Heart Rate Recovery Research Articles

Comparison of cardiac autonomic functions in elite endurance athletes and non-athletic healthy population: A cross-sectional study

Objectives: Long-term endurance training in elite endurance athletes (EEA) is known to affect the autonomic function by increasing the vagal tone which reflects in resting heart rate variability (HRV) but does this high resting vagal tone also affects the post-exercise heart rate recovery (HRR) remains unknown. Post-exercise HRR is used to prescribe and monitor athletic training. Hence, the aim was to determine HRR after maximal exercise among EEA and non-athletics healthy (NAH) populations and correlate it with resting HRV. Materials and Methods: Fifteen EEA and 15 NAH active male subjects of >18 years participated in this study. The resting HRV was measured with a continuous lead II electrocardiogram in the supine position for 10 min. The incremental exercise testing was done and post-exercise HRR data were collected. Results: In time domain analysis, average RR, median RR, root mean square of sequential deviations and percentage of successive interval difference larger than 50 ms were significantly higher, whereas the average heart rate was significantly lower in the EEA group. In the frequency domain analysis, low-frequency power–normalised units (LFnu), and low frequency (LF)/high frequency (HF) was significantly lower while high-frequency power––normalised units were significantly higher in the EEA group. The resting HRV indices did not correlate to HRR in both groups. Conclusion: The athletes have better adapted cardiac autonomic function as compared to the NAH group with higher resting vagal tone and better HRR. HRR did not correlate with resting HRV in either group, suggesting that parasympathetic activity causing a rapid decrease in heart rate post-exercise is independent of basal parasympathetic tone.

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

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

Influence of Cardiorespiratory Fitness on Cardiac Autonomic Recovery Among Active-Duty Firefighters.

Abstract Cornell, DJ, Flees, RJ, Shemelya, CM, and Ebersole, KT. Influence of cardiorespiratory fitness on cardiac autonomic recovery among active-duty firefighters. J Strength Cond Res 38(1): 66–73, 2024—It has been suggested that an inability of the autonomic nervous system (ANS) to recover after strenuous events is a potential cause of sudden cardiac death among firefighters. The purpose of this study was to examine the influence of cardiorespiratory fitness (CRF) on the heart rate recovery (HRR) kinetics of firefighters. Thirty-seven male career active-duty firefighters completed both a submaximal step test and a maximal treadmill graded exercise test. A monoexponential curve was fit to postexercise submaximal and maximal HRR data of each subject. Subjects were placed into Low CRF (n = 13) and High CRF (n = 24) groups based on the standard peak aerobic capacity (V̇O2peak) criterion of &lt;42 ml·kg−1·minute−1 and ≥42 ml·kg−1·minute−1, respectively. After controlling for age and body mass index, CRF was significantly (p &lt; 0.05) correlated with the decay rate ( ) and asymptote ( ) after submaximal exercise (r sp = −0.556; r sp = −0.637, respectively), as well as the , , and amplitude ( ) after maximal exercise (r sp = −0.353; r sp = −0.416; r sp = 0.603, respectively). High CRF firefighters demonstrated a significantly faster after both submaximal (p = 0.003) and maximal exercise (p = 0.043), a lower after submaximal exercise (p = 0.002), and a higher after maximal exercise (p = 0.001), than Low CRF firefighters. Greater CRF was associated with enhanced HRR kinetics after submaximal and maximal exertion, suggesting that CRF may positively influence the ANS recovery of firefighters.

Data-efficient machine learning methods in the ME-TIME study: Rationale and design of a longitudinal study to detect atrial fibrillation and heart failure from wearables

Smartwatches enable continuous and noninvasive time series monitoring of cardiovascular biomarkers like heart rate (from photoplethysmograms), step counter, skin temperature, et cetera; as such, they have promise in assisting in early detection and prevention of cardiovascular disease. Although these biomarkers may not be directly useful to physicians, a machine learning (ML) model could find clinically relevant patterns. Unfortunately, ML models typically need supervised (ie, annotated) data, and labeling of large amounts of continuous data is very labor intensive. Therefore, ML methods that are data efficient, ie, needing a low number of labels, are required to detect potential clinical value in patterns found in wearable data. The primary study objective of the ME-TIME (Machine Learning Enabled Time Series Analysis in Medicine) study is to design an ML model that can detect atrial fibrillation (AF) and heart failure (HF) from wearable data in a data-efficient manner. To achieve this, self-supervised and weakly supervised learning techniques are used. Two hundred subjects (100 reference, 50 AF, and 50 HF) are being invited to participate in wearing a Fitbit fitness tracker for 3 months. Interested volunteers are sent a questionnaire to determine their health, in particular cardiovascular health. Volunteers without any (history of) serious illness are assigned to the reference group. Participants with AF and HF are recruited in the Haga teaching hospital in The Hague, The Netherlands. Enrollment commenced on May 1, 2022, and as of the time of this report, 62 subjects have been included in the study. Preliminary analysis of the data reveals significant inter-subject variability. Notably, we identified heart rate recovery curves and time-delayed correlations between heart rate and step count as potential strong indicators for heart disease. Using self-supervised and multiple-instance learning techniques, we hypothesize that patterns specific to AF and HF can be found in continuous data obtained from smartwatches.

Delayed blood pressure recovery after exercise stress test is associated with autonomic dysfunction and pulse pressure in a middle-aged healthy group.

Delayed heart rate (HR) and blood pressure recovery after exercise test is known as the reliable indexes of autonomic dysfunction. Here we tried to evaluate the serial changes in various indicators during exercise test and correlations with recovery of HR and blood pressure in a normotensive healthy middle-aged group. A total of 122 patients without hypertension or diabetes was enrolled (mean age, 55.6 ± 11.0; male, 56.6%; mean blood pressure, 124.8 ± 16.6 / 81.5 ± 9.6 mmHg). Treadmill test was performed for evaluation of chest pain. Patients with coronary artery disease, positive treadmill test result, left ventricular dysfunction or renal failure were excluded. Heart rate recovery was calculated by subtracting the HR in the first or second minute of recovery period from the HR of peak exercise (HRR1 or HRR2). Systolic blood pressure in the 4th minute of recovery stage (SBPR4) was used to show delayed blood pressure recovery. Metabolic equivalents (METs) and HR in stage 2 to 4 were significantly correlated with both HRR1 and HRR2. Multiple regression analysis of HRR revealed significant correlation of METs and SBPR4. SBPR4 was significantly correlated with both HRR1 and HRR2 (HRR1, r = -0.376, p<0.001; HRR2, r = -0.244, p = 0.008) as well as SBP in the baseline to stage 3 and pulse pressure (r = 0.406, p<0.001). Delayed BP recovery after peak exercise test revealed significant association with autonomic dysfunction and increased pulse pressure in normotensive middle-aged healthy group. It can be a simple and useful marker of autonomic dysfunction and arterial stiffness.

Reliability of 400-m Walk Test Performance and Postexercise Cardiac Autonomic Markers in Older Women

The 400-m walk test (400MWT) is a useful tool to assess mobility and aerobic fitness, while postexercise heart rate recovery (HRR) and heart rate variability (HRV) are noninvasive tools for assessing cardiovascular health. However, measures of reliability, agreement, minimal detectable change (MDC), and coefficient of variation (CV) in older women with different levels of physical activity are lacking. This study aimed to evaluate measures of the reliability of the 400MWT and postexercise markers of cardiac autonomic control in active and sedentary older women. Eighteen physically active and 18 sedentary older women, performed the 400MWT twice, followed by measures of HRR at 1 (HRR1′) and 2 min (HRR2′), and HRV. Reliability was assessed by the intraclass correlation coefficient (ICC) and agreement by Bland–Altman plots. The standard error of measurement, CV, and MDC were calculated. The active group walked faster and completed the 400MWT in a shorter time than the sedentary group (all ps ≤ .03). In addition, in general, the active group presented higher HRR1′ and HRR2′ (all ps ≤ .04). 400MWT performance showed good reliability in both groups (ICC ≥ .78; all ps &lt; .001; CVs ≤ 14% and MDC &lt; 49 s). Indexes of cardiac autonomic control showed poor to good reliability (all ps &lt; .001) with higher CVs than the 400MWT: HRV (ICC ≥ .39; CVs = 41.9%–97.6%; MDC = 12.1–31), HRR1′ (ICC ≥ .63; CVs = 36.2%–49.5%; MDC = 8.3–14.3 bpm), and HRR2′ (ICC ≥ .77; CVs = 33%–43.2%; MDC = 12.7–13.8 bpm). The 400MWT and HRR are reliable measures for the assessment of sedentary and physically active older women, but the reliability of HRV indexes varies according to the group.

Effectiveness of different recovery postures during high-intensity interval training.

High-intensity interval training (HIIT) has become a very popular mode of exercise practiced by the elite as well as recreationally active adults. The aim of this study was to evaluate the effects of four recovery postures that are typically used by exercisers on recovery rate and performance in subsequent bouts of HIIT. Sixteen young, healthy adults performed four HIIT trials with randomized recovery postures. Each trial consisted of four sets of modified Wingate anaerobic power tests (20-sec duration) on a cycle ergometer (Monark 894E, Vansbro, Sweden) separated by four-minute recovery between each exercise set. Participants adopted one of four recovery postures immediately following each set: standing still with hands on the back of the head (head), standing still with hands resting on knees (knees), slow walking with hands on hips (walking), or supine rest (supine). Differences were assessed by a two-way (posture × set) repeated measures analysis of variance. Peak and mean anaerobic power progressively declined within each set (P<0.05), with no differences between postures. Fatigue rate was significantly slower during supine (59±12%) than knees (63±13%). Heart rate recovery was faster (P<0.001) during supine than the other three standing postures. Pulmonary ventilation was not significantly different between postures. Blood lactate concentrations measured after HIIT were not significantly different between postures. Supine posture appears to be more advantageous in facilitating recovery when compared to the three standing postures. None of the recovery postures examined was responsible for better performance in subsequent bouts of HIIT.

The Effect of Exercise on Cardiovascular Autonomic Nervous Function in Patients with Diabetes: A Systematic Review.

Diabetic neuropathy, including autonomic neuropathy, is a severe complication in patients with poorly controlled diabetes. Specifically, cardiovascular autonomic neuropathy (CAN) plays a significant prognostic role in cardiovascular morbidity and mortality. Exercise, an essential component of diabetes treatment, may have a therapeutic effect on patients with diabetes complicated by CAN. However, it remains unclear whether exercise has a therapeutic or protective effect in diabetes patients with CAN. The author conducted a systematic search of PubMed/MEDLINE, Embase, and The Cochrane Library, resulting in the identification of eight eligible randomized controlled trials for this review. Exercise, including aerobic exercise combined with resistance training (RT), high-intensity interval training, and progressive RT, has shown a beneficial effect on cardiac autonomic function (CAF) in patients with type 2 diabetes, as measured by heart rate variability, heart rate recovery, and baroreflex sensitivity. However, most studies had low quality. Moreover, there were no relevant studies examining the effect of exercise on CAF in older patients, patients with poorly controlled diabetes, and patients with type 1 diabetes. Exercise has the potential to manage patients with CAN by balancing sympathetic and parasympathetic nervous system functions; however, further studies are warranted in the future.

Assessment of Cardiovascular Parameters on Submaximal Treadmill Exercise in Obese versus Nonobese Adults.

Obesity and overweight, irrespective of metabolic status, confer an increased risk of adverse consequences including cardiovascular diseases (CVDs). The mechanisms underlying altered cardiovascular responses in obese individuals during and after submaximal treadmill exercise are the subjects of great interest to public health. After graded exercise, delayed heart rate recovery (HRR), exaggerated blood pressure (BP) response, and prolongation of QT interval are the powerful predictors of cardiovascular morbidity and mortality that may facilitate timely identification of individuals at risk of CVD and help to evaluate the effectiveness of treatment interventions. To compare the cardiovascular parameters on submaximal treadmill exercise in obese and nonobese adults. This study was conducted on 80 subjects, 40 obese (cases) and 40 normal-weight individuals (controls), belonging to the age group of 18-60 years. Each participant was subjected to submaximal treadmill exercise according to the Bruce protocol. Heart rate (HR), systolic BP and diastolic BP (SBP and DBP), mean arterial pressure (MAP), QT and corrected QT (QTc) intervals, and rate pressure product (RPP) were measured preexercise, immediately after exercise, and during passive recovery at 1 min and 5 min after exercise. The Chi-square test and Mann-Whitney U-test, whichever is appropriate, were employed for the comparison of variables between the two study groups. P < 0.05 was considered statistically significant. Mean HR immediately after exercise, at 1 min and 5 min postexercise was significantly higher in obese when compared to nonobese participants (P = 0.006, P = 0.001, P = 0.001) despite similar resting HR in both the groups (P = 0.874). Mean SBP, DBP, MAP, and RPP were significantly higher in obese in comparison to nonobese subjects in all stages, i.e. before exercise, immediately after exercise, at 1 min and 5 min after exercise. QT and QTc intervals were also found to be significantly greater in obese than nonobese subjects in all stages (P = 0.001 each). Obese subjects had higher resting BP (SBP, DBP, and MAP), QT/QTc interval, RPP, and increased response to submaximal treadmill exercise activity. Delayed HRR after exercise was also noted in obese subjects which indicates that obese populations are at risk of developing CVDs due to alteration in autonomic functions with sympathetic hyperactivity.

Spatio-temporal repolarization dispersion before and after exercise in patients with long QT syndrome type 1 vs controls - probing into the arrhythmia substrate.

Congenital long QT syndrome (LQTS) carries an increased risk for syncope and sudden death. QT prolongation promotes ventricular extrasystoles which in the presence of an arrhythmia substrate might trigger ventricular tachycardia degenerating into fibrillation. Increased electrical heterogeneity (dispersion) is the suggested arrhythmia substrate in LQTS. In the most common subtype LQT1, physical exercise predisposes for arrhythmia and spatio-temporal dispersion was therefore studied in this context. Thirty-seven patients (57% on beta-blockers) and 37 healthy controls (mean age 31 vs 35, range 6-68 vs 6-72 years) performed an exercise test. Frank vectorcardiography was used to assess spatio-temporal dispersion as Tamplitude, Tarea, the ventricular gradient (VG), and the Tpeak-end interval from 10s-signal averages before and 7±2 min after exercise; during exercise too much signal disturbance excluded analysis. Baseline and maximum heart rates as well as estimated exercise intensity were similar, but heart rate recovery was slower in patients. At baseline QT and heart rate corrected QT (QTcB) were significantly longer in patients (as expected), while dispersion parameters were numerically larger in controls. After exercise QTpeakcB and Tpeak-endcB increased significantly more in patients (18±23 vs 7±10ms and 12±17 vs 2±6ms; p<0.001 and p<0.01). There was, however, no difference in the change in Tamplitude,Tarea and VG between groups. In conclusion, while temporal dispersion of repolarization increased significantly more after exercise in LQT1 patients, there were no signs of exercise-induced increase in global dispersion of action potential duration and morphology. The arrhythmia substrate/mechanism in LQT1 warrants further study.

StartXFit—Nine Months of CrossFit® Intervention Enhance Cardiorespiratory Fitness and Well-Being in CrossFit Beginners

Insufficient physical activity (PA) is associated with low cardiorespiratory fitness, which favors cardiovascular and other noncommunicable diseases. Additionally, it evidentially affects mental health. Considering the WHO PA guidelines, CrossFit® represents a versatile exercise program that combines aerobic and resistance training with mobility and could help reduce disease incidences among sedentary people. Yet, long-term CrossFit research is sparse. We conducted a nine-month intervention (≥2 CrossFit workouts/week) in 16 beginners (14 males, 35 ± 6.8 years, 180 ± 8.6 cm, 85. 5 ± 19.1 kg). As a primary endpoint, VO2max was assessed at baseline, four, and nine months. A repeated-measures ANOVA and Pearson correlation were conducted. Well-being was investigated by the WHO-5 Index pre- and post-intervention. For exploratory purposes, body composition and heart rate recovery (HRR) were tracked. In a second step, all males were categorized into two groups based on body fat percentage and analyzed by repeated measures ANOVA again. The main outcome was an 11.5% VO2max improvement with a large effect (p &lt; 0.01, ηp2 = 0.27). Strong negative correlations between baseline VO2max and its progression after nine months (p = 0.006, r = −0.654) were found. Well-being increased by 8.7% (p = 0.024, d = 0.51). HRR improved both at 1 min (p &lt; 0.05, ηp2 = 0.34) and at 5 min (p &lt; 0.05, ηp2 = 0.27) post-exercise. Resting metabolic rate increased by 2.2% (p = 0.042). Analysis by group revealed improved HRR at 1 min (p &lt; 0.05, ηp2 = 0.62) only for the “high body fat” group. This study reveals the potential of CrossFit to enhance physiological and psychological health in beginners. For more robust results, larger sample sizes with a higher proportion of women are needed.

Assessment of the functional state of the cardiovascular system of students during a mountain hiking trip

Background and Study Aim. In the conditions of hiking trip, a particularly important role is played by the high adaptive abilities of the body, based on the reactivity and lability of functional systems. Of particular importance is the assessment of the functional state of the cardiovascular system of students when participating in a mountain hike. The purpose of the study is to evaluate the effect of physical activity on the state of the cardiovascular system of students in the process of overcoming a mountain hiking trip. Material and Methods. The study involved 30 students aged 18-22 years old who were involved in various sports at the amateur level. The hiking trip lasted six days and covered 114 km. Canyon SportMaster hand-held heart rate monitors were used to determine the power of the students' cardiovascular system. When overcoming climbs during a mountain hike, the rate of heart rate recovery after physical activity was determined (heart rate indicators were recorded before the climb, at the end of the climb, and two minutes after the climb). Results. Analysis of the data obtained showed that the power of the cardiovascular system changed during the hiking trip. The third day turned out to be the most difficult day; the level of power of the cardiovascular system on this day was 76% of the maximum. In all subsequent days, the tourists’ cardiovascular system coped with the stress much better. The indicators obtained on the last day of the hike indicate the adaptive changes that occurred in the athletes’ bodies. Conclusions. It was found that on the first day of the hike the cardiovascular system worked at a sufficient level. In the next two days, there was a decrease in recovery rates and a deterioration in the performance of the cardiovascular system. This is explained by fatigue after the first day, and the fact that the body has not yet had time to work and adapt to unusual loads. Analysis of the last three days of the hike clearly indicates that the body systems have adapted to the stress and environment. Heart rate recovery indicators went up sharply, and the heart rate system worked at only 65% of maximum power. Also, important factors that also need to be taken into account: the weight of the backpacks, the length of the distance, weather conditions, temperature conditions, the psychological atmosphere in the group, equipment, etc.

Heart rate dynamics during a simulated fireground test: The influence of physical characteristics and fitness1.

Firefighting is a physiologically demanding occupation and there is a need to evaluate physical and fitness characteristics that are related to attenuated physiological stress during fireground tasks. Previous studies have not measured associations between heart rate responses during simulated fireground tasks with a standardized work rate. The purpose of this study was to examine associations between heart rate during a standardized pace simulated fireground test (SFGT) and heart rate recovery and variability following the SFGT. In addition, this study sought to evaluate associations between heart rate measures versus physical and fitness characteristics in structural firefighter recruits. Twenty-one fire academy recruits performed a standardized pace SFGT while mean heart rate reserve (HRRes) during the SFGT, change in heart rate variability from rest to post-SFGT (LnRMSSDRest-Post), and 60-second post-SFGT heart rate recovery (HRR60) were measured. Regression analyses were conducted between HRRes, LnRMSSDRest-Post and HRR60 and between heart rate measures versus physical and fitness characteristics while accounting for differences in SFGT completion time. HRRes was associated with LnRMSSDRest-Post, but not HRR60. Height and pull-ups explained most of the variance in HRRes, height explained most of the variance in LnRMSSDRest-Post and push-ups and 1.5-mile run explained most of the variance in HRR60. Greater cardiovascular stress during fireground tasks is associated with greater depression of post-SFGT heart rate variability, but not heart rate recovery. Physical and fitness characteristics are important to consider in relation to firefighters' ability to cope with physical stress on the fireground.

The physiological response during optogenetic-based cardiac pacing in awake freely moving mice.

There are several methods to control a heart rate, such as electrical stimulation and drug administration. However, these methods may be invasive or affect other organs. Recently, an optogenetic-based cardiac pacing method has enabled us to stimulate the cardiac muscle in non-contact. In many previous studies, the pacing was applied ex vivo or in anesthetized animals. Therefore, the physiologic response of animals during optogenetic pacing remains unclear. Here, we established a method of optogenetic-based cardiac pacing in awake, freely moving mice and simultaneously measured electrocardiogram, blood pressure, and respiration. As a result, light-induced myocardial contraction produces blood flow and indirectly affects the respiration rhythm. Additionally, light illumination enabled heart rate recovery in bradycardic mice. These findings may be employed for further research that relates a heartbeat state to animal behavior. Together, this method may drive the development of less invasive pacemakers without pacing leads.

Effects of participant-selected versus researcher-selected music on stress and mood – The role of gender

ObjectivePrevious research suggests differential effects of participant-selected (PS) vs. researcher-selected (RS) music on emotional responses to music listening. This study investigates whether such selection strategies, as well as gender, influence (1) stress and (2) mood responses. Additionally, we examine the role of (3) stimulus-induced emotions and (4) emotion regulation strategies. MethodsParticipants (N = 61) listened to auditory stimuli (PS music, RS music, sound of lapping water (LW); randomized) on three days and underwent a cold pressor test (CPT) while listening. Stress parameters (subjective acute stress, heart rate, parameter RMSSD, salivary alpha-amylase, salivary cortisol), mood dimensions (calmness, valence, energetic arousal), emotions, and emotion regulation strategies were measured. Multilevel and mediation analyses were conducted. Results(1) There were no direct effects of selection strategy or gender on stress responses, but interaction effects indicated that women showed the strongest subjective stress response and the longest HR recovery with PS music, while men showed the lowest HR response to the CPT with PS music. (2) No mood differences emerged between PS and RS music overall. Women showed stronger variability in calmness overall as well as perceived higher arousal when listening to PS music compared to men. (3) Higher stimulus-induced anger in men compared to women and with LW compared to PS was associated with lower calmness and valence, while no consistent pattern emerged for the stress responses. (4) Women scored higher on reappraisal, associated with a decrease in parasympathetic activity, whereas men scored higher on suppression, associated with an increase in endocrine activity. ConclusionsMusic selection and gender appear to have no direct impact on stress and mood responses overall, although men tend to benefit more from self-selected music than women. Our findings provide first indications that avoiding music stimuli that induce anger may facilitate mood management via music. Furthermore, finding alternative emotion regulation strategies to the strategy of suppression may be a helpful approach to improve music-based stress management.

Effects of Sitting Recovery Protocols on Postexercise Heart Rate in Young Adults

Abstract Background We aimed to compare the effects of 3 different upright seated recovery protocols on heart rate recovery (HRR) after a submaximal ergometer exercise. Methods The study included 30 young adult volunteers (15 men and 15 women). Participants performed a submaximal cycle exercise test at a constant workload of 60 Watts until a steady HR was achieved. This was followed by 5 min of: (a) inactive, (b) active loadless, and (c) passive recovery protocols. The HRR was assessed as the difference between the peak exercise HR and the HR recorded following 1 min of recovery and as the percentage HR decline after 1 min postexercise. Abnormal HRR was defined as a reduction of 1-min HRR ≤12 b · min−1 or ≤15 b · min−1 or ≤18 b · min−1. Results In both sexes, HRR was faster during inactive recovery compared with active recovery. In males, HRR was faster during inactive recovery compared with passive recovery protocol. In females, HRR was faster during passive recovery compared with active recovery protocol. The prevalence of impaired HRR was greater in the active recovery compared with the passive and inactive recovery protocols in both sexes. Conclusion The present findings suggest that in both sexes, the postexercise HRR was mediated by a combined action of the central command and other inputs or stimuli arising from skeletal muscle activities. In addition, the active recovery protocol resulted to a slower HRR and elicited more abnormal postexercise HR responses compared with the other recovery protocols.

Exercise Test Predicts Both Noncardiovascular and Cardiovascular Death in a Primary Prevention Population

ObjectiveTo identify specific causes of death and determine the prevalence of noncardiovascular (non-CV) deaths in an exercise test referral population while testing whether exercise test parameters predict non-CV as well as CV deaths. Patients and MethodsNon-imaging exercise tests on patients 30 to 79 years of age from September 1993 to December 2010 were reviewed. Patients with baseline CV diseases and non-Minnesota residents were excluded. Mortality through January 2016 was obtained through Mayo Clinic Records and the Minnesota Death Index. Exercise test abnormalities included low functional aerobic capacity (ie, less than 80%), heart rate recovery (ie, less than 13 beats/min), low chronotropic index (ie, less than 0.8), and abnormal exercise electrocardiogram (ECG) of greater than or equal to 1.0 mm ST depression or elevation. We also combined these four abnormalities into a composite exercise test score (EX_SCORE). Statistical analyses consisted of Cox regression adjusted for age, sex, diabetes, hypertension, obesity, current and past smoking, and heart rate–lowering drug. ResultsThe study identified 13,382 patients (females: n=4736, 35.4%, 50.5±10.5 years of age). During 12.7±5.0 years of follow-up, there were 849 deaths (6.3%); of these 162 (19.1%) were from CV; 687 (80.9%) were non-CV. Hazard ratios for non-CV death were significant for low functional aerobic capacity (HR, 1.42; 95% CI, 1.19 to 1.69; P<.0001), abnormal heart rate recovery (HR, 1.36; 95% CI, 1.15 to 1.61; P<.0033), and low chronotropic index (HR, 1.49; 95% CI, 1.26 to 1.77; P<.0001), whereas abnormal exercise ECG was not significant. All exercise test abnormalities including EX_SCORE were more strongly associated with CV death versus non-CV death except abnormal exercise ECG. ConclusionNon-CV deaths predominated in this primary prevention cohort. Exercise test abnormalities not only predicted CV death but also non-CV death.

Comparison of postexercise heart rate recovery times between athletes and nonathletes in Saudi Arabia

Comparison of postexercise heart rate recovery times between athletes and nonathletes in Saudi Arabia

Prediction Models of Blood Glucose Change During Aerobic Exercise Using Machine Learning Techniques

PURPOSE: This study aimed to explore the relationship between blood glucose level changes and body characteristics during exercise and to present six models for predicting changes in blood glucose levels during exercise.METHODS: 148 healthy men and women (age: 31.9±9.7 year, fasting blood glucose: 102.1±14.1 mg/dL, &lt;i&gt;p&lt;/i&gt;=.032) participated in the study, and 30 of them participated in the study. Eight variables were selected to build two prediction models: 24-hour ingested carbohydrates, age, blood glucose, heart rate changes, sex, skeletal muscle mass, heart rate recovery after exercise, and resting heart rate. Logistic regression and random forest classifier models were used to predict the changes in blood glucose levels during exercise.RESULTS: A total of six models were created for all participants, male and female. Random forest classification (training set: AUC=0.837, Youden index=0.66; validation set: AUC=0.730, Youden index=0.53) and logistic regression classification models (training set: AUC=0.807, Youden index=0.55; validation set: AUC=0.735, Youden index=0.57) were built.CONCLUSION: The random forest model showed good performance in classifying internal data, whereas the logistic regression classification model demonstrated relatively good performance in classifying validation data.

Effect of Smoking on Heart Rate at Rest, During Exercise, and on Heart Rate Recovery in Young Males

Background and need of research: Smoking contributes to several respiratory diseases due to its hazardous effect on respiratory and circulatory system which ultimately affects cardiovascular system. HR is very important, non-invasive and easy-to-measure index of myocardial work. From this study, difference in heart rate can be identified at an early stage among smokers to prevent effects of smoking on cardiac system. Method: An Observational study was conducted in individuals of age between 18 to 45 years. 50 Male subjects who were smoking since more than 2 years, having normal BMI (18.5-22.9Kg/m2) according to Asian classification were included. Person with Severe Cardio respiratory disorder, neurological conditions, any fracture or musculoskeletal disorder which may hamper in step test were excluded. Subjects were divided into 2 groups: 1] Smokers and 2] Non-smokers.HR was measured at rest, during and post 5 minutes of Queens College Step Test to compare between both groups. Result: Mean age, BMI, HR rest, HR during exercise and post HR of smokers were (36.24±6.65), (22.09±0.7), (77.2±4.89), (120.96±5.54) and (90.16±5.72) and in non-smokers were (35.76±7.03), (21.78±1.1), (46.88±6.46), (139.16±8.17) and (73.92±5.9) respectively. Comparison was done using unpaired-t test, Smokers had significantly higher HR at rest, slower HR increase during exercise compared to non-smokers. During recovery, the HR decline was significantly attenuated in smokers. Conclusion and clinical implication: Smoking is found to affect young male smokers’ Heart Rate. Therefore, more actions should be taken to spread awareness about its harmful effects and smoking cessation, especially in young adults. Keywords: Smoking, Queens College Step Test, Heart Rate