Relation between heart rate recovery after exercise testing and body mass index

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

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 <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 < 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.

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

Background

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.

Aim

To compare the cardiovascular parameters on submaximal treadmill exercise in obese and nonobese adults.

Materials and Methods

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.

Results

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).

Conclusion

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.

A comparison of low and high dose of moderate intensity aerobic exercise on heart rate recovery of the sedentary adults: a pragmatic randomized controlled trial

BACKGROUND

Heart rate recovery (HRR) has been used as a prognostication marker of health. A slower drop in HRR is linked to a higher risk of cardiovascular diseases and all-cause mortality. Since aerobic exercise has been shown to have favorable effects on HRR, we aimed to compare the effects of two different aerobic exercise doses on HRR among a sedentary adult population.

METHODS

A pragmatic randomised controlled trial was conducted on 29 healthy sedentary adults (seven males and 22 females) in a 12-week exercise program. They were randomly assigned to group A (75 min/week, N.=15) or group B (150 min/week, N.=14) of moderate intensity aerobic exercise groups. HRR at 1-minute (HRR1), HRR at 2-minute (HRR2), and peak oxygen uptake (VO<inf>2peak</inf>) were measured pre- and post-intervention.

RESULTS

The improvements of HRR1 and HRR2 were seen in both groups but was only significant (P<0.05) for group A with HRR1, -4.07 bpm (post 24.47±6.42 - pre 20.40±5.51, P=0.018) and HHR2, -3.93 bpm (post 43.40±13.61 - pre 39.47±10.68, P=0.046). Group B showed increment of HRR1, -1.14 bpm (post 21.14±5.35 - pre 20.00±6.30, P=0.286) and HRR2, -2.5 bpm, (post 39.36±8.01 - pre 36.86±9.57, P=0.221). Improvement of the VO<inf>2peak</inf> was only significant in group B with an increment of 1.52±2.61 (P=0.049).

CONCLUSIONS

In conclusion, our study suggests that improvements in heart rate recovery (HRR1 and HRR2) among sedentary healthy adults can be achieved by engaging in moderate intensity exercise at a dose lower than the current recommended guidelines. The lower dose seems to be more attainable and may encourage exercise compliance. Future studies should further explore the effects of different exercise volumes on HRR in a larger sample size and also by controlling for BMI or gender.

Heart rate recovery as an assessment of cardiorespiratory fitness in young adults

BACKGROUND

Cardiorespiratory fitness, typically measured as peak oxygen uptake (VO_2peak) during maximal graded exercise testing (GXT_max), is a predictor of morbidity, mortality, and cardiovascular disease. However, measuring VO_2peak is costly and inconvenient and thus not widely used in clinical settings. Alternatively, postexercise heart rate recovery (HRRec), which is an index of vagal reactivation, is a valuable assessment of VO_2peak in older adults and athletes. However, the validity of HRRec as a clinical indicator of cardiorespiratory fitness in young, sedentary adults, who are a rapidly growing population at risk for developing obesity and cardiovascular disease, has not been fully elucidated.

METHODS

We investigated the association between cardiorespiratory fitness, measured by VO_2peak (mL·kg^-1·min^-1), and HRRec measures after a GXT_max in 61 young (25.2 ± 6.1 years), sedentary adults (40 females) using 3 methods. We examined the relationship between VO_2peak and absolute (b·min^-1) and relative (%) HRRec measures at 1, 2, and 3 min post GXT_max, as well as a measure of the slow component HRRec (HRRec 1 min minus HRR 2 min), using Pearson's correlation analysis.

RESULTS

VO_2peak (36.5 ± 7.9 mL·kg^-1·min^-1) was not significantly correlated with absolute HRRec at 1 min (r = 0.18), 2 min (r = 0.04) or 3 min (r = 0.01). We also found no significant correlations between VO_2peak and relative HRRec at 1 min (r = 0.09), 2 min (r = -0.06) or 3 min (r = -0.10). Lastly, we found no correlation between the measure of the slow component HRRec and VO_2peak (r = -0.14).

CONCLUSIONS

Our results indicate that HRRec measures are not a valid indicator of cardiorespiratory fitness in young, sedentary adults.

Heart Rate Recovery, Central Systolic Pressure, and Augmentation Index in Young Healthy Individuals

Purpose

Measuring heart rate recovery (HRR) holds valuable cardiovascular information and requires minimal technical skill and cost. Understanding the associations between HRR and more robust cardiovascular indicators, such as central systolic blood pressure (CSBP), can provide valuable cardiovascular information with less involvement. CSBP is a strong predictor of certain cardiovascular diseases. The study aims to examine the association between measures of HRR and CSBP and the augmentation index (AIx) in a group of young, healthy individuals and based on sex.

Participants and Methods

One-hundred and seven participants (men – 55, women – 52) were measured for HRR at one minute (HRR₁) and two minutes (HRR₂) after maximum oxygen consumption (VO_2max) testing, CSBP, and the AIx at a heart rate of 75 beats∙min⁻¹ (AIx@75).

Results

The Pearson correlation indicated no association between HRR₁, HRR₂, and CSBP in men and women combined: r = 0.06, P = 0.53; r = 0.05, P = 0.59, respectively, or based on sex: men = r = 0.01, P = 0.95; r = 0.04, P = 0.79, respectively, and women = r = −0.05, P = 0.75; r = −0.09, P = 0.52, respectively. However, there were associations between HRR₁ and AIx@75 in men and women combined: r = −0.37, P < 0.001, and based on sex: men = r = −0.31, P = 0.02, and women = r = −0.38, P < 0.01.

Conclusion

Measures of HRR were not associated with CSBP in a combined group of young men and women or based on sex. Most measures of HRR, especially those established by parasympathetic nervous activity, were associated with lower AIx@75. Though measures of HRR might be good indicators of cardiovascular disease, they might not be good indicators of CSBP in young, healthy individuals.

Influence of Body Composition on Post-Exercise Parasympathetic Reactivation of Firefighter Recruits

Firefighters have a sustained risk for experiencing a sudden cardiac event after completing a fire call. Heart rate recovery (HRR) can be utilized to characterize autonomic nervous system (ANS) recovery and has been linked to cardiac events. Research suggests that body composition influences post-exercise HRR responses in non-firefighter populations. The purpose of this study was to examine the influence of body mass index (BMI), waist circumference (WC), and percent body fat (BF) on the HRR response of firefighter recruits. BMI (kg·m-2), WC (cm), and BF (%) data from 57 firefighter recruits were collected. HRR (b·min-1) data were collected at completion (HR0), as well as 15 (HR15), 30 (HR30), 45 (HR45), 60 (HR60), 120 (HR120), and 180 (HR180) seconds following a submaximal step test, and commonly utilized clinical HRR indices were calculated (ΔHRR30, ΔHRR60, ΔHRR120, and ΔHRR180). After controlling for sex, linear mixed regression models did not identify significant interactions between body composition (ps > 0.05) and HRR response across time. However, significant (ps < 0.05) indirect semi-partial correlations were identified between BF and ΔHRR30 (rsp = -0.31) and ΔHRR60 (rsp = -0.27), respectively. Reducing overall BF (vs. BMI or WC) should be prioritized to improve the post-exercise ANS recovery of firefighter recruits.

Heart rate variability and recovery following maximal exercise in endurance athletes and physically active individuals

The purpose of this study was to determine potential adverse cardiac effects of chronic endurance training by comparing sympathovagal modulation via heart rate variability (HRV) and heart rate recovery (HRR) in middle-aged endurance athletes (EA) and physically active individuals (PA) following maximal exercise. Thirty-six (age, 53 ± 5 years) EA and 19 (age, 56 ± 5 years) PA were recruited to complete a 2-week exercise diary and graded exercise to exhaustion. Time domain and power spectral HRV analyses were completed on recorded R-R intervals. EA had a greater HRR slope following exercise (95% confidence interval, 0.0134-0.0138 vs. 0.0101-0.0104 beats/s; p < 0.001). While EA had greater HRR at 1-5 min after exercise (all p < 0.01), PA and EA did not differ when expressed as a percentage of baseline heart rate (130 ± 19 vs. 139 ± 19; p = 0.2). Root mean square of successive differences in R-R intervals (rest and immediately after exercise) were elevated in EA (p < 0.05). Low-frequency (LF) and high-frequency (HF) spectral components were nonsignificantly elevated after exercise (p = 0.045-0.147) in EA while LF/HF was not different (p = 0.529-0.986). This data suggests greater HRR in EA may arise in part due to a lower resting HR. While nonsignificant elevations in HF and LF in EA produces a LF/HF similar to PA, absolute spectral component modulation differed. These observations require further exploration. Novelty Acute effects of exercise on HRV in EA compared with a relevant control group, PA, are unknown. EA had greater HRR and nonsignificant elevations in LF and HF compared with PA, yet LF/HF was not different. Future work should explore the implications of this observation.

Risk Factors Associated with Cardiac Autonomic Modulation in Obese Individuals

Obesity leads to an imbalance in the autonomic nervous system, especially in increased sympathetic modulation and decreased vagal tone, and some anthropometric, metabolic, and lifestyle variables may increase the risk of developing cardiovascular disease. Objective. To analyze the association between cardiovascular autonomic modulation and biochemical and anthropometric markers, food intake, and physical activity level in severely obese individuals. Methodology. The present study is a cutout of a randomized clinical trial "Effect of nutritional intervention and olive oil in severe obesity" (DieTBra Trial), where the baseline data were analyzed. Anthropometric data, biochemical exams, heart rate variability (HRV), accelerometry, and 24 h recall (R24H) of obese patients (body mass index BMI ≥35 kg/m2) were collected. Results. 64 obese patients were analyzed, with a mean age of 39.10 ± 7.74 years (27 to 58 years). By HRV analysis, in the frequency domain, the obese had a higher predominance of sympathetic autonomic modulation (low frequency (LF) 56.44 ± 20.31 nu) and lower parasympathetic modulation (high frequency (HF) 42.52 ± 19.18 nu). A negative association was observed between the variables Homeostasis Evaluation Model (HOMA-IR) and HF (p = 0.049). In the physical activity analysis, there was a negative association between moderate to vigorous physical activity and the sympathetic component (p = 0.043), and for sedentary time (ST), there was a negative association with HF (p = 0.049) and LF/HF (p = 0.036) and a positive association with LF (p = 0.014). For multiple linear regression, waist circumference (WC) and HOMA-IR values were negatively associated with HF (β = -0.685, p = 0.010; β = -14.989, p = 0.010; respectively). HOMA-IR (β = 0.141, p = 0.003) and the percentage of lipids ingested (β = -0.030, p = 0.043) were negatively associated with LF/HF. Conclusion. Among the cardiovascular risk variables studied, insulin resistance and central adiposity showed the greatest influence on cardiac autonomic modulation of obese, increasing the risk for cardiovascular disease.

Obesity and parasympathetic reactivation of the heart following exercise testing in young male adults: a pilot study

BACKGROUND

In elderly people, obesity may induce changes in the autonomic nervous system via alteration of the balance between the sympathetic and parasympathetic nervous systems. Little is known about obesity and parasympathetic reactivation following exercise testing, particularly in young people in Saudi Arabia, and its relationship with body composition parameters.

OBJECTIVES

Compare parasympathetic reactivation using heart rate recovery (HRR) following the exercise test between young obese and nonobese people and explore the association between body composition parameters with HRR.

DESIGNS

Cross-sectional study.

SETTING

University research lab.

PATIENTS AND METHODS

Twenty-seven young male college students underwent anthropometric measurements and treadmill exercise testing, during which the heart rate was monitored via 12-lead electro-cardiography. Participants were divided into a group (n=15) with high body fat percentage (>30%), and a group (n=12) with a normal body fat percentage (<30%) to compare multiple parameters including HRR, which was defined as the absolute change from heart rate (HR) peak during exercise to 1-minute post-HR peak.

MAIN OUTCOME MEASURES

HRR, body mass index, waist-to-hip ratio, fat percentage, and trunk fat. SAMPLE SIZE AND CHARACTERISTICS: n=27, mean (SD) age=22.4 (0.98) years, range 21-25 years.

RESULTS

There was no significant difference in HRR between the groups (32.20 [13.42] bpm for high body fat percentage vs 35.42 [13.35] bpm for normal body fat percentage) ( P=.54). We found a non-significant inverse correlations of HRR with BMI (r=-0.18, P=.37), WHR (r=-0.04, P=.86), fat percentage (r=-0.18, P=.38) and trunk fat (r=-0.23, P=.25).

CONCLUSION

HRR was preserved in our young obese people and was not different from nonobese people. Furthermore, it seems that obese people with higher body composition parameters may have slower HRR, or slower recovery indicating poorer parasympathetic reactivation.

LIMITATIONS

Need a larger sample to confirm the findings of this pilot study.

CONFLICT OF INTEREST

None.

Effect of different doses of supervised aerobic exercise on heart rate recovery in inactive adults who are overweight or obese: results from E-MECHANIC

PURPOSE

Heart rate recovery (HRR) after exercise is an independent risk factor for cardiovascular disease and mortality. Regular aerobic exercise can improve HRR, yet little is known regarding the dose necessary to promote increases. The aim was to assess the impact of different doses of vigorous-intensity aerobic exercise on HRR in individuals with overweight/obesity.

METHODS

Data from 137 sedentary adults with overweight/obesity from E-MECHANIC were analyzed. Participants were randomized to either a moderate-dose exercise group (8 kcal/kg body weight/week; KKW), a high-dose exercise group (20 KKW), or a non-exercise control group. HRR was defined as the difference between peak heart rate (HR) during a graded exercise test and the HR after exactly 1 min of active recovery at 1.5 mph and level grade.

RESULTS

Change in HRR did not differ significantly by exercise group; therefore, the data from both exercise groups were combined. The combined exercise group showed an improvement in HRR of 2.7 bpm (95% CI 0.1, 5.4; p = 0.04) compared to the control group. Those participants who lost more weight during the intervention (non-compensators) increased HRR by 6.2 bpm (95% CI 2.8, 9.5; p < 0.01) compared to those who lost less weight (compensators). Multiple linear regression models indicated that improvements in HRR are independently associated with increases in VO_2peak (β = 0.4; 95% CI 0.1, 0.7; p = 0.04) but also influenced by concomitant weight loss (β = 0.6; 95% CI 0.2, 1.1; p = 0.01).

CONCLUSION

Exercise-induced improvements in 1-min HRR are likely due to increases in cardiorespiratory fitness as well as concomitant weight loss.

A new equation to predict peak VO2 in obese patients during cardiopulmonary exercise testing

We aimed to develop an equation to predict peak VO₂ in obese subjects undergoing CPET. In addition, we evaluated and compared three published equations. We randomized 346 obese subjects undergoing CPET into a group for developing the equation (n = 272) and a group for cross-validation (n = 74), compared through the Bland and Altman method. Height, sex and age were responsible for 85·5% of total variability of the peak VO2. Additional 1% and 0·7% of the variability were, respectively, explained by physical inactivity and diabetes. The equation devised was as follows: peakVO2mlmin-1=-677·8+(2135·9×heightm)+(706·8×sexmales=1;females=0)-(15·5×ageyears)-(161·1×physicalinactivityyes=1;no=0)-(176·3×diabetesyes=1;no=0). The mean difference between the estimated and measured peak VO₂ was 7 ml min^-1 , with a 23·9% bias. Published equations overestimated the peak VO2 by 35·3%, 49·1% and 46·2% bias. The equation developed in this study performed better in predicting peak VO₂ in obese adults improving ramp protocol design and CRF evaluations in obese subjects.

Sexual dimorphism in heart rate recovery from peak exercise

PURPOSE

There is lack of consensus on whether sex, per se, affects heart rate recovery (HRR). To discriminate between the role of sex and that of cardiovascular fitness on HRR, we compared two groups of male and female participants matched for age and peak oxygen uptake (VO_2peak) percentile.

METHODS

Forty healthy individuals with above-average cardiovascular fitness (VO_2peak >50th percentile), aged 18-27 years (23 men; 17 women), performed maximal cycle-ergometer tests with cardiorespiratory measurements. HRR was obtained at 1 and 2 min of passive recovery. Multiple linear regression analysis was used to determine whether the relationship between VO_2peak and HRR differed between sexes.

RESULTS

Men attained greater peak values for VO₂ and work rate (p < 0.05). Both groups of participants exhibited similar heart rate response to peak exercise and no sex differences were observed in VO_2peak percentile or ventilatory threshold. HRR at 1 and 2 min of passive recovery was similar between sexes. In multiple linear models, VO_2peak explained 11.2% of the variance in HRR_1min both in men and women (p < 0.05). Most importantly, sex, VO_2peak, and their interaction were all significant predictors of HRR_2min (explained variance 29.2%) (p < 0.05).

CONCLUSIONS

This study shows that, for a given VO_2peak percentile (>50th percentile), there is no sexual dimorphism in HRR obtained at 1 or 2 min of recovery. It also demonstrates that, in persons with similar VO_2peak values, HRR obtained at 2 min of peak exercise cessation is affected by sex.

Caracterização da variabilidade da frequência cardíaca em indivíduos com síndrome metabólica

RESUMO Introdução: A variabilidade da frequência cardíaca (VFC) tem sido considerada um mecanismo de modulação do sistema nervoso autônomo. A diminuição da VFC pode estar associada à síndrome metabólica (SM). Objetivo: Comparar a VFC e variáveis de saúde em indivíduos com e sem SM. Métodos: Cento e dezenove participantes foram divididos em dois grupos: sem SM (SSM, n = 68) e com SM (CSM, n = 51). Foi avaliada a análise espectral da VFC em repouso, durante teste cardiopulmonar de exercício (TCPE) e na recuperação em bandas de baixa frequência (LF = 0,04-0,15 Hz), alta frequência (HF = 0,15-0,4 Hz) e razão LF/HF. Adicionalmente, a frequência cardíaca (FC) de repouso (FCrep), FC máxima (FCmáx), pressão arterial sistólica (PAS) e diastólica (PAD), glicemia, perfil lipídico, consumo de oxigênio pico (VO2pico) e composição corporal foram avaliados. Resultados: A FCrep e o VO2pico não apresentaram diferenças entre o CSM e o SSM (73,3 ± 9,1 vs. 70,1 ± 11,0 bpm) (26,8 ± 4,6 vs. 28,1 ± 6,6 ml.kg-1.min-1), respectivamente. A VFC foi similar entre os grupos nos diferentes momentos analisados. A glicemia (99,8 ± 22,5 vs. 87,6 ± 8,6 mg/dl) foi superior no CSM comparado ao SSM. Os valores de triglicérides (159,5 ± 68,8 vs. 89,2 ± 34,3 mg/dl) e VLDL-c (31,9 ± 13,8 vs. 17,8 ± 6,9 mg/dl) foram superiores no CSM comparado ao SSM. O HDL-c (40,7 ± 11,5 vs. 49,3 ± 9,8 mg/dl) foi menor no CSM comparado ao SSM. O IMC (33,1 ± 4,7 vs. 30,8 ± 3,8 Kg/m²) foi superior no CSM comparado ao SSM. A PAS (128,6 ± 12,9 vs. 119,5 ± 11,3 mmHg) e a PAD (77,2 ± 10,5 vs. 72,9 ± 8,1 mmHg) foram superiores no CSM comparado ao SSM, p < 0,05. Conclusão: Os resultados sugerem que a presença de SM não é suficiente para provocar alterações nos índices de VFC em repouso, durante teste cardiopulmonar de exercício (TCPE) e na recuperação quando os pacientes são comparados a indivíduos sem a doença.

Chronotropic Response and Cognitive Function in a Cohort at Risk for Alzheimer's Disease

The objective of this study was to examine the association of chronotropic response (CR) and heart rate (HR) recovery- two indices of cardiovascular function within the context of a graded exercise test- with cognitive performance in a cognitively healthy, late-middle-aged cohort at risk for Alzheimer's disease (AD). Ninety participants (age = 63.52±5.86 years; 65.6% female) from the Wisconsin Registry for Alzheimer's Prevention participated in this study. They underwent graded exercise testing and a comprehensive neuropsychological assessment that assessed the following four cognitive domains: Immediate Memory, Verbal & Learning Memory, Working Memory, and Speed & Flexibility. Regression analyses, adjusted for age, sex, and education, were used to examine the association between CR, HR recovery, and cognition. We found significant associations between CR and cognitive performance in the domains of Immediate Memory, Verbal Learning & Memory, and Speed & Flexibility. In contrast, HR recovery was not significantly associated with cognitive function. The association between CR and cognition persisted even after controlling for HR recovery. Together, these findings indicatethat, in a cognitively normal, late-middle-aged cohort, CR is a stronger correlate of cognitive performance than HR recovery. Overall, this study reinforces the idea that cardiovascular health plays an important role in cognitive function, specifically in a cohort at risk for AD; and that interventions that promote vascular health may be a viable pathway to preventing or slowing cognitive decline due to AD.

Obesity and the Role of Short Duration Submaximal Work on Cardiovascular and Cerebral Hemodynamics

The objective of this study was to compare gas exchange, cardiac and cerebral hemodynamic responses between 10 non-obese and 10 obese men during submaximal work. With the increasing prevalence of obesity, there is a need to understand the impact of obesity on work-induced responses. Participants completed a step-wise incremental cycling until they reached 60% of their age-predicted maximum heart rate. Gas exchange, cardiac and pre-frontal cortex hemodynamic responses were simultaneously measured during rest, work, and recovery. The non-obese group reached ~43% of their predicted maximal aerobic capacity as compared to ~34% in the obese group, with the non-obese working at a relatively higher workload and for more duration than the obese. The obese had elevated baseline heart rate and reduced whole-body oxygen uptake per body weight at baseline and task termination. Other cardiac and cerebral responses, although increased from baseline, were similar between groups during submaximal effort. In the obese, during recovery oxygen uptake and heart-rate recovery were slowest; cardiac output and rate pressure product were greatest, and left ventricle ejection time was shortest. However, both groups exhibited similar cerebral hemodynamics during recovery. These finding imply that, irrespective of their low aerobic fitness, obesity does not impair myocardial performance and cerebrovascular function during graded submaximal work, however, recovery from a short duration of work was influenced by their fitness level. Since a majority of activities of daily living are performed at individual’s submaximal level, understanding influence of obesity on submaximal work is critical.

Heart rate recovery after physical exertion tests in elderly hypertensive patients undergoing resistance training

Abstract Introduction: Heart rate recovery after exercise is a valuable variable, associated with prognosis and it has been used as an indicator of cardiorespiratory fitness, especially in patients with heart disease, as hypertensive patients. Objective: This study aimed to analyze the response of heart rate recovery in elderly hypertensive patients undergoing a resistance training program. Methods: Sample was composed for 10 elderly women with a mean age of 70.7 ± 7.4 years. Exercise test and six-minute walk test were developed and we checked heart rate recovery in the 1st and 2nd minute post tests, before and after resistance training. Results: There was an increase in mean heart rate recovery in the analyzed minutes in both tests, but only in the 1st minute after six minutes walk test we found a significant increase (p = 0.02). Conclusion: The results suggest the efficacy of resistance training to improve cardiorespiratory fitness of elderly hypertensive patients.