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Back to Archives | Back to October 2012 Contents 

Research in Brief: Suspect Physiology Associated with Common Law Enforcement Tools and Tactics Gives Insight to Likely Cause of Arrest-Related Deaths

By Jeffrey Ho, MD, Deputy Sheriff and Medical Director, Meeker County Sheriff’s Office, Litchfield, Minnesota

The IACP Research Advisory Committee is proud to offer the monthly “Research in Brief” column. This column features evidence-based research summaries that highlight actionable recommendations for Police Chief magazine readers to consider within their own agencies.
The goal of the column is to feature research that is innovative, credible, and relevant to a diverse law enforcement audience.

A medical direction agreement between the Meeker County, Minnesota, Sheriff’s Office and the Hennepin County, Minnesota, Medical Center yielded an award-winning research project that has been published in a peer-reviewed scientific medical journal.1 The findings provide information to help authorities understand the physiologic interplay between common officer tactics and suspect behaviors during resistive custodial arrest situations. This understanding of physiology is important when making training, policy, and operational decisions about the safest practices during dynamic resistance situations.


Sudden arrest-related deaths (ARDs) have occurred for decades, are often poorly understood, and represent an area of high liability for law enforcement agencies. When an ARD occurs, there are several commonalities that seem to be present. One common factor typically is highly agitated suspects being restrained, often with drug intoxication or mental illness present. Common tools and tactics used to control such suspects include manual grappling, chasing on foot, oleoresin capsicum (OC) use, electronic control device use, or canine use. It is believed that ARDs occur because f a combination of exhaustion (acidosis) and catecholamine excess (adrenaline surge). Extreme states of acidosis or adrenaline surge are associated with cardiac arrest and subsequent death. This research evaluated the acidosis and the adrenaline surge associated with common behaviors, tools, and tactics surrounding the control of a human.


After receiving permission to proceed with this human study from the Minneapolis Medical Research Foundation’s Institutional Review Board, 60 human volunteers at a law enforcement training course were approached to provide informed consent to participate. They were assigned to one of five experimental tasks that evaluated common behaviors, tools, and tactics seen during the control of agitated persons. No volunteer was involved in more than one task. An intravenous catheter was placed, and blood was withdrawn before testing for baseline acidosis and adrenaline (specifically, the pH, the lactate, the epinephrine, the norepinephrine, and the dopamine) levels, and again immediately after the experimental task and at two-minute intervals until ten minutes post-task. A final sample was drawn at 24 hours post-task. The 24-hour post-task sample was to ensure a return to baseline physiology after completion of the experiment.

The five study arms follow:

  • Maximal Fleeing on Foot. Sprint 150 meters from rest with a 44-inch wall hurdle at the end of the sprint. This task simulated a short foot chase with negotiation of a vertical obstacle.
  • Maximal Physical Resistance. Maximal exertion from rest to keep a heavy bag away from the participant for 45 seconds. This task simulated heavy physical activity and grappling to prevent an officer (the bag) from getting close enough to the subject to take the subject into custody.
  • TASER X26 Device Exposure. Ten-second exposure at rest via deployed probes to the back. This task simulated a common restraint tactic used to control resistive suspects.
  • Maximal Canine Resistance. Sprint 40 yards from rest away from a canine. The canine is then released, allowed to give chase, and able to take the subjects down. The subjects then had to physically resist the canine for 20 seconds. This task simulated a common situational behavior and tactic in a fleeing, resistive suspect.
  • OC Spray Exposure. Five-second spray to the face and neck while the subject was at rest. This task simulated a common tool and tactic used to control resistive suspects.

What We Learned

Action Items
  1. View the complete study for a better understanding of how common activities, tools, tactics, and behaviors affect suspect physiology during resistive arrest encounters and place them at risk for ARD.
  2. Train personnel to recognize persons at risk for ARD, and train in measures that limit prolonged, resistive encounters in the field.
  3. Ensure that your agency’s policy is supportive of the tools and tactics that will allow your personnel to operate as they train.
Interested in submitting a research summary for Research in Brief?
This was the first randomized study to comprehensively examine an underlying cause of ARD in a prospective fashion. The worst acidosis and adrenaline surge was seen with physical resistance, fleeing on foot, and canine resistance—in that order. Over time, OC spray caused a much higher and longer duration adrenaline surge (due to prolonged pain) that exceeded the measurements from the other tasks. The most physiologically dangerous actions in a subject at risk for ARD appear to be the voluntary subject behaviors of resistive fighting and fleeing on foot. Please see the complete study for full details and graphic data presentation.2

There are important lessons to be learned from this research that apply to law enforcement professionals and the community. Law enforcement authorities should understand, train on, and utilize tactics that minimize the ability of the at-risk ARD subject to fight, resist, or flee, and minimize the time to transfer these subjects to appropriate emergency medical care. These data may be helpful to present to agency risk managers and boards of oversight inquiries. Additionally, individuals need to be informed of the self-induced, physiologic danger if they choose to resist, fight, or flee on foot during a law enforcement action. These lessons are crucial for understanding and preventing ARD in the community. ♦

1Jeffrey D. Ho, MD, et al., “Acidosis and Catecholamine Evaluation Following Simulated Law Enforcement ‘Use of Force’ Encounters,” Academic Emergency Medicine 17, no. 7 (2010): 60–68. To view the document online, visit, select the October 2012 issue, and click Web-Only Articles.

Please cite as:

Jeffrey Ho, "Suspect Physiology Associated with Common Law Enforcement Tools and Tactics Gives Insight to Likely Cause of Arrest-Related Deaths," Research in Brief, The Police Chief 79 (October): 12.



From The Police Chief, vol. LXXIX, no. 10, October 2012. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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