Is breathing voluntary or involuntary motion? Positioning textbooks say voluntary, but sources differ

Bontrager’s and Merrill’s, the two positioning textbooks we read, class breathing as voluntary motion. Bontrager’s defines voluntary motion as motion the patient can control. Not every source agrees, so we won’t tell you it’s a settled exam answer.

Which sources say what?

Source	How it treats breathing
Bontrager’s Textbook, 9th ed.	Voluntary: motion the patient can control, including breathing
Merrill’s Atlas, 15th ed.	Voluntary: breathing is on its voluntary list, not its involuntary list
Bushong, 11th ed.	Groups motion of the heart and lungs as involuntary

Bontrager’s says motion from breathing can be prevented or at least minimized by controlled breathing, while Bushong pairs the lungs with the heart. ARRT®‘s specifications say it “avoids content when there are multiple resources with conflicting perspectives”, and neither ARRT outline says how to classify breathing. Our inference is that the safer thing to learn is the reasoning: can this patient control it on instruction?

Our own materials follow the positioning textbooks and list breathing as voluntary.

What counts as involuntary motion?

Both positioning textbooks name these:

• Peristalsis
• Tremors
• Chills

Merrill’s adds heart pulsation, spasm and pain.

How do you fix each type?

Short exposure time helps with both. Raise the mA to hold the mAs. Beyond that, the fix depends on the type.

Type	What helps
Voluntary	Clear instructions, patient comfort, supports, immobilization and short exposure time
Involuntary	Short exposure time is the best and sometimes the only control (Bontrager’s). Merrill’s also mentions tape or sponges to prevent involuntary movement of the hand

Good instructions matter most for breathing. Merrill’s advises having the patient practice the breathing method until the necessary actions are clearly understood. For patients who can’t cooperate, such as young children, shortening the exposure time is the best tool.

How does it look on the image?

Bontrager’s gives a useful way to tell them apart. Voluntary motion blurs linked structures across the image, such as the ribs, heart and diaphragm on a chest. Involuntary motion is more localized, such as blur along part of the bowel, while other bowel edges stay sharp.

Both outlines list motion under factors affecting radiographic quality, and respiration under positioning. Our Image Production guide shows how motion affects spatial resolution, and our positioning foundations chapter covers motion control. The Procedures guide gives breathing instructions for the chest and spine, and you can test yourself with the image acquisition questions.