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Understanding limitations of the “fight or flight” response

Tactical training can and does help an officer anticipate and identify bodily responses to danger


When stress levels are high, other physiological responses can include auditory exclusion, tunnel vision and loss of motor control.

This article is featured in the magazine, Rebuilding Resiliency: A Treatment Guide. This free publication provides in-depth information to help officers and their families better understand treatment options so they can remain strong and resilient.

By Dr. Carrie Steiner, contributor to In Public Safety

During a life or death situation, an officer experiences physiological reactions and bodily responses that can – and often do – supersede their tactical training. Significant biological changes happen when an officer’s “fight or flight” stress response is triggered, which affects what they hear, see and can do. These biological and physiological reactions during threatening situations can save officers’ lives, but can also limit their ability to respond accurately and effectively.

Lifesaving Biological Responses to Threat

Once danger has been sensed, the sympathetic nervous system (SNS) is activated and anything the body deems as non-essential will be limited and suppressed. For example, if an officer is injured after eating a large meal, their body will not work on digestion and may even void the bladder. Instead, it will prioritize more important activities such as getting blood to the extremities to help the body move quickly away from danger or to limit the amount of blood loss from vital organs.

In addition, when the body’s innate alarm system is activated, adrenaline is released to provide lightning fast response to threat. The body receives a burst of energy, blood pumps faster, muscles tense, eyes widen, respirations are faster, and hands tremble, and so on. As the body remains in this phase, unessential fine motor skills (e.g., writing and typing) deteriorate, but lifesaving gross motor skills (e.g., running and jumping) improve.

How Heart Rate Affects Performance

Optimal BPM: When an officer is in a life or death situation, optimal performance happens when their heart rate is between 115-145 beats per minute (BPM). This is when their complex motor skills (running, jumping, etc.), visual reaction time and cognitive reaction time are at their peak.

Detrimental BPM: While the body’s response to threat can be beneficial, when an officer’s heart rate increases above 145 BPM, their complex motor skills begin to deteriorate.

When the heart rate reaches above 175 BPM, officers experience the most detrimental impact on their sympathetic nervous system. For example, this is when vasoconstriction – which is when blood vessels contract – is at its highest, causing reduced blood flow through the body.

Biological Reactions Can Negatively Impact Response

When stress levels are high, other physiological responses can include auditory exclusion (temporary loss of hearing), tunnel vision and loss of motor control.

In life or death situations, an officer’s body often assesses situations in a more vague way (i.e., looking at the general situation rather than details) and jumps to conclusions based on rough similarities. For example, if an officer sees somebody holding something shiny in their hand and acting aggressively, they may incorrectly conclude it could be some type of weapon. The body registers that they might be in danger and acts to eliminate the threat in order to avoid risking their life by assuming it is not a threat.

It is important for agencies, officers, civilians and the court system to understand that when an officer says he or she cannot recall something or has a distortion in their report, they are often not lying or trying to hide something. Instead, they likely experienced biological consequences of being in a life or death situation.

Tactical training can and does help an officer anticipate and identify bodily responses to danger. For example, officers can practice breath control to increase the flow of oxygen and lower their heart rate. These tactical training measures can help officers decrease the likelihood of their body’s natural biological responses taking over during a critical incident. However, biological responses can never be completed negated.

About the Author

Dr. Carrie Steiner is a licensed clinical psychologist and founder of the First Responders Wellness Center, a private practice, full-service agency focused on meeting the needs of police and first responders’ emotional wellness. As a psychologist, she conducts police and public safety psychological evaluations and specializes in trauma therapy utilizing EMDR, exposure, biofeedback and cognitive behavioral therapy.

Dr. Steiner is a 13-year former Chicago police officer, Crisis Intervention Team (CIT) leader, peer support team member and Chicago Police Academy instructor. While working for the Chicago Police Department, she spearheaded veteran CIT training and autism spectrum training for law enforcement. She also has FBI hostage negotiation training, has worked as a psychologist for Cook County and Kane County Jails, as well as collaborated with federal government agencies on high-risk cases. She speaks nationally on mental illness and police response, officer wellness, trauma, CIT, peer support, PTSD, and has several national and local awards. To contact the author, email For more articles featuring insight from industry experts, subscribe to In Public Safety’s bi-monthly newsletter.

In Public Safety is an American Military University (AMU) sponsored blog that features analysis and commentary on issues relating to law enforcement, emergency management, fire services and national intelligence. This blog features in-depth discussions authored by leading experts with decades of experience in their field.

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