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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.
Mark Stephenson; Andrew Thompson; Justin Merrigan; Jason Stone; Joshua Hagen. Applying Heart Rate Variability to Monitor Health and Performance in Tactical Personnel: A Narrative Review. International Journal of Environmental Research and Public Health 2021, 18, 8143 .
AMA StyleMark Stephenson, Andrew Thompson, Justin Merrigan, Jason Stone, Joshua Hagen. Applying Heart Rate Variability to Monitor Health and Performance in Tactical Personnel: A Narrative Review. International Journal of Environmental Research and Public Health. 2021; 18 (15):8143.
Chicago/Turabian StyleMark Stephenson; Andrew Thompson; Justin Merrigan; Jason Stone; Joshua Hagen. 2021. "Applying Heart Rate Variability to Monitor Health and Performance in Tactical Personnel: A Narrative Review." International Journal of Environmental Research and Public Health 18, no. 15: 8143.
Force plate assessments, such as countermovement jumps and isometric mid-thigh pulls, examine performances (e.g., jump height, force, power) and movement strategies (e.g., asymmetries, durations), and are best suited to characterize and monitor physical capabilities, not predict injuries. To begin applying force plate technologies, users must first; (1) develop a data management plan to visualize and capture data over time; (2) select appropriate force plates for their scenario; (3) design appropriate testing protocols to ensure valid and reliable data. Force plate assessments may be added to existing testing, serve as separate testing batteries for annual profile testing to compare individuals and understand initial physical capabilities, or for more frequent testing (i.e., monthly or weekly) to monitor training-related adaptations or neuromuscular fatigue. Although these assessments inform evidence-based program designs, human performance practitioners must understand the considerations for conducting appropriate force plate testing, as well as proper visualizations and management of force plate data. Thus, the aim of this review is to provide evidence-based practices for utilizing force plates in tactical populations (e.g., military, firefighters, police). This includes best practices to implement testing for performance profiling, training adaptations, and monitoring neuromuscular fatigue and force asymmetries. Of note, due to the large amount of force-time metrics to choose from, this article provides general examples of important metrics to monitor and training recommendations based on changes to these force-time metrics, followed by specific examples in three case studies.
Justin Merrigan; Jason Stone; Joel Martin; William Hornsby; Scott Galster; Joshua Hagen. Applying Force Plate Technology to Inform Human Performance Programming in Tactical Populations. Applied Sciences 2021, 11, 6538 .
AMA StyleJustin Merrigan, Jason Stone, Joel Martin, William Hornsby, Scott Galster, Joshua Hagen. Applying Force Plate Technology to Inform Human Performance Programming in Tactical Populations. Applied Sciences. 2021; 11 (14):6538.
Chicago/Turabian StyleJustin Merrigan; Jason Stone; Joel Martin; William Hornsby; Scott Galster; Joshua Hagen. 2021. "Applying Force Plate Technology to Inform Human Performance Programming in Tactical Populations." Applied Sciences 11, no. 14: 6538.
The purpose was to evaluate neuromuscular fatigue’s effect on unloaded and loaded countermovement jump (CMJ) force-time characteristics during high-intensity tactical training. Eighteen male and sixteen female Marines completed two maximal effort CMJs, in unloaded (PVC pipe) and loaded (10 kg weight vest and 20 kg barbell) conditions, prior to, and 24, 48, and 72 h after starting the 4-day event. The top three variables from three principal components (PC) were analyzed using mixed-effects modeling (PC1—concentric mean power, eccentric peak force, and modified reactive strength index; PC2—countermovement depth, eccentric mean power, and eccentric mean velocity; PC3—braking duration, jump height, peak power). Metrics from PC1 and PC3 were reduced across training and from both loading conditions. Metrics from PC2 were similarly affected by external loading but were less influenced by training-induced fatigue. Jump performances with the barbell and with shallower countermovement depths did not change throughout training. Thus, 20 kg loaded CMJs are stable neuromuscular measures suitable for tracking chronic training adaptations. Monitoring unloaded and 10 kg loaded CMJ performances, along with movement strategies (i.e., countermovement rates and depth), may help identify moments of accumulated fatigue to inform training and recovery adjustments and improve the sustainability of personnel.
Justin Merrigan; Jason Stone; Jad Ramadan; Joshua Hagen; Andrew Thompson. Dimensionality Reduction Differentiates Sensitive Force-Time Characteristics from Loaded and Unloaded Conditions throughout Competitive Military Training. Sustainability 2021, 13, 6105 .
AMA StyleJustin Merrigan, Jason Stone, Jad Ramadan, Joshua Hagen, Andrew Thompson. Dimensionality Reduction Differentiates Sensitive Force-Time Characteristics from Loaded and Unloaded Conditions throughout Competitive Military Training. Sustainability. 2021; 13 (11):6105.
Chicago/Turabian StyleJustin Merrigan; Jason Stone; Jad Ramadan; Joshua Hagen; Andrew Thompson. 2021. "Dimensionality Reduction Differentiates Sensitive Force-Time Characteristics from Loaded and Unloaded Conditions throughout Competitive Military Training." Sustainability 13, no. 11: 6105.
The purpose of this longitudinal, descriptive study was to observe changes in maximal strength measured via isometric clean grip mid-thigh pull and home runs (total and home runs per game) across three years of training and three competitive seasons for four National Collegiate Athletic Association (NCAA) Division 1 baseball players. A one-way repeated measures analysis of variance (ANOVA) was performed, revealing significant univariate effects of time for peak force (PF) (p = 0.003) and peak force allometrically scaled (PFa) (p = 0.002). Increases in PF were noted from season 1 to season 2 (p = 0.031) and season 3 (p = 0.004), but season 2 was not significantly different than season 3 (p = 0.232). Additionally, increases in PFa were noted from season 1 to season 2 (p = 0.010) and season 3 (p < 0.001), but season 2 was not significantly different than season 3 (p = 0.052). Home runs per game rose from the 2009 (0.32) to 2010 season (1.35) and dropped during the 2011 season (1.07). A unique aspect of the study involves 2010 being the season in which ball-bat coefficient of restitution (BBCOR) bats were introduced to the NCAA competition.
W. Hornsby; Abigail Tice; Jason Stone; Justin Merrigan; Joshua Hagen; John Wagle; Aaron Cunanan; Michael Stone. Changes in Maximal Strength and Home Run Performance in NCAA Division I Baseball Players Across 3 Competitive Seasons: A Descriptive Study. Journal of Functional Morphology and Kinesiology 2021, 6, 4 .
AMA StyleW. Hornsby, Abigail Tice, Jason Stone, Justin Merrigan, Joshua Hagen, John Wagle, Aaron Cunanan, Michael Stone. Changes in Maximal Strength and Home Run Performance in NCAA Division I Baseball Players Across 3 Competitive Seasons: A Descriptive Study. Journal of Functional Morphology and Kinesiology. 2021; 6 (1):4.
Chicago/Turabian StyleW. Hornsby; Abigail Tice; Jason Stone; Justin Merrigan; Joshua Hagen; John Wagle; Aaron Cunanan; Michael Stone. 2021. "Changes in Maximal Strength and Home Run Performance in NCAA Division I Baseball Players Across 3 Competitive Seasons: A Descriptive Study." Journal of Functional Morphology and Kinesiology 6, no. 1: 4.
The purpose of this study was to evaluate intrasession reliability of countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) force–time characteristics, as well as relationships between CMJ and IMTP metrics. Division I sport and club athletes (n = 112) completed two maximal effort CMJ and IMTP trials, in that order, on force plates. Relative and absolute reliability were assessed using intraclass correlation coefficients (ICCs) > 0.80 and coefficients of variation (CVs) < 10%. Intrasession reliability was acceptable for the majority of the CMJ force–time metrics except for concentric rate of force development (RFD), eccentric impulse and RFD, and lower limb stiffness. The IMTP’s time to peak force, instantaneous force at 150 ms, instantaneous net force, and RFD measures were not reliable. Statistically significant weak to moderate relationships (r = 0.20–0.46) existed between allometrically scaled CMJ and IMTP metrics, with the exception of CMJ eccentric mean power not being related with IMTP performances. A majority of CMJ and IMTP metrics met acceptable reliability standards, except RFD measures which should be used with caution. Provided CMJs and IMTPs are indicative of distinct physical fitness capabilities, it is suggested to monitor athlete performance in both tests via changes in those variables that demonstrate the greatest degree of reliability.
Justin J. Merrigan; Jason D. Stone; W. Guy Hornsby; Joshua A. Hagen. Identifying Reliable and Relatable Force–Time Metrics in Athletes—Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump. Sports 2020, 9, 4 .
AMA StyleJustin J. Merrigan, Jason D. Stone, W. Guy Hornsby, Joshua A. Hagen. Identifying Reliable and Relatable Force–Time Metrics in Athletes—Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump. Sports. 2020; 9 (1):4.
Chicago/Turabian StyleJustin J. Merrigan; Jason D. Stone; W. Guy Hornsby; Joshua A. Hagen. 2020. "Identifying Reliable and Relatable Force–Time Metrics in Athletes—Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump." Sports 9, no. 1: 4.
A necessarily high standard for physical readiness in tactical environments is often accompanied by high incidences of injury due to overaccumulations of neuromuscular fatigue (NMF). To account for instances of overtraining stimulated by NMF, close monitoring of neuromuscular performance is warranted. Previously validated tests, such as the countermovement jump, are useful means for monitoring performance adaptations, resiliency to fatigue, and risk for injury. Performing such tests on force plates provides an understanding of the movement strategy used to obtain the resulting outcome (e.g., jump height). Further, force plates afford numerous objective tests that are valid and reliable for monitoring upper and lower extremity muscular strength and power (thus sensitive to NMF) with less fatiguing and safer methods than traditional one-repetition maximum assessments. Force plates provide numerous software and testing application options that can be applied to military’s training but, to be effective, requires the practitioners to have sufficient knowledge of their functions. Therefore, this review aims to explain the functions of force plate testing as well as current best practices for utilizing force plates in military settings and disseminate protocols for valid and reliable testing to collect key variables that translate to physical performance capacities.
Justin J. Merrigan; Jason D. Stone; Andrew G. Thompson; W. Guy Hornsby; Joshua A. Hagen. Monitoring Neuromuscular Performance in Military Personnel. International Journal of Environmental Research and Public Health 2020, 17, 9147 .
AMA StyleJustin J. Merrigan, Jason D. Stone, Andrew G. Thompson, W. Guy Hornsby, Joshua A. Hagen. Monitoring Neuromuscular Performance in Military Personnel. International Journal of Environmental Research and Public Health. 2020; 17 (23):9147.
Chicago/Turabian StyleJustin J. Merrigan; Jason D. Stone; Andrew G. Thompson; W. Guy Hornsby; Joshua A. Hagen. 2020. "Monitoring Neuromuscular Performance in Military Personnel." International Journal of Environmental Research and Public Health 17, no. 23: 9147.
The ongoing Coronavirus 2 (COVID-19) pandemic abruptly halted athletic competition and standard training practices, consequently generating great confusion surrounding when and how to safely reintroduce sports. Therefore, tangible solutions disseminated to performance staff, coaches, and athletes are warranted to ensure optimal levels of health and physical performance for all personnel during both the current social distancing standards as well as the impending return of competition despite continued risks. In this commentary, we offer strategies for utilizing technology and data tools as components of longitudinal COVID-19 surveillance based on ongoing research efforts as well as current guidance from governing bodies, while also serving the performance needs of the athletes and staff. Recommended data sources include digital symptom and well-being surveys, standardized and routine physical performance testing, sleep and sleep physiology monitoring, cognitive applications, and temperature. This system is flexible to numerous commercially available products and is designed for easy implementation that permits instant feedback provided directly to the athlete as well as their support staff for early intervention, ultimately mitigating COVID-19 risks. We will discuss multiple options, including examples of data, data visualizations and recommendations for data interpretation and communication.
Joshua Hagen; Jason Stone; W. Hornsby; Mark Stephenson; Robert Mangine; Michael Joseph; Scott Galster. COVID-19 Surveillance and Competition in Sport: Utilizing Sport Science to Protect Athletes and Staff during and after the Pandemic. Journal of Functional Morphology and Kinesiology 2020, 5, 69 .
AMA StyleJoshua Hagen, Jason Stone, W. Hornsby, Mark Stephenson, Robert Mangine, Michael Joseph, Scott Galster. COVID-19 Surveillance and Competition in Sport: Utilizing Sport Science to Protect Athletes and Staff during and after the Pandemic. Journal of Functional Morphology and Kinesiology. 2020; 5 (3):69.
Chicago/Turabian StyleJoshua Hagen; Jason Stone; W. Hornsby; Mark Stephenson; Robert Mangine; Michael Joseph; Scott Galster. 2020. "COVID-19 Surveillance and Competition in Sport: Utilizing Sport Science to Protect Athletes and Staff during and after the Pandemic." Journal of Functional Morphology and Kinesiology 5, no. 3: 69.
The purpose of this study was to assess the validity of utilizing heart rate to derive an estimate of core body temperature in American Football athletes. This was evaluated by combining commercially available Zephyr Bioharness devices, which includes an embedded estimated core temperature (ECT) algorithm, and an ingestible radio frequency core temperature pill during the highest heat injury risk timepoint of the season, summer training camp. Results showed a concordance of 0.643 and 78% of all data points fell within +/−1.0 °F. When the athletes were split into Upper (>/=6.0%) and Lower (<6.0%) body composition groups, there was a statistical improvement in accuracy with the Upper Body Fat% reaching 0.834 concordance and 93% of all values falling within +/−1.0 °F of the Gold Standard. Results suggest that heart rate derived core temperature assessments are a viable tool for heat stress monitoring in American football, but more work is required to improve on accuracy based on body composition.
Joshua Hagen; Aaron Himmler; Joseph Clark; Jad Ramadan; Jason Stone; Jon Divine; Robert Mangine. Test and Evaluation of Heart Rate Derived Core Temperature Algorithms for Use in NCAA Division I Football Athletes. Journal of Functional Morphology and Kinesiology 2020, 5, 46 .
AMA StyleJoshua Hagen, Aaron Himmler, Joseph Clark, Jad Ramadan, Jason Stone, Jon Divine, Robert Mangine. Test and Evaluation of Heart Rate Derived Core Temperature Algorithms for Use in NCAA Division I Football Athletes. Journal of Functional Morphology and Kinesiology. 2020; 5 (3):46.
Chicago/Turabian StyleJoshua Hagen; Aaron Himmler; Joseph Clark; Jad Ramadan; Jason Stone; Jon Divine; Robert Mangine. 2020. "Test and Evaluation of Heart Rate Derived Core Temperature Algorithms for Use in NCAA Division I Football Athletes." Journal of Functional Morphology and Kinesiology 5, no. 3: 46.
The purpose of the present investigation was to examine the acute effects of whole body vibration (WBV) on isometric mid-thigh pull force–time curve (FTC) characteristics. Eleven recreationally trained subjects were randomly assigned to three treatment conditions: sham no vibration protocol (T1), vibration protocol 30 Hz 2–4 mm amplitude (T2), and vibration protocol 30 Hz 2–4 mm (T3). After completing a standardized warm-up, the subject stood on a vibration platform with the knee at a 120° angle and performed one of the three interventions. Each treatment condition required the subject to stand on the platform for thirty-second treatments, each separated by thirty seconds of recovery. Five minutes after the completion of the treatment conditions, the subjects performed the isometric mid-thigh pull. All FTCs were analyzed with standardized procedures for peak force (PF) and peak rate of force development (PRFD). A 1 × 3 repeated measures analysis of variance (ANOVA) was used to compare the three treatments. Additionally, coefficients of variance (CV), as well as intraclass and interclass correlations, were performed. There were no significant differences (p > 0.05) for any of the FTC analyses performed in this investigation. The CV and the 95% confidence interval (CI) indicate that the WBV protocol resulted in trivial changes in PF and beneficial changes in PRFD. A 30 Hz 2–4 mm amplitude WBV does not result in a significant increase in isometric mid-thigh pull performance.
W. Guy Hornsby; Mark A. South; Jason D. Stone; Hugh S. Lamont; G. Gregory Haff; Michael H. Stone. The Acute Effects of Whole Body Vibration on Isometric Mid-Thigh Pull Performance. Vibration 2020, 3, 85 -98.
AMA StyleW. Guy Hornsby, Mark A. South, Jason D. Stone, Hugh S. Lamont, G. Gregory Haff, Michael H. Stone. The Acute Effects of Whole Body Vibration on Isometric Mid-Thigh Pull Performance. Vibration. 2020; 3 (2):85-98.
Chicago/Turabian StyleW. Guy Hornsby; Mark A. South; Jason D. Stone; Hugh S. Lamont; G. Gregory Haff; Michael H. Stone. 2020. "The Acute Effects of Whole Body Vibration on Isometric Mid-Thigh Pull Performance." Vibration 3, no. 2: 85-98.