Heart Rate Variables Research Articles

Minimal Detectable Change Thresholds and Responsiveness of Zephyr Bioharness and Fitbit Charge Devices.

Nazari, G and MacDermid, JC. Minimal detectable change thresholds and responsiveness of zephyr bioharness and Fitbit Charge devices. J Strength Cond Res 34(1): 257-263, 2020-The aim of the current study was to define the minimal detectable change (MDC) thresholds for Zephyr Bioharness (ZB) and Fitbit Charge Heart Rate (FC-HR) variables and to establish the internal responsiveness of ZB and FC-HR devices in terms of their HR, respiratory rate variables, and number of steps taken variables, in a healthy sample of men and women at resting, submaximal activity and throughout recovery phases. A total of sixty participants (30 women, 48 ± 15) and (30 men, 48 ± 15) were recruited using stratified convenience and snowball sampling approaches from our university student, staff, and faculty population. At rest, MDC90 values of ±4.89 and ±5.15 were noted for ZB and FC-HR devices, respectively. Throughout the recovery, thresholds of ±8.14 for ZB and 8.74 for FC-HR were reported. During the submaximal phases, scores of ±8.18 and ±9.35 were established for ZB and FC-HR, respectively. From a resting to a submaximal state, the standardized response means (SRMs) for ZB and FC-HR variables exhibited large responsiveness of SRMZB-HR = 4.42; SRMFC-HR = 4.04. In addition, the ZB respiratory rate variable showed the largest effect size of SRMZB-RR = 2.55. Similarly, the large effect size of SRMFC-ST = 1.76 was reported for the FC-HR steps taken variable. From a submaximal to a recovery state, the SRMs for ZB and FC-HR variables demonstrated effect sizes of SRMZB-HR = -3.10; SRMFC-HR = -3.12. Furthermore, the ZB respiratory rate variable displayed similar internal responsiveness measures of SRMZB-RR = -2.45. To conclude, Similar MDC HR thresholds can be expected using the ZB and FC-HR devices and that the two devices demonstrated large internal responsiveness in our healthy male and female cohort when transitioning from resting to submaximal states and vice-versa. Our findings suggest that the ZB and FC-HR devices can be used in monitoring performance improvements or deterioration over time and would allow qualified personnel in assessing the effectiveness of exercise programs in healthy individuals.

Postoperative analgesic efficacy of fluoroscopy-guided erector spinae plane block after percutaneous nephrolithotomy (PCNL): A randomized controlled study.

Background:Percutaneous nephrolithotomy (PCNL) a minimally invasive method for the removal of renal calculi and is associated with significant pain in postoperative period. Conventionally, intravenous opioids, local anesthetic infiltration, and regional blocks (intercostal/paravertebral blocks) have been tried with less efficacy to control postoperative pain. The present study is conducted to assess the effectiveness of erector spinae plane block (ESPB) performed under fluoroscopy guidance for postoperative analgesia during PCNL.Subjects and Methods:After obtaining ethical clearance, the study was conducted on 61 American Society of Anaesthesiologists (ASA) I and II patients aged between 18–65 years admitted for PCNL. Group I (n = 30) did not receive ESPB while Group II (n = 31) received ESPB under fluoroscopy guidance and 20 ml of 0.375% ropivacaine was administered after PCNL. Patient-reported pain intensity using visual analogue scale (VAS) was considered as a primary outcome. The hemodynamic variables (heart rate, systolic, diastolic, and mean blood pressure) was considered as a secondary outcome. Statistical analysis was performed using Student's t-test and Mann–Whitney U test. Data analysis was performed using the Statistical Package for the Social Sciences version 23.0.Results:Postoperatively VAS score was significantly lower in Group II at 0, 1, 2, 3, 4, 6, 12, 18, and 24 hours after PCNL (P < 0.001). Dose of rescue analgesia significantly decreased in Group II compared to Group I.Conclusion:ESPB performed under fluoroscopic guidance is a simple and effective technique and it provides significantly better postoperative pain relief.

Relationship between biomechanical and psychophysiological indicators and performance in a vertical mountain race

In order to know the relationship between biomechanical and psychophysiological indicators, as well as the possible pre-post psychophysiological differences and the use of poles in the uphill performance on mountain runners, we performed a prospective and descriptive study of one vertical mountain race. Thus, it was analysed biomechanical (speed and strength/power manifestations) and psychophysiological variables (lactate, heart rate and subjective perception of fatigue) with a total of nine (n = 9) experienced runners divided into groups to use (n = 4) or not (n = 5) poles during the race. Nonparametric analyses were performed to observe the correlations between variables, the differences between groups and the differences between the psychophysiological values before and after the test. The results do not present significant (p &lt; 0.05) differences or correlations of performance between those that used poles or not. There are significant differences between the psychophysiological variables pre and post, in addition they show correlations of performance (final time and relation of time with the first classified) with higher mean and maximum heart rate, as well as a lower lactate accumulation. It is concluded that a better performance in a mountain vertical race is associated to higher physiological efficiency but not to greater strength and power jump manifestations in trained runners.

Estudio piloto sobre escalas predictivas de transfusión masiva: ¿iguales en el paciente traumático que en el médico?

Introduction and objectivesMassive bleeding and associated coagulation disorders are one of the main causes of mortality in critically ill patients. Current studies claim that the majority of massive bleeding is due to traumatic injury, but there is a lack of data about predictive scales and massive transfusion (MT) protocols in non-trauma patients. The objective of this study is to assess the applicability of using the massive transfusion prediction scores of trauma patients in non-trauma patients. MethodsA retrospective exploratory cohort study was conducted between January-December 2017 that included patients older than 18 years admitted to a multidisciplinary ICU of a tertiary hospital for non-traumatic diseases that required MT. An analysis was performed on the relationship between haemodynamic variables (blood pressure and heart rate), biochemistry (lactate, base excess, urea, creatinine, prothrombin activity, thromboplastin activity, INR), as well as the diagnostic group on admission and its association with MT. ResultsA total of 72 patients were included, of which 50 (69.44%) were male. The mean age was 64.33 years. No statistical significance was found in the analysis between the risk factors considered: age, gender, and cardiology history. The mortality was 82%. No statistical significance was found between mortality and haemodynamic variables, biochemical analytical results, or with the TASH (Trauma Associated Severe Haemorrhage score) and the ABC (Assessment of Blood Consumption) score. ConclusionsThe predictive scales used in the trauma scenario are not valid for non-trauma scenarios and would need to be modified. The association of MT with a mortality increase is confirmed.

Simple Prediction of Metabolic Equivalents of Daily Activities Using Heart Rate Monitor without Calibration of Individuals

Background: Heart rate (HR) during physical activity is strongly affected by the level of physical fitness. Therefore, to assess the effects of fitness, we developed predictive equations to estimate the metabolic equivalent (MET) of daily activities, which includes low intensity activities, by % HR reserve (%HRR), resting HR, and multiple physical characteristics. Methods: Forty volunteers between the ages of 21 and 55 performed 20 types of daily activities while recording HR and sampling expired gas to evaluate METs values. Multiple regression analysis was performed to develop prediction models of METs with seven potential predictors, such as %HRR, resting HR, and sex. The contributing parameters were selected based on the brute force method. Additionally, leave-one-out method was performed to validate the prediction models. Results: %HRR, resting HR, sex, and height were selected as the independent variables. %HRR showed the highest contribution in the model, while the other variables exhibited small variances. METs were estimated within a 17.3% difference for each activity, with large differences in document arrangement while sitting (+17%), ascending stairs (−8%), and descending stairs (+8%). Conclusions: The results showed that %HRR is a strong predictor for estimating the METs of daily activities. Resting HR and other variables were mild contributors. (201 words)

Use of natural language processing to improve predictive models for imaging utilization in children presenting to the emergency department

ObjectiveTo examine the association between the medical imaging utilization and information related to patients’ socioeconomic, demographic and clinical factors during the patients’ ED visits; and to develop predictive models using these associated factors including natural language elements to predict the medical imaging utilization at pediatric ED.MethodsPediatric patients’ data from the 2012–2016 United States National Hospital Ambulatory Medical Care Survey was included to build the models to predict the use of imaging in children presenting to the ED. Multivariable logistic regression models were built with structured variables such as temperature, heart rate, age, and unstructured variables such as reason for visit, free text nursing notes and combined data available at triage. NLP techniques were used to extract information from the unstructured data.ResultsOf the 27,665 pediatric ED visits included in the study, 8394 (30.3%) received medical imaging in the ED, including 6922 (25.0%) who had an X-ray and 1367 (4.9%) who had a computed tomography (CT) scan. In the predictive model including only structured variables, the c-statistic was 0.71 (95% CI: 0.70–0.71) for any imaging use, 0.69 (95% CI: 0.68–0.70) for X-ray, and 0.77 (95% CI: 0.76–0.78) for CT. Models including only unstructured information had c-statistics of 0.81 (95% CI: 0.81–0.82) for any imaging use, 0.82 (95% CI: 0.82–0.83) for X-ray, and 0.85 (95% CI: 0.83–0.86) for CT scans. When both structured variables and free text variables were included, the c-statistics reached 0.82 (95% CI: 0.82–0.83) for any imaging use, 0.83 (95% CI: 0.83–0.84) for X-ray, and 0.87 (95% CI: 0.86–0.88) for CT.ConclusionsBoth CT and X-rays are commonly used in the pediatric ED with one third of the visits receiving at least one. Patients’ socioeconomic, demographic and clinical factors presented at ED triage period were associated with the medical imaging utilization. Predictive models combining structured and unstructured variables available at triage performed better than models using structured or unstructured variables alone, suggesting the potential for use of NLP in determining resource utilization.

Retrospective study of allometric relationship between heart rate, electrocardiographic parameters and bodyweight in dogs

ABSTRACT The allometric relationship between bodyweight (BW) and heart rate (HR) has been described as inversely proportional in domestic species, but that has been refuted. The relationship between HR and electrocardiographic variables is described in literature. However, studies about the variation and influence of factors on the hemodynamic and electrocardiographic parameters in dogs are not abundant. As the metabolic rate is defined as the production and dissipation of heat by the body surface area (BSA) in m², it is essential to define that relationship. A retrospective study was conducted to analyze the correlation between HR, ECG parameters and BW in dogs. One thousand electrocardiographic tracings were analyzed in addition to the ECG parameters and clinical data such as gender, age and bodyweight. The determination of BSA was performed as follows: BSA (m2) = (10.1 x bodyweight 0.67) X 10-4. When the unified groups were analyzed, there was a negative but weak correlation (r= -0.14, P&lt; 0.0001) between bodyweight and HR. There were differences between weight groups regarding electrocardiographic variables. There is no allometric relationship between BW and HR in dogs. Weight was associated with changes in ECG variables.

Hammock and nesting in preterm infants: randomized controlled trial.

To compare the physiological variables and the sleep-wake pattern presented by preterm in nesting and hammock positions after diaper change. This is a crossover randomized controlled trial. It was conducted with 20 preterm infants who, after diaper change, were placed in nests or hammocks. These preterm infants were evaluated for physiological variables (heart rate and oxygen saturation) and behavioral variables (sleep and wakefulness). There was no statistically significant difference in the studied variables between nesting and hammock positions. However, regarding the categorical variable sleep, the comparison between the research phases for the hammock position showed differences between the baseline phase and the immediate recovery (p=0.00), baseline and late recovery (p=0.00), response and immediate recovery (p=0.00), response and late recovery (p=0.00). No differences were identified between the nest and the hammock; however, the use of the hammock favored the sleep of preterm infants compared to its non-use.

Cardiovascular autonomic reflex tests and serum FGF21 levels in overweight and normal-weight men and women

Objective We evaluated cardiovascular autonomic reflexes and serum fibroblast growth factor 21 (FGF21), a surrogate marker of mitochondrial function, in a cohort of overweight and normal-weight adults (n = 42). Methods Indices of autonomic function were monitored during supine rest, autonomic reflex tests and submaximal clinical exercise test, with heart rate variables and blood pressure measured with an automatic system. Results Markers of sympathetic dominance were accentuated in overweight adults, including elevated resting low-frequency to the high-frequency ratio for heart rate variability (203 ± 227 vs. 96 ± 42; p = .01), and handgrip diastolic blood pressure (36 ± 15 mmHg vs. 25 ± 12 mmHg; p = .01). A weak non-significant trend has been found for a negative correlation between blood pressure responses to isometric handgrip test and FGF21 in the overweight group (r = −0.37; p = .09). Conclusions Excess body weight appears to trigger sympathetic overactivity in overweight adults, yet autonomic dysregulation might not be associated with notable changes in serum FGF21.

Ergonomic risk identification for rice harvesting worker

This paper studies important factors that influence the physical workload of rice harvesters. Rice harvesting in Java, Indonesia, mostly uses manual and semi-mechanical methods that require significant physical energy. These harvesting methods have potential Ergonomic Risk Factors (ERFs) that are skeletal, muscle, and peripheral nerve disorders called Musculoskeletal Disorders (MSDs). Surveys and observations of 7 workers of manual and 9 workers of semi-mechanical rice harvesting practices were done in Bantul Regency, Yogyakarta Province. The dependent variable of Cardio-vascular Load (CVL) was formulated in multiple linear regression equations by some independent variables, that were age, smoking habits, heart rate, and ambient temperature. The results showed that age and ambient temperature variables correlate strongly with CVL manual worker. CVL semi-mechanical worker was strongly correlated with age and heart rate. By F test, manual worker workload, 94.5% was significantly influenced by variables of age, smoking habits, heart rate and ambient temperature. CVL semi-mechanical workers were only 91.1%. To avoid high CVL, the age factor of workers is a major consideration. MSDs occur in the upper and lower back for manual workers, while semi-mechanical workers occur on the lower back and both hands. From the assessment of work posture in 4 elements of harvesting, transporting element was the activity with the worst posture. Ergonomic interventions are needed to reduce ergonomic risks in transportation.

Working Overtime: The Effects of Overtime Periods on Game Demands in Basketball Players.

To quantify and compare internal and external workloads in regular and overtime games and examine changes in relative workloads during overtime compared with other periods in overtime games in male basketball players. Starting players for a semiprofessional male basketball team were monitored during 2 overtime games and 2 regular games (nonovertime) with similar contextual factors. Internal (rating of perceived exertion and heart-rate variables) and external (PlayerLoad and inertial movement analysis variables) workloads were quantified across games. Separate linear mixed-models and effect-size analyses were used to quantify differences in variables between regular and overtime games and between game periods in overtime games. Session rating-of-perceived-exertion workload (P = .002, effect size 2.36, very large), heart-rate workload (P = .12, 1.13, moderate), low-intensity change-of-direction events to the left (P = .19, 0.95, moderate), medium-intensity accelerations (P = .12, 1.01, moderate), and medium-intensity change-of-direction events to the left (P = .10, 1.06, moderate) were higher during overtime games than during regular games. Overtime periods also exhibited reductions in relative PlayerLoad (first quarter P = .03, -1.46, large), low-intensity accelerations (first quarter P = .01, -1.45, large; second quarter P = .15, -1.22, large), and medium-intensity accelerations (first quarter P = .09, -1.32, large) compared with earlier periods. Overtime games disproportionately elevate perceptual, physiological, and acceleration workloads compared with regular games in starting basketball players. Players also perform at lower external intensities during overtime periods than earlier quarters during basketball games.

The Role of Perceived Control in the Psychophysiological Responses to Disgust of Subclinical OCD Women.

Obsessive‒compulsive disorder (OCD), and especially contamination obsessions and washing compulsions, has been related to disgust. However, when its cardiovascular correlates have been studied, contradictory results have been found, including heart rate accelerations and decelerations. The aim of this study is to analyze emotional, cognitive, and cardiovascular responses in nonclinical (control) and subclinical participants with obsessive‒compulsive contamination/washing symptoms when confronted with a disgusting stimulus. Twenty-seven participants (14 subclinical OCD) completed a behavioral avoidance task with a contamination-based stimulus while their heart rate and subjective variables were measured. Results showed heart rate reductions in both samples, whereas subjective measures reflected higher disgust, anxiety, dirtiness, and emotional valence in the subclinical sample. However, at the same time, the sense of dominance was lower in the control group. In conclusion, our results support a heart rate deceleration during exposure to a disgusting stimulus dissociated from the subjective experience.

Potential Physiological Parameters to Indicate Inner States in Dogs: The Analysis of ECG, and Respiratory Signal During Different Sleep Phases.

The sleeping activity of family dogs has been studied increasingly in the past years. Recently, a validated, non-invasive polysomnographic method has been developed for dogs, enabling the parallel recording of several neurophysiological signals on non-anesthetized family dogs, including brain activity (EEG), eye movements (EOG), cardiac (ECG), and respiratory activity (PNG). In this study, we examined the ECG (N = 30) and respiratory signals (N = 19) of dogs during a 3-h sleep period in the afternoon, under laboratory conditions. We calculated four time-domain heart rate variables [mean heart rate (HR), SDNN, RMSSD, and pNN50] from the ECG and the estimated average respiratory frequency from the respiratory signal. We analyzed how these variables are affected by the different sleep-wake phases (wakefulness, drowsiness, NREM, and REM) as well as the dogs’ sex, age and weight. We have found that the sleep-wake phase had a significant effect on all measured cardiac parameters. In the wake phase, the mean HR was higher than in all other phases, while SDNN, RMSSD, and pNN50 were lower than in all other sleep phases. In drowsiness, mean HR was higher compared to NREM and REM phases, while SDNN and RMSSD was lower compared to NREM and REM phases. In REM, SDNN, and RMSSD was higher than in NREM. However, the sleep-wake phase had no effect on the estimated average respiratory frequency of dogs. The dogs’ sex, age and weight had no effect on any of the investigated variables. This study represents a detailed analysis of the cardiac and respiratory activity of dogs during sleep. Since variations in these physiological signals reflect the dynamics of autonomic functions, a more detailed understanding of their changes may help us to gain a better understanding of the internal/emotional processes of dogs in response to different conditions of external stimuli. As such, our results are important since they are directly comparable to human findings and may also serve as a potential basis for future studies on dogs.

Prospective validation and refinement of the APPROACH cardiovascular surgical intensive care unit readmission score

PurposeThe APPROACH cardiovascular surgical intensive care unit (CVICU) readmission score has excellent discrimination and calibration for CVICU readmission after discharge to a surgical ward; however, it has not been prospectively validated. Material and methodsIn a prospective consecutive cohort of 805 patients ≥18 years admitted to the CVICU after coronary artery bypass and/or valvular surgery, the APPROACH CVICU readmission score was calculated at the time of discharge to a surgical ward. The study compared observed versus predicted CVICU readmission and the model discrimination was evaluated using AUC c-index. The incremental prognostic utility of 6 pre-specified prospectively collected respiratory (re-intubation, tracheostomy, oxygen at discharge) and hemodynamic variables (heart rate, systolic blood pressure, inotropes at discharge) were tested using net reclassification index (NRI) and integrated discrimination improvement (IDI). ResultsA total of 37 (4.6%) patients were readmitted to the CVICU. The median CVICU length of stay (9.0 vs 2.0 days, p < .001) and all-cause in-hospital mortality (8.1% vs 0.4%, p < .001) was higher among readmitted patients. The model had good discrimination (c-index = 0.748). Systolic blood pressure at discharge yielded the largest improvement in model discrimination (c-index = 0.782; Hosmer-Lemshow p = .749). ConclusionsIn a prospective validation cohort, the APPROACH CVICU readmission risk score had good discrimination and could be operationalized in future research and clinical practice.

OFFICE, HOME AND AMBULATORY BLOOD PRESSURE LONG-TERM CHANGES IN THE GENERAL POPULATION

Objective: The PAMELA is an epidemiological study performed on a population sample, including office, home and 24 h ambulatory blood pressure (BP) measurements. Measurements were made at baseline, after 11 years, and repeated in a 3rd survey 26 years later. Design and method: 3200 subjects were randomly selected to represent the population of Monza (North Italy) aged 25–74 years. In each subject body mass index (BMI), office (sphygmomanometer), home (semiautomatic validated device), 24 h (validated automatic oscillometric device) systolic (S) and diastolic (D) BP measurements, heart rate (HR) and biochemical variables were obtained. All values were measured at baseline (1st survey, 1990–91), 11 years later (2nd survey, 2001–02) and after further 15 years (3rd survey, 2016–17). Results: 562 subjects (279/283 males/females, mean age 41 ± 10 yrs) participated at the 3 surveys. Baseline average office, home and 24 h SBP/DBP were respectively 122/81 ± 14/9, 116/73 ± 15/10, 116/73 ± 9/7 mmHg and increased respectively of 5/1 ± 14/9, 4/1 ± 14/9 and 4/2 ± 10/7 mmHg at the 2nd survey. At the 3rd survey a further increase of 11/2 ± 7/11, 8/3 ± 16/10 and 13/2 ± 15/9 mmHg was observed in office, home and 24 h BP respectively. The baseline-3rd survey office, home and 24 h SBP difference was unrelated to age, while the DBP increase was inversely related to age (r = −0.32, −0.39 and −0.38, respectively, P < 0.0001). The baseline-3rd survey increase in office, home and 24 h DBP was significantly directly related to the concomitant BMI increase (r = 0.23, 0.17 and 0.14, respectively, P < 0.005). Office and home HR was similar in the 3 surveys. A reduction in 24 h HR was detected between the 1st and 3rd survey (−4.0 ± 8.2 b/min). At baseline hypertensive subjects were 22.2% (office BP), 19.3% (home BP) and 20.7% (24 h BP), and increased to 37.7%, 33.8% and 43.5% at the 2nd survey and to 68.7%, 65.8% and 80.8% at the 3rd survey respectively. Conclusions: The PAMELA 26-year follow-up represents the longest survey ever done describing the long-term changes of BP measurements in general population. It shows a long-term increase in office, home and 24 h BP only partially accompanied by HR changes, and an increase in the prevalence of hypertension, particularly pronounced when defined with 24 h measurements.

Music Therapy for Pain and Anxiety Management in Nasal Bone Fracture Reduction: Randomized Controlled Clinical Trial.

To evaluate whether listening to music through binaural headphones contributes to the perception of pain and anxiety in patients undergoing closed nasal bone fracture reductions. Randomized controlled trial. We recruited patients from San Juan de Dios Hospital with displaced nasal fractures who required a reduction and assigned them to a control group or a music group. For both groups, a protocolized closed reduction of the nasal fracture with local anesthesia was performed. The music group heard music through headphones during the pre-, intra-, and postprocedural periods of the intervention. Physiological variables (blood pressure and heart rate) were measured. An anxiety survey (State-Trait Anxiety Inventory) and the visual analog scale for measuring pain were also applied. The music group exhibited significantly lower levels of systolic blood pressure (P = .0001), anxiety (P < .0001), and pain (P = .0004) than the control group. Listening to music through headphones-a safe and low-cost intervention-appears to aid in pain and anxiety management associated with procedures that are usually uncomfortable, such as the reduction of nasal bone fractures with local anesthesia. We believe that this effect is achieved by the modulation of pain and anxiety on an emotional-affective dimension at a central level. Given its safety, feasibility, and low cost, music therapy should be considered a complementary treatment for pain and anxiety management for nasal fracture reduction performed with local anesthesia, as well as for other medical procedures of similar pain levels conducted without general anesthesia.

The Influence of AlterG Treadmill Training on Cardiorespiratory Performance in Cross Country Runners

Running on an AlterG® Treadmill (AGT) at reduced bodyweight allows runners to aerobically train with reduced orthopedic stress. However, to maintain the training stimulus, the speed must be increased if heart rate (HR) response is to match overground running. This allows one to run at faster speeds for longer durations, without increasing impact forces or HR intensity beyond typical training. Yet it is unknown how this speed intensity chronically influences cardiorespiratory performance. PURPOSE: Investigate the effect of an AGT training program on cardiorespiratory performance. METHODS: As an offseason supplement, 19 healthy uninjured high school boy cross country runners replaced 2 overground running sessions/week for 6 weeks with AGT runs at 80-85% of bodyweight. Speed was increased to elicit a HR intensity and distance/time consistent with each runner’s mile pace for that day. Pulmonary gas exchange and HR data were collected during treadmill graded exercise tests (GXT) at pre and post AGT training program. Paired t-test were used to assess pre-post changes in cardiorespiratory and HR variables from the GXT (p≤0.05). RESULTS: The mean speed of AGT runs was 9.0 ± 0.5 mph at a mean distance of 4.2 ± 0.6 miles. The mean of the fastest speed for each runner was 9.8 ± 0.6 mph (range 8.6-11.4) at a mean run time of 27.6 ± 8.4 min. (range 16-40 minutes). HR [180 ± 9 vs. 167 ± 10 bpm] significantly decreased while oxygen uptake remained unchanged [46.6 ± 3.6 vs. 47.0 ± 3.2 ml/kg/min] at the anaerobic threshold (AT) post AGT training. However, peak oxygen uptake [60.8 ± 6.4 vs. 62.7 ± 5.0 ml/kg/min], peak minute ventilation [124.7 ± 22.6 vs. 132.2 ± 24.9 L/min], and peak respiratory frequency [61 ± 10 vs. 64 ± 11 breaths/min] significantly improved post AGT training, while peak HR remained unchanged [196 ± 20 vs. 192 ± 12 bpm]. CONCLUSION: AGT training with reduced bodyweight at faster speeds had little influence on cardiorespiratory performance variables occurring at lower levels of intensity (AT). However, all peak cardiorespiratory performance variables at higher levels of intensity improved, likely due to training at faster than normal speeds. This would benefit runners by allowing training to occur with reduced orthopedic loading at typical HR intensities, and yet still concurrently improve peak cardiorespiratory performance.

Horned and dehorned dairy cows differ in the pattern of agonistic interactions investigated under different space allowances

Limited space in dairy cattle farming is associated with frequent encounters between cows, often resulting in agonistic interactions and injuries, especially in horned cows. Previous studies with dairy cows investigated space allowances in the waiting area in front of the parlour, the lying area, and the outdoor exercise area with respect to social behaviour. However, direct comparisons between horned and dehorned cows are lacking. In the present study, we compared social behaviour, locomotor activity, and heart rate variability of horned and dehorned dairy cows at four space allowances of the outdoor exercise area (5, 8, 12, 15 m2 per cow) for 1 h on 4 consecutive days. The study involved 12 farms, six with horned and six with dehorned cows. On each farm, 20 cows were used, of which six (two of high, medium, and low rank each) were selected as focal animals. Results showed that the total number of agonistic interactions decreased with increasing space allowance for both horned and dehorned cows. Agonistic interactions were highest in cows of high rank and lowest in cows of low rank, irrespective of horn status. The proportion of agonistic behaviour without body contact was higher in horned than in dehorned cows and increased with increasing space allowance. The proportion of head butts resulting in avoidance behaviour of the receiver (successful head butts) was higher in horned than in dehorned cows and was lowest at the smallest space allowance, irrespective of horn status. Locomotor activity was highest at the beginning of the experimental hour, irrespective of horn status and rank, but on a higher level for low-ranking cows compared with medium- and high-ranking cows. Results of the heart rate variables were inconclusive. The RMSSD (root mean square of successive differences of interbeat intervals) generally increased with increasing locomotor activity and was slightly higher in high- and medium-ranking cows compared with low-ranking cows. The RMSSD/SDNN ratio (SDNN: standard deviation of all interbeat intervals) decreased in all rank categories with an increase in locomotor activity and was on a slightly higher level in high-ranking than in medium- and low-ranking cows. In conclusion, irrespective of space allowance, horned cows did not show more agonistic behaviour than dehorned cows. However, horned cows displayed a different pattern of agonistic interactions as dehorned cows showing more interactions without body contact. To mitigate agonistic interactions, horned and dehorned cows would benefit from enlarged space allowances.

Physiological and Perceived Exertion Responses during Exercise: Effect of β-blockade.

This study investigated the effect of β-blockade on physiological and perceived exertion (RPE) responses during incremental treadmill exercise. Sixteen healthy participants (n = 8 men; age, 25.3 ± 4.6 yr) performed a maximal treadmill exercise test after ingestion of 100 mg metoprolol or placebo, with a double-blind, randomized, and counterbalanced design. Heart rate (HR), ventilatory, and gas exchange variables were measured continuously, and participants reported RPE at the end of each minute. Physiological and RPE responses during each condition were compared at the ventilatory threshold (VT), respiratory compensation point, and at maximal exercise using repeated-measures ANOVA. Linear regression modeled relationships between perceived exertion and physiological variables. The HR and V˙O2 at the VT, respiratory compensation point, and maximal exercise were all significantly lower after β-blockade (P < 0.05). However, when standardized to within condition peak values, differences were no longer significant. The RPE associated with VT was higher after β-blockade (12.9 ± 1.0 vs 12.3 ± 1.2, P < 0.05) but lower at maximal exercise (19.1 ± 0.6 vs 19.4 ± 0.5, P < 0.05). Increases in RPE relative to HR were greater after β-blockade and remained significant when expressed relative to peak HR. There was no difference in the growth of the relationship between RPE and V˙O2 across conditions, although the origin of the relationship was higher with β-blockade. Although β-blockade resulted in a significant reduction in exercising HR and V˙O2, the RPE for a given relative intensity remained unchanged. The relationship between RPE and V˙O2 was not affected by β-blockade. The results provide evidence that RPE is a useful and reliable measure for exercise testing and prescription in patients prescribed β-blockade therapy.

Cooperation Between Strangers in Face-to-Face Dyads Produces More Cardiovascular Activation Than Competition or Working Alone

Abstract. Individual and shared goals can be achieved through social interpersonal interaction, cooperation and competition being two different yet similar strategies to reach such aims and objectives. Nevertheless, there is a gap in the literature analyzing the effect of these types of social interactions, especially in cooperation, on autonomic nervous system responses using noninvasive measures, such as heart rate (HR). The regulation of HR and other cardiovascular variables of the central nervous system offers information about how to encourage or discourage social engagement and prosocial behaviors. In fact, a more flexible engagement with the environment and efficient emotions regulation is enabled by an efficient cardiac control. Hence, the main aim of this study was to investigate heart rate variability (HRV) in strangers (180 healthy young participants) who were set to cooperate or compete in face-to-face dyads (between same-gender participants) or to work alone (as the control condition), considering outcomes in these tasks (positive or negative) and gender as moderating variables. We found that participants who cooperated had higher HRs and lower high frequency (HF) HRV than those who competed and/or worked alone. Regarding gender and outcome, men who cooperate and lose have lower HF-HRV levels than men on the simple task with negative outcomes. Hence, our study indicates that cooperation between strangers in face-to-face dyads may produce less parasympathetic activation than competition or working on the task without any social interaction. Research in this field may help us understand the psychophysiological basis of social interaction, providing an opportunity to establish interaction strategies that would be physiologically desirable, in order to promote well-being.