Autonomic response to tactical pistol performance measured by heart rate variability

Cardiorespiratory demands of firearms training instruction and 15m shuttle tests in British law enforcement

OBJECTIVES

Law enforcement agencies require minimum fitness standards to safeguard their officers and training staff. Firearms instructors (FI) are expected to maintain the same standards as their operational counterparts. This study aimed to quantify the daily physiological demands placed on FI.

METHODS

19 FI (45 ± 5 years) completed occupational tasks whilst wearing heart rate (HR) monitors for a minimum 10 days. Maximal oxygen consumption (VO2max) testing was conducted on FI during a treadmill test (TT) and a multistage shuttle test (ST). Linear regression models were used to model the relationship between VO2 and HR throughout the TT. This model was applied to HR data from occupational tasks to infer oxygen consumption. Repeated Measures ANOVAs were used to compare time spent in VO2max equivalent zones throughout.

RESULTS

The VO2max achieved during ST (45.1 ± 5.6 ml/kg/min) was significantly higher than TT (39 ± 3 ml/kg/min) (p = 0.014). Time to exhaustion (TTE) was sooner on ST (06:26 min) compared to TT (13:16 min) (p < .001). FI spent ~85% of occupational time with an oxygen demand ≤20 ml/kg/min (p < .005). The most intense occupational tasks saw FI achieve VO2max ≥30 ml/kg/min, but <40 ml/kg/min.

CONCLUSION

Using ST to assess cardiorespiratory fitness resulted in a quicker TTE and a higher VO2max. Predominantly, FI occupational tasks are low intensity with sporadic exposures requiring a VO2max of >40 ml/kg/min. To safeguard FI from occupational-related cardiorespiratory or long-term health issues, it is intuitive to suggest fitness standards should exceed a VO2max of 40 ml/kg/min.

Relationship between state anxiety, heart rate variability, and shooting performance in adolescent shooters

OBJECTIVE

By comparing the differences in pre-competition state anxiety, inter-competition heart rate variability (HRV), and shooting performance of young athletes of different grades, and revealing the correlation between these variables, it provides a potential basis for improving athletes' shooting performance.

METHODS

A total of 45 adolescent shooters were selected in Chongqing, China, and completed 40 effective shots at self-pace in real shooting scenes. The pre-competition state anxiety, inter-competition HRV, and shooting performance of the athletes were monitored and evaluated respectively.

RESULTS

(1) There was a significant difference in the pre-match state anxiety of the adolescent shooters, which showed that the cognitive state anxiety and physical state anxiety of the first-level athletes were significantly lower than those of the second-level athletes, while the state confidence was significantly higher than that of the second-level athletes. (2) There were significant differences in HRV of athletes with different sports levels during the competition, showing that the root mean square differences of the standard deviation (RMSSD), total power (TP), and high-frequency of normal (HFn) of the first-level athletes were significantly higher than those of second-level athletes, while low-frequency of normal (LFn) was significantly lower than the latter. (3) The shooting performance of first-level athletes was significantly better than that of second-level athletes. (4) Among adolescent shooters of different grades, there was a significant correlation between pre-competition state anxiety, inter-competition HRV, and shooting performance. The negative dimension of state anxiety was positively correlated with sympathetic activity in HRV, negatively correlated with parasympathetic activity, and negatively correlated with shooting performance. The positive dimension of state anxiety was negatively correlated with sympathetic activity in HRV, positively correlated with parasympathetic activity, and significantly positively correlated with motor performance.

CONCLUSION

Adolescent shooters with higher sports levels usually have better pre-competition mental state and emotional regulation ability, and could better maintain autonomic nerve dynamic balance and focus attention resources on shooting tasks during the competition, so it was easier to achieve good shooting performance. Meanwhile, pre-competition state anxiety and HRV during competition could be used as objective indicators to monitor and evaluate the competitive state of young shooters.

Heart rate of fire: exploring direct implementation of physiological measurements in realistic shoot/don't-shoot simulations

Introduction

Shooting simulations provide an excellent opportunity to train use-of-force decisions in controlled environments. Recently, military and law enforcement organizations have expressed a growing desire to integrate physiological measurement into simulations for training and feedback purposes. Although participants can easily wear physiological monitors in these scenarios, direct implementation into training may not be simple. Theoretical problems exist in the ultra-short heart rate variability windows associated with use-of-force training, and practical problems emerge as existing scenario libraries at training organizations were not designed for physiological monitoring.

Methods

The current study explored the challenges and possibilities associated with direct implementation of physiological monitoring into an existing library of firearms training scenarios. Participants completed scenarios in a shooting simulator using existing military training scenarios while wearing a device to monitor their heart rate.

Results

The results revealed lower heart rate variability (approximately 6%) occurred in scenarios where participants did not have to fire weapons, indicating that don't-shoot scenarios may actually impose more cognitive stress on shooters. Additional evidence further demonstrated how both behavioral and physiological factors could be used concomitantly to predict unintentionally firing on non-hostile actors. However, behavioral measures were more predictive (e.g., β = .221) than physiological measures (e.g., β = -.132) when the latter metrics were limited to specific scenarios. Qualitative results suggest that simply applying physiological monitoring to existing shooting simulations may not yield optimal results because it would be difficult to directly integrate physiological measurement in a meaningful way without re-designing some elements of the simulations, the training procedure, or both.

Discussion

Future use-of-force shooting simulations should consider designing novel scenarios around the physiological measurement rather than directly implementing physiological assessments into existing libraries of scenarios.

Parasympathetic Nervous System Functioning Moderates the Associations between Callous-Unemotional Traits and Emotion Understanding Difficulties in Late Childhood

BACKGROUND

Callous-unemotional (CU) traits are characterized by low empathy, guilt, and prosociality, putting children at risk for lifespan antisocial behavior. Elevated CU traits have been linked separately to difficulties with emotion understanding (i.e., identifying emotional states of others) and disrupted parasympathetic nervous system (PNS) functioning. However, no study has investigated how PNS functioning and emotion understanding are jointly related to CU traits.

METHOD

We explored associations between CU traits, emotion understanding, and PNS functioning (indexed via respiratory sinus arrhythmia [RSA]) among children aged 7-10 years old (n = 55). We also tested whether deficits in emotion understanding differ across specific emotions (i.e., fear, pain, happiness, anger). Each child's RSA was continuously recorded while they watched a film that included emotionally evocative social interactions. To assess emotion understanding, children identified emotions replayed in 1s animations of scenes from the film. Parents reported on child CU traits, conduct problems, and demographic information.

RESULTS

Higher CU traits were related to lower emotion understanding (β = -0.43, p = 0.03). PNS activity during the film moderated this association (β = -0.47, p < 0.001), such that CU traits were associated with lower emotion understanding among children with mean (B = -0.01, t = -2.46, p = 0.02) or high (i.e., 1 SD > M; B = -0.02, t = -3.00, p < 0.001) RSA levels during the film, but not among children with low RSA levels (i.e., 1 SD < M; B = 0.00, t = -0.53, p = 0.60). Moreover, we found that the observed moderated associations are driven by deficits in fear, specifically.

CONCLUSIONS

The link between poorer emotion understanding, fear understanding in particular, and CU traits was attenuated for children who demonstrated patterns of PNS functioning consistent with attentional engagement while viewing the emotion stimuli.

Psychophysiology, Cognitive Function, and Musculoskeletal Status Holistically Explain Tactical Performance Readiness and Resilience

ABSTRACT

Thompson, AG, Ramadan, JH, Alexander, JS, and Galster, SM. Psychophysiology, cognitive function, and musculoskeletal status holistically explain tactical performance readiness and resilience. J Strength Cond Res 37(12): 2443-2456, 2023-This study aimed to advance the techniques used in quantifying holistic readiness and resilience within military personnel. Tactical performers, instructors, and applied human performance scientists designed a weeklong competition to reflect realistic operational demands, test specific underlying performance constructs, and elucidate how modernized assessments could drive programmatic action. By placing first in their installation's local preliminary competition, 34 active-duty Marines earned the opportunity to compete in a series of 7 intense events for the title of champion. All inferential statistics were set to a p ≤ 0.05 level of significance. Morning heart rate variability identified top from bottom quartile finishers before a single competition event. By day 3, morning countermovement jump force production (normalized reactive strength index-modified) and cognitive psychomotor vigilance were significant indicators of performance resilience and final competition group rank. Heart rate variability also tracked performer readiness across time, identifying within-group and between-group differences among top, bottom, and field. Collectively, these holistic assessments proved significant markers of acute and chronic tactical performance capabilities. In summary, the incorporation of psychophysiological monitoring, cognitive performance testing, and musculoskeletal force plate evaluations could help inform selection and support needs, drive workload or recovery modulation, and provide critical metrics for evaluating training efficacy and operational readiness. Defense organizations should consider routinely incorporating and actioning similar holistic status monitoring strategies in training and operational settings. Moreover, leveraging other tactical competitions may provide key opportunities for advancing the standard of practice through additional scientific investigation.

Don't Shoot Me: Potential Consequences of Force-on-Force Training Modulate the Human Stress Response

ABSTRACT

Jensen, AE, Bernards, JR, Hamilton, JA, Markwald, RR, Kelly, KR, and Biggs, AT. Do not shoot me: potential consequences of force-on-force training modulate the human stress response. J Strength Cond Res 37(9): 1761-1769, 2023-Close-quarters combat (CQC) engagements trigger the "fight-or-flight" response, activating the sympathetic nervous system and hypothalamic-pituitary-adrenal axis in response to perceived threats. However, it has yet to be shown if a force-on-force (FoF) CQC training environment will lead to adaptations in the physiological stress response or performance. United States Marines and Army infantry personnel participated in a 15-day CQC training program. The CQC program focused heavily on FoF training with the use of nonlethal training ammunition (NLTA). Data collections occurred on training days 1 and 15, during a simulated FoF-hostage rescue (HR) scenario and photorealistic target drill. For the FoF-HR, subjects were instructed to clear the shoot house, rescue the hostage, and only shoot hostile threat(s) with NLTA. The photorealistic target drills were similar, but replaced the role players in the FoF-HR with paper targets. Salivary alpha-amylase (sAA) and salivary cortisol were obtained immediately before entering and exiting the shoot house. Time to completion significantly decreased, between days 1 and 15, for both the FoF-HR and the photorealistic drills by 67.7 and 54.4%, respectively ( p < 0.05). Analyses revealed that the change in sAA, nonsignificantly, doubled from day 1 to 15 during FoF-HR ( p > 0.05), whereas the change in sAA decreased during the photorealistic drills across days ( p < 0.05). Cortisol was significantly higher during the FoF-HR in comparison to the photorealistic drills ( p < 0.05). These data suggest that potential consequences of FoF training heighten the stress response in conjunction with enhanced performance.

Not according to plan: Cognitive failures in marksmanship due to effects of expertise, unknown environments, and the likelihood of shooting unintended targets

Shooting errors have multi-faceted causes with contributing factors that include sensorimotor activity and cognitive failures. Empirical investigations often assess mental errors through threat identification, yet other cognitive failures could contribute to poor outcomes. The current study explored several possible sources of cognitive failures unrelated to threat identification with live fire exercises. Experiment 1 examined a national shooting competition to compare marksmanship accuracy, expertise, and planning in the likelihood of hitting no-shoot or unintended targets. Experts demonstrated an inverse speed/accuracy trade-off and fired upon fewer no-shoot targets than lesser skilled shooters, yet overall, greater opportunity to plan produced more no-shoot errors, thereby demonstrating an increase in cognitive errors. Experiment 2 replicated and extended this finding under conditions accounting for target type, location, and number. These findings further dissociate the roles of marksmanship and cognition in shooting errors while suggesting that marksmanship evaluations should be re-designed to better incorporate cognitive variables.

Relationship between pistol players' psychophysiological state and shot performance: Activation effect of EEG and HRV

OBJECTIVE

To understand the mechanism of dual activation of the brain and heart in pistol athletes during shooting performances, through synchronized monitoring of electroencephalogram (EEG) and electrocardiogram (ECG).

METHODS

Eighteen adolescents air pistol athletes were placed in a simulated competition environment and performed 40 self-paced shooting tasks, and simultaneously monitored the athletes' EEG, ECG, and shooting performance during the preparation period.

RESULTS

(1) In the successful performance, the power values of the alpha wave of the athlete's T7 area showed a significant upward trend 6 s before the shot, but there was no significant change in the alpha wave in the T8 area. In the failure performance, the alpha wave in the T7 and T8 areas did not change significantly 6 s before the shot. (2) The Fz theta wave power value of athletes in successful performance showed a significant upward trend in the 6 s before firing, and in the failure performance, it showed an "inverted U-shaped" characteristic of rising first and then decreasing. (3) Regardless of whether it was a success or a failure, the SMR wave power value of the athlete's central area has no significant change before the shot. (4) At 6 s before the shot, the athlete's heart rate and R-R interval (RRI) in the successful performance showed a significant decline and rise, respectively, but there was no significant change in the failure performance. (5) Approaching the firing time, the athletes' EEG and ECG have a more significant correlation in successful performance and a more synchronized trend, while the correlation was lower in failure performance.

CONCLUSIONS

The psychophysiological state of young air pistol athletes was closely related to shooting performance. If the brain-cardiac system maintains a benign dual activation level during the aiming and firing period, it will be beneficial to the improvement of shooting performance, otherwise, it was easy to reduce shooting performance.

Psychophysiological Stress Status of Soldiers Prior to an Operative Deployment

An anticipatory stress response develops before an internal or external stimulus, which initiates a homeostasis process through a chain of responses that enable human organisms to face different threats, thus allowing them to adapt to a continuous and eliciting environment. In the current research, we analyzed the psychophysiological anticipatory anxiety response of professional soldiers prior to a real mission in an actual theater of operation. Autonomic modulation through the heart rate variability values, muscular strength manifestation, and psychological stress of 53 military personnel of Army Airmobile Forces (age: M = 35.4 years, SD = 5.88 years; height: M = 1.75 m, SD = 6.87 cm; body mass: M = 77.33 kg, SD = 11.95 kg; military duty = 14.44 years, SD = 6.43; military operation experience = 4 months, SD = 4.25 months) and a control group of 33 civil participants were analyzed. The military personnel presented significant differences in some HRV values related to the activation of sympathetic systems. We found that the military personnel presented an anticipatory anxiety response only at an autonomic level, showing an increased sympathetic modulation, but not at a psychological level, since their anxiety levels were not significantly different than those of the control civilians. In addition, this anticipatory anxiety response did not affect muscular strength manifestation, as it presented no significant differences between the military personnel and the control group.

Effects of overnight military training and acute battle stress on the cognitive performance of soldiers in simulated urban combat

Understanding the effect of stress, fatigue, and sleep deprivation on the ability to maintain an alert and attentive state in an ecologically valid setting is of importance as lapsing attention can, in many safety-critical professions, have devastating consequences. Here we studied the effect of close-quarters battle (CQ battle) exercise combined with overnight military training with sleep deprivation on cognitive performance, namely sustained attention and response inhibition. In addition, the effect of the CQ battle and overnight training on cardiac activity [heart rate and root mean square of the successive differences (RMSSD)] during the cognitive testing and the relationship between cardiac activity and cognitive performance were examined. Cognitive performance was measured with the psychomotor vigilance task (PVT) and the sustained attention to response task (SART). Altogether 45 conscripts participated in the study. The conscripts were divided into control (CON) and experimental (EXP) groups. The CON completed the training day after a night of sleep and the EXP after the overnight military training with no sleep. Results showed that the effect of the overnight training on cognitive performance and the between-group difference in heart rate (HR) and heart rate variability (HRV) depended on the cognitive test. Surprisingly, the cognitive performance was not largely affected by the CQ battle. However, as expected, the CQ battle resulted in a significant decrease in RMSSD and an increase in HR measured during the cognitive testing. Similarly, the HR parameters were related to cognitive performance, but the relationship was found only with the PVT. In conclusion, fatigue due to the overnight training impaired the ability to maintain sufficient alertness level. However, this impairment in arousal upregulation was counteracted by the arousing nature of the SART. Hence, the conscripts' cognitive performance was mainly preserved when performing a stimulating task, despite the fatigue from the sleep loss of the preceding night and physical activity.

Pistol Shooting Performance Correlates with Respiratory Muscle Strength and Pulmonary Function in Police Cadets

Breathing patterns play a crucial role in shooting performance; however, little is known about the respiratory muscle strength and pulmonary capacities that control these patterns. The present study aimed to examine the relationship between shooting performance, respiratory muscle strength, and pulmonary function and to determine differences in respiratory capacities according to the shooting performance categories in police cadets. One hundred sixty-seven police cadets were recruited to assess respiratory muscle strength, pulmonary function, and shooting performance in a well-controlled environment. Measurements included maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), slow vital capacity (SVC), maximal voluntary ventilation (MVV), and pistol shooting scores. The shooting score had a moderate positive correlation with MIP (ρ = 0.33) and MEP (ρ = 0.45). FVC (ρ = 0.25), FEV1 (ρ = 0.26), SVC (ρ = 0.26) (p < 0.001) and MVV (ρ = 0.21) (p < 0.05) were slightly correlated with shooting score. There were differences between shooting performance categories in MIP, MEP, FVC, FEV1, SVC, and MVV (p < 0.001, p < 0.05). The results imply that both strong respiratory muscles and optimal pulmonary function may be one of the necessary prerequisites for superior shooting performance in police.

Effects of Acute Stress on Psychophysiology in Armed Tactical Occupations: A Narrative Review

The ability to perform under extreme pressure is one of the most sought-after qualities in both sports and tactical (military, law enforcement, fire, and rescue, etc.) occupations. While tactical performance relies on both physical and mental capabilities to achieve a desired outcome, it is often hampered by the stressful environments in which these personnel work. The acute stress experienced by tactical personnel can interfere with occupational performance, impacting both physical execution of tasks and decision-making. This narrative review discusses the implications of acute stress on the psychophysiology and physical performance of personnel serving in armed tactical occupations.

Applying Heart Rate Variability to Monitor Health and Performance in Tactical Personnel: A Narrative Review

Human performance optimization of tactical personnel requires accurate, meticulous, and effective monitoring of biological adaptations and systemic recovery. Due to an increased understanding of its importance and the commercial availability of assessment tools, the use of heart rate variability (HRV) to address this need is becoming more common in the tactical community. Measuring HRV is a non-invasive, practical method for objectively assessing a performer's readiness, workload, and recovery status; when combined with additional data sources and practitioner input, it provides an affordable and scalable solution for gaining actionable information to support the facilitation and maintenance of operational performance. This narrative review discusses the non-clinical use of HRV for assessing, monitoring, and interpreting autonomic nervous system resource availability, modulation, effectiveness, and efficiency in tactical populations. Broadly, HRV metrics represent a complex series of interactions resulting from internal and external stimuli; therefore, a general overview of HRV applications in tactical personnel is discussed, including the influence of occupational specific demands, interactions between cognitive and physical domains, and recommendations on implementing HRV for training and recovery insights into critical health and performance outcomes.

Effects of Dynamic Resilience on the Reactivity of Vagally Mediated Heart Rate Variability

Dynamic resilience is a novel concept that aims to quantify how individuals are coping while operating in dynamic and complex task environments. A recently developed dynamic resilience measure, derived through autoregressive modeling, offers an avenue toward dynamic resilience classification that may yield valuable information about working personnel for industries such as defense and elite sport. However, this measure classifies dynamic resilience based upon in-task performance rather than self-regulating cognitive structures; thereby, lacking any supported self-regulating cognitive links to the dynamic resilience framework. Vagally mediated heart rate variability (vmHRV) parameters are potential physiological measures that may offer an opportunity to link self-regulating cognitive structures to dynamic resilience given their supported connection to the self-regulation of stress. This study examines if dynamic resilience classifications reveal significant differences in vagal reactivity between higher, moderate and lower dynamic resilience groups, as participants engage in a dynamic, decision-making task. An amended Three Rs paradigm was implemented that examined vagal reactivity across six concurrent vmHRV reactivity segments consisting of lower and higher task load. Overall, the results supported significant differences between higher and moderate dynamic resilience groups' vagal reactivity but rejected significant differences between the lower dynamic resilience group. Additionally, differences in vagal reactivity across vmHRV reactivity segments within an amended Three Rs paradigm were partially supported. Together, these findings offer support toward linking dynamic resilience to temporal self-regulating cognitive structures that play a role in mediating physiological adaptations during task engagement.

Changes in Short-Term and Ultra-Short Term Heart Rate, Respiratory Rate, and Time-Domain Heart Rate Variability Parameters during Sympathetic Nervous System Activity Stimulation in Elite Modern Pentathlonists-A Pilot Study

Monitoring of markers reflecting cardiac autonomic activity before and during stressful situations may be useful for identifying the physiological state of an athlete and may have medical or performance implications. The study aimed to determine group and individual changes in short-term (5 min) and ultra-short-term (1 min) heart rate (HR), respiratory rate (RespRate), and time-domain heart rate variability (HRV) parameters during sympathetic nervous system activity (SNSa) stimulation among professional endurance athletes. Electrocardiographic recordings were performed in stable measurement conditions (Baseline) and during SNSa stimulation via isometric handgrip in 12 elite modern pentathlonists. Significant increases in short-term HR and decreases in time-domain HRV parameters with no changes in RespRate were observed during SNSa stimulation. Significant differences were observed between Baseline (all minutes) and the last (i.e., 5th) minute of SNSa stimulation for ultra-short-term parameters. Analysis of intra-individual changes revealed some heterogeneity in responses. The study provides baseline responses of HR, RespRate, and time-domain HRV parameters to SNSa stimulation among elite pentathlonists, which may be useful for identifying abnormal responses among fatigued or injured (e.g., concussed) athletes. More attention to individual analysis seems to be necessary when assessing physiological responses to sympathetic stimuli in professional endurance athletes.

Effects of Coping-Related Traits and Psychophysiological Stress Responses on Police Recruits' Shooting Behavior in Reality-Based Scenarios

Police officers are often required to perform under high-stress circumstances, in which optimal task performance is crucial for their and the bystanders' physical integrity. However, stress responses, particularly anxiety and increased cortisol levels, shift attention from goal-directed to stimulus-driven control, leaving police officers with poor shooting performance under stress. Cardiac vagal activity and coping-related traits (i.e., self-control, sensation seeking) might help individuals to maintain performance under stress. So far, only few studies have integrated coping-related traits, psychophysiological stress markers and occupationally meaningful measures of behavior to investigate police officers' work performance under stress. Therefore, the present study investigated 19 police recruits (M _age = 22.84, SD = 3.30) undergoing a reality-based shooting scenario in two experimental conditions in a within-design: low stress (LS) against a non-threatening mannequin, and high stress (HS), involving physical threat by an opponent. Psychological (i.e., anxiety, mental effort) and physiological stress responses (i.e., salivary cortisol, alpha-amylase, cardiac vagal activity) as well as shooting accuracy were repeatedly assessed. It was hypothesized that under stress, police recruits would demonstrate elevated psychophysiological stress responses and impaired shooting performance. Elevated psychophysiological stress responses would negatively influence shooting performance, whereas self-control, sensation seeking and cardiac vagal activity would positively influence shooting performance. While recruits reported significantly higher anxiety and mental effort in the HS scenario, both scenarios elicited comparable physiological responses. Overall, shooting accuracy was low and did not significantly decrease in the HS scenario. Shooting performance was predicted by self-control in the LS scenario and by post-task cardiac vagal activity in the HS scenario. While increased anxiety hints at a successful stress manipulation, physiological responses suggest similar stress levels for both scenarios, diminishing potential behavioral differences between the scenarios. Performance efficiency decreased under stress, as indicated by increasing mental effort. Findings on self-control suggest that suppressing negative stress responses might lead to impaired goal-directed attention, resulting in performance decrements. For police research and training, high-realism scenarios afford an opportunity to investigate and experience psychophysiological stress responses.

The Contribution of Coping-Related Variables and Cardiac Vagal Activity on Prone Rifle Shooting Performance Under Pressure

Abstract. The aims of this study were to assess the predictive role of coping-related variables (CRV) on cardiac vagal activity (derived from heart rate variability), and to investigate the influence of CRV (and cardiac vagal activity) on prone rifle shooting performance under low pressure (LP) and high pressure (HP) conditions. Participants ( n = 38) competed in a shooting task under LP and HP. Cardiac vagal activity measurements were taken at baseline, task, and recovery for 5 min, alongside ratings of stress via a visual analogue scale. Upon task conclusion, self-report measures of motivation, stress appraisal, attention, perceived pressure, and trait CRV questionnaires (Decision-Specific Reinvestment Scale [DSRS], Movement-Specific Reinvestment Scale [MSRS], and Trait Emotional Intelligence Questionnaire [TEIQue]) were completed. Results indicated that task cardiac vagal activity was predicted by resting cardiac vagal activity and self-control in HP and LP. Post-task cardiac vagal activity was predicted by resting cardiac vagal activity in both conditions with the addition of a trait and state CRV in HP. Cardiac vagal reactivity, the change from resting to task, was predicted by resting cardiac vagal activity and self-control in LP and HP. Cardiac vagal recovery, the change from task to post-task, was predicted by a trait CRV in HP. Shooting performance was predicted by experience and cardiac vagal activity in LP and cardiac vagal activity and a trait in HP. Findings suggest both CRV and cardiac vagal activity influence cardiac vagal activity throughout a pressure task. Additionally, shooting performance directly influences cardiac vagal recovery.

The elevation training mask induces modest hypoxaemia but does not affect heart rate variability during cycling in healthy adults

This study examined the acute effects of the elevation training mask (ETM) on haemodynamics and heart rate variability (HRV) at rest, during cycling, and during recovery in healthy adults. Fifteen healthy male (N=9) and female (N=6) adults (27.0 ± 1.14 years) completed two trials with the mask (MASK) and without the mask (CON). The 40-minute cycling exercise protocol included 10-minute phases of (1) rest, (2) 50% of VO_2peak cycling, (3) 70% of VO_2peak cycling, and (4) recovery. Blood pressure and pulse oximetry saturation (S_PO₂) were measured at each phase. An Actiwave-Cardio ECG monitor (CamNtech, UK) was used to measure HRV variables including time and frequency domains. A greater response in systolic blood pressure (p=.035) was observed at rest while S_PO₂ (p=.033) was lower during high-intensity cycling (70% of VO_2peak) in the MASK trial. The HRV indices were not different between trials during cycling. However, heart rate (p=.047) was greater while inter-beat interval and sympathovagal balance (the ratio between low-frequency and high-frequency components; ln LF/HF, p=.01) were lower in the MASK than the CON trials during recovery. Wearing an ETM during high-intensity cycling (70% of VO_2peak) induces modest hypoxaemia. Although this device did not affect HRV changes during cycling, it seems to delay the cardiac-autonomic recovery from exercise. Healthy adults may be required to perform high-intensity exercise with an ETM to simulate a hypoxic environment, but future studies are needed to determine whether repeated exposure to this condition provides similar benefits as altitude training.

The Effects of High-Intensity Interval Training vs. Moderate-Intensity Continuous Training on Heart Rate Variability in Physically Inactive Adults

Physically inactive adults are prevalent worldwide. This study compared the effects of short-term high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on heart rate variability (HRV) in physically inactive adults as a preliminary study. Thirteen physically inactive male adults (27.5 ± 3.80 years) were randomly assigned to HIIT (N = 7) or MICT (N = 6). The HIIT program consisted of 20 min of interval training with cycling to rest ratio of 10/50 s at ≥90% HR_peak, while the MICT program consisted of 40 min of continuous cycling at 60–75% HR_peak. Both groups completed eight sessions of training within two weeks. Time and frequency domains of HRV were measured for 20 min with Actiwave-Cardio monitor (CamNtech, UK). The number of R-R interval and inter-beat interval (IBI) were significantly improved (p < 0.05) in both HIIT and MICT programs following eight sessions of training. A significant interaction effect for group by time was found in the lnLF/HF ratio (p < 0.05) where it was only improved in the HIIT group from pre- to post-test. The HIIT program is superior to MICT in improving HRV in physically inactive adults. The HIIT program can be applied as a time-efficient program for improving cardiac-autoregulation.

EFEITO DO ESFORÇO FÍSICO NO DESEMPENHO DE TIRO DE POLICIAIS MILITARES DO BATALHÃO DE CHOQUE

RESUMO Introdução: O uso de arma de fogo por policiais militares normalmente é precedido por perseguição a pé, e as alterações fisiológicas produzidas pelo esforço físico podem afetar o desempenho do tiro. Objetivo: Verificar o efeito do esforço físico sobre o desempenho de tiro em policiais militares. Métodos: A amostra foi constituída por 15 homens (34,1 ± 5,4 anos; 81,4 ± 8,8 kg; 171,3 ± 5,6 cm; 27,7 ± 2,3 kg/m²; 44,9 ± 4,0 ml.kg-1.min-1) do batalhão de choque da polícia militar. Na primeira sessão, os participantes realizaram um teste de esforço máximo em esteira no qual se mediu o consumo pico de oxigênio (VO2pico). Na segunda sessão, foi avaliado o desempenho (pontuação) e tempo de tiro pré e pós-esforço físico e o tempo gasto no circuito de corrida com obstáculos (297 m). O índice de eficiência de tiro foi calculado pela razão entre a pontuação total e tempo de execução de tiro. O teste de Shapiro-Wilk confirmou a normalidade da distribuição dos dados. Utilizou-se o teste t pareado para comparação das variáveis desfecho pré e pós-esforço e o coeficiente de correlação de Pearson. Resultados: O tempo para completar o percurso de corrida foi 75,3 ± 4,4 s. O desempenho (20,4 ± 11,4 vs. 17,6 ± 9,3 pontos), tempo (4,48 ± 1,1 vs. 4,23 ± 0,9 s) e eficiência de tiro (4,69 ± 2,7 vs. 4,35 ± 2,7 pts./s) não apresentaram diferenças significativas (P > 0,2). Além disso, detectou-se uma correlação entre o VO2pico e o tempo de execução da corrida (r = -0,64; P = 0,01), mas não com o desempenho de tiro (P > 0,05). Conclusão: O esforço físico não afeta o desempenho de tiro de policiais militares. Apesar de o nível de aptidão aeróbica não ser associado ao desempenho de tiro, foi associado ao desempenho físico realizado previamente aos disparos.

Can biofeedback training of psychophysiological responses enhance athletes' sport performance? A practitioner's perspective

BACKGROUND

In recent years, biofeedback has become increasingly popular for its proven success in peak performance training - the psychophysiological preparation of athletes for high-stakes sport competitions, such as the Olympic games. The aim of this research was to test whether an 8-week period of exposure to biofeedback training could improve the psychophysiological control over competitive anxiety and enhance athletic performance in participating subjects.

METHODS

Participants of this study were highly competent athletes, each training in different sport disciplines. The experimental group consisted of 18 athletes (4 women, 14 men), whereas the Control group had 21 athletes (4 women, 17 men). All athletes were between 16 and 34 years old. The biofeedback device, Nexus 10, was used to detect and measure the psychophysiological responses of athletes. Athletes from both groups (control and experimental) were subjected to stress tests at the beginning of the study and once again at its conclusion. In between, the experimental group received training in biofeedback techniques. We then calculated the overall percentage of athletes in the experimental group compared with those in the control group who were able to control respiration, skin conductance, heart rate, blood flow amplitude, heart rate variability, and heart respiration coherence. One year following completion of the initial study, we questioned athletes from the experimental group, to determine whether they continued to use these skills and if they could detect any subsequent enhancement in their athletic performance.

RESULTS

We demonstrated that a greater number of participants in the experimental group were able to successfully control their psychophysiological parameters, in comparison to their peers in the control group. Significant results (p < 0.05) were noted in regulation of GSR following short stress test conditions (p = 0.037), in regulation of HR after exposure to STROOP stressor (p = 0.037), in regulation of GSR following the Math and GSR stressors (p = 0.033, p = 0.409) and in achieving HR - breathing coherence following the math stressor (p = 0.042).

CONCLUSION

One year following completion of the training program, all participants from the experimental group indicated that they were still using the biofeedback - psycho-regulation skills. Furthermore, these participants uniformly reported believing that these skills had enhanced their athletic performance and general well-being.