Lower to the floorBalanced over midfoot
Load 61% on the right
Side view
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Sandbag over shoulder

Take care: Keep the back flat as you lift; skip it with a sore lower back.

A 30 kg sandbag lifted from the floor to the lap, then the hips drive through to hoist it up onto one shoulder, alternating shoulders each rep. Shown to the right shoulder and lowered back to the floor; in competition the bag goes over the shoulder to the floor behind.

-1°Ankle dorsiflexion
4°Knee flexion
16°Hip flexion
2°Trunk from vertical
48°Arm to trunk
137°Elbow flexion
64Ankle spacing, cm
26Hand spacing, cm
-11Knee outside ankle, cm
–Knee cave, ° inside toe line
39 / 61Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 30 kg. Balance and joint demand re-solve as you change it.

Lower back
63 / 341
Hip extensors
33 / 197
Knee flexors
37 / 49
Calves
57 / 65
Shoulder, per side
69 / 99
Elbow, per side
37 / 52

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
Lower back
64 pts
Upper back
46 pts
Quads
35 pts
Biceps
35 pts

Effort and your quota

8/10 effort8.3fatigue per set

Your quota per set: 10 reps at 30 kg, stopping 2 reps short of failure.

One hard set earns 217 legs points, 67 pull points, 35 arms points, 64 core points.

Prime movers

Gluteus maximus, hamstrings, spinal erectors, upper back, quadriceps, biceps.

What to look for

  • Get the bag into the lap first, chest over it.
  • Snap the hips through and drive it up to the shoulder.
  • Turn the head away and let the bag ride up and over.
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.