Heart Rate Variables Research Articles

Nocturnal Heart Rate Variability and Morning Orthostatic Test as Tools to Monitor Training Load

Both the nocturnal heart rate variability (HRV) and the morning Orthostatic Test are widely used to monitor training load and recovery status of athletes. Both measurements have been observed to be associated with cardiac autonomic regulation. But less is known whether the measurements show similar responses to training load. PURPOSE: This study investigated the effects of easy and hard training days on the nocturnal HRV and the Orthostatic Test. In addition, the aim was to investigate relationships between nocturnal and morning HRV variables. METHODS: Thirty-four recreational endurance runners performed nocturnal R-R interval recordings and the morning Orthostatic test (5 min supine + 3 min standing) after an easy and a hard training day (moderate- or high-intensity endurance training). Nocturnal HRV was analyzed as four-hour period starting 30 min after going to bed for sleep. Morning HRV was analyzed over 4 min supine (00:30-04:30) and 2 min standing position (06:00-08:00). In addition, peak HR after stand-up and Orthostatic heart rate (HR) (HRstanding - HRsupine) were analyzed. RESULTS: Training load (session RPE) of hard training day (638 ± 638) was significantly (P < 0.001) greater compared to easy training day (50 ± 100). Nocturnal HR was lower (52 ± 6 vs. 57 ± 9, P < 0.001) and all nocturnal HRV variables were higher (Total power: 8.86 ± 0.63 vs, 8.41 ± 0.79, P < 0.001) after easy training day. HR in supine position was lower (53 ± 7 vs. 56 ± 7, P = 0.011) and high frequency power in supine position was higher (8.06 ± 0.89 vs. 7.74 ± 0.93, P = 0.027) after easy day. Other Orthostatic test variables were not different between easy and hard training days. Nocturnal HR and HRV variables showed moderate correlations (r = 0.62 - 0.78, P < 0.001) to the morning supine variables, but trivial and small correlations (0.19 - 0.39) to standing variables. CONCLUSIONS: Different training load after easy and hard training days can be observed in both nocturnal HRV and Orthostatic Test. However, the differences are greater in nocturnal HRV recordings compared the morning Orthostatic Test. In addition, it seems that standing variables are not able to evaluate the training load of the previous day. The results suggest that both nocturnal HRV and selected, supine variables of the Orthostatic test can be used in monitoring training load.

Effects of fragrance inhalation of essential oil on control of blood pressure and muscle sympathetic nerve activity in humans

AimsWe recently reported that inhalation of fragrance of Grapefruit essential oil increased blood pressure (BP) while that of Marjoram essential oil decreased BP in humans. In this study, we investigated the effects of fragrance inhalation of Grapefruit and Marjoram essential oil on control of BP and muscle sympathetic nerve activity (MSNA), and also cardiovagal and sympathetic baroreflex function.MethodsThirteen healthy subjects participated in each trial of this study. The experiment was performed in the supine position. Subjects breathed blank air through a face mask for 10 min as baseline. Then, they inhaled air with the fragrance of Grapefruit or Marjoram essential oil from Douglas bags for 10 min. Throughout the trial, MSNA (peroneal nerve, microneurography), beat‐by‐beat heart rate and BP, and breath‐by‐breath respiratory variables were recorded continuously.ResultsBy inhalation of the fragrance of Grapefruit essential oil, diastolic BP increased at 8 to 10 min of inhalation (64 ± 9 mmHg) compared to baseline (62 ± 9 mmHg), whereas MSNA burst rate remained unchanged at the period of inhalation (14.2 ± 8.5 bursts/min) from baseline (13.2 ± 7.0 bursts/min). Cardiovagal (10.8 ± 5.6 vs. 11.9 ± 9.6 ms/mmHg) or sympathetic baroreflex sensitivity (−0.84 ± 0.61 vs. −1.03 ± 0.78 au/mmHg) remained unchanged from baseline at the period of inhalation. On the other hand, by inhalation of the fragrance of Marjoram essential oil, diastolic BP increased at 8 to 10 min of inhalation (61 ± 7 mmHg) compared to baseline (60 ± 8 mmHg) against our previous studies, while MSNA burst rate remained unchanged at the period of inhalation (14.0 ± 8.5 bursts/min) from baseline (12.0 ± 9.4 bursts/min). Cardiovagal (12.0 ± 7.3 vs. 14.9 ± 13.1 ms/mmHg) or sympathetic baroreflex sensitivity (−1.06 ± 0.65 vs. −0.97 ± 0.54 au/mmHg) remained unchanged from baseline at the period of inhalation. Heart rate and respiratory variables remained unchanged in both trials.ConclusionsThe fragrance stimulation of Grapefruit essential oil increased BP without increase in MSNA nor modulating cardiovagal and sympathetic control of BP in humans.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Characterisation of cardiac autonomic function in multiple sclerosis based on spontaneous changes of heart rate and blood pressure

BackgroundPrevalence of cardiovascular autonomic dysfunction (CAD) in multiple sclerosis (MS) varies between studies. Cardiac autonomic function is usually assessed by cardiovascular reflex tests. We hypothesized that MS is associated with CAD, quantifiable by non-invasive means including quantification of baroreceptor sensitivity (BRS) and heart rate variability. MethodsIn this study a comprehensive suite of cardiovascular autonomic tests based only on the spontaneous changes of heart rate and blood pressure was applied to 23 MS patients and age and gender-matched controls. From 5-min continuous non-invasive recording of the electrocardiogram and blood pressure, heart-rate, blood pressure, and autonomic function variables were calculated. Analysis included heart rate variability in the time domain, heart rate and blood pressure variability in the frequency domain, and baroreceptor sensitivity in both the time and frequency domain. ResultsBRS measured by the frequency technique in high frequency band was found to be significantly lower in MS (16 ± 9 ms/mmHg) compared to controls (29 ± 17 ms/mmHg) (p < 0.05). Also mean of BRS modulus in MS averaged 15 ± 8 ms/mmHg which is significantly lower compared to controls (25 ± 15 ms/mmHg) (p < 0.05). Systolic blood pressure variability in the high frequency band (0.15–0.5 Hz) was found to be significantly higher in the MS compared to controls (5.8 ± 16.7 mmHg2 vs. 1.3 ± 0.8 mmHg2) (p < 0.05). ConclusionsThe results, using techniques novel to MS investigation, showed diminished baroreceptor reflex and impaired sympathetic function using frequency domain systolic blood pressure variability analysis.

Combined effect of whole-body vibration and ambient lighting on human discomfort, heart rate, and reaction time.

This study aimed to investigate the effect of whole-body vibration and ambient lighting, as well as their combined effect on human discomfort, heart rate, and reaction time in laboratory conditions. 44 men were recruited with an average age of 25.4 ± 1.9years. Each participant was subjected to 12 experimental steps, each step lasting five minutes for four different vibration accelerations in X, Y, and Z axes at a fixed frequency; three different lighting intensities of 50, 500, and 1000lx were also considered. At each step, a visual computerized reaction test was taken from subjects and their heart rate recorded by pulse oximeter. In addition, the discomfort rate of subjects was measured using Borg scale. Increasing vibration acceleration significantly increased the discomfort rate and heart beat but not the reaction time. Lack of lighting caused more discomfort in the subjects, but there was no significant correlation between lighting intensity with heart rate and reaction time. The results also showed that the combined effect of vibration and lighting had no significant effect on any of the discomfort, heart rate, and reaction time variables. Whole-body vibration is an important factor in the development of human subjective and physiological reactions compared to lighting. Therefore, consideration of the level of vibration to which an individual is exposed in workplaces subject to vibration plays an important role in reducing the level of human discomfort, but its interaction with ambient lighting does not have a significant effect on human subjective and physiological responses.

Efeitos fisiológicos da hidroterapia em balde em recém-nascidos prematuros

Objetivo: Este estudo examinou os efeitos da hidroterapia em balde em parâmetros fisiológicos e ganho de peso em recém-nascidos prematuros hospitalizados. Métodos: Participaram 30 recém-nascidos prematuros estáveis (221,13 ± 2,74 dias de gestação), com pelo menos 1,500 kg de peso corporal com ganho crescente nos últimos dias. A hidroterapia foi administrada em duas sessões em dias alternados, realizada com o recém-nascido em um balde com água aquecida, até as clavículas, durante 10 min. As avaliações foram realizadas três vezes por sessão: pré-intervenção (15 min antes da hidroterapia), pós-intervenção (imediatamente após) e seguimento (30 minutos após). As análises comparativas foram realizadas considerando as variáveis: freqüência cardíaca (FC), freqüência respiratória (FR), saturação de oxigênio (SaO2) e peso corporal (PC). Resultados: Houve aumento do PC dos recém-nascidos de 1983,00 ± 55,70 para 2044,00 ± 57,44 gramas durante as sessões (p &lt;0,001). A FC foi menor no seguimento do que nas medidas pré e pós-intervenção em ambas as sessões (p &lt;0,05). A FR e a SaO2 permaneceram constantes. Conclusões: A hidroterapia em balde com água aquecida pode ter promovido melhor funcionamento comportamental nos recém-nascidos prematuros. Isso pode ter resultado em menor FC. A terapia foi segura, uma vez que os parâmetros fisiológicos e o ganho de peso corporal não foram afetados negativamente.

EFFECTS OF TRAINING MASK ON HEART RATE AND ANXIETY DURING THE GRADED EXERCISE TEST AND RECOVERY

The aim of this study is to examine the effect of training mask on heart rate (HR) and related anxiety during Graded Exercise Exercise (GXT). Six volunteer participants (age 20,5 ± 0,5 yrs, height 181,8 ± 5,5 cm, weight 74,5 ± 7 kg, BMI 22,51 ± 0,81) have been included in the study. PARQ and ACSM (American College of Sports Medicine) risk factor analysis have been made to all of the participants before the tests. Only healthy experimental subjects have been included in the study. The participants have been randomly separated into two groups (A, B) including 3 people. On the first day of the test, Group A completed the test with the training mask (TM) while the Group B completed it without training mask (NTM). Two days later, the groups were changed and they repeated the tests (Crossover Design). GXT have been applied to the participants on the treadmill until they got exhausted. During the 5-minute recovery time given after the end of GXT, HR variables have been measured. At the end of recovery, Becks Anxiety Inventory (BAI) has been implemented. In order to determine the differences came out at the measurements made after TM and NTM exercises, non-parametric t-test has been used and the confidence interval has been taken as p˂0,05. At the end of GXT and the following 5-minute recovery time, a significant difference has been found in HR variables between both groups (p˂, 005). The termination process of the test with TM has been 2.45% earlier (from 15.02 sec. to 14.49 sec.) than the NTM group and HR average at the end of recovery period has been found 9.12% lower than NTM group. In addition to this, there is no significant difference between anxiety total scores of the two groups (p˃, 005). As a conclusion, while low HR averages of TM group can be explained as CO 2 diaspora, it can be figured that the similarity in terms of anxiety levels between the groups has resulted from the fact that the running test has been finished up to the participation own decision. Article visualizations:

EFFECTS OF TRAINING MASK ON HEART RATE AND ANXIETY DURING THE GRADED EXERCISE TEST AND RECOVERY

The aim of this study is to examine the effect of training mask on heart rate (HR) and related anxiety during Graded Exercise Exercise (GXT). Six volunteer participants (age 20,5 ± 0,5 yrs, height 181,8 ± 5,5 cm, weight 74,5 ± 7 kg, BMI 22,51 ± 0,81) have been included in the study. PARQ and ACSM (American College of Sports Medicine) risk factor analysis have been made to all of the participants before the tests. Only healthy experimental subjects have been included in the study. The participants have been randomly separated into two groups (A, B) including 3 people. On the first day of the test, Group A completed the test with the training mask (TM) while the Group B completed it without training mask (NTM). Two days later, the groups were changed and they repeated the tests (Crossover Design). GXT have been applied to the participants on the treadmill until they got exhausted. During the 5-minute recovery time given after the end of GXT, HR variables have been measured. At the end of recovery, Becks Anxiety Inventory (BAI) has been implemented. In order to determine the differences came out at the measurements made after TM and NTM exercises, non-parametric t-test has been used and the confidence interval has been taken as p˂0,05. At the end of GXT and the following 5-minute recovery time, a significant difference has been found in HR variables between both groups (p˂, 005). The termination process of the test with TM has been 2.45% earlier (from 15.02 sec. to 14.49 sec.) than the NTM group and HR average at the end of recovery period has been found 9.12% lower than NTM group. In addition to this, there is no significant difference between anxiety total scores of the two groups (p˃, 005). As a conclusion, while low HR averages of TM group can be explained as CO 2 diaspora, it can be figured that the similarity in terms of anxiety levels between the groups has resulted from the fact that the running test has been finished up to the participation own decision. Article visualizations:

A Pilot Study Validating Select Research-Grade and Consumer-Based Wearables Throughout a Range of Dynamic Exercise Intensities in Persons With and Without Type 1 Diabetes: A Novel Approach.

The increasing popularity of wearable technology necessitates the evaluation of their accuracy to differentiate physical activity (PA) intensities. These devices may play an integral role in customizing PA interventions for primary prevention and secondary management of chronic diseases. For example, in persons with type 1 diabetes (T1D), PA greatly affects glucose concentrations depending on the intensity, mode (ie, aerobic, anaerobic, mixed), and duration. This variability in glucose responses underscores the importance of implementing dependable wearable technology in emerging avenues such as artificial pancreas systems. Participants completed three 40-minute, dynamic non-steady-state exercise sessions, while outfitted with multiple research (Fitmate, Metria, Bioharness) and consumer (Garmin, Fitbit) grade wearables. The data were extracted according to the devices' maximum sensitivity (eg, breath by breath, beat to beat, or minute time stamps) and averaged into minute-by-minute data. The variables of interest, heart rate (HR), breathing frequency, and energy expenditure (EE), were compared to validated criterion measures. Compared to deriving EE by laboratory indirect calorimetry standard, the Metria activity patch overestimates EE during light-to-moderate PA intensities (L-MI) and moderate-to-vigorous PA intensities (M-VI) (mean ± SD) (0.28 ± 1.62 kilocalories· minute-1, P < .001, 0.64 ± 1.65 kilocalories· minute-1, P < .001, respectively). The Metria underestimates EE during vigorous-to-maximal PA intensity (V-MI) (-1.78 ± 2.77 kilocalories · minute-1, P < .001). Similarly, compared to Polar HR monitor, the Bioharness underestimates HR at L-MI (-1 ± 8 bpm, P < .001) and M-VI (5 ± 11 bpm, P < .001), respectively. A significant difference in EE was observed for the Garmin device, compared to the Fitmate ( P < .001) during continuous L-MI activity. Overall, our study demonstrates that current research-grade wearable technologies operate within a ~10% error for both HR and EE during a wide range of dynamic exercise intensities. This level of accuracy for emerging research-grade instruments is considered both clinically and practically acceptable for research-based or consumer use. In conclusion, research-grade wearable technology that uses EE kilocalories · minute-1 and HR reliably differentiates PA intensities.

Performance indicators in individual rhythmic gymnastics: Correlations in competition

The aim of this study was to identify the training variables that can determine the score in elite rhythmic gymnasts. Seven female rhythmic gymnasts participated in the study (age 15.7 ± 1.2). Performance data were collected from elite gymnasts (n=7) in competition exercises executed over 10 sessions occurring in the competition period. Additional variables such as heart rate, subjective rate of perceived exertion, competition category, number of apparatus, number of competitive exercises and number of training sessions were also collected. Data were examined using linear regression. Results showed that the heart rate average values ranged between 137 and 154 beats per minute. At the end of the competitive period, a decrease in the perceived exertion and the average score of the exercises were observed. An increase in the heart rate (p <0.01) and in the perceived exertion (p <0.05) has a positive impact on the total final score. The variables of heart rate and subjective rate of perceived exertion are significant to control the effects of training on the performance of individual rhythmic gymnasts. Moreover, they enable the coaches to control the training load in an affordable and reliable way.

Retrospective Evaluation of the Effect of Heart Rate on Survival in Dogs with Atrial Fibrillation.

BackgroundAtrial fibrillation (AF) usually is associated with a rapid ventricular rate. The optimal heart rate (HR) during AF is unknown.Hypothesis/ObjectivesHeart rate affects survival in dogs with chronic AF.AnimalsForty‐six dogs with AF and 24‐hour ambulatory recordings were evaluated.MethodsRetrospective study. Holter‐derived HR variables were analyzed as follows: mean HR (meanHR, 24‐hour average), minimum HR (minHR, 1‐minute average), maximum HR (maxHR, 1‐minute average). Survival times were recorded from the time of presumed adequate rate control. The primary endpoint was all‐cause mortality. Cox proportional hazards analysis identified variables independently associated with survival; Kaplan‐Meier survival analysis estimated the median survival time of dogs with meanHR <125 bpm versus ≥125 bpm.ResultsAll 46 dogs had structural heart disease; 31 of 46 had congestive heart failure (CHF), 44 of 46 received antiarrhythmic drugs. Of 15 dogs with cardiac death, 14 had CHF. Median time to all‐cause death was 524 days (Interquartile range (IQR), 76–1,037 days). MeanHR was 125 bpm (range, 62–203 bpm), minHR was 82 bpm (range, 37–163 bpm), maxHR was 217 bpm (range, 126–307 bpm). These were significantly correlated with all‐cause and cardiac‐related mortality. For every 10 bpm increase in meanHR, the risk of all‐cause mortality increased by 35% (hazard ratio, 1.35; 95% CI, 1.17–1.55; P < 0.001). Median survival time of dogs with meanHR<125 bpm (n = 23) was significantly longer (1,037 days; range, 524‐open) than meanHR ≥125 bpm (n = 23; 105 days; range, 67–267 days; P = 0.0012). Mean HR was independently associated with all‐cause and cardiovascular mortality (P < 0.003).Conclusions and Clinical ImportanceHolter‐derived meanHR affects survival in dogs with AF. Dogs with meanHR <125 bpm lived longer than those with meanHR ≥ 125 bpm.

Resting Heart Rate, QTc Interval, and Laboratory Variables in Relation to Risk Factors of Metabolic Syndrome in Korean Adult Male

Objectives Each of resting heart rate, QTc interval, blood uric acid, leukocyte count, erythrocyte count, and calcium and other laboratory variables were reported to be related to metabolic syndrome. Thus, more variables including the above are extensively examined together to verify the effect on metabolic syndrome in Korean adult male. Methods A total of 889 male subjects who have undergone healthy volunteer screening from June 2011 to January 2016 for phase 1 clinical trial were analyzed. The criteria for metabolic syndrome included blood pressure, fasting plasma glucose, triglyceride, high-density lipoprotein (HDL) by American Heart Association/National Heart Lung and Blood Institute (AHA/NHLBI, 2005), and body mass index (BMI) by American Association of Clinical Endocrinologists (AACE, 2003). Heart rate, QTc interval, complete blood cell count, serum creatinine, uric acid, calcium, AST, ALT, and alkaline phosphatase were included as risk factors for metabolic syndrome. The data were analyzed by t-test, ANOVA, Pearson correlation coefficient, and multiple linear regression analysis using SAS 9.4. Results About 4.4% of subjects had at least 3 of 5 criteria for metabolic syndrome. Age, leukocyte count, erythrocyte count, AST, ALT, uric acid, and calcium were positive correlated (p<0.05) with the count of satisfied metabolic syndrome criteria among age, resting heart rate, QTc interval, laboratory variables. Six variables-Age, erythrocyte count, uric acid, ALT, calcium, and leukocyte-were selected as significant variables for explaining the count of satisfied criteria for metabolic syndrome by multiple regression analysis, of which the coefficient of determination was 11%. Conclusions The count of satisfied criteria for metabolic syndrome increased as the age becomes older, which signifies the importance of management in the old age. Other variables such as erythrocyte, uric acid, ALT, calcium, leukocyte should be managed or monitored more carefully to reduce metabolic syndrome. Key words: Metabolic syndrome, Male, Blood cell counts, Blood chemical analyses, Heart rate

Telemedicine for Facio-Scapulo-Humeral Muscular Dystrophy: A multidisciplinary approach to improve quality of life and reduce hospitalization rate?

BackgroundFacio-Scapulo-Humeral Muscular Dystrophy (FSHD) is an autosomal dominant inherited disorder characterized by a variable and asymmetric involvement of facial, trunk, upper and lower extremity muscles. Although respiratory weakness is a relatively unknown feature of FSHD, it is not rare. Telemedicine has been used in a variety of health care fields, but only recently, with the advent of sophisticated technology, its interest among health professionals became evident, even in such diseases. ObjectiveTo demonstrate the telemedicine efficacy in FSHD. MethodsFour siblings affected by a severe form of FSHD, living in a rural area far away from the referral center for neuromuscular diseases, who used a wheelchair, suffered from chronic respiratory failure and were provided with long-term non-invasive mechanical ventilation, received a 6-month period of telemedicine support. This consisted of video conferencing (respiratory physiotherapy, psychological support, neurological and pneumological assessment, nurse-coach supervision) and telemonitoring of cardiorespiratory variables (oxygen saturation, blood pressure, and heart rate). ResultsWe performed 540 video conference sessions per patient, including three daily contacts with short monitoring oximetry measurements, blood pressure, and heart-rate measurements, psychological support, neurological and pneumological assessment, nurse-coach supervision. ConclusionsOur findings indicate that our telemedicine system was user-friendly, efficient for the home treatment of FSHD, and allowed reducing hospital admissions.

Continuous coloured light altered human brain haemodynamics and oxygenation assessed by systemic physiology augmented functional near-infrared spectroscopy

Exposure to artificial coloured light is unavoidable in our modern life, but we are only just beginning to understand the impact of coloured light on human physiology. The aim of the present study was to determine effects of coloured light exposure on human systemic and brain physiology using systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). We measured changes in haemoglobin concentrations and tissue oxygen saturation in the left and right prefrontal cortices (L-PFC, R-PFC) by fNIRS, and also recorded skin conductance (SC), partial pressure of end-tidal CO2 (PETCO2), and heart-rate variability variables. 17 healthy adults (median age: 29 years, range: 25–65 years, 6 women) were exposed to blue, red, green, or yellow light for 10 minutes. Pre-light and post-light conditions were in darkness. In the L-PFC the yellow evoked a brain activation. SC and PETCO2 did not change during any of the coloured light exposures, but SC increased and PETCO2 decreased for all colours (except green) in the post-light period. Changes in L-PFC haemoglobin concentration were also observed during the post-light period but have to be interpreted with care, because heart rate and SC increased while PETCO2 decreased. The detected effects are potentially of high relevance for choosing room lighting and may possibly be applied therapeutically.

Assessment of butorphanol-azaperone-medetomidine combination as anesthesia for semen collection and evaluation of semen quality in white-tailed deer (Odocoileus virginianus)

The aim of this current study was to evaluate the level of anesthesia produced by a combination of butorphanol-azaperone-medetomidine (BAM) for semen collection by electroejaculation on captive white-tailed bucks (Odocoileus virginianus). Ten male white-tailed deer, weighing 68.2–115.9kg, ranging in age from one to four years were randomly selected from housing pens and anesthetized with the BAM drug combination at a dose volume of 2.0mL each. Semen was collected from each animal using a standard cervid electroejaculation protocol while under BAM anesthesia. Physiological data was recorded following induction of anesthesia and during semen collection. Collected ejaculates were prepared for analysis using a standard extender protocol for cryopreservation. Eleven sperm viability parameters were quantified for each sample using a Computerized Assisted Sperm Analysis system, including total seminal volume; sperm concentration and total sperm number. kinematic parameters of motile spermatozoa were also assessed. Results demonstrated that BAM provided an effective plane of anesthesia for successful collection of viable sperm. Measured physiological variables of heart rate, respiration and body temperature all remained within safe, normal limits. Data recorded on semen characteristics from all collected ejaculates correlated well with key traits determined to be important for successful fertilization through measurement of total semen volume; sperm concentration; total sperm number; and kinematic parameters of motile spermatozoa. There were no serious adverse events. This field study indicates that BAM anesthesia is suitable for semen collection in white-tailed deer.

Physiological Profile of an Uphill Time Trial in Elite Cyclists.

While a number of studies have researched road-cycling performance, few have attempted to investigate the physiological response in field conditions. To describe the physiological and performance profile of an uphill time trial (TT) frequently used in cycling competitions. Fourteen elite road cyclists (mean ± SD age 25 ± 6y, height 174 ± 4.2cm, body mass 64.4 ± 6.1kg, fat mass 7.48% ± 2.82%) performed a graded exercise test to exhaustion to determine maximal parameters. They then completed a field-based uphill TT in a 9.2-km first-category mountain pass with a 7.1% slope. Oxygen uptake (VO2), power output, heart rate (HR), lactate concentration, and perceived-exertion variables were measured throughout the field-based test. During the uphill TT, mean power output and velocity were 302 ± 7W (4.2 ± 0.1W/kg) and 18.7 ± 1.6km/h, respectively. Mean VO2 and HR were 61.6 ± 2.0mL · kg-1 · min-1 and 178 ± 2beats/min, respectively. Values were significantly affected by the 1st, 2nd, 6th, and final kilometers (P < .05). Lactate concentration and perceived exertion were 10.87 ± 1.12mmol/L and 19.1 ± 0.1, respectively, at the end of the test, being significantly different from baseline measures. The studied uphill TT is performed at 90% of maximum HR and VO2 and 70% of maximum power output. To the authors' knowledge, this is the first study assessing cardiorespiratory parameters combined with measures of performance, perceived exertion, and biochemical variables during a field-based uphill TT in elite cyclists.

Causal attribution and psychobiological response to competition in young men

A contribution to a special issue on Hormones and Human Competition.Psychoneuroendocrine effects of competition have been widely accepted as a clear example of the relationship between androgens and aggressive/dominant behavior in humans. However, results about the effects of competitive outcomes are quite heterogeneous, suggesting that personal and contextual factors play a moderating role in this relationship. To further explore these dimensions, we aimed to examine (i) the effect of competition and its outcome on the psychobiological response to a laboratory competition in young men, and (ii) the moderating role of some cognitive dimensions such as causal attributions. To do so, we compared the responses of 56 healthy young men faced with two competitive tasks with different instructions. Twenty-eight men carried out a task whose instructions led subjects to think the outcome was due to their personal performance (“merit” task), whereas 28 other men faced a task whose outcome was attributable to luck (“chance” task). In both cases, outcome was manipulated by the experimenter. Salivary steroid hormones (testosterone and cortisol), cardiovascular variables (heart rate and blood pressure), and emotional state (mood and anxiety) were measured at different moments before, during and after both tasks. Our results did not support the “winner-loser effect” because no significant differences were found in the responses of winners and losers. However, significantly higher values on the testosterone and cardiovascular variables, along with slight decreases in positive mood, were associated with the merit-based competition, but not the chance-based condition. In addition, an exploratory factorial analysis grouped the response components into two patterns traditionally related to more active or more passive behaviors. Thus, our results suggest that the perception of contributing to the outcome is relevant in the psychobiological response to competition in men. Overall, our results reveal the importance of the appraisal of control and causal attribution in understanding human competitive interactions.

Mercury, omega-3 fatty acids, and seafood intake are not associated with heart rate variability or QT interval

ABSTRACTMercury (Hg), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) concentrations differ across seafood types. Our aim was to investigate the association of Hg, EPA, and DHA, as well as avid consumption of diverse seafood types, with cardiovascular variables heart rate variability (HRV) and QT interval duration (QTc) in a contemporary population. We measured HRV and QTc by Holter monitor, EPA and DHA in plasma, total Hg in whole blood, and possible confounders in 94 avid seafood consumers from Long Island, NY. Participants had mean Hg of 8.4 mcg/L, mean EPA of 1.2%, and mean DHA of 3.7% of total fatty acids. Adjusted for possible confounders, EPA+DHA, Hg, and total seafood consumption were not associated with HRV or QTc. Associations with consumption of specific seafood types were suggested (eg, tuna steak with QTc and anchovies with HRV) but require verification.

Effects of acepromazine and trazodone on anesthetic induction dose of propofol and cardiovascular variables in dogs undergoing general anesthesia for orthopedic surgery.

OBJECTIVE To compare the doses of propofol required to induce general anesthesia in dogs premedicated with acepromazine maleate or trazodone hydrochloride and compare the effects of these premedicants on cardiovascular variables in dogs anesthetized for orthopedic surgery. DESIGN Prospective, randomized study. ANIMALS 30 systemically healthy client-owned dogs. PROCEDURES 15 dogs received acepromazine (0.01 to 0.03 mg/kg [0.005 to 0.014 mg/lb], IM) 30 minutes before anesthetic induction and 15 received trazodone (5 mg/kg [2.27 mg/lb] for patients > 10 kg or 7 mg/kg [3.18 mg/lb] for patients ≤ 10 kg, PO) 2 hours before induction. Both groups received morphine sulfate (1 mg/kg [0.45 mg/lb], IM) 30 minutes before induction. Anesthesia was induced with propofol (4 to 6 mg/kg [1.82 to 2.73 mg/lb], IV, to effect) and maintained with isoflurane or sevoflurane in oxygen. Bupivacaine (0.5 mg/kg [0.227 mg/lb]) and morphine (0.1 mg/kg [0.045 mg/lb]) were administered epidurally. Dogs underwent tibial plateau leveling osteotomy (n = 22) or tibial tuberosity advancement (8) and were monitored throughout anesthesia. Propofol induction doses and cardiovascular variables (heart rate and systemic, mean, and diastolic arterial blood pressures) were compared between groups. RESULTS The mean dose of propofol required for anesthetic induction and all cardiovascular variables evaluated did not differ between groups. Intraoperative hypotension developed in 6 and 5 dogs of the acepromazine and trazodone groups, respectively; bradycardia requiring intervention developed in 3 dogs/group. One dog that received trazodone had priapism 24 hours later and was treated successfully. No other adverse effects were reported. CONCLUSIONS AND CLINICAL RELEVANCE At the described dosages, cardiovascular effects of trazodone were similar to those of acepromazine in healthy dogs undergoing anesthesia for orthopedic surgery.

Modeling the effect of tilting, passive leg exercise, and functional electrical stimulation on the human cardiovascular system.

Long periods of bed rest negatively affect the human body organs, notably the cardiovascular system. To avert these negative effects and promote functional recovery in patients dealing with prolonged bed rest, the goal is to mobilize them as early as possible while controlling and stabilizing their cardiovascular system. A robotic tilt table allows early mobilization by modulating body inclination, automated passive leg exercise, and the intensity of functional electrical stimulation applied to leg muscles (inputs). These inputs are used to control the cardiovascular variables heart rate (HR), and systolic and diastolic blood pressures (sBP, dBP) (outputs). To enhance the design of the closed-loop cardiovascular biofeedback controller, we investigated a subject-specific multi-input multi-output (MIMO) black-box model describing the relationship between the inputs and outputs. For identification of the linear part of the system, two popular linear model structures-the autoregressive model with exogenous input and the output error model-are examined and compared. The estimation algorithm is tested in simulation and then used in four study protocols with ten healthy participants to estimate transfer functions of HR, sBP and dBP to the inputs. The results show that only the HR transfer functions to inclination input can explain the variance in the data to a reasonable extent (on average 69.8%). As in the other input types, the responses are nonlinear; the models are either not reliable or explain only a negligible amount of the observed variance. Analysis of both, the nonlinearities and the occasionally occurring zero-crossings, is necessary before designing an appropriate MIMO controller for mobilization of bedridden patients.

A clinical evaluation of the pharmacokinetics and pharmacodynamics of intravenous alfaxalone in cyclodextrin in male and female rats following a loading dose and constant rate infusion

ObjectiveTo characterise, as a clinical study, the pharmacokinetics and pharmacodynamics and describe the hypnotic effect of the neurosteroid alfaxalone (3α-hydroxy-5 α-pregnane-11, 20-dione) formulated with 2-hydroxypropyl-β-cyclodextrin in male and female rats. Study designProspective, experimental laboratory study. AnimalsA total of 12 (six male and six female) adult, aged-matched Sprague Dawley rats. MethodsSurgery and instrumentation was performed under isoflurane anaesthesia in an oxygen/nitrous oxide mixture (1:2) and local anaesthetic infiltration. All animals received a loading dose (1.67 mg kg−1 minute−1) for 2.5 minutes followed by a constant rate infusion (0.75 mg kg−1 minute−1) for 120 minutes of alfaxalone. Isoflurane and nitrous oxide was discontinued 2.5 minutes after the alfaxalone infusion started. Cardiorespiratory variables (heart rate, respiratory rate, arterial blood pressure and end tidal carbon dioxide tension) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Carotid artery blood samples were collected at strategic time points for blood gas analysis, haematology, biochemistry, and plasma concentrations of alfaxalone. Plasma samples were assayed using liquid chromatography-mass spectrometry. ResultsThere were significant differences between the sexes for plasma clearance (p=0.0008), half-life (p=0.0268) and mean residence time (p=0.027). Mean arterial blood pressure was significantly higher in the male rats (p=0.0255). Conclusions and clinical relevanceThis study confirms that alfaxalone solubilised in 2-hydroxypropyl-β-cyclodextrin provides excellent total intravenous anaesthesia in rats. Sex-based differences in pharmacokinetics and pharmacodynamics were demonstrated and must be considered when designing biomedical research models using alfaxalone.