Low Cardiorespiratory Fitness Groups Research Articles

Measurement of Sedentary Behavior-The Outcomes of the Angle for Posture Estimation (APE) Method.

Hip-worn accelerometers are commonly used to assess habitual physical activity, but their accuracy in precisely measuring sedentary behavior (SB) is generally considered low. The angle for postural estimation (APE) method has shown promising accuracy in SB measurement. This method relies on the constant nature of Earth's gravity and the assumption that walking posture is typically upright. This study investigated how cardiorespiratory fitness (CRF) and body mass index (BMI) are related to APE output. A total of 3475 participants with adequate accelerometer wear time were categorized into three groups according to CRF or BMI. Participants in low CRF and high BMI groups spent more time in reclining and lying postures (APE ≥ 30°) and less time in sitting and standing postures (APE < 30°) than the other groups. Furthermore, the strongest partial Spearman correlation with CRF (r = 0.284) and BMI (r = -0.320) was observed for APE values typical for standing. The findings underscore the utility of the APE method in studying associations between SB and health outcomes. Importantly, this study emphasizes the necessity of reserving the term "sedentary behavior" for studies wherein the classification of SB is based on both intensity and posture.

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.

A bout of endurance and resistance exercise transiently decreases plasma levels of bile acids in young, sedentary adults.

Circulating bile acids (BA) are signaling molecules that control glucose and lipid metabolism. However, the effects of acute exercise on plasma levels of BA in humans remain poorly understood. Here, we evaluate the effects of a bout of maximal endurance exercise (EE) and resistance exercise (RE) on plasma levels of BA in young, sedentary adults. Concentration of eight plasma BA was measured by liquid chromatography-tandem mass spectrometry before and 3, 30, 60, and 120 min after each exercise bout. Cardiorespiratory fitness (CRF) was assessed in 14 young adults (21.8 ± 2.5 yo, 12 women); muscle strength was assessed in 17 young adults (22.4 ± 2.5 yo, 11 women). EE transiently decreased plasma levels of total, primary, and secondary BA at 3 and 30 min after exercise. RE exerted a prolonged reduction in plasma levels of secondary BA (p < 0.001) that lasted until 120 min. Primary BA levels of cholic acid (CA) and chenodeoxycholic acid (CDCA) were different across individuals with low/high CRF levels after EE (p ≤ 0.044); CA levels were different across individuals with low/high handgrip strength levels. High CRF individuals presented higher levels of CA and CDCA 120 min after exercise vs baseline (+77% and +65%) vs the low CRF group (-5% and -39%). High handgrip strength levels individuals presented higher levels of CA 120 min after exercise versus baseline (+63%) versus the low handgrip strength group (+6%). The study findings indicate that an individual's level of physical fitness can influence how circulating BA respond to both endurance and resistance exercise. Additionally, the study suggests that changes in plasma BA levels after exercising could be related to the control of glucose homeostasis in humans.

Cardiorespiratory Fitness Level Alters Blood Pressure Responses Induced By Histamine H1- And H2-receptor Blockade During Dynamic Exercise

INTRODUCTION: Epidemiological studies have reported that greater cardiorespiratory fitness (CRF) is associated with lower blood pressure (BP). Histamine receptor-mediated peripheral vasodilation contributes to post-exercise hypotension and lowing exercising BP responses. Previously, our laboratory found that overactive BP responses to exercise were induced by the inability of histamine receptors in individuals with prehypertension. However, it is still unknown that CRF can impact BP responses elicited by the inability of the receptors. PURPOSE: This study was to assess whether aerobic fitness is effective in lowering excessive BP responses induced by the blockade of histamine receptors METHODS: In twelve male and female subjects (6 high CRF and 6 low CRF), we examined the effects of histamine H1- and H2- receptor blockades on heart rate (HR), stroke volume (SV), cardiac output (CO), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and total peripheral resistance (TPR) at workloads corresponding to 40% and 60% workloads of VO2peak during cycling exercise. RESULTS: Our study indicated that compared to the high CRF group, changes in MAP from the baselines were higher in the low CRF group before the blockade at each workload (40%: D14±2 vs. 8±1 mmHg; 60%: D21±3 vs. 15±2 mmHg). The changes in MAP in response to the blockade during exercise were substantially lower in the high CRF group (40%: D18±2 vs. 11±1 mmHg; 60%: D29±3 vs. 19±2 mmHg). CONCLUSIONS: Our study suggests that an improvement in CRF likely reduces exaggerated BP responses elicited due to the inability of histamine receptors in pathological conditions such as prehypertension and hypertension.

How adherence to the updated physical activity guidelines should be assessed with accelerometer?

BackgroundThe aerobic part of the recently updated physical activity (PA) guidelines for adults recommends at least 150 min of moderate or at least 75 of vigorous-intensity PA or an equivalent combination of both. PA can be accumulated of any bout duration. On an absolute scale, moderate-intensity threshold is 3 metabolic equivalents (METs) and vigorous 6 METs. On a scale relative to individual’s personal capacity, moderate-intensity threshold is 40% and vigorous 60% of the oxygen uptake reserve. In this study, the adherence to the new guidelines was evaluated using both absolute and relative thresholds.MethodsTotally, 1645 adults aged 20–64 years, participated in this population-based study and their cardiorespiratory fitness (CRF) was estimated with 6-min walking test. The participants with estimated maximal oxygen uptake <7.9 MET were categorized as low CRF group and the others as adequate CRF group. The participants were instructed to wear a triaxial hip-worn accelerometer for 1 week and their adherence to PA guidelines was assessed from the accelerometer data.ResultsThe adequate CRF group had higher adherence to PA guidelines with the absolute thresholds, but the use of relative thresholds inverted the results. The adherence varied from 20% to 99% in the total sample depending on the analysis parameters of accelerometer data.ConclusionsThe absolute thresholds provide a more appropriate basis to assess the adherence to PA guidelines in population-based samples and interventions. The use of individually determined relative thresholds may be more useful for individual exercise prescriptions in PA counseling.

P-103 Physical fitness is positively associated with sperm quality in healthy young men

Abstract Study question Do sperm quality parameters differ between “high” and “low” cardiorespiratory fitness (CRF) and muscular strength levels in healthy young men? Summary answer Self-reported CRF was positively associated with sperm count and concentration, while muscular strength (objectively measured and self-reported) did not correlate with seminal parameters. What is known already Physical activity (i.e., any body movement that results in energy expenditure) levels are positively associated with sperm quality parameters in healthy men. In this context, physical fitness, which is modifiable by physical activity, is a powerful marker of health that integrates several body functions such as hematocirculatory, skeletomuscular, phsychoneurological and endocrine-metabolic. In particular, the main components of physical fitness (i.e., CRF and muscular strength) have been negatively related to the risk of all-cause mortality in any age population. However, the association of CRF and muscular strength with sperm quality parameters in healthy young men is unknown. Study design, size, duration This cross-sectional study included 253 healthy men (age= 22.63 ± 5.04 years, BMI= 22.84 ± 1.33). Semen samples and physical fitness assessment were performed between March 2019 and July 2021 at the sperm biobank (Ceifer Biobank – NextClinics). The study was approved by the Ethics Committee of Investigación Biomédica de Andalucía. Participants/materials, setting, methods CRF was self-reported using the The International FItness Scale (IFIS). Muscular strength was objectively assessed using a handgrip dynamometer and self-reported with IFIS. Semen samples were analysed by clinical technicians to determine sperm count, sperm concentration and progressive motility. Analysis of covariance (ANCOVA) was performed to obtain adjusted mean differences on sperm quality parameters between high and low CRF and muscular strength groups after including age and body mass index as confounders. Main results and the role of chance Men with higher CRF presented increased sperm count and concentration compared to men with lower CRF values (adjusted mean differences 43.581 x 106 [2.630, 84.532; 95% confidence interval] and 10.131 x 106/ml [0.799, 19.463; 95% confidence interval]; both p &amp;lt; 0.05). Muscular strength (objectively measured and self-reported) was not associated with any semen quality parameter (all p &amp;gt; 0.05) when including age and body mass index as covariates. Limitations, reasons for caution This study reported a positive association between self-reported CRF using IFIS questionnaire and sperm count and concentration in healthy young men. Although the validity of the self-reported CRF using IFIS has been widely proved in healthy young adults, objectively measured CRF is needed to further confirm our findings. Wider implications of the findings Infertility has increased in the last decades. Therefore, more research is needed to identify health indicators that affect sperm quality. Our results suggest that self-reported CRF could contribute to the identification of young men with poor seminal quality and a higher risk of infertility later in life. Trial registration number NA

High fitness levels attenuate the increased risk of heart failure due to low socioeconomic status: A cohort study

High fitness levels attenuate the increased risk of heart failure due to low socioeconomic status: A cohort study

Sex Differences in the Prevalence of Metabolic Syndrome Based on Leg Strength, Cardiorespiratory Fitness, and Skeletal Muscle Mass in Elderly

Background: Metabolic syndrome (MetS) is characterized by abdominal obesity, high blood glucose, and dyslipidemia. Low fitness, muscle mass, and strength increase the risk of MetS. The characteristics of these variables are highly interrelated. This cross-sectional study aimed to analyze the prevalence of MetS by combining leg strength (LSTR), cardiorespiratory fitness (CRF), and appendicular skeletal muscle mass (ASM) in elderly men and women. Methods: Participants included 1420 persons aged 65–79 years (men: 753, women: 667). An isokinetic dynamometer was used to measure LSTR; CRF was evaluated by measuring maximum oxygen uptake; and ASM was assessed using bio-impedance analysis. The measured CRF, LSTR, and ASM were converted to relative values by dividing by body weight and grouped into ‘high’ and ‘low’ based on the median value. The diagnosis of MetS was based on five criteria: waist circumference, blood pressure, high-density lipoprotein cholesterol, triglycerides, and fasting glucose. MetS was diagnosed when the participant fulfilled 3 or more of the criteria, and odds ratios (ORs) were analyzed using logistic regression. Results: MetS was diagnosed in 32.1% and 30.3% of men and women, respectively. The relative LSTR and ASM values were significantly higher in the non-MetS group compared to those of the MetS group in both sexes. The OR for MetS in men was 3.6-fold higher in the low LSTR group, 3.5-fold higher in the low CRF group, and 2.3-fold higher in the low ASM group than in the high groups. In women, the OR for MetS increased 1.3-fold in the group with low LSTR and 3.7-fold in the group with low CRF. The OR for MetS exhibited a 3.5-fold increase in men and a 2.4-fold increase in women for combined low LSTR and low ASM compared to those of the combined high LSTR and high ASM group. Despite high ASM, the OR for MetS was a 3.5-fold higher in men and a 3.9-fold in women for low LSTR and low CRF group. Conclusions: The prevalence of MetS increased in elderly with relatively decreased LSTR, ASM and decreased CRF. Furthermore, the prevalence of MetS is increased when both LSTR and ASM are low despite high CRF. In addition, even if ASM was low, the risk of metabolic syndrome did not increase when both CRF and LSTR were high. In conclusion, when two or more of the three variables CRF, LSTR, and ASM were low, the prevalence of MetS increased.

Association between Cardiorespiratory Fitness, Muscle Strength, and Non-Alcoholic Fatty Liver Disease in Middle-Aged Men

Background: Nonalcoholic fatty liver disease (NAFLD) occurs when more than 5% of fat accumulates in the liver parenchyma without excess alcohol consumption. The objective of this study is to investigated the association between cardiorespiratory fitness (CRF), muscle strength (MS), and NAFLD. Methods: The subjects of this study were 1325 males aged 40–50 who had visited the National Fitness Center located in the Republic of Korea from 2017 to 2019. Abdominal ultrasonography testing was used for NAFLD diagnosis. For CRF, an MS test was used to measure maximal oxygen intake and grip strength. CRF and MS were classified into 3 quartiles (high, middle, low-level). In addition, both the CRF level and MS level were classified into 9 quadrants. Results: With confounding factors (age, body mass index, exercise, smoking) controlled, there was no relative risk of NAFLD between middle and high levels of CRF (95% CI, 0.92–2.17). However, the relative risk of NAFLD in the case of low-level CRF was 1.63-fold (95% CI, 1.03–2.60, p &lt; 0.05) higher than that in the case of high-level CRF. Meanwhile, there was no significant difference between middle-level MS (95% CI, 0.68–1.65) and high-level MS (95% CI, 0.84–1.99) in terms of NAFLD relative risk. The NAFLD relative risk in the case of low-level CRF/MS was 2.27-fold (95% CI, 0.94–1.99, p &lt; 0.05) higher than that of high-level CRF/MS. Conclusions: The low CRF and MS group had a higher risk of NAFLD compared with the high CRF and MS group. Maintenance of high CRF and MS may be beneficial in preventing NAFLD.

Cardiorespiratory fitness and electroanatomical remodelling in patients with atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Atrial fibrillation (AF) is the most common clinically-relevant arrhythmia. Its initiation and maintenance is linked to the presence cardiovascular risk factors such as hypertension and obesity. Higher cardiorespiratory fitness (CRF) has been associated with a better prognosis. However, specific electroanatomical features associated with baseline CRF have not been described. Purpose Compare electroanatomical substrate across exercise capacity levels in patients with AF Methods Patients referred for de novo AF radiofrequency ablation at the Centre for Heart Rhythm Disorders from August 2017 until June 2020 were screened for inclusion and CRF was evaluated in metabolic equivalents (METs) by a symptom-limited maximal treadmill exercise test using the standard Bruce protocol prior to ablation. Predicted CRF was calculated based on established equations and patients were categorized according to the percentage of predicted CRF achieved; low (&amp;lt;85%), adequate (85-100%) and high (&amp;gt;100%). Total mean and regional peak-to-peak bipolar voltages, percent of low voltage areas (% LVA), conduction velocity (CV) and percent of complex fractionated electrograms (% CFE) in sinus rhythm were compared across groups. Results There were no between-group differences in baseline characteristics, medication use or echocardiographic features. Total mean voltage was significantly lower in the low CRF group compared to both adequate and high CRF. Compared to the high CRF group, roof (3.25 ± 1.2 mV vs 1.9 ± 1.3 mV, p &amp;lt; 0.05), posterior (3.8 ± 1.8 mV vs 1.7 ± 0.9 mV, p &amp;lt; 0.001) and inferior mean voltages (3.4 ± 2 mV vs 1.6 ± 0.7 mV, p &amp;lt; 0.05) were significantly lower in the low CRF group (figure 1A). Furthermore, compared with the adequate CRF group, mean voltages were significantly lower in the posterior (3.7 ± 1.5 mV vs 1.7 ± 0.9 mV, p &amp;lt; 0.001), inferior (3.4 ± 1 mV vs 1.6 ± 0.7 mV, p &amp;lt; 0.001) and lateral (4.2 ± 2.2 mV vs 2.1 ± 1.4 mV, p &amp;lt; 0.05) walls of the low CRF group. Anterior and septal mean voltages were not significantly different across CRF groups (P for trend = 0.07, 0.3 and 0.15, respectively). Conduction velocities were not significantly different across groups. The inferior %LVA was significantly higher in the low CRF (5.6 ± 6%) compared to adequate CRF group (23 ± 18%) (p &amp;lt; 0.05) (figure 1B). Total and regional % CFE was higher in the low CRF compared to adequate and high CRF. Conclusion Participants in the lower baseline CRF category showed significant reductions in regional voltages along with higher fractionation with preserved conduction velocities. Research on the effect of physical activity and CRF on left atrial arrhythmogenic substrate is required. Abstract Figure. Global and regional mV and % LVA by CRF

Do Patients Maintain Proper Long-Term Cardiopulmonary Fitness Levels After Cardiac Rehabilitation? A Retrospective Study Using Medical Records.

ObjectiveTo examine whether patients who participated in a cardiac rehabilitation (CR) program after hospitalization for acute coronary syndrome maintained cardiorespiratory fitness (CRF) in the community.MethodsWe conducted a retrospective study including 78 patients who underwent percutaneous coronary intervention or coronary artery bypass graft surgery at our hospital’s cardiovascular center and participated in a CR program and a 5-year follow-up evaluation. Patients were divided into a center-based CR (CBCR) group, participating in an electrocardiography-monitored exercise training in a hospital setting, and a home-based CR (HBCR) group, receiving aerobic exercise training and performed self-exercise at home.ResultsNo significant differences were found between groups (p>0.05), except the proportion of non-smokers (CBCR 59.5% vs. HBCR 31.7%; p=0.01). In both groups, the maximal oxygen consumption (VO2max) increased significantly during the first 12 weeks of follow-up and remained at a steady state for the first year, but it decreased after the 1-year follow-up. Particularly, VO2max at 5 years decreased below the baseline value in the HBCR group. In the low CRF group, the CRF level significantly improved at 12 weeks, peaked at 1 year, and was still significantly different from the baseline value after 5 years. The high CRF group did not show any significant increase over time relative to the baseline value, but most patients in the high CRF group maintained relatively appropriate CRF levels after 5 years.ConclusionContinuous support should be provided to patients to maintain optimal CRF levels after completing a CR program.

Separate and combined relationships for cardiorespiratory fitness and muscular strength with visceral fat and insulin sensitivity in adolescents with obesity.

We examined the separate and combined associations for cardiorespiratory fitness (CRF) and muscular strength (MS) with total and regional fat, and insulin sensitivity (IS) in 204 adolescents (BMI ≥85th percentile, 12-18 years) at UPMC Children's Hospital of Pittsburgh. CRF was measured by maximum oxygen consumption during a graded treadmill test. MS was quantified by combining 1-repetition maximum test for the leg and bench press. Participants were stratified as having either high or low CRF and MS based on sex-specific median split. Both high CRF and high MS groups had lower (P < 0.05) total fat after adjustment for sex, Tanner stage and ethnicity than the low CRF and MS groups (Difference: 6.6, 2.6-9.6% and 5.4, 2.4-8.3%, respectively). High CRF, but not high MS, had lower visceral (67.5 versus 77.9 cm2, P < 0.01) and intermuscular fat (3.6 versus 4.0 kg, P = 0.01) than the low CRF groups. Differences by CRF remained significant after adjustment for MS. High CRF, but not high MS, was associated (P < 0.05) with lower fasting glucose and higher IS after accounting for sex, Tanner stage and ethnicity than the low CRF group, and high CRF remained associated with these markers after adjustment for MS. High CRF is associated with lower total and regional fat, and higher IS after adjustment for MS. Novelty: CRF is associated with lower total fat, visceral and intermuscular fat, and higher insulin sensitivity adjusting for muscular strength. Muscular strength is not associated with regional body fat and insulin sensitivity after accounting for CRF.

Influence of aerobic fitness on the correspondence between heart rate variability and ventilatory threshold

The aims of this study were to verify the correspondence between heart rate variability (HRV) and ventilatory thresholds during a progressive exercise test and the relationship with low and high aerobic fitness levels. Twenty male volunteers (29.5±6.2 years; 75.9±13.0 kg; 175.0±7.4 cm) were recruited. The subjects were allocated to two groups according to their VO2max &lt;48.8 ml•kg−1•min−1 (low cardiorespiratory fitness group) (n=10) and &gt;48.81 ml•kg−1•min−1 (high cardiorespiratory fitness group) (n=10). A progressive test was performed, consisting of 3-min stages beginning at 25 watts and increasing by 25 watts every 3-min. The HRV threshold (HRVT) and ventilatory threshold (VT) analyses were performed through visual inspection. The comparisons with RMSSD values in percentage of maximum workload resulted in a higher effect size (ES) than the SDNN values. The VO2 in the high cardiorespiratory fitness group at VT (+32%), HRVTRMSSD (+27%), and HRVTSDNN (+31%) was signifi cantly higher compared to the group with low cardiorespiratory fitness. Higher values were observed for relative load (W•kg-1) at VT and HRVTSDNN in the high cardiorespiratory fitness group in comparison with the low cardiorespiratory fitness group (P&lt;0.05), but no difference for VT and HRVTRMSSD. Signifi cant correlations between at VT and HRVTSDNN (r=0.77) were found only in the low cardiorespiratory fitness group. Cardiorespiratory fitness should be regarded as a factor for HRVT evaluation. The HRVTSDNN was closer to the VT in the low cardiorespiratory fitness group than the HRVTRMSSD, however, the use of vagal modulation assessed using the HRV parameter was more sensitive to observe possible differences regarding cardiorespiratory fitness.

Influence of aerobic fitness on the correspondence between heart rate variability and ventilatory threshold

The aims of this study were to verify the correspondence between heart rate variability (HRV) and ventilatory thresholds during a progressive exercise test and the relationship with low and high aerobic fitness levels. Twenty male volunteers (29.5±6.2 years; 75.9±13.0 kg; 175.0±7.4 cm) were recruited. The subjects were allocated to two groups according to their VO2max &lt;48.8 ml•kg−1•min−1 (low cardiorespiratory fitness group) (n=10) and &gt;48.81 ml•kg−1•min−1 (high cardiorespiratory fitness group) (n=10). A progressive test was performed, consisting of 3-min stages beginning at 25 watts and increasing by 25 watts every 3-min. The HRV threshold (HRVT) and ventilatory threshold (VT) analyses were performed through visual inspection. The comparisons with RMSSD values in percentage of maximum workload resulted in a higher effect size (ES) than the SDNN values. The VO2 in the high cardiorespiratory fitness group at VT (+32%), HRVTRMSSD (+27%), and HRVTSDNN (+31%) was signifi cantly higher compared to the group with low cardiorespiratory fitness. Higher values were observed for relative load (W•kg-1) at VT and HRVTSDNN in the high cardiorespiratory fitness group in comparison with the low cardiorespiratory fitness group (P&lt;0.05), but no difference for VT and HRVTRMSSD. Signifi cant correlations between at VT and HRVTSDNN (r=0.77) were found only in the low cardiorespiratory fitness group. Cardiorespiratory fitness should be regarded as a factor for HRVT evaluation. The HRVTSDNN was closer to the VT in the low cardiorespiratory fitness group than the HRVTRMSSD, however, the use of vagal modulation assessed using the HRV parameter was more sensitive to observe possible differences regarding cardiorespiratory fitness.

Ratings of perceived exertion at the ventilatory anaerobic threshold in people with coronary heart disease: A CARE CR study.

Exercise prescription guidelines for individuals undergoing cardiovascular rehabilitation (CR) are often based on heart rate training zones and rating of perceived exertion (RPE). United Kingdom guidelines indicate that patients should exercise at an intensity of RPE 11 to 14. We aimed to determine the accuracy of this approach by comparing this RPE range with an objectively measured marker of exercise intensity, the ventilatory anaerobic threshold (VAT), and examine whether baseline directly determined cardiorespiratory fitness (CRF) affects the association between VAT and RPE. Participants underwent a maximal cardiopulmonary exercise test before an 8-week community-based CR programme. Peak oxygen uptake (V̇O2peak) and VAT were recorded, and RPE at the workload at which VAT was identified was recorded. Data were then split into tertiles, based on VO2peak, to determine whether RPE at the VAT differed in participants with low, moderate or higher CRF. We included 70 individuals [mean (SD) age 63.1 (10.0) years; body mass index 29.4 (4.0)kg/m2; 86% male]. At baseline, the mean RPE at the VAT (RPE@VAT) was 11.8 (95% confidence interval 11.0-12.6) and significantly differed between low and high CRF groups (P<0.001). The mean RPE@VAT was 10.1 (8.7-11.5), 11.8 (10.5-13.0), and 13.7 (12.5-14.9) for low, moderate and high CRF groups, respectively. When using RPE to guide exercise intensity in CR populations, one must consider the effect of baseline CRF. Mean RPEs of ∼10, 12 and 14 correspond to the VAT in low, moderate and higher-fit patients, respectively.

Higher baseline cardiorespiratory fitness is associated with lower arrhythmia recurrence and death after atrial fibrillation ablation

Cardiorespiratory fitness (CRF) has been shown to correlate with incident atrial fibrillation (AF) and AF burden. In recent years there has been increasing recognition of the pivotal role of modifying risk factors before AF ablation. The purpose of this study was to investigate whether higher baseline CRF measured using exercise stress testing (EST) was associated with improved outcomes after AF ablation. We studied 591 patients who underwent EST within 12 months before AF ablation. Patients were categorized into low (<85% predicted), adequate (85%-100% predicted), and high (>100% predicted) CRF groups. Outcomes of interest included arrhythmia recurrence, cessation of antiarrhythmic therapy, repeat hospitalization for arrhythmia, repeat rhythm control procedures, and all-cause mortality. During mean follow-up of 32 months after ablation, arrhythmia recurrence was observed in 79% of patients in the low CRF group compared to 54% in the adequate CRF group and 27.5% in the high CRF group (P <.0001). Similarly, rates of repeat arrhythmia-related hospitalization, repeat rhythm control procedures, and need for ongoing antiarrhythmic therapy were significantly lower in the high CRF group (P <.0001). Death occurred in 2.5% of patients in the high CRF group compared to 4% in the adequate CRF group and 11% in the low CRF group (P <.0001). In Cox proportional hazards analyses, high CRF was significantly associated with lower arrhythmia recurrence. Higher CRF is associated with reduced arrhythmia recurrence rates and death among patients undergoing AF ablation. Efforts should be made to enhance CRF before AF ablation.

Cardiorespiratory Fitness And The Cerebrovascular Response To A Metabolic Stimulus Following Cyclooxygenase Inhibition

Cardiorespiratory fitness (CRF) is positively associated with cerebrovascular function and cognition. We have previously shown that prostaglandins play an important role in regulating the cerebral vasodilator response to hypercapnia, and that the magnitude of change in cerebral vasodilator responses during cyclooxygenase (COX) inhibition is associated with CRF in older adults. However, it is unknown if CRF also influences the cerebrovascular response to a metabolic stimulus in older adults. PURPOSE: To determine the effects of CRF on the cerebrovascular response to a metabolic stimulus before and during COX inhibition in older adults. METHODS: Thirty-five participants completed a maximal exercise test on a cycle ergometer. Participants were split into two groups, High CRF (10 men, 8 women, age = 62 ± 5y) or Low CRF (7 men, 10 women, age = 66 ± 7y), based on the median VO2max (ml/kg/min). All participants completed two levels of the Stroop Color Word Test. Beat-to-beat mean arterial pressure (MAP) and middle cerebral artery velocity (MCAv) were measured at baseline and in response to each level of the Stroop test before and after administration of the COX inhibitor Indomethacin (INDO). The maximum MAP, MCAv, and cerebral pulsatility index (PI) responses were calculated as the highest 3-beat average during each cognitive challenge. RESULTS: There were no differences between high and low CRF groups in MCAv at rest or in response to the metabolic stimulus. There was a trend for lower PI at rest (p = 0.09) and in response to the Stroop test (p = 0.09) in the high CRF group compared with the low CRF group. During INDO, MCAv decreased (Low CRF: -29 ± 4%, High CRF: -27 ± 3%; p < 0.01) and PI increased (Low CRF: 22 ± 3%, High CRF: 17 ± 3%; p < 0.01). During INDO, MCAv at rest was not different between groups; however, PI was lower in the high CRF compared to low CRF group (Low CRF: 0.98 ± 0.05, High CRF: 0.87 ± 0.03; p < 0.05). Lastly, the change in MCAv and PI in response to the metabolic stimulus did not differ between groups. CONCLUSION: In older adults, elevated levels of CRF may lead to a lower PI at rest and in response to a metabolic stimulus. Additionally, COX inhibition did not alter the cerebrovascular response to a metabolic stimulus. Supported by NIH Grant HL118154.

Changes in cardiorespiratory fitness through adolescence predict metabolic syndrome in young adults

Background and aimsHigher cardiorespiratory fitness (CRF) has been suggested to reduce the risk of metabolic syndrome (MetS). We aimed to longitudinally examine the changes of CRF on MetS and its risk factors from adolescence to adulthood. Methods and resultsAt the age of 15 years, 1076 subjects were recruited from 2 cohorts. CRF was measured on a cycle ergometer. MetS was classified as having at least 3 of the following parameters above the threshold of risk factors: waist circumference, triglycerides, high-density lipoprotein cholesterol (HDL), high blood pressure (BP) and fasting glucose. In addition, insulin, total cholesterol and low-density lipoprotein cholesterol were measured and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Persistently high, increasing, decreasing and persistently low CRF groups were formed according to change in CRF from adolescence to adulthood. Longitudinal increase in CRF was positively associated with change in HDL and negatively associated with change in insulin, HOMA-IR, triglycerides, BP and prevalence of MetS after adjustment for potential confounders. Subjects with persistently low CRF had 11.5- to 34.4-times higher risk of MetS at the age of 25 and 33 years compared to subjects with persistently high CRF and 14.6- to 15.9-times higher risk compared to the increasing CRF group. ConclusionHigher CRF is strongly related to lower values of MetS risk factors. Increasing CRF from adolescence to adulthood reduces the risk to have MetS later in adulthood. High CRF in adolescence that decreases during adulthood has similar risks to MetS compared to individuals with persistently low CRF.

Sports participation improves metabolic profile in adolescents: ABCD growth study.

To analyze the impact of participation in sports with different cardiorespiratory fitness (CRF) demands on changes in metabolic and cardiovascular markers in adolescents. Longitudinal study with 12 months of follow-up (Analysis of Behaviors of Children During Growth [ABCD Growth Study]). Overall, 184 adolescents (age 15.6 ± 2.1) were classified according to sports participation: non-sport (control), low CRF sports, and high CRF sports. Metabolic outcomes were total cholesterol (TC) and its fractions, triacylglycerol (TG), glucose, insulin levels, and the insulin resistance index. Cardiovascular outcomes were arterial thickness (carotid and femoral [ultrasound]), blood pressure, and resting heart rate. Adolescents engaged in sports classified as high CRF demand presented a significant increase in HDL-c (1.2 mg/dL [95%CI: -0.5 to 3.0]) when compared to the non-sport group (-2.4 mg/dL [95%CI: -4.4 to -0.5]). Regular engagement in high CRF sports was significantly related to changes in TC (β = -0.027 [95%CI: -0.048 to -0.005]), HDL-c (β = 0.009 [95%CI: 0.001 to 0.019]), LDL-c (β = -0.032 [95%CI: -0.049 to -0.016]), and glucose (β = -0.017 [95%CI: -0.025 to -0.008]), while engagement in low CRF sports was related to changes in TG (β = -0.065 [95%CI: -0.112 to -0.019]). No significant relationships for cardiovascular parameters were observed in the low CRF group, but one significant relationship was found between high CRF sports and changes in SBP (β = -0.063 [95%CI: -0.117 to -0.009]). In conclusion, engagement in sports seems to be beneficial for improvements in metabolic and cardiovascular parameters in adolescents, mainly sports with higher CRF demand.

Cardiorespiratory Fitness, Different Measures of Adiposity, and Cardiovascular Disease Mortality Risk in Women.

Background: Associations among cardiorespiratory fitness (CRF), different adiposity exposures, and cardiovascular disease (CVD) mortality in women are not well defined. Materials and Methods: A total of 19,838 women completed a baseline examination between 1971 and 2013. Measures included body mass index (BMI), waist circumference (WC), waist-to-height (W:HT) ratio, skinfold-derived percent body fat (% Fat), and CRF estimated from a maximal treadmill test. CRF categories were low (quintile 1), moderate (quintiles 2-3), and high (quintiles 4-5); standard cut points were used for adiposity exposures. Hazard ratios (HRs) were estimated using Cox regression. Results: During a mean follow-up period of 19.2 ± 10.3 years, 391 cardiovascular deaths occurred. HRs (95% confidence interval) for CVD in moderate and low CRF groups, using high CRF as the referent, were 1.87 (1.46-2.38) and 2.54 (1.93-3.35), respectively (p trend <0.001). HRs of obese women within each adiposity exposure were higher when compared with normal-weight women (p ≤ 0.03). Joint associations of CRF × adiposity showed a positive trend in CVD mortality across decreasing categories of CRF within each category of W:HT and % Fat, as well as within the normal and overweight BMI categories and the normal WC category (p ≤ 0.03 for each). Conclusion: Higher levels of CRF are associated with lower CVD mortality risk in women, and predict lower risk of CVD mortality in normal-weight women and in obese women. Using different measures of adiposity to predict CVD mortality risk in women may be misleading unless CRF is taken into account. These results support the American Heart Association (AHA) recommendation for including CRF as a clinical vital sign.