Hike backBalanced over midfoot
Side view
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Dumbbell skier swing

Take care: A ballistic hip hinge: keep the back flat and learn the hinge first if your lower back is sore.

A 10 kg dumbbell in each hand at the sides: the arms swing back past the hips as the hips hinge to about 55°, then forward to shoulder height as they snap through, like poling on skis. Shown quasi-statically.

-2°Ankle dorsiflexion
10°Knee flexion
15°Hip flexion
2°Trunk from vertical
75°Arm to trunk
8°Elbow flexion
28Ankle spacing, cm
61Hand spacing, cm
-2Knee outside ankle, cm
–Knee cave, ° inside toe line
50 / 50Load left / right, %
0Pelvis drop, cm

Load and joint demand

Load in the model: 10 kg each hand. Balance and joint demand re-solve as you change it.

Lower back
158 / 164
Hip extensors
80 / 87
Knee flexors
43 / 44
Calves
36 / 36
Shoulder, per side
75 / 76
Elbow, per side
36 / 36

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
Shoulders
46 pts
Forearms and grip
35 pts

Effort and your quota

7/10 effort7.3fatigue per set

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

One hard set earns 182 legs points, 46 push points, 18 arms points, 64 core points.

Prime movers

Gluteus maximus, hamstrings, spinal erectors, anterior deltoid, grip.

What to look for

  • Hinge at the hips; the knees bend only a little.
  • Swing the dumbbells back past the hips, close to the legs.
  • Stand tall as they float forward.
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.