Continuous Heart Rate Recordings Research Articles

Non-Invasive HRV Protocol and New Index to Assess Internal Training Load During Basketball Warm Up

The aim is to establish an specific, non-invasive, sub-maximum and applicable day-to-day protocol to assess the internal training load (IL) for basketball players using Heart Rate Variability (HRV) analysis before practice or competitions. Another aim is to propose a new IL index as a standardized parameter (%), to manage IL before practice sessions or competition. Twelve amateur male basketball players (age: 26.5 ± 8.8 years) completed HRV tests before a submaximal and intermittent drill (Activity Lay Up Wheel; ALUWIL 6min-test). Players performed a 5on5 scrimmage (MATCH) the following day during 10 min, completing rate of perceived exertion (RPE), total quality recovery (TQR) and wellness questionnaires, and continuous heart rate recordings. Players showed higher values of IL parameters based on heart rate (summatory heart rate zones, SHRZ; and training impulse, TRIMP), higher RPE values and lower recovery values during MATCH than ALUWIL (p<0.01). The parameter % of summatory of heart rate zones (SHRZ) showed stronger correlations than SHRZ and TRIMP during MATCH (p<0.001), and significant relations with RMSSD (square of the mean root of the adjacent R-R intervals) during the HRV test (p<0.05). During the ALUWIL test, %SHRZ shows higher and stronger correlations than SHRZ with RRmean (mean of the R-R intervals) (-.807) but similar than SHRZ with RMSSD. In this specific context, ALUWIL test could offer reliable and applied information as a standardized and integrated protocol to assess internal training load in basketball players using cardiac parameters before practice and games. The parameters RRMean, RMSSD and %SHRZ could be a specific indicator for IL management on basketball. However, more research is needed to validate these proposals in a complex context. Key words: HRV, internal training load, basketball, heart rate, submaximal test, SHRZ.

Decentering and baroreflex sensitivity in adults with elevated blood pressure

Previous studies have linked the ability to decenter, a non-judgmental view of emotions, with lower arterial stiffness and better nocturnal blood pressure dipping in adults. It is unknown however if autonomic regulation of blood pressure is linked to decentering. Therefore, the purpose of this study was to determine if decentering ability is related to cardiovagal or sympathetic baroreflex sensitivity. Thirty-three adults (age 25±6 years; BMI 25±3 kg/m2) with resting blood pressure ≥120/80 mmHg volunteered for this study. All participants had a BMI <30 kg/m2, and had no history of smoking, diabetes, or prescriptions for blood pressure or cardiac function. Participants completed an 11-item experiences questionnaire to evaluate decentering, and then were equipped for a supine autonomic evaluation. The autonomic evaluation included continuous recording of heart rate via 3-lead ECG, muscle sympathetic nerve activity (MSNA) via microneurography, and beat-to-beat blood pressure via finger photoplethysmography. Cardiovagal baroreflex sensitivity (n=33) included estimation of vagal activation by evaluating up-up relationships between systolic arterial pressure (SAP) and R-R intervals of the ECG. Vagal withdrawal was also estimated via the down-down relationships between SAP and R-R intervals. Spontaneous sympathetic baroreflex sensitivity (n=26) was evaluated by evaluating the relationship between changes in diastolic arterial pressure (DAP) in 3 mmHg bins vs. changes in MSNA burst incidence (i.e., bursts / 100 heart beats). Results from 2-tailed Pearson correlation analyses revealed that there was not a relationship between decentering and vagal activation (r=-0.07; p=0.71) or between decentering and vagal withdrawal (r=-0.28; p=0.12). Likewise, there was no relationship between decentering and sympathetic baroreflex sensitivity (r=0.10; p=0.64). Our findings suggest that there is not a clear link between decentering and autonomic regulation of blood pressure as estimated through both cardiovagal and baroreflex sensitivity. NIH (1R15HL140596-01); Nils K. Nelson Endowment Fund This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Acute Effects of Liothyronine Administration on Cardiovascular System and Energy Metabolism in Healthy Volunteers.

ContextThe pharmacokinetics of liothyronine causes concerns for cardiovascular toxicity. While the effects of sustained increase in serum T3 concentrations are well described, little is known on the effects of acute changes in T3 concentrations due to rapid action of thyroid hormone.ObjectiveTo assess the clinical relevance of transient increase of T3 levels on cardiovascular system and energy metabolism.SettingDouble-blind, three arms, placebo controlled, cross-over study (ClinicalTrials.gov Identifier: NCT03098433).Study ParticipantsTwelve volunteers (3 females, 9 males), age 27.7 ± 5.1 years.InterventionOral administration of liothyronine 0.7 mcg/kg, equimolar dose of levothyroxine (0.86 mcg/kg), or placebo in three identical study visits. Blood samples for total T3, free T4 were collected at times 0’, 60’ 120’ 180’ 240’. Continuous recording of heart rate, blood pressure, and hemodynamic data was performed using the volume clamp method. Resting energy expenditure was measured by indirect calorimetry. An echocardiogram was performed on each study visit at baseline and after the last blood sampling.Main Outcome MeasuresChanges in cardiovascular function and energy expenditure.ResultsFollowing the administration of liothyronine, serum T3 reached a Cmax of 421 ± 57 ng/dL with an estimated Tmax of 120 ± 26 minutes. No differences between study arms were observed in heart rate, blood pressure, hemodynamics parameters, energy expenditure, and in echocardiogram parameters.ConclusionsThe absence of measurable rapid effects on the cardiovascular system following a high dose of liothyronine supports the rationale to perform long-term studies to assess its safety and effectiveness in patients affected by hypothyroidism.

Late Breaking Abstracts

Late Breaking Abstracts

394 A convolutional neural networks model for the detection of cortical arousals from heart rate

Abstract Introduction Cortical arousals are transient events of disturbed sleep that occur frequently in sleep disordered breathing (SDB) and can be used as an indicator of sleep quality. While cortical arousals are typically scored from the electroencephalogram (EEG), arousals are associated with increased sympathetic activity and could therefore be detected from measures of sympathetic activity such as heart rate. Most home sleep test and consumer wearable devices enable continuous recording of heart rate via the electrocardiogram (ECG) or optical heart rate sensors without the inconvenience of EEG electrodes. In this preliminary study, we developed a deep learning-based convolutional neural networks (CNN) model to detect arousals from heart rate. Methods This study included 1,083 polysomnograms (PSGs) from five independent studies (Tucson Children’s Assessment of Sleep Apnea, Mechanisms of Pharyngeal Collapse in Sleep Apnea, Impact of the Arousal Threshold in Obstructive Sleep Apnea, Predicting Successful Sleep Apnea Treatment with Acetazolamide in Heart Failure Patients, Combination Therapy for the Treatment of Obstructive Sleep Apnea) that were scored for arousals according to American Academy of Sleep Medicine scoring rules. These studies included PSGs from both children and adults (ages 6 and above), with most data coming from participants with evidence or diagnosis of SDB. We used the Pan-Tomkins algorithm to detect R-peaks from the raw ECG signal, transformed the peaks into normalized instantaneous heart rate at 1 Hz frequency, and produced arousal probability in 1-second resolution using a simple CNN model. Due to slight asynchrony between the appearance of arousals in the EEG versus the heart rate, all overlaps between model-predicted arousals and manually scored arousals were considered true-positives. Results We evaluated the model on a validation set (n=216). The model achieved a gross area under precision-recall curve score of 0.67 and a gross area under receiver operating characteristics curve of 0.91 Correlation between the number of model-detected and manually scored arousal events was r=0.76. Conclusion This preliminary study demonstrates that a deep learning approach has the potential to accurately detect arousals in home sleep tests and consumer wearable devices that measure heart rate. Support (if any) The study was supported by grant #207-SR-19 from the American Academy of Sleep Medicine Foundation.

Effects of glucose intake on stress reactivity in young, healthy men

The psychobiological stress response has a broad impact on energy metabolism, while the availability of energy may, in turn, affect the stress response. Specifically, a reduced cortisol response has been found after 8−11 hours of fasting, while glucose intake has led to an increase in cortisol reactivity. We compared the effects of standardized glucose or artificial sweetener drinks, as well as water, ingested prior to a physical (cold pressor test, CPT) or a psychosocial stressor (Trier Social Stress Test, TSST) after four hours of fasting. Healthy male subjects (N = 151) were randomized to one of six groups (either glucose, sweetener or water group and stress induction with the CPT or TSST). Thirty minutes after ingestion, participants were exposed to the stressor. Repeated measures of the subjective stress response, salivary cortisol and alpha amylase as well as continuous heart rate recordings were taken to capture the psychobiological stress response. Capillary blood glucose levels were measured four times. We found significant psychobiological stress responses for all variables and both stressors, but significantly stronger responses for the TSST. Moreover, we found a significant but small effect for a slightly stronger cortisol response to stress after glucose ingestion, which is presumably driven by a more pronounced effect in the TSST compared to the CPT condition. Responder rates did not differ for the three conditions in either the TSST or in the CPT. Our results demonstrate that even after a short fasting timeframe of four hours, higher glucose availability results in slightly higher cortisol stress responses in men.

Symposium 4: BDNF as a biomarker for vulnerability to stress and stress-related disease

The psychobiological stress response has a broad impact on energy metabolism, while the availability of energy may, in turn, affect the stress response. Specifically, a reduced cortisol response has been found after 8−11 hours of fasting, while glucose intake has led to an increase in cortisol reactivity. We compared the effects of standardized glucose or artificial sweetener drinks, as well as water, ingested prior to a physical (cold pressor test, CPT) or a psychosocial stressor (Trier Social Stress Test, TSST) after four hours of fasting. Healthy male subjects (N = 151) were randomized to one of six groups (either glucose, sweetener or water group and stress induction with the CPT or TSST). Thirty minutes after ingestion, participants were exposed to the stressor. Repeated measures of the subjective stress response, salivary cortisol and alpha amylase as well as continuous heart rate recordings were taken to capture the psychobiological stress response. Capillary blood glucose levels were measured four times. We found significant psychobiological stress responses for all variables and both stressors, but significantly stronger responses for the TSST. Moreover, we found a significant but small effect for a slightly stronger cortisol response to stress after glucose ingestion, which is presumably driven by a more pronounced effect in the TSST compared to the CPT condition. Responder rates did not differ for the three conditions in either the TSST or in the CPT. Our results demonstrate that even after a short fasting timeframe of four hours, higher glucose availability results in slightly higher cortisol stress responses in men.

Changes in couple dynamics between ovulation and menses

The psychobiological stress response has a broad impact on energy metabolism, while the availability of energy may, in turn, affect the stress response. Specifically, a reduced cortisol response has been found after 8−11 hours of fasting, while glucose intake has led to an increase in cortisol reactivity. We compared the effects of standardized glucose or artificial sweetener drinks, as well as water, ingested prior to a physical (cold pressor test, CPT) or a psychosocial stressor (Trier Social Stress Test, TSST) after four hours of fasting. Healthy male subjects (N = 151) were randomized to one of six groups (either glucose, sweetener or water group and stress induction with the CPT or TSST). Thirty minutes after ingestion, participants were exposed to the stressor. Repeated measures of the subjective stress response, salivary cortisol and alpha amylase as well as continuous heart rate recordings were taken to capture the psychobiological stress response. Capillary blood glucose levels were measured four times. We found significant psychobiological stress responses for all variables and both stressors, but significantly stronger responses for the TSST. Moreover, we found a significant but small effect for a slightly stronger cortisol response to stress after glucose ingestion, which is presumably driven by a more pronounced effect in the TSST compared to the CPT condition. Responder rates did not differ for the three conditions in either the TSST or in the CPT. Our results demonstrate that even after a short fasting timeframe of four hours, higher glucose availability results in slightly higher cortisol stress responses in men.

Psychosocial Strengths & Afternoon Basal Cortisol in Mexican-origin Adolescents

The psychobiological stress response has a broad impact on energy metabolism, while the availability of energy may, in turn, affect the stress response. Specifically, a reduced cortisol response has been found after 8−11 hours of fasting, while glucose intake has led to an increase in cortisol reactivity. We compared the effects of standardized glucose or artificial sweetener drinks, as well as water, ingested prior to a physical (cold pressor test, CPT) or a psychosocial stressor (Trier Social Stress Test, TSST) after four hours of fasting. Healthy male subjects (N = 151) were randomized to one of six groups (either glucose, sweetener or water group and stress induction with the CPT or TSST). Thirty minutes after ingestion, participants were exposed to the stressor. Repeated measures of the subjective stress response, salivary cortisol and alpha amylase as well as continuous heart rate recordings were taken to capture the psychobiological stress response. Capillary blood glucose levels were measured four times. We found significant psychobiological stress responses for all variables and both stressors, but significantly stronger responses for the TSST. Moreover, we found a significant but small effect for a slightly stronger cortisol response to stress after glucose ingestion, which is presumably driven by a more pronounced effect in the TSST compared to the CPT condition. Responder rates did not differ for the three conditions in either the TSST or in the CPT. Our results demonstrate that even after a short fasting timeframe of four hours, higher glucose availability results in slightly higher cortisol stress responses in men.

Heart rate responses of a master athlete during ultra-endurance swimming

Abstract Aim: Swimming races outside swimming pools take place all over the world, but studies focusing on their physiological aspects are scarce. In fact, rules forbid any direct contact with swimmers during sanctioned events. This case report presents heart rate responses of a master athlete during an ultra-endurance open water solo swim and analyzes results based on a prior cardiopulmonary exercise test. Methods: The swimmer performed a cardiopulmonary exercise test on a treadmill, following a ramp protocol, with continuous electrocardiogram recording. The athlete performed a 36 km swimming race with continuous heart rate recording. Description of swimming heart rate accordingly to heart rate training zones and correlation analysis between HR and swim speed was assessed. Results: The athlete swam the 36 km event in 11 hours, 16 minutes and 15 seconds. Most of the swim time was spent in training zone 3 (55%), and only 2% of race time was spent in zone 5. Swimming speed (3.2 ± 0.7 km/h) failed to correlate with HR during the event (r2 = 0.1334, p > 0.05). Conclusion: Although HR did not correlate with swimming speed it successfully indicated exercise intensity during this 36 km event. These results can be used in the preparation and monitoring of other solo long-distance swimmers.

Effect of Modified Valsalva Maneuver on Heart Rate and ECG among Young Non –Athletes and Athletes


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Introduction
 Valsalva maneuver (VM) is an indicator of cardiac Autonomic function as well as it is used clinically for testing patency of Eustachian tube in Ear examination. According to one Cochrane systematic review, the modified maneuver may be effective in 19–54% of cases and there is insufficient evidence to either recommend it or advise against it in supra-ventricular tachycardia.
 Material and Method
 The present cross sectional study was conducted in research lab, Department of Physiology, Late Shree Barat Ratana Atal Bihari Vajpeyi Memorial Medical college, Rajnandgaon (C.G) India, during study period April to october 2016. There are two study groups-young athletes engaged in endurance sports and non athletes, first year students of medical college. All the subjects had been demonstrated and practiced modified Valsalva Maneuver and after that subjects was selected for the study (30 in each group comprising of males and females). During modified Valsalva Maneuver continuous recording of Heart Rate and ECG is done. Data obtained so will be recorded and analyzed.
 Observations
 Heart rate was significantly higher after Modified Valsalva Maneuver in athlete, while it was significantly lower in non athlete after Modified Valsalva Maneuver. No significant difference in heart rate between athlete & non athlete group before Modified Valsalva Maneuver. But there was significant difference heart rate between both groups after Modified Valsalva Maneuver. Significantly higher no. of Athletes showed increase t wave duration & prolonged TP Segment as compared to non athletes.
 Conclusion
 Modified Valsalva Maneuver is good index of cardiovascular system.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Achieving Guideline-Directed Heart Rate ControlEarly Posthospitalization

Guidelines for the treatment of heart failure (HF) recommend the titration of β blockers (BB) to a target dosage shown to be effective in clinical trials. The benefit of BBs is associated with heart rate (HR) control, with a target resting HR <70 bpm which in clinical trials have been associated with improved clinical outcomes. The primary purpose of this study was to gauge the ability to achieve guideline-directed medical therapy HR control in the early posthospitalization period for HF patients with the wearable cardioverter defibrillator (WCD), assessing whether the WCD could be used to evaluate HR both at rest and during activity to determine if targets were being met and to adequately direct clinical decision making. The WCD platform allows continuous recording of HR. To assess the guideline-directed therapy goals for reduction of resting HR, HR was evaluated both at rest (nighttime: midnight-7 a.m.; daytime: 7 a.m. midnight), and during activity of daily living. HR data during activity of daily living (ADL) and rest were collected from patients with HF that wore the WCD for ≥5 weeks (n = 1,353) between 2015 and 2017. First, 643,891 activity episodes from 1,353 patients were analyzed. Daytime and nighttime resting HRs significantly dropped from beginning to end of WCD use (day: 72.5 bpm vs 69.0 bpm, p <0.0001; night: 68.1 vs 64.3, p <0.0001). However, 43% of patients still had an average daytime resting HR ≥70 bpm during the last week of WCD use. When comparing a patient's peak activity HR during the first week of WCD use to the last week, there was no difference (93.6 bpm vs 94.1 bpm, p = 0.23). During ADL, 31% of patients had a HR ≥100 bpm, 14% of patients had a HR ≥110 bpm, and 6% had a HR ≥120 bpm. In conclusion, months after hospital discharge, 43% of patients did not meet guideline-directed resting target HR control, indicating they may not have been effectively managed with BB. HR during ADL may have also been higher than preferred. Remote HR monitoring may help physicians to adequately titrate guideline-directed medical therapy, thus improving clinical outcomes in HF patients.

The PerPot Simulated Anaerobic Threshold - A Comparison to Typical Lactate-based Thresholds

Intensity description as exercise prescription is a main challenge for sport scientists and coaches. Most commonly used in endurance sports are percentages of the heart rate at Maximal Lactate Steady State (MLSS). Since the late 1970s, MLSS is approximated by several anaerobic thresholds based on lactate extraction during graded incremental tests. Since then, scientists look for non-invasive methods to approximate these thresholds. Our new approach uses the sports computer science Performance Potential model (PerPot) for determination. The antagonistic model PerPot models the relation between load (speed) and performance (heart rate). This investigation compares lactate based and PerPot simulated thresholds. Fifteen male handball players performed a graded incremental test with lactate extraction and continuous heart rate recording. Lactate measurement was used for determination of four established lactate-based anaerobic thresholds (OBLA, Dickhuth, Keul, Simon). Speed and heart rate processes were used for PerPot determination of the threshold. Both Pearson correlations (r=0.883 - r=0.895) and intraclass correlations (ICC=0.894 - ICC=0.932) show high correlations between lactate-based and PerPot simulated thresholds. Using anaerobic threshold (AT) for exercise prescription is the ideal case. Because of adaptation, AT changes and should therefore be determined periodically. In practice, this is rarely done because of high cost and difficult invasive determination in laboratory. PerPot provides a low cost, non-invasive method for AT determination. It is therefore an ideal method for verifying former results of sports medicine diagnostics periodically. In addition, simple portability of results to field is an advantage, because the graded incremental tests can also be performed outdoors.

Six Years in the Life of a Mother Bear - The Longest Continuous Heart Rate Recordings from a Free-Ranging Mammal

Physiological monitoring of free-ranging wild animals is providing new insights into their adaptations to a changing environment. American black bears (Ursus americanus) are highly adaptable mammals, spending up to half the year hibernating, and the remainder of the year attempting to gain weight on a landscape with foods that vary seasonally and year to year. We recorded heart rate (HR) and corresponding activity of an adult female black bear over the course of six years, using an implanted monitor. Despite yearly differences in food, and an every-other year reproductive cycle, this bear exhibited remarkable consistency in HR and activity. HR increased for 12 weeks in spring, from minimal hibernation levels (mean 20–25 beats/minute [bpm]; min 10 bpm) to summer active levels (July daytime: mean 95 bpm). Timing was delayed following one cold winter. In August the bear switched from primarily diurnal to nocturnal, coincident with the availability of baits set by legal hunters. Activity in autumn was higher when the bear was with cubs. Birthing of cubs in January was identified by a transient increase in HR and activity. Long-term physiological and behavioral monitoring is valuable for understanding adaptations of free-ranging animals to climate change, food availability, and human-related stressors.

Astaxanthin‐rich green alga Haematococcus pluvialis enhanced extreme endurance performance and improved heart rate recovery in exercised rats

Astaxanthin has been known to enhance muscle endurance and limit muscle damage in exercised human and models. However, there is no study on heart rate recovery (HRR). Here we examined the effects of astaxanthin‐rich green alga Haematococcus pluvialis on extreme endurance performance and HRR in exercised rats. Wistar rats were randomly divided into 3 groups of 6 rats; control (olive oil), low dose (LD, 1 g dry algae meal (50 mg astaxanthin)) and high dose (HD, 2 g dry algae meal (100 mg astaxanthin)). After 3 weeks of the acclimation period, 15 good runners were selected and implanted with a subcutaneous heart rate monitor for continuous heart rate recording. Starting on Day 1 of the study, the rats received the targeted dose orally by a daily gavage. The rats ran on a treadmill twice a week for 4 weeks; 15 minutes running ‐ 7 minutes rest ‐ 15 minutes running at 30 m/min, with a final sprint of 1 min at 40 m/min for the first running day of the week with a 5° slope. As the results, HRR time in the supplemented groups was significantly decreased compared to the control. Especially early phases of HRR, to 30% of resting values, were achieved fastest with LD. Also heart rate deflection point in the supplemented groups tended to be prolonged during intermittent extreme endurance conditions compared to the control. Furthermore maximal sprinting force was also significantly improved in the supplemented groups. Dose dependent effect was not found.

Effects of mobile phone radiation on heart rate variability of healthy young subjects

Background and Aim: The potential health risk of the radiofrequency electromagnetic fields which are emitted by mobile phones (MPs) is of considerable public interest. The aim of the present study was to determine the influence of the call with a MP on heart rate variability (HRV) in healthy young male and female subjects. Methods: Heart rate variability was measured in 100 young healthy subjects of either sex from 5 min continuous recording of heart rate using windows-based HRV analysis system during three conditions: (1) When MP is switched off (Period I) (2) when MP is switched on (Period II) (3) during call on MP for 5 min (Period III). Results: In female subjects, we found that the time domain parameters like root of the mean of the sum of the squares of differences between adjacent NN intervals, standard deviation of differences between adjacent NN intervals, NN50, pNN50 were significantly reduced during Period II and Period III as compared to Period I. Furthermore, the frequency domain parameters such as low frequency (LF) and LF/high frequency (HF) were significantly increased during Period II and Period III as compared to Period I. Whereas HF was significantly reduced during Period II and Period III as compared to Period I in female subjects. In the male, only NN50 count was significantly reduced during Period II and Period III as compared to Period I. Conclusion: Increase in the sympathetic tone concomitant with the decrease in the parasympathetic tone was observed during the MP usage in female subjects. However, only the parasympathetic tone may be reduced in male subjects while using MPs.

Trimethylamine-N-Oxide: A Carnitine-Derived Metabolite That Prolongs the Hypertensive Effect of Angiotensin II in Rats

BackgroundRecent evidence suggests that an elevated plasma trimethylamine N-oxide (TMAO) level is associated with an increased risk of adverse cardiovascular events in humans; however, the mechanism is not clear. The aims of this study were to establish the plasma TMAO level in rats and to evaluate the effect of TMAO on arterial blood pressure (BP) and the hemodynamic effects of angiotensin II (Ang II). MethodsTwelve-week-old, Sprague-Dawley rats were implanted with telemetric transmitters, and continuous recordings of heart rate, systolic BP (SBP), and diastolic BP (DBP) were made for 7 days before and 14 days during osmotic minipump-driven subcutaneous infusion of saline (controls), TMAO, low-dose Ang II, or Ang II + TMAO. Plasma TMAO concentration was evaluated using liquid chromatography coupled with triple-quadrupole mass spectrometry. ResultsThe plasma TMAO concentration in controls was 0.57 μmol/L, whereas in TMAO-infused rats it was 58 μmol/L. Neither saline nor TMAO infusion affected SBP and DBP. Infusion of Ang II significantly increased SBP and DBP for the first 5 days of infusion only. In contrast, infusion of Ang II + TMAO produced a hypertensive response that lasted until the end of the experiment. TMAO infusions did not affect body weight and motor activity. ConclusionsWe showed that physiological plasma TMAO concentration in rats was approximately 10 times lower than that reported in humans. Furthermore, the new finding of the study is that TMAO does not affect BP in normotensive animals. However, it prolongs the hypertensive effect of Ang II.

The investigation of heart rate variation on endurance of professional soccer players

The main aim of the present study was to determine whether performance on the Yo-Yo intermittent endurance test can predict the real match performances, or not. The sample of players consists of elite professional soccer players (age 23.02±4.49 years, soccer experience 10.04±4.2 years, body mass 73.61±6,15 kg, height 1,79 ±0,52 m, body mass index 19,12 ±0,4 kg m , body fat 8,32 ±2,96 %) who were the members of the 2 Turkish Soccer Federation. For assessment of aerobic endurance performance used, the Yo-Yo intermittent endurance test level 1 was performed. Heart rate was recorded by a Polar Vantage NV heart rate monitor placed around the chest for continuous heart rate recordings throughout selected stages of the test. Descriptive statistics were calculated. Data are expressed as means and standard deviations for each variable. It is seen that the research group uses 83 % of MaxHR in average Heart Rate according to minimum, average and maximum HR values obtained according to max HR values of the research group. As a conclusion, it is understood that heart rate is an important factor obtained from the yo-yo test that the soccer players show similar efforts during the competition. So the heart rate values taken from this test used as intermittent test has the quality to estimate the players match performance.

Low markers of muscle damage and inflammation following a 3-day trail run

Objectives. To investigate the effect of a 3-day trail run on markersof muscle damage and inflammation in recreational runners.Main outcome measures. Pre-and post-stage and 24-hour and 72-hour post-race concentrations of serum creatine phosphokinase (CPK), high sensitivity C-reactive Protein (hsCRP), cortisol, cardiac Troponin T (cTnT), and osmolality (sOsm) as well as urinary myoglobin (uMb), changes in body mass, delayed onset muscle soreness (DOMS) and thigh circumference (TC) were measured. Continuous recordings of heart rate (HR) and intestinal temperature (Tintest ) were made throughout each stage.Results. Heart rate ranged between 77% and 83% age-predicted maximum (APmax) and Tintest between 36.1 and 40.2ºC during the three stages. Significant rises in mean serum CPK, hsCRP, sOsm and blood neutrophil count reached peak concentrations of 1488U/l, 8.91mg/l, 298mosm/l and 10.21 109/l (p&lt;0.001), respectively. No evidence of elevations in uMb and cTnT were detected. The stage-induced increments in DOMS correlated positively with CPK, r=0.71; 95% CI [0.62, 0.78], TC decreased significantly post S1post and S2post (p&lt;0.05) and a maximum mean body mass loss of 3.09% (±1.04%) occurred during S2.Conclusion. Three consecutive days of 95-km trail running resulted in low markers of muscle damage and inflammation, despite the maintenance of a heart rate above 77% APmax, Tintest rising above 39oC and mean body mass decrement of &gt;2.0%.

Respuesta de la frecuencia cardiaca y consumo de oxígeno de atletas varones en competiciones de duatlón sprint

The aim of this study is to describe the percentages loads of heart rate and oxygen consumption achieved by athletes in duathlon sprint competitions (5 km run, 20 km bike and 2.5 km run = C1-BK-C2) For the study, the physiological data were collected from five duathlon sprint competitions very similar in altitude and terrain. Ten male athletes, chosen from high national level duathletes, participated in the study. Continuous recordings of heart rate were obtained during competitions and subsequently in the laboratory where they were tested by two maximal graded exercise tests, one on a treadmill and another on a cycle ergometer, to obtain physiological reference values for each athlete. The results show that athletes had a very similar percentage of heart rate in the three competition sectors, with C1: 94.63% ± 3%; BK: 94.50% ± 2.94% and C2: 92.71% ± 3.54%. The oxygen consumption levels were estimated as a dependent variable by linear regression, from heart rate and oxygen consumption values of the effort test, showing a similar values in three segments (C1: 89.70% ± 6.11%; BK: 85.73% ± 6.89%, C2: 87.30% ± 8.67%). The lowest VO 2% of BK with respect to C1 and C2 ( p < .01) could be justified by lower use of total muscle mass and therefore a lower energy expenditure. The study showed that in sprint duathlon competitions the per cent load of the heart rate range between 92% and 95% of maximal heart rate and oxygen consumption between 85% and 89% of VO 2max, confirming high levels of maximal aerobic power and heart rate. These data being considered as a reference for the use of sports training loads in continuous, variable continuous, and long interval extended types of sport.