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Home  >  Topics  >  Use of Force

November 04, 2013
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Force Science Institute Destroying Myths & Discovering Cold Facts
with Force Science Institute

Scientific probe challenges alleged danger of prone positioning and hog-tying

The tactic of “proning out” and “hog-tying” a combative suspect has taken repeated bad raps over the years as a potential cause of arrest-related death.

Yet rigorous scientific studies have failed to substantiate the technique’s alleged danger. 

Now add the findings of yet another research group to the controversy--findings that again seem to support prone positioning as a viable option for controlling combative subjects. 

Five Separate Trials
​Headed by Dr. Davut Savaser, an emergency medicine specialist, a team of eight physicians and one PhD from the University of California-San Diego School of Medicine investigated the claim that prone positioning and the force required to place a suspect in that posture can “adversely impact cardiovascular function” to the point that “restrained individuals may be at significant risk” of dying. 

The team’s test subjects were 25 male volunteers from the UCSD campus who ranged in age from 22 to 42. In random order, each underwent five separate trials in different body positions while their heart and circulatory functions were closely monitored. Specifically they were studied while supine (face up), prone (face down), prone with “maximal restraint” (hog-tied), prone maximal with 50 lbs. of weight on their back, and with 100 pounds of weight. 

In the maximal positions, the subjects were handcuffed behind their back, with “ankles secured together within one to two feet of the wrists via restraint straps.” Plate weights laid in the center of their back were intended “to simulate the force often required to place individuals” in those positions. 

The volunteers stayed in each posture for three minutes before any cardiovascular measurements were taken “to allow for physiological adjustment.” Each subject had at least five minutes’ rest between positions. 

Multiple readings, including heart rate, oxygen saturation, blood pressure, and blood flow, were taken and analyzed and sonographic images were made for cardiographic evaluation. 

At 100 pounds of weight, subjects experienced a statistically significant increase in heart rate compared to other positions, but the rate still “remained within the normal range,” the researchers found. 

Minimal Changes in Vitals
Overall, they write, “We found no or minimal changes in vital signs...in all the prone positions [and] we found no differences in [cardiac output] between any of the positions with and without weight force.” 

Without change in cardiac output and no evidence of compromise of vital signs, the team found no data to support the accusation that prone positioning can produce “sudden cardiovascular collapse.” 

Earlier studies have tended to rule out so-called “positional asphyxia,” a dire compromise of the respiratory system, as a cause of arrest-related deaths among proned-out subjects. With the latest findings relative to alleged cardio threats, “the exact cause of death in many of these cases remains unclear,” the researchers conclude. 

Savaser’s team admits to limitations in their work. For example, “We did not replicate all potential conditions in the field, including physical exertion, psychological stress, drug intoxication, and trauma, which might impact cardiovascular function.” Also greater weight on a suspect’s back reflecting the force to control a struggling individual in the field might also alter results. 

Because there remains much about arrest-related deaths that is unknown, officers are still cautioned to take a conservative approach where prone positioning is concerned. Attorney Mildred (Missy) O’Linn of the Los Angeles law firm Manning & Kass, Ellrod, Ramirez, Trester, a former LEO who specializes in defending officers and agencies, told Force Science News: 

“I continue to advise officers to avoid dog-piling proned suspects if possible without jeopardizing the safety of themselves or other innocent parties. If during an incident there is need for a swarming type of control, try to shorten the time frame and lighten the load on the subject as much as tactically advisable. Get the subject into a seated position, monitor him or her closely, and involve EMS personnel as early as possible. 

“It’s important to go the extra mile with precautions because when legal challenges arise later, you want to be able to show that you tried to act in a reasonable and humane fashion.” 

(Previously, we have referenced a multi-officer, ground-control technique for minimizing risk in restraining the head and limbs of a violent offender, as well as other recommended arrest procedures in combative circumstances. See FSN #201, “Special protocol for ExDS response is a valuable liability shield,” 4/9/12. Be reminded that arrest-related deaths are extremely rare. The average LEO will not be involved in one in his career.) 

A full report on the Savaser study appears in the Journal of Forensic and Legal Medicine, under the title “The Effect of the Prone Maximal Restraint Position with and without Weight Force on Cardiac Output and Other Hemodynamic Measures.” To access a free abstract or to download the study for a fee, click here. 


About the author

The Force Science Institute was launched in 2004 by Executive Director Bill Lewinski, PhD. - a specialist in police psychology -- to conduct unique lethal-force experiments. The non-profit Force Science Institute, based at Minnesota State University-Mankato, uses sophisticated time-and-motion measurements to document-for the first time-critical hidden truths about the physical and mental dynamics of life-threatening events, particularly officer-involved shootings. Its startling findings profoundly impact on officer training and safety and on the public's naive perceptions.

For more information, visit www.forcescience.org or e-mail info@forcescience.org. If you would benefit from receiving updates on the FSRC's findings as well as a variety of other use-of-force related articles, please visit www.forcesciencenews.com and click on the "Please sign up for our newsletter" link at the front of the site. Subscriptions are free.





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