Action Pose Drawing: Motion Lines and Dynamic Balance

Object Drawing Lessons

Action poses read as dynamic when the body's weight, direction, and movement are visible. This lesson teaches a repeatable method: establish a balance axis from the support point through the center of mass, then add motion lines that follow the pose's trajectory. You will apply the method to running, jumping, and reaching figures, using simple arithmetic to check balance and line placement. All measurements are hypothetical examples; measure your own paper and tools. The convention for motion lines is defined below so that valid alternatives can be assessed fairly.

Practice materials: Printable downloads are not available for this lesson yet. Use the instructions and four exercises below.

Balance Axis and Center of Mass

Every action pose has a support point or support area where the body meets the ground or an object. The center of mass (COM) is roughly at the lower torso for a standing figure, shifting with limb positions. Draw a light balance axis: a line from the support point through the COM. If the COM projects outside the support area, the pose reads as falling or off-balance unless that is intended.

For a running figure, the support point is the contact foot. The COM should be near or slightly ahead of that foot during the drive phase. For a jump, the support point is the takeoff foot or both feet; during flight there is no support, so the balance axis becomes a trajectory line. For a reaching figure, the support area is the feet and the COM shifts toward the reach, so the axis tilts.

Use a simple check: mark the support point S and the COM C. Draw the vertical projection of C onto the ground line. For this lesson, use one foot-length as the chosen limit: if the horizontal distance from S to that projection is more than one foot-length, the pose will read as strongly off-balance. You may substitute your own limit, but the worked example and exercises use one foot-length. Label any numerical values as hypothetical examples.

1. Draw the ground line and mark the support point or area.
2. Sketch the figure's torso and mark the COM at the lower torso.
3. Draw a light balance axis from support through COM.
4. Check the horizontal offset between support and COM projection; adjust limbs to bring it within your chosen limit.

Motion Lines Convention

Motion lines show the path and speed of a body part or the whole figure. Use a consistent convention: lines are drawn behind the moving part, following the direction of travel, and taper toward the trailing end. A line's length indicates the distance traveled in the same time interval; longer lines mean faster motion. Lines should not cross the figure's silhouette unless showing an object passing in front.

For a running figure, motion lines trail from the back foot and the swinging arm. For a jump, lines follow the vertical trajectory and may fan out at the apex. For a reach, lines trail from the reaching hand and the opposite hip. Keep lines parallel to the movement direction; curved lines suggest rotation or a change of direction.

Valid alternatives: you may use dashed lines, tapered strokes, or short parallel strokes, as long as the direction and relative speed are clear. The rubric below accepts any of these if the convention is applied consistently.

1. Identify the main moving part and its direction.
2. Draw a tapered line behind it, longer for faster motion.
3. Add one or two secondary lines for other moving parts.
4. Check that lines do not obscure the figure's key joints.

Running Pose: Drive and Recovery

A running pose has a drive leg pushing off and a recovery leg swinging forward. The balance axis runs from the contact foot through the COM, which is slightly ahead of the foot. The torso leans forward; the arms swing opposite the legs. Motion lines trail from the back foot and the forward-swinging arm.

Check the pose by measuring the horizontal distance from the contact foot to the COM projection. If it is less than half a foot-length, the pose may look too upright; if more than one foot-length, it may look like a fall. Adjust the torso lean or the recovery leg position.

1. Draw the ground line and contact foot.
2. Place the COM slightly ahead of the foot and draw the balance axis.
3. Sketch the drive leg extended back and the recovery leg forward.
4. Add motion lines trailing from the back foot and the opposite arm.

Jumping and Reaching Poses

A jumping pose has a takeoff or flight phase. During flight, replace the balance axis with a trajectory line through the COM. Motion lines follow the trajectory and fan at the apex. For a reaching pose, the support area is the feet and the COM shifts toward the reach; the balance axis tilts. Motion lines trail from the reaching hand.

Check the jump by ensuring the trajectory line passes through the COM and the motion lines are parallel to it. Check the reach by measuring the horizontal offset from the support area to the COM projection; if it exceeds one foot-length, widen the stance or lower the reach.

1. For a jump, draw the trajectory line through the COM and add motion lines parallel to it.
2. For a reach, mark the support area and shift the COM toward the reach.
3. Draw the balance axis from support through COM.
4. Add motion lines trailing from the reaching hand and the opposite hip.

Worked example

A running figure contacts the ground with the right foot. The COM is 2 cm ahead of the foot horizontally. The foot-length unit is 4 cm. Is the pose within the one-foot-length balance limit?

Four practice exercises

Common mistakes

• Drawing motion lines in random directions. Align every motion line with the moving part's direction of travel; use the convention of tapered lines behind the part.
• Placing the COM far outside the support area without intending a fall. Measure the horizontal offset from support to COM projection; adjust limbs or stance to bring it within your chosen limit.
• Using the same motion line length for slow and fast parts. Make lines longer for faster motion and shorter for slower motion, keeping the convention consistent.
• Letting motion lines cross the figure's silhouette. Draw lines behind the moving part and stop them at the silhouette unless showing an object in front.

Self-check rubric

• Balance axis is drawn from support point or area through the COM.
• COM projection is within one foot-length of the support point unless a fall is intended.
• Motion lines follow the direction of travel and taper toward the trailing end.
• Motion line length varies with speed and is consistent with the convention.
• Motion lines do not cross the figure's silhouette unless showing an object in front.
• Pose clearly reads as running, jumping, or reaching.
• Valid alternatives (dashed, tapered, parallel strokes) are accepted if applied consistently.

Questions and answers