Step upCentre of mass inside base of support
Side view
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Step-up

Front foot on a 40 cm box, 12 kg dumbbells. The pelvis rises over the front foot; the trailing leg leaves the floor in the last half and finishes beside it.

1°Ankle dorsiflexion
80°Knee flexion
99°Hip flexion
20°Trunk from vertical
22°Arm to trunk
0°Elbow flexion
23Ankle spacing, cm
44Hand spacing, cm
1Knee outside ankle, cm
0°Knee cave, ° inside toe line
49 / 51Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 12 kg each hand. Balance and joint demand re-solve as you change it.

Lower back
92 / 92
Hip extensors
56 / 56
Knee extensors
23 / 31
Shins
2 / 89

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

Quads
100 pts
Glutes
100 pts

Effort and your quota

6.5/10 effort6.8fatigue per set

Your quota per set: 10 reps at 12 kg each hand, stopping 2 reps short of failure.

One hard set earns 200 legs points.

Prime movers

Quadriceps and gluteus maximus of the working leg.

What to look for

  • Drive through the whole front foot; the rear foot should not push you up.
  • At the top all the weight is over one foot.
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.