Sprint
Side view
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Sprint

Running flat out: a strong forward lean from the ankles, a high knee drive and a heel kick right up under the hips, the foot striking under the body, and a big arm swing with the elbows at about 90°. Shown on the spot, as on a treadmill.

42°Ankle dorsiflexion
98°Knee flexion
42°Hip flexion
11°Trunk from vertical
8°Arm to trunk
88°Elbow flexion
18Ankle spacing, cm
48Hand spacing, cm
2Knee outside ankle, cm
–Knee cave, ° inside toe line
–Load left / right, %
0Pelvis drop, cm

Load and joint demand

Bodyweight exercise: the load slider has no effect here; body mass comes from your limits.

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

Glutes
100 pts
Hamstrings
82 pts
Quads
64 pts
Abs and core
46 pts
Calves and shins
35 pts

Effort and your quota

8/10 effort8fatigue per set

Your quota per set: 20 s hard, stopping 2 reps short of failure.

One hard set earns 271 legs points, 46 core points.

Prime movers

Gluteus maximus, hamstrings, quadriceps, hip flexors, calves.

What to look for

  • Drive the knees forward and the arms hard.
  • Strike the ground under the hips, not out in front.
  • Stay tall and relaxed through the face and shoulders.
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.