Descent, eccentric
Side view
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Smith machine squat

Bar runs on fixed vertical rails, feet 10 cm ahead of it. The trunk angle is solved to keep the bar on its rail, not for balance, because the machine holds the lifter up.

3°Ankle dorsiflexion
2°Knee flexion
18°Hip flexion
12°Trunk from vertical
47°Arm to trunk
138°Elbow flexion
42Ankle spacing, cm
84Hand spacing, cm
-6Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load left / right, %
0Pelvis drop, cm

Load and joint demand

Machine or cable load (80 kg at this setting) is not modelled, so joint demand shows the body only.

No gravity-based joint demand to show for this exercise.

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
82 pts

Effort and your quota

5.5/10 effort5.7fatigue per set

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

One hard set earns 182 legs points.

Prime movers

Quadriceps, gluteus maximus.

What to look for

  • Feet forward lets the trunk stay upright on the fixed bar path.
  • Compare the balance with the free back squat: the machine does part of that job.
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.