps short of failure.

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

Prime movers

Gluteus maximus, hamstrings, obliques, grip.

What to look for

  • Resist the twist the one-sided bell creates.
  • Hips drive the bell; the arm guides it.
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.