ARL-TN-0754 ● APR 2016

US Army Research Laboratory

Examining the Influence of Heartbeat on 

Expert Marksman Performance

by Tommy Goris and Keith Brawner

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ARL-TN-0754 ● APR 2016

US Army Research Laboratory

Examining the Influence of Heartbeat on 

Expert Marksman Performance

by Tommy Goris

University of Central Florida

Orlando, FL

Keith Brawner

Human Research and Engineering Directorate, ARL

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April 2016

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Technical Note

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1 November 2015–31 March 2016

4. TITLE AND SUBTITLE

Examining the Influence of Heartbeat on Expert Marksman Performance

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6. AUTHOR(S)

Tommy Goris and Keith Brawner

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Department of Labor 1356233

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US Army Research Laboratory

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Aberdeen Proving Ground, MD 21005-5425

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ARL-TN-0754

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13. SUPPLEMENTARY NOTES

14. ABSTRACT

Marksmanship training in the US Army follows a process that all marksmen must learn, understand, and experience to 

improve their shot. This standard can be broken down into key factors over which a marksman has control and needs to 

develop to improve his or her marksmanship. For that reason, in this technical note we examine the role of the heartbeat as 

observed from expert marksmen. The influence of the heartbeat is categorized into 3 different areas: 1) if expert marksmen 

time the shot on a heartbeat, 2) if they fire between heartbeats, or 3) if they simply ignore their heartbeat during 

marksmanship. The data support that expert marksmen ignore their heartbeat when firing. Because of this evaluation of expert 

behavior, we determine the heartbeat to be a nonfactor in marksmanship training.

15. SUBJECT TERMS

heartbeat, marksmanship, training, behavior, factors

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Keith Brawner

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Contents

List of Figures iv

1. Introduction 1

2. The Heartbeat 2

3. History of Marksmanship and Data Capture 3

3.1 Specific Data and Its Capture 3

3.2 Hypothesis and Investigation of the Data Postprocessing 4

3.3 Postprocessing 4

4. Results and Discussion 5

5. Conclusions 7

6. References 8

Distribution List 9
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List of Figures

Fig. 1 Sample QRS complex............................................................................3

Fig. 2 A t-test assuming unequal variances compared to a random model is 

used to determine whether heartbeats are a random factor in 

marksmanship ........................................................................................5

Fig. 3 A t-test assuming unequal variances compared to a random model is 

used to determine whether heartbeats are a random factor....................6
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1. Introduction

US Army marksmanship training focuses on Basic Rifle Marksmanship (BRM),

which consists of the 4 fundamentals of marksmanship: steady position, aiming, 

breath control, and trigger squeeze. Marksmen in the US Army first receive 

training in BRM fundamentals, such as communication, movement, and shooting,

which are critical to the basic functions of a Soldier. Once the marksmen have

mastered the fundamentals, they have a better understanding of correct and 

incorrect shooting behaviors. These behaviors can be analyzed and studied to 

provide better instructional feedback on the shot of other marksmen when 

compared to that of an expert marksman (Chung et al. 2009b).

The 4 fundamentals of marksmanship are the primary factors that influence how a 

marksman shoots, but there are also secondary factors. These factors are included 

as subsets of the 4 main factors, such as eye focus for aiming or trigger finger for 

trigger squeeze. Other factors, such as heartbeat and heart rate, may play a role on 

a marksman’s shot as well. For instance, work has been done to determine the 

effect of heart rate on expert marksmanship. The results of that work show that an 

expert marksman’s performance did not change in regard to heart rate. (Pojman et 

al. 2009). An expert may have control of all these factors, with each factor 

influencing a marksman’s shot by a different margin. Observing these factors

from an expert marksman can help to characterize the correct factors, which 

influence a marksman’s shot, and the wrong factors, which do not influence 

performance. Once these factors are observed and characterized, they can be used 

to provide instruction and feedback for other marksmen to improve their 

technique. The instruction and feedback are in the form of basic training 

guidelines or multimedia-based instruction for novice marksmen, evaluated from 

the factors observed from expert marksman. The focus of this work is to examine 

expert behavior to determine which factors influence performance and should be 

trained and which factors have little or no influence over performance and can be 

safely avoided in a training regimen.

Marksmanship is not a simple skill to master; the collection of the factors outlined 

in the BRM and all the other factors a marksman has to control inevitably add up 

to portray marksmanship as a complex psychomotor skill. Even a slight 

movement on the gun from breathing, heartbeat, or muscle tremors can contribute 

to deviating the marksman’s shot significantly from its target (Chung et al.

2009a). In addition to the factors a marksman has to control, shooters are under a 

high cognitive workload. During this period of high cognitive workload, the 

marksman’s decision accuracy, shooting accuracy, and response time all vary 

greatly because of the time stress effect of shooting (Kerick and Allender 2004). 
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The factors observed from experts, in conjunction with novices training on these 

factors, constitute the first step in providing novices a way in improve 

performance. The ability to utilize all the behaviors an expert displays and put

them it into practice is, of course, the final step to master the skill.

The first step is to determine which factors correlate positively with a marksman’s 

shot. In this technical note, we examine the behavior of expert marksmen during 

shooting events, with respect to their heartbeat. The effect of the heartbeat on a 

marksman’s shot compared to other factors, such as breath control or aiming, may 

seem small, but it is important to determine if the heartbeat does have some 

influence on how an expert shoots. We aim to ultimately review and change 

training guidelines as needed to either include or exclude the heartbeat as a factor 

for training marksmanship. In the present study, we explore data from 8 expert 

marksmen in the US Army to observe their behaviors and draw conclusions on 

whether their heartbeat has an influence on their shot. The goal is to strengthen 

our understanding of marksmanship and provide an overview of how the 

heartbeat affects an expert marksman. 

2. The Heartbeat

Heartbeats are represented by a sudden rise and sudden decline on an 

electrocardiogram, also known as an ECG. These ECG values taken from the 

expert marksmen form the heartbeats during the duration of the marksmanship 

phase. (The ECG values are not to be confused with the heart rate, which is the 

frequency of the cardiac cycle.) The heartbeat on an ECG is represented by the 

QRS complex, which is the graphical representation of the heartbeat. The first 

part of the QRS complex is the Q wave, or the first negative deflection of the 

complex. The R wave is the first positive deflection, and the S wave is the 

negative deflection following an R wave. Overall, the QRS complex represents 

the depolarization of the right and left ventricles of the human heart, otherwise 

known as the start and end of a heartbeat. The QRS signal is shown graphically in 

Fig. 1.
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Fig. 1 Sample QRS complex

3. History of Marksmanship and Data Capture

Effort has gone into researching the concepts of marksmanship. Some of this 

focus has been placed on the development of rifle marksmanship based on 

different factors (Chung et al. 2009a). This research is extremely important in 

improving our understanding of the basic and advanced rifle techniques in the US 

Army. One element of marksmanship research is to fully comprehend the 

differences between a novice and an expert marksman. These differences are the 

basic concepts of marksmanship that are known to work and can be applied. The 

other element of marksmanship research is the training. Even without new ways 

of applying marksmanship fundamentals, there are many training programs and 

simulations. Since the fundamentals of marksmanship are more or less set and 

new knowledge limited, research heavily favors the training.

3.1 Specific Data and Its Capture

Heartbeat data were collected from 8 expert marksmen from the US Army 

Marksmanship Unit’s Service Rifle Team out of Fort Benning, Georgia. These

marksmen have repeatedly been shown to possess great marksmanship skill, 

making them perfect for this study. The demographics for the expert marksman 

are 7 males and one female, with an average age of 28. The marksmen were 

equipped with the Zephyr Technology BioHarness BT, a compact electronics 

module, armed with ECG and breathing detection sensors. The BioHarness made 

it possible to get accurate results of the expert marksmen’s heartbeats. All 

marksmen in this study exhibited expert-level performance during data collection. 

For additional information on the data, see the initial publications (Goldberg et al. 

2014).
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3.2 Hypothesis and Investigation of the Data Postprocessing

The main objective is to identify the influence of the heartbeat on performance. 

Given that all experts performed at an expert level, the question is how shot 

timing relates to heartbeat. There are 3 possibilities. The first of these is whether 

experts time their shot while their heart is undergoing a heartbeat. The second is 

that shots are timed so as to be between heartbeats. The third is that the experts 

fire randomly without regard to their heartbeat. In the first 2 cases, the expert 

marksman is actively reacting to how his heartbeat functions while he is shooting, 

rendering it likely for the heartbeat to have influence over performance. In simple 

terms, if experts exhibit this behavior, then it is likely that it is important for 

training. For the last case, if the heartbeat is effectively disregarded while 

shooting, it is likely that the heart has no influence on how an expert marksman 

shoots. Nonetheless, we hypothesize a difference when firing between heartbeats.

The data include heartbeat, or ECG values, for the 8 expert marksmen, with the 

time of occurrence of each heartbeat. Since we are testing whether the heartbeat 

plays a role in marksmanship, the times of each shot taken by the expert

marksmen are also required. In all, we draw comparisons between the time a 

heartbeat occurs and the time a shot is taken. 

3.3 Postprocessing 

A heartbeat is composed of 3 different parts, as detailed by the QRS complex. To 

draw a fair comparison between 2 different heartbeats, we use the middle of the 

heartbeat, or the R wave of the QRS complex, as the point of comparison between 

other heartbeats. To begin, both of the ECG values, including the time for each 

heartbeat and the times of each marksmanship shot, are used to construct a 

comparison based on the time distance a marksmanship shot is taken after a 

heartbeat. This distance is calculated by obtaining the heartbeat just before a shot 

and the heartbeat just after a shot, and comparing it to the time the shot is taken 

between the 2 heartbeats. The time distance of a shot between heartbeats is the 

end result of this calculation. This time distance is represented as the percentage 

of the way a marksmanship shot is fired between heartbeats. Since we are using 

the R wave as our point of comparison, the low and high percentage values of the 

time distance represent times where the expert marksman shot during a heartbeat, 

and the middle percentage values represent times where the expert marksman shot 

between heartbeats. These measurements are taken until we have obtained all the 

time–distance percentages for each shot. The end goal is to characterize each 

percentage on whether it lies during a heartbeat or between heartbeats. 
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All the percentages are divided into 5 parts, from a scale of 0 to 100. In this case, 

the frequency of each shot between 0 and 20, 20 and 40, 40 and 60, 60 and 80, 

and 80 and 100 is calculated. The frequency of the percentages in the 0–20 and 

80–100 sections will be the only sections to contain percentages located on a 

heartbeat while the other sections contain only percentages of shots fired between 

heartbeats. Classifying and analyzing these sections based on their count and 

comparing them to other models is the final step in determining the heartbeat as a 

factor in expert marksmanship.

4. Results and Discussion

The time distance a shot is fired between heartbeats in percentages is shown in 

Fig. 2. We tested the observed data against a randomly generated sample, also 

shown in Fig. 2. The random model and model of observed frequencies of shots 

bare close resemblance to one another observationally. This finding is supported 

through the performance of a t-test on the frequency model of shots compared to 

the random model assuming unequal variances. This test is shown in Fig. 3. The 

random model and the frequency model in the t-test have statistically similar 

mean and variance values, indicating that the null hypothesis of unequal variances 

should be rejected and the alternative hypothesis of equal variances is accepted. 

This implies that expert marksmen disregard heartbeats while shooting.

Fig. 2 A t-test assuming unequal variances compared to a random model is used to 

determine whether heartbeats are a random factor in marksmanship
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Fig. 3 A t-test assuming unequal variances compared to a random model is used to 

determine whether heartbeats are a random factor

It may be a bit surprising to see that the heartbeat, in regard to an expert 

marksman’s shot, is completely ignored and follows a random pattern. We 

expected to see expert marksmen put some effort into timing their shot with their 

heartbeat to avoid unnecessary movement caused by the heartbeat. It is possible 

expert marksmen rely more on other factors they have more control over and 

follow this premise, ignoring smaller factors such as the heartbeat. 

Another view on why the heartbeats of expert marksmen might follow a random 

pattern could be due to the accumulated experience these expert marksmen have. 

An expert marksman is less likely to succumb to pressure during a shooting event, 

allowing him or her to stay relaxed during the event. In this relaxed state, 

improved over the years, the heartbeat is unimportant, while the expert marksman 

prepares for the shot. Based on all factors contributing to the shot during this 

phase, the heartbeat might contribute to some change in accuracy, but the change 

is very small compared to other factors the expert marksman has more control 

over. It is also entirely possible that the 8 expert marksmen found no need to time

their shot to their heartbeat, as the influence would have been nonexistent.

Comparing this behavior of ignoring the heartbeat to the behaviors observed in 

other marksmen is a key element in marksman training. If it is possible to achieve 

mastery in marksmanship without training the marksman to monitor the heartbeat, 

then there is no need to train the factor. In a sense, the contribution the heart plays 

in marksmanship is abysmal compared to what other factors contribute. Training a 

novice marksman to better control breathing instead of training the heartbeat 

would save the marksman time and effort on a skill contributing to the mastery of 

his marksmanship, where training the heartbeat would be insignificant.
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The result of the heartbeat being random completely negated our hypothesis when 

testing to see if the heartbeat would improve a shot based on whether it was fired 

during a heartbeat or between heartbeats. The heartbeat plays no significant role 

in how an expert marksman shoots, and so the shot is neither improved nor 

hindered. 

5. Conclusions

For the present study, work has been done in determining the influence the 

heartbeat has, as a factor, on the marksmanship of an expert marksman. 

Comparisons are drawn based on the times of the marksmanship shots and 

heartbeats, creating the calculation needed to justify whether the heartbeat plays a 

role in expert marksmanship. The timing of heartbeats and firings of expert 

marksmen were binned into specific segments to determine whether experts are 

consistently firing while taking heartbeat information into consideration. 

Nevertheless, expert marksmen do not appear to be actively controlling the timing 

of their heartbeats with respects to their shots, at least with any statistical 

significance. We believe that this applies to all marksmen.

The purpose of determining the role of heartbeat during a shot is to be able to 

compare the behaviors of expert and novice marksmen. This comparison allows 

us to characterize and evaluate factors based on their importance in regards to 

how the factor affects marksmanship. Identifying the factors that improve 

marksmanship allows us to share ideas and knowledge with other shooters and 

train skills vital for marksmanship, and ignore skills unnecessary for 

marksmanship. This is a way for marksmen, preferably new or novice marksmen, 

to be able to learn from the behaviors of expert marksman.

For future research, the behaviors of novice marksmen will be examined and

compared to the behaviors of expert marksmen. Currently, our data conclude that 

expert marksmen fire without regard to timing in heartbeats; as such, it is not 

recommended to train this behavior in novices.
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6. References

Chung GK, Nagashima SO, Espinosa PD, Berka C, Baker EL. The influence of 

cognitive and non-cognitive factors on the development of rifle 

marksmanship skills. Los Angeles (CA): National Center for Research on 

Evaluation, Standards and Student Testing; 2009a. CRESST Report 753.

Chung GK, Nagashima SO, Espinosa PD, Berka C, Baker EL. An exploratory 

investigation of the effect of individualized computer-based instruction on 

rifle marksmanship performance and skill. Los Angeles (CA): National 

Center for Research on Evaluation, Standards and Student Testing; 2009b. 

CRESST Report 754.

Goldberg B, Amburn C, Brawner K, Westphal M. Developing models of expert 

performance for support in an adaptive marksmanship trainer.

Interservice/Industry Training, Simulation, and Education Conference 

(I/ITSEC); 2014; Orlando, FL.

Kerick S, Allender L. Effects of cognitive workload on decision accuracy, 

shooting performance, and cortical activity of soldiers; 2004. Defense 

Technical Information Center Document No.: ADA433487.

Pojman N., Behneman A., Kintz N., Johnson R., Chung G., Nagashima S., 

Espinosa P., Berka C. Characterizing the psychophysiological profile of 

expert and novice marksmen. In: Schmorrow DD, Estabrooke KK, Grootjen 

M, editors. Foundations of augmented cognition. Neuroergonomics and 

operational neuroscience. Springer; 2009; p. 524–532.
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