ExtendBalanced over midfoot
Side view
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Single-arm triceps kickback

Hinged to about 60° with the left hand braced on the left thigh; the right upper arm is held along the trunk while the elbow extends from 90° to straight behind the body.

0°Ankle dorsiflexion
24°Knee flexion
83°Hip flexion
60°Trunk from vertical
10°Arm to trunk
90°Elbow flexion
36Ankle spacing, cm
38Hand spacing, cm
-3Knee outside ankle, cm
0°Knee cave, ° inside toe line
44 / 56Load left / right, %
0Pelvis drop, cm

Load and joint demand

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

Lower back
134 / 134
Hip extensors
89 / 89
Knee flexors
29 / 29
Calves
32 / 32
Shoulder, per side
25 / 71
Elbow, per side
13 / 32

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

Triceps
100 pts

Effort and your quota

1.5/10 effort1.6fatigue per set

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

One hard set earns 100 push points, 100 arms points.

Prime movers

Triceps brachii.

What to look for

  • Keep the upper arm still and parallel to the torso.
  • Squeeze at full extension.
  • Lower only to a right angle at the elbow.
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.