The Effects of the Abdominal Drawing-In Maneuver on Intra-Abdominal Pressure and Torque During Trunk Rotation.
Asuka Kimura, Ryota Kurokawa, Reoto Fukuyama and 1 others
PMID 41777431WHAT IT FOUND
Drawing the lower abdomen in during a maximal trunk rotation dropped intra-abdominal pressure from 96.7 to 34.9 mmHg and rotational torque from 68.7 to 49.1 Nm, compared with rotating without any abdominal instruction.
The authors suggest bracing or the Valsalva for high-load rotational tasks.
Key findings
01Rotating the trunk while pulling the lower abdomen in produced much lower pressure inside the abdomen than rotating with no instruction about the abdomen (96.7 versus 34.9 mmHg), a statistically significant difference with a large effect size.
02Rotational torque was also significantly lower with the draw-in than with spontaneous rotation (68.7 versus 49.1 Nm).
03Participants took in much less air with the draw-in (66.9% versus 26.4% of vital capacity), and the authors state the lower abdominal pressure and torque should be read alongside this change in breathing rather than as an effect of pressure alone.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 15 people took part, all healthy young men aged 18 to 30 who were not competitive athletes. Nothing here tells you what happens in women, older adults, athletes, or anyone with back pain. The task was a seated isometric trunk rotation against a fixed dynamometer. That is a narrow, stationary version of a movement that is normally fast and free, so the authors themselves warn against applying the numbers directly to clinical practice or sport. The breathing itself was not tightly controlled. In the spontaneous condition people may have braced or held their breath in their own way, which the authors say may have affected the pressure readings. No muscle activity or muscle length was measured, so the explanation for the lower pressure and torque remains a proposal rather than something the study demonstrated. Waist circumference was used as a stand-in for what the abdominal wall was doing, and body fat can distort that measure. One of the 15 participants showed the opposite pattern for how much air was taken in, which the authors say points to individual differences in how people respond to the draw-in cue. The draw-in was judged to have been performed when waist circumference fell below 98% of each person's baseline, a threshold set by the researchers rather than a measure of how well the maneuver was done.
Declared interests
The authors declare no conflicts of interest. The work was funded by the Japan Society for the Promotion of Science (JSPS) KAKENHI, grant number 24K14546. The paper does not state that the funder had any role in designing, running or writing the study.
The easy way to misread this
Do not take this as evidence that the drawing-in maneuver is harmful or that it weakens patients. The comparison changed two things at once, the pull-in of the abdomen and how much air was taken in, and the authors say the lower pressure and torque cannot be separated from the smaller breaths. It also tested 15 healthy young men in one seated isometric task, so nothing here shows the maneuver is wrong for retraining movement or for a patient with back pain.
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