A Novel Metric "Exercise Cardiac Load" Proposed to Track and Predict the Deterioration of the Autonomic Nervous System in Division I Football Athletes.

Current metrics like baseline heart rate (HR) and HR recovery fail in predicting overtraining (OT), a syndrome manifesting from a deteriorating autonomic nervous system (ANS). Preventing OT requires tracking the influence of internal physiological loads induced by exercise training programs on the ANS. Therefore, this study evaluated the predictability of a novel, exercise cardiac load metric on the deterioration of the ANS. Twenty male American football players, with an average age of 21.3 years and body mass indices ranging from 23.7 to 39.2 kg/m2 were included in this study. Subjects participated in 40 strength- and power-focused exercise sessions over 8 weeks and wore armband monitors (Warfighter Monitor, Tiger Tech Solutions) equipped with electrocardiography capabilities. Exercise cardiac load was the product of average training HR and duration. Baseline HR, HR variability (HRV), average HR, and peak HR were also measured. HR recovery was measured on the following day. HRV indices assessed included the standard deviation of NN intervals (SDNN) and root mean square of successive RR interval differences (rMSSD) Linear regression models assessed the relationships between each cardiac metric and HR recovery, with statistical significance set at α < 0.05. Subjects were predominantly non-Hispanic black (70%) and aged 21.3 (±1.4) years. Adjusted models showed that exercise cardiac load elicited the strongest negative association with HR recovery for previous day (ß = -0.18 ± 0.03; p < 0.0000), one-week (ß = -0.20 ± 0.03; p < 0.0000) and two-week (ß = -0.26 ± 0.03; p < 0.0000) training periods compared to average HR (ßetas: -0.09 to -0.02; p < 0.0000) and peak HR (ßetas: -0.13 to -0.23; p < 0.0000). Statistically significant relationships were also found for baseline HR (p < 0.0000), SDNN (p < 0.0000) and rMSSD (p < 0.0000). Exercise cardiac load appears to best predict ANS deterioration across one- to two-week training periods, showing a capability for tracking an athlete's physiological tolerance and ANS response. Importantly, this information may increase the effectiveness of exercise training programs, enhance performance, and prevent OT.

Exercise Cardiac Load and Autonomic Nervous System Recovery during In-Season Training: The Impact on Speed Deterioration in American Football Athletes.

Fully restoring autonomic nervous system (ANS) function is paramount for peak sports performance. Training programs failing to provide sufficient recovery, especially during the in-season, may negatively affect performance. This study aimed to evaluate the influence of the physiological workload of collegiate football training on ANS recovery and function during the in-season. Football athletes recruited from a D1 college in the southeastern US were prospectively followed during their 13-week "in-season". Athletes wore armband monitors equipped with ECG and inertial movement capabilities that measured exercise cardiac load (ECL; total heartbeats) and maximum running speed during and baseline heart rate (HR), HR variability (HRV) 24 h post-training. These metrics represented physiological load (ECL = HR·Duration), ANS function, and recovery, respectively. Linear regression models evaluated the associations between ECL, baseline HR, HRV, and maximum running speed. Athletes (n = 30) were 20.2 ± 1.5 years, mostly non-Hispanic Black (80.0%). Negative associations were observed between acute and cumulative exposures of ECLs and running speed (ß = -0.11 ± 0.00, p < 0.0000 and ß = -0.15 ± 0.04, p < 0.0000, respectively). Similarly, negative associations were found between baseline HR and running speed (ß = -0.45 ± 0.12, 95% CI: -0.70, -0.19; p = 0.001). HRV metrics were positively associated with running speed: (SDNN: ß = 0.32 ± 0.09, p < 0.03 and rMSSD: ß = 0.35 ± 0.11, p < 0.02). Our study demonstrated that exposure to high ECLs, both acutely and cumulatively, may negatively influence maximum running speed, which may manifest in a deteriorating ANS. Further research should continue identifying optimal training: recovery ratios during off-, pre-, and in-season phases.

Recovery of the autonomic nervous system following football training among division I collegiate football athletes: The influence of intensity and time.

The autonomic nervous system (ANS) is profoundly affected by high intensity exercise. However, evidence is less clear on ANS recovery and function following prolonged bouts of high intensity exercise, especially in non-endurance athletes. Therefore, this study aimed to investigate the relationships between duration and intensity of acute exercise training sessions and ANS recovery and function in Division I football athletes. Fifty, male football athletes were included in this study. Subjects participated in 135 days of exercise training sessions throughout the 25-week season and wore armband monitors (Warfighter Monitor, Tiger Tech Solutions) equipped with electrocardiography capabilities. Intensity was measured via heart rate (HR) during an 'active state', defined as HR ≥ 85 bpm. Further, data-driven intensity thresholds were used and included HR < 140 bpm, HR < 150 bpm, HR < 160 bpm, HR ≥ 140 bpm, HR ≥ 150 bpm and HR ≥ 160 bpm. Baseline HR and HR recovery were measured and represented ANS recovery and function 24h post-exercise. Linear regression models assessed the relationships between time spent at the identified intensity thresholds and ANS recovery and function 24h post-exercise. Statistical significance set at α < 0.05. Athletes participated in 128 training sessions, totaling 2735 data points analyzed. Subjects were predominantly non-Hispanic black (66.0%), aged 21.2 (±1.5) years and average body mass index of 29.2 (4.7) kg⋅(m2)-1. For baseline HR, statistically significant associations between duration and next-day ANS recovery were observed at HR < 140 bpm (ß = -0.08 ± 0.02, R2 = 0.31, p < 0.001), HR above 150 and 160 bpm intensity thresholds (ß = 0.25 ± 0.02, R2 = 0.69, p < 0.0000 and ß = 0.59 ± 0.06, R2 = 0.71, p < 0.0000). Similar associations were observed for HR recovery: HR < 140 bpm (ß = 0.15 ± 0.03, R2 = 0.43, p < 0.0000) and HR above 150 and 160 bpm (ß = -0.33 ± 0.03, R2 = 0.73, p < 0.0000 and ß = -0.80 ± 0.06, R2 = 0.71, p < 0.0000). The strengths of these associations increased with increasing intensity, HR ≥ 150 and 160 bpm (baseline HR: ß range = 0.25 vs 0.59, R2: 0.69 vs 0.71 and HR recovery: ß range = -0.33 vs -0.80, R2 = 0.73 vs 0.77). Time spent in lower intensity thresholds, elicited weaker associations with ANS recovery and function 24h post-exercise, with statistical significance observed only at HR < 140 bpm (ß = -0.08 ± 0.02, R2 = 0.31, p < 0.001). The findings of this study showed that ANS recovery and function following prolonged high intensity exercise remains impaired for more than 24h. Strength and conditioning coaches should consider shorter bouts of strenuous exercise and extending recovery periods within and between exercise training sessions.

COVID-19-Induced Changes in Photoplethysmography.

INTRODUCTION: Photoplethysmography (PPG) is the science behind many commonly used medical devices such as the pulse oximeter. PPG changes, herein as "PPG dropouts," have been described in existing in vitro studies following artificially induced clot activation. Because COVID-19 causes increased arterial, venous, and microvascular clot formation, our hypothesis is that PPG dropouts identified in vitro can also be found in vivo in patients with COVID-19. The aim of this study is to evaluate PPG recordings and D-dimer levels for patients hospitalized with COVID-19 and compare them with the PPG tracings from non-COVID controls. MATERIALS AND METHODS: PPG recordings were obtained for 197 ICU patients with COVID-19 and 300 non-COVID controls. PPG tracings were obtained using a TigerTech CovidPlus monitor, which received U.S. FDA emergency use authorization in March 2020 for monitoring the biometrics of patients with COVID-19 and featured unfiltered red and infrared spectrum PPG monitoring. D-dimer lab results were also recorded whenever available. RESULTS: The results demonstrated significant differences in the prevalence rate of PPG dropout among patients with COVID-19 vs. non-COVID controls. The median PPG dropout rate was 0.58 for COVID-19 patients (median 0.58, IQR 0.42-0.72, P < .05) as opposed to a median 0.0 for non-COVID patients (median 0.0, IQR 0.0-0.0, P < .05). Furthermore, at least one incidence of PPG dropout was detected in 100% of COVID-19 patients, as opposed to 2.3% of non-COVID controls (P < .05). PPG dropout also correlated closely with the normalized serum D-dimer levels taken on the same day. The change in the normalized D-dimer levels was plotted against the change in PPG dropout, and a line of best fit was created. Linear regression resulted in R2 = 0.743 (P < .05), indicating that changes in the PPG dropout rate correlate with hemorheological changes in COVID-19 patients. CONCLUSIONS: PPG dropout, like D-dimer, may not be specific for COVID-19. However, the inflammatory nature of the disease and the prevalence of prolonged ICU created a large sample size and allowed the authors to observe PPG changes in vivo in a statistically meaningful way. Further confirmatory studies are needed to confirm the potential application of PPG dropout as a measure of inflammation in other disease processes.

Internal or External Training Load Metrics: Which Is Best for Tracking Autonomic Nervous System Recovery and Function in Collegiate American Football?

Sport coaches increasingly rely on external load metrics for designing effective training programs. However, their accuracy in estimating internal load is inconsistent, and their ability to predict autonomic nervous system (ANS) deterioration is unknown. This study aimed to evaluate the relationships between internal and external training load metrics and ANS recovery and function in college football players. Football athletes were recruited from a D1 college in the southeastern US and prospectively followed for 27 weeks. Internal load was estimated via exercise cardiac load (ECL; average training heartrate (HR) × session duration) and measured with an armband monitor equipped with electrocardiographic capabilities (Warfighter MonitorTM (WFM), Tiger Tech Solutions, Miami, FL, USA). External load was estimated via the summation and rate of acceleration and decelerations as measured by a triaxial accelerometer using the WFM and an accelerometer-based (ACCEL) device (Catapult Player Load, Catapult Sports, Melbourne, Australia) worn on the mid-upper back. Baseline HR, HR variability (HRV) and HR recovery served as the indicators for ANS recovery and function, respectively. For HRV, two, time-domain metrics were measured: the standard deviation of the NN interval (SDNN) and root mean square of the standard deviation of the NN interval (rMSSD). Linear regression models evaluated the associations between ECL, ACCEL, and the indicators of ANS recovery and function acutely (24 h) and cumulatively (one- and two-week). Athletes (n = 71) were male and, on average, 21.3 ± 1.4 years of age. Acute ECL elicited stronger associations for 24 h baseline HR (R2 0.19 vs. 0.03), HR recovery (R2 0.38 vs. 0.07), SDNN (R2 0.19 vs. 0.02) and rMSSD (R2 0.19 vs. 0.02) compared to ACCEL. Similar results were found for one-week: 24 h baseline HR (R2 0.48 vs. 0.05), HR recovery (R2 0.55 vs. 0.05), SDNN (R2 0.47 vs. 0.05) and rMSSD (R2 0.47 vs. 0.05) and two-week cumulative exposures: 24 h baseline HR (R2 0.52 vs. 0.003), HR recovery (R2 0.57 vs. 0.05), SDNN (R2 0.52 vs. 0.003) and rMSSD (R2 0.52 vs. 0.002). Lastly, the ACCEL devices weakly correlated with ECL (rho = 0.47 and 0.43, p < 0.005). Our findings demonstrate that ACCEL poorly predicted ANS deterioration and underestimated internal training load. ACCEL devices may "miss" the finite window for preventing ANS deterioration by potentially misestimating training loads acutely and cumulatively.

Exposures to Elevated Core Temperatures during Football Training: The Impact on Autonomic Nervous System Recovery and Function.

Exercising with elevated core temperatures may negatively affect autonomic nervous system (ANS) function. Additionally, longer training duration under higher core temperatures may augment these negative effects. This study evaluated the relationship between exercise training duration and 24 h ANS recovery and function at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds in a sample of male Division I (D1) collegiate American football athletes. Fifty athletes were followed over their 25-week season. Using armband monitors (Warfighter MonitorTM, Tiger Tech Solutions, Inc., Miami, FL, USA), core temperature (°C) and 24 h post-exercise baseline heart rate (HR), HR recovery and heart rate variability (HRV) were measured. For HRV, two time-domain indices were measured: the root mean square of the standard deviation of the NN interval (rMSSD) and the standard deviation of the NN interval (SDNN). Linear regression models were performed to evaluate the associations between exercise training duration and ANS recovery (baseline HR and HRV) and function (HR recovery) at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds. On average, the athletes were 21.3 (± 1.4) years old, weighed 103.0 (±20.2) kg and had a body fat percentage of 15.4% (±7.8%, 3.0% to 36.0%). The duration of training sessions was, on average, 161.1 (±40.6) min and they ranged from 90.1 to 339.6 min. Statistically significant associations between training duration and 24 h ANS recovery and function were observed at both the ≥38.0 °C (baseline HR: ß = 0.10 ± 0.02, R2 = 0.26, p < 0.0000; HR recovery: ß = -0.06 ± 0.02, R2 = 0.21, p = 0.0002; rMSSD: ß = -0.11 ± 0.02, R2 = 0.24, p < 0.0000; and SDNN: ß = -0.16 ± 0.04, R2 = 0.22, p < 0.0000) and ≥39.0 °C thresholds (ß = 0.39 ± 0.05, R2 = 0.62, p < 0.0000; HR recovery: ß = -0.26 ± 0.04, R2 = 0.52, p < 0.0000; rMSSD: ß = -0.37 ± 0.05, R2 = 0.58, p < 0.0000; and SDNN: ß = -0.67 ± 0.09, R2 = 0.59, p < 0.0000). With increasing core temperatures, increases in slope steepness and strengths of the associations were observed, indicating accelerated ANS deterioration. These findings demonstrate that exercise training under elevated core temperatures (≥38 °C) may negatively influence ANS recovery and function 24 h post exercise and progressively worsen.

Single limb electrocardiogram using vector mapping: Evaluation and validation of a novel medical device.

INTRODUCTION: The Tiger Tech Warfighter Monitor (WFM) is a novel single-limb device for ECG acquisition. The WFM provides true (not derived) single limb Electrocardiogram monitoring (ECG) to provide heart rate and R-R interval monitoring between QRS complexes. Herein, we evaluate the diagnostic accuracy of the WFM heart rate, R-R interval monitoring, and heart rate variability monitoring in comparison to a 2­lead chest ECG. METHODS: Data was collected under Institutional Review Board (IRB) approval. Patients available within our institution's pre-operative holding unit were randomly selected to undergo simultaneous chest and WFM ECG monitoring. 3-5-min measurements were taken depending on the patient's availability. Data was saved to two separate mobile phones and time-stamped for synchronization. A proprietary Tiger Tech extraction algorithm was used to tag proper features on both the WFM 1-Limb ECG and Chest ECG data files. A separate algorithm was then used to compare the beat-to-beat variations between the ECGs. RESULTS: Data was extracted and analyzed on 26 subjects. Linear regression of heart rate analysis revealed excellent correlations with an R2 of 0.99 (p < 0.05). Similar linear regression evaluation of R-R interval correlation demonstrated a mean R2 value of 0.95 (p < 0.05). Statistically significant correlation was achieved in all 26 included study participants. Heart rate variability also achieved excellent correlation (SDNN R2 = 0.997, RMSSD R2 = 0.995, LnRMSSD R2 = 0.992, p << 0.05). CONCLUSION: Results demonstrate that the WFM achieves excellent correlation with chest ECG for heart rate, R-R internals, and heart rate variability.

Integration of Intercultural Learning into an International Advanced Pharmacy Practice Experience in London, England.

As the number of international advanced pharmacy practice experiences (APPEs) continues to grow, this is an opportunity to incorporate intercultural learning (ICL) to further advance student pharmacist training. Purdue University student pharmacists participated in a clinical research focused APPE in London, England. To prepare for this APPE, students completed a one-credit course focused on intercultural learning and travel preparation. The purpose of this report is to describe the implementation and assessment of ICL during this course and international APPE. The course includes interactive ICL activities, reflective assignments, and personalized assessments. During the eight-week APPE, student pharmacists worked on an individualized Intercultural Development Plan®, which includes ICL activities, focused reflection, and check-ins. ICL was assessed using the Intercultural Development Inventory® (IDI®) at the beginning of the course and at least four weeks after APPE completion. Student APPE feedback was also reviewed for evidence of ICL. Twenty-seven students completed the course and APPE from 2018 to 2020. The average IDI developmental orientation (DO) before the course was 91.7, placing students in minimization. The average perceived orientation was 120.9, placing students in acceptance. There were 18 students who completed the post-APPE IDI: 12 students demonstrated growth in the DO (range: 1.5-23.72), and six students experienced a decrease in their DO. Intercultural learning can be implemented and assessed as part of an international APPE.

Heart Rate Variability as a Possible Predictive Marker for Acute Inflammatory Response in COVID-19 Patients.

INTRODUCTION: Increases in C-reactive protein (CRP) are used to track the inflammatory process of COVID-19 and are associated with disease state progression. Decreases in heart rate variability (HRV) correlate with worsening of disease states. This observational study tracks changes in HRV relative to changes in CRP in COVID-19 patients. MATERIALS AND METHODS: In accordance with an Institutional Review Board-approved study, 17 patients were followed using the wearable, noninvasive Tiger Tech Warfighter Monitor (WFM) that records HRV from a single limb electrocardiogram. Intermittent, daily short-segment data sets of 5 to 7 minutes over a minimum of 7 days were analyzed. Changes in HRV were compared to changes in CRP. RESULTS: Decreases in HRV of greater than 40% preceded a 50% increase in CRP during the ensuing 72 hours in 10 of the 12 patients who experienced a dramatic rise in CRP. The effectiveness of HRV as a leading indicator of a rise in CRP was evaluated; the sensitivity, specificity, positive predictive value, and negative predictive value for 40% decreases in HRV preceding 50% increases in CRP were 83.3%, 75%, 90.9%, and 60%, respectively. CONCLUSION: Substantial decreases in HRV preceded elevations in CRP in the ensuing 72 hours with a 90.9% positive predictive value. Early detection of increasing inflammation may prove vital in mitigating the deleterious effects of an abnormal inflammatory response, particularly in COVID-19 patients. This capability could have a major impact in triage and care of moderate to severe COVID-19 patients in major medical centers as well as field hospitals. This study demonstrates the potential value of short-segment, intermittent HRV analysis in COVID-19 patients.

Genome of the opportunistic pathogen Streptococcus sanguinis.

The genome of Streptococcus sanguinis is a circular DNA molecule consisting of 2,388,435 bp and is 177 to 590 kb larger than the other 21 streptococcal genomes that have been sequenced. The G+C content of the S. sanguinis genome is 43.4%, which is considerably higher than the G+C contents of other streptococci. The genome encodes 2,274 predicted proteins, 61 tRNAs, and four rRNA operons. A 70-kb region encoding pathways for vitamin B(12) biosynthesis and degradation of ethanolamine and propanediol was apparently acquired by horizontal gene transfer. The gene complement suggests new hypotheses for the pathogenesis and virulence of S. sanguinis and differs from the gene complements of other pathogenic and nonpathogenic streptococci. In particular, S. sanguinis possesses a remarkable abundance of putative surface proteins, which may permit it to be a primary colonizer of the oral cavity and agent of streptococcal endocarditis and infection in neutropenic patients.