Maximal Treadmill Exercise Test Research Articles

Reassembling the Field-based Applicability of the Lactate Threshold for Old Age.

This study aimed to investigate the applicability of the Lactate Threshold (LT) to predict maximal oxygen uptake (˙VO2max) and demarcate the boundary between the moderate- to heavy-intensity domain (HRm-h) in old age in comparison to the most utilized methods. A cross-sectional validation study was conducted. Participants aged 61 to 77 performed a familiarization procedure, an incremental maximal exercise treadmill test (CPX) for ˙VO2max determination, the Six-minute Walk Test (6MWT), and a discontinuous incremental field test for LT determination. Lower (P<0.01) internal effort was required for LT testing (76±8%HRmax) compared to 6MWT (92±9%HRmax). The application of the 6MWT reference equations overestimated ˙VO2max by 10-23%. LTs better estimated the ˙VO2max (r ≈0.90, SEE: ≈3.0] compared to the 6MWT (r=0.68, SEE=5.5). HRm-h determined by the CPX differed (20%; P=0.001) from that obtained by LT. HRm-h stratification indicated participants fall into the very light to the vigorous intensity domains. LT testing is more submaximal than the 6MWT, and is a valuable tool to estimate the ˙VO2max in older male adults. Implementation of LT testing in physical activity programs might help improving the quality of aerobic exercise training in older men.

EXPLORING THE ROLE OF SKELETAL MUSCLE MICROVASCULAR BLOOD FLOW IN EXERCISE CAPACITY AMONG INDIVIDUALS WITH CONTROLLED TYPE 2 DIABETES

INTRODUCTION &amp; AIMS The cardiac and macrovascular system is vital for human exercise capacity, yet the microvascular network is primarily responsible for delivering nutrients and oxygen to metabolically active tissues like skeletal muscle. Due to methodological limitations, few studies have investigated the role of muscle microvascular blood flow in determining exercise capacity or intolerance in individuals with chronic conditions such as type 2 diabetes. Our aim was to use modern contrast-enhanced ultrasound to directly measure microvascular blood flow in skeletal muscle at rest and after a maximal treadmill exercise test in individuals with controlled type 2 diabetes. METHODS Fifteen adults with controlled type 2 diabetes (age: 62.5 ± 8.0 years [M ± SD]; BMI: 31.6 ± 6.9 kg/m2; HbA1c: 6.7 ± 0.9%; 13 females and 2 male) attended the laboratory after a 2-hour fast and completed a Modified Bruce treadmill exercise test until exhaustion. Microvascular blood velocity, volume, and flow in the vastus lateralis muscle was assessed at rest, immediately post-exercise, and 30 minutes post-exercise via contrast-enhanced ultrasound during a constant-rate intravenous contrast agent infusion (DEFINITY®). Participants also completed a whole-body dual x-ray absorptiometry scan and a six-minute walk test (6MWT). RESULTS Microvascular blood velocity, volume, and flow increased immediately after exercise (∼230%, ∼79%, and ∼529%, respectively; all p&amp;lt;0.001), and remained elevated above baseline levels 30 minutes post-exercise (∼79%, ∼25%, and ∼139%, respectively; all p≤0.003). Resting and post-exercise skeletal muscle microvascular blood flow measures were not associated with VO2peak (ml/min/kg), time to exhaustion, or six-minute walk distance (all p&amp;gt;0.05). CONCLUSION Muscle microvascular blood flow remains elevated for up to 30 minutes following maximal aerobic exercise in individuals with controlled type 2 diabetes. The lack of association between muscle microvascular blood flow and exercise capacity is not clear but may indicate considerable blood flow redundancy or reserve within the vascular network.

Measuring Cardiorespiratory Fitness without Exercise Testing: The Development and Validation of a New Tool for Spanish Adults.

Background: Cardiorespiratory fitness (CRF) is an important component of overall physical fitness and is associated with numerous health benefits, including a reduced risk of heart disease, diabetes, and obesity. However, direct measurement of CRF is time-consuming and therefore not feasible for screening purposes. Methods: A maximal treadmill exercise test with the Bruce protocol was performed to estimate VO2max in 1047 Spanish men and women aged 17 to 62 years. Weight, height, and heart rate were measured. Leisure-time physical activity (LTPA) was recorded using the Minnesota Leisure Time Physical Activity Questionnaire. A multiple linear regression model was developed to predict exercise-based VO2max. The validity of the model was examined by correlation, concordance, Bland-Altman analysis, cross-validation, and construct validity analysis. Results: There was no significant difference between VO2max obtained by the Bruce protocol (43.56 mL/kg/min) or predicted by the equation (43.59 mL/kg/min), with R2 of 0.57, and a standard error of the estimate of 7.59 mL/kg/min. Pearson's product-moment correlation and Lin's concordance correlation between measured and predicted CRF values were 0.75 and 0.72, respectively. Bland-Altman analysis revealed a significant proportional bias of non-exercise eCRF, overestimating unfit and underestimating highly fit individuals. However, 64.3% of participants were correctly classified into CRF tertile categories, with an important 69.9% in the unfit category. Conclusions: The eCRF equation was associated with several cardiovascular risk factors in the anticipated directions, indicating good construct validity. In conclusion, the non-exercise eCRF showed a reasonable validity to estimate true VO2max, and it may be a useful tool for screening CRF.

Attenuated peripheral oxygen extraction and greater cardiac output in women with posttraumatic stress disorder during exercise.

Posttraumatic stress disorder (PTSD) is associated with an increased risk of developing cardiovascular disease, especially in women. Evidence indicates that men with PTSD exhibit lower maximal oxygen uptake (V̇o2max) relative to controls; however, whether V̇o2max is blunted in women with PTSD remains unknown. Furthermore, it is unclear what determinants (i.e., central and/or peripheral) of V̇o2max are impacted by PTSD. Therefore, we evaluated the central (i.e., cardiac output; Q̇c) and peripheral (i.e., arteriovenous oxygen difference) determinants of V̇o2max in women with PTSD; hypothesizing that V̇o2max would be lower in women with PTSD compared with women without PTSD (controls), primarily due to smaller increases in stroke volume (SV), and therefore Q̇c. Oxygen uptake (V̇o2), heart rate (HR), Q̇c, SV, and arteriovenous oxygen difference were measured in women with PTSD (n = 14; mean [SD]: 43 [11] yr,) and controls (n = 17; 45 [11] yr) at rest, and during an incremental maximal treadmill exercise test, and the Q̇c/V̇o2 slope was calculated. V̇o2max was not different between women with and without PTSD (24.3 [5.6] vs. 26.4 [5.0] mL/kg/min; P = 0.265). However, women with PTSD had higher Q̇c [P = 0.002; primarily due to greater SV (P = 0.069), not HR (P = 0.285)], and lower arteriovenous oxygen difference (P = 0.002) throughout exercise compared with controls. Furthermore, the Q̇c/V̇o2 slope was steeper in women with PTSD relative to controls (6.6 [1.4] vs. 5.7 [1.0] AU; P = 0.033). Following maximal exercise, women with PTSD exhibited slower HR recovery than controls (P = 0.046). Thus, despite attenuated peripheral oxygen extraction, V̇o2max is not reduced in women with PTSD, likely due to larger increases in Q̇c.NEW & NOTEWORTHY The current study indicates that V̇o2max is not different between women with and without PTSD; however, women with PTSD exhibit blunted peripheral extraction of oxygen, thus requiring an increase in Q̇c to meet metabolic demand during exercise. Furthermore, following exercise, women with PTSD demonstrate impaired autonomic cardiovascular control relative to sedentary controls. We interpret these data to indicate that women with PTSD demonstrate aberrant cardiovascular responses during and immediately following fatiguing exercise.

Association between baseline levels of muscular strength and risk of stroke in later life: The Cooper Center Longitudinal Study

PurposeMuscular strength is an important component of physical fitness. We evaluated the relationship between baseline muscular strength and risk of stroke among adults who were aged ≥65 years during follow-up. MethodsWe included 7627 healthy adults (mean age = 43.9 years, 86.0% male) underwent a baseline physical examination between 1980 and 1989. Muscular strength was determined by 1-repetition maximum measures for bench press and leg press and categorized into age- and sex-specific tertiles for each measure. Cardiorespiratory fitness (CRF) was assessed via a maximal treadmill exercise test. Those enrolled in fee-for-service Medicare from 1999 to 2019 were included in the analyses. Associations between baseline strength and stroke outcomes were estimated using a modified Cox proportional hazards model. In a secondary analysis, we examined stroke risk by categories of CRF where Quintile 1 = low, Quintiles 2–3 = moderate, and Quintiles 4–5 = high CRF based on age and sex. ResultsAfter 70,072 person-years of Medicare follow-up, there were 1211 earliest indications of incident stroke. In multivariable analyses, the hazard ratio (95% confidence interval (95%CI)) for stroke across bench press categories were 1.0 (referent), 0.96 (0.83–1.11), and 0.89 (0.77–1.04), respectively (p trend = 0.14). The trend across categories of leg press was also non-significant (p trend = 0.79). Adjusted hazard ratio (95%CI) for stroke across ordered CRF categories were 1.0 (referent), 0.90 (0.71–1.13), and 0.72 (0.57–0.92) (p trend < 0.01). ConclusionWhile meeting public health guidelines for muscular strengthening activities is likely to improve muscular strength as well as many health outcomes in older adults, performing such activities may not be helpful in preventing stroke. Conversely, meeting guidelines for aerobic activity is likely to improve CRF and lower stroke risk.

Effects of low-versus high-volume high-intensity interval training on glycemic control and quality of life in obese women with type 2 diabetes: A randomized controlled trial

Background/objectiveComparison between different training volumes of high-intensity interval training (HIIT) is understudied in type 2 diabetes. This study aimed to compare the effects of low- and high-volume HIIT on glycemic control, blood lipids, blood pressure, anthropometric adiposity measures, cardiorespiratory fitness, and health-related quality of life (HRQoL) in women with type 2 diabetes. MethodsSeventy-two obese women with type 2 diabetes aged 36–55 were randomly assigned to a low-volume HIIT group (i.e., 2 × 4-min high-intensity treadmill exercise at 85%–90% of peak heart rate, with a 3-min active recovery interval in between), a high-volume HIIT group (i.e., 4 × 4-min high-intensity treadmill exercise at 85%–90% of peak heart rate, with three 3-min active recovery intervals in between), and a non-exercising control group. Patients in HIIT groups exercised three days a week for 12 weeks. All patients received oral hypoglycemic medications with no calorie restrictions. The outcome measures were glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG), 2-hour postprandial blood glucose (2-hr PPBG), total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL), systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), waist circumference (WC), waist-to-hip ratio, time to maximal exhaustion determined from a maximal treadmill exercise test (i.e., a measure of cardiorespiratory fitness), and HRQoL assessed by the 12-item Short Form (SF-12) Health Survey. ResultsThe low- and high-volume HIIT groups showed significant improvements in all outcome measures compared to the baseline and the non-exercising group (P < 0.05), except for DBP in the low-volume HIIT group (p > 0.05). Also, both low- and high-volume HIIT groups showed similar improvements in TC, HDL, SBP, DBP, BMI, WC, waist-to-hip ratio, and the SF-12 scores, with no significant between-groups difference (p > 0.05). The high-volume HIIT group, however, showed more significant improvements in HbA1c, FBG, 2-hr PPBG, TG, LDL, and treadmill time to maximal exhaustion than the low-volume HIIT group (p < 0.05). The non-exercising group showed non-significant changes in all outcome measures (p > 0.05). ConclusionLow-volume HIIT could be equally effective as high-volume HIIT for improving TC, HDL, blood pressure, anthropometric adiposity measures, and HRQoL in obese women with type 2 diabetes. Nevertheless, high-volume HIIT could have a greater impact on glycemic control, TG, LDL, and cardiorespiratory fitness in these patients. Trial registrationClinicalTrials.gov, NCT05110404.

Higher exercise capacity, but not omega-3 fatty acid consumption, predicts lower coronary artery calcium scores in women and men with coronary artery disease

Background and aimsHigher coronary artery calcium (CAC) scores are associated with increased cardiovascular (CVD) events and mortality. Exercise capacity is predictive of CVD events. Our aim was to examine the relationship between exercise capacity and CAC in women and men. MethodsCAC was measured in 203 men and 38 women with clinical coronary artery disease using multidetector coronary tomography. They were randomized to 3.36 g eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) daily or none for 30 months. Maximal exercise treadmill testing was performed at baseline with calculation of metabolic equivalents of task (METs) achieved as a measure of exercise capacity. ResultsDespite similar ages at baseline (64.0 ± 6.7 vs 62.7 ± 7.8 years, respectively, p = 0.225), women had lower CAC scores compared to men: 106.7 Agatston units [AU] vs 535.3, respectively, p < 0.001, and at every age (p < 0.001). Female CAC scores did not equal those of men until women were 20 years older. Higher levels of METs were associated with lower CAC scores in both women and men. After multivariate adjustment, METs was the most important predictor of CAC score in women at baseline and 30 months (p = 0.001 and 0.029, respectively) whereas only age predicted in men (p = 0.019 and 0.004, respectively). Annual CAC progression was significantly greater in men compared to women (94.8 AU/year vs 38.0, respectively, p = 0.014). No difference was observed in CAC progression in the EPA + DHA group compared to control in either men or women. ConclusionsThe association of higher METs with lower CAC scores in both women and men supports recommending exercise to maximize cardiorespiratory fitness as this may minimize CAC scores and thus, potentially decrease risk for CVD events. This may be especially important for women since METs independently predicted baseline and 30 month CAC in women.

Performance of the FreeStyle Libre Flash Glucose Monitoring System during an Oral Glucose Tolerance Test and Exercise in Healthy Adolescents.

This study's aim was to assess FreeStyle Libre Flash glucose monitoring (FGM) performance during an oral glucose tolerance test (OGTT) and treadmill exercise in healthy adolescents. This should advance the feasibility and utility of user-friendly technologies for metabolic assessments in adolescents. Seventeen healthy adolescents (nine girls aged 12.8 ± 0.9 years) performed an OGTT and submaximal and maximal treadmill exercise tests in a laboratory setting. The scanned interstitial fluid glucose concentration ([ISFG]) obtained by FGM was compared against finger-prick capillary plasma glucose concentration ([CPG]) at 0 (pre-OGTT), -15, -30, -60, -120 min post-OGTT, pre-, mid-, post- submaximal exercise, and pre- and post- maximal exercise. Overall mean absolute relative difference (MARD) was 13.1 ± 8.5%, and 68% (n = 113) of the paired glucose data met the ISO 15197:2013 criteria. For clinical accuracy, 84% and 16% of FGM readings were within zones A and B in the Consensus Error Grid (CEG), respectively, which met the ISO 15197:2013 criteria of having at least 99% of results within these zones. Scanned [ISFG] were statistically lower than [CPG] at 15 (-1.16 mmol∙L-1, p < 0.001) and 30 min (-0.74 mmol∙L-1, p = 0.041) post-OGTT. Yet, post-OGTT glycaemic responses assessed by total and incremental areas under the curve (AUCs) were not significantly different, with trivial to small effect sizes (p ≥ 0.084, d = 0.14-0.45). Further, [ISFGs] were not different from [CPGs] during submaximal and maximal exercise tests (interaction p ≥ 0.614). FGM can be a feasible alternative to reflect postprandial glycaemia (AUCs) in healthy adolescents who may not endure repeated finger pricks.

Cardiorespiratory Fitness and All-Cause Mortality in Women with Metabolic Syndrome.

Purpose: To examine the association between cardiorespiratory fitness (fitness) and all-cause mortality in women with metabolic syndrome (MetSyn). Methods: The sample included 1798 women with MetSyn (mean age 50.2 years) who received a comprehensive preventive baseline examination between 1978 and 2016, with mortality follow-up through December 31, 2017. MetSyn was identified using Adult Treatment Panel-III Guidelines. Fitness was determined by duration of a maximal treadmill exercise test and grouped as fit or unfit on the basis of the upper 80% and lower 20% of the age-standardized fitness distribution. Age- and smoking-adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated in a proportional hazards regression model. Results: During a mean follow-up of 16.6 ± 8.7 years, 204 deaths occurred. Crude all-cause mortality rates were 6.8 and 6.9 deaths per 10,000 woman-years in fit and unfit groups, respectively. The adjusted HR (95% CI) for all-cause mortality in unfit versus fit women (referent) with MetSyn was 1.36 (95% CI 1.01-1.83). Conclusions: Higher levels of fitness significantly attenuate the risk of all-cause mortality in women with MetSyn. In accordance with the American Heart Association scientific statement, to more accurately determine mortality risk in this population, health care professionals should measure or estimate fitness and should strongly encourage women to meet current public health guidelines for physical activity with the goal of reaching higher fitness levels.

Sport Mont 2023, 21(1), 9-15 | DOI: 10.26773/smj.230202 Abstract The military parachutists are responsible of special air operations who require certain capabilities in their physical condition, due to their intense professional career. The analysis of oxygen con-sumption (VO2) and heart rate (HR) allows the determination of aerobic (VT1) and anaerobic (VT2) thresholds and used to study the adequacy of the

The military parachutists are responsible of special air operations who require certain capabilities in their physical condition, due to their intense professional career. The analysis of oxygen con-sumption (VO2) and heart rate (HR) allows the determination of aerobic (VT1) and anaerobic (VT2) thresholds and used to study the adequacy of the organism to exercise and in the analysis of sporting performance. The aim of this study was to determine the effect of tactical equipment on the stress test performance of elite parachutists. 10 parachutists parti-cipated in the study, between 22 and 36 years old with an average of 27.75 years (±4.20). Anthropometric values were determined of: weight 75.69 kg (±8.79), height 173.34 cm (±5.72) and body mass index (BMI) 25.23 (±2.98). Each one, performed 2 maximal treadmill exercise testing: one a conventional stress test (A) and another with the tactical equipment (weight 20 kg) (B). We obtained maximum oxygen consumption (Metalyzer 3B) and monitored the electrocardiogram continuously. The test started at a speed of 6km/h and a slope of 1%. The results of the two test were compared. The average value and standard deviation (SD) of different variables with equipment (B) and without it (A) and p-value were obtained: velocity (A: 14.80±3.29; B: 11.50±1.42 Km/h; p=0.073), HR (A: 182.7±58.62; B: 177.75±9.71 b/m; p=0.038), VO2 (A: 51.75±13.60; B: 54.00±30.82 ml/Kg/min; p=0.891). Al-so, the values of ventilatory thresholds: VT1 and VT2 of both tests were obtained, with sig-nificant differences. Tactical equipment causes a decrease in stress test performance with changes in VT1 and VT2.

Associations among cardiorespiratory fitness, C-reactive protein, and all-cause mortality in men and women.

We examined individual and joint associations among high-sensitivity C-reactive protein (CRP), cardiorespiratory fitness (fitness), and mortality in healthy men and women. Between January 1, 2000 and December 31, 2016, 30,077 adults (31.3% women) received a comprehensive physical examination. Fitness was determined from maximal treadmill exercise test duration. Participants were categorized as unfit (Quintile 1) and fit (Quintiles 2-5), and by normal (<2 mg/L) and elevated (≥2 mg/L) CRP categories. Adjusted hazard ratios (HRs) with 95% confidence interval (CI) for all-cause mortality were computed with Cox regression. During an average of 10.1 years of follow-up, 576 deaths occurred. Following adjustment for age, smoking status, sex, exam year, body mass index, systolic blood pressure, total cholesterol, triglyceride:high-density lipoprotein ratio, and fasting glucose, HR (95% CI) for all-cause mortality were 1.0 (referent) and 1.52 (1.14-2.02) for fit and unfit categories, respectively. Corresponding values for normal and elevated CRP categories were 1.0 and 1.50 (1.20-1.89), respectively. When grouped by fitness and CRP category, there was significantly greater mortality risk in the unfit than the fit category within the elevated CRP category (HR = 1.77 (1.14-2.75)), but not in the normal CRP category (HR = 1.38 (0.96-1.98)). Each 1 metabolic equivalent increment in fitness and 1 mg/L increment in CRP were associated with 10.0% (95% CI: 5.1-14.8%) decreased and 7.3% (95% CI: 2.0%-12.9%) increased mortality hazard, respectively. Compared to the unfit, fit individuals have an attenuated mortality risk within each CRP category. Thus, higher fitness appears to provide some protection against all-cause mortality, particularly among those with elevated levels of inflammation.

The effects of moderate-intensity step-aerobics, spinning, and educational game exercise programs on plasma dopamine and oxytocin levels in women in the menopausal transition period

Background/Aim: Menopausal transition (MT) is defined as the transition from reproductive to post-reproductive life. Oxytocin has beneficial effects on health problems, such as sexual activity disorder, vaginal atrophy, cardiovascular system diseases and acceleration in bone mass loss, which may develop due to changes in reproductive hormone levels during the MT period. During exercise, which can be used as adjuvant therapy for most of these health problems, a temporary increase in catecholamine levels is required for response to exercise-induced stress. However, the effects of exercise programs applied during the MT period on plasma dopamine (pDA) and plasma oxytocin (pOT) levels are unknown. The aim of this study was to investigate the effects of three different types of exercise on plasma dopamine (pDA) and plasma oxytocin (pOT) levels in sedentary women in the MT period. Methods: Twenty-six sedentary healthy participants in the MT period whose fitness levels in the standard maximal exercise treadmill test were at a level that would complement the exercise programs in our study, were included in the study. Participants with the following conditions were excluded from the study: physical disability that would not allow exercise, systemic disease, unilateral oophorectomy, or history of smoking. In addition, participants who could not complete any of the exercise programs for any reason were excluded from the study. Three different exercise programs at moderate intensity [maximum heart rate (HR) = 50%-60%] of 60 minutes duration were performed by the participants at one-week intervals: (i) step-aerobics (SA), (ii) spinning (SP) and (iii) station work in the form of recreational educational games (EG). pOT and pDA levels were measured using the enzyme-linked immunosorbent assay method in venous blood samples taken from participants before the exercise and during the last five minutes of the exercise. pOT and pDA levels measured before the exercise and in the last five minutes of the exercise were compared. Results: The median age was 45 (41-45) and the body mass index (BMI) was 29 (27-34). There was a significant increase in mean pDA levels during exercise compared to pre-exercise in all three activities of moderate-intensity, SA, SP, and EG (P = 0.008, P = 0.001 and P = 0.030, respectively). The mean pOT level increased significantly during moderate-intensity SA and EG (P = 0.003 and P = 0.001, respectively). When the relationships between pDA and pOT levels and the variables of age, BMI, pulse rate, and maximum HR during all three exercises were evaluated, there was a significant positive correlation between pOT levels and maximum HR only during EG (r = 0.439, P = 0.028). Conclusions: This study showed that SA and EG applied in women in the MT period increased both pDA and pOT levels, while SP only increased the pDA level significantly. Therefore, SA and EG exercises can contribute positively to the quality of life of women with health problems due to low pOT levels during the MT period.

Examining the Gradient of All-Cause Mortality Risk in Women across the Cardiorespiratory Fitness Continuum.

Although cardiorespiratory fitness (CRF) is inversely associated with all-cause mortality in women, less is known regarding the gradient of mortality risk in women, particularly at the lower end of the CRF continuum. A total of 17,901 healthy women (mean age, 45.9 yr) completed a baseline clinical examination, including a maximal treadmill exercise test at the Cooper Clinic in Dallas, TX, between 1971 and 2016. Participants were placed into CRF quintiles based on age and treadmill time. After a mean follow-up period of 17.9 yr, 1198 all-cause deaths occurred. More favorable cardiometabolic risk factors, smoking status, and physical activity levels were observed across ordered CRF quintiles ( P < 0.001 for all). Adjusted all-cause mortality hazard ratios with 95% confidence intervals were 1.71 (1.40-2.09), 1.55 (1.29-1.87), 1.25 (1.03-1.51), 1.16 (0.97-1.38), and 1.0 (referent), respectively, across CRF quintiles ( P trend ≤ 0.001). When utilizing CRF as a continuous variable in a spline analysis and using 4.5 METs as the referent, we estimate a 10% reduction in mortality risk per 1-MET increment in CRF ( P < 0.001) until a threshold of approximately 11 METs. Mortality risk was approximately 50% lower at the 11-MET threshold when compared with the referent. No further significant reduction in mortality risk was observed beyond the 11-MET threshold. In addition, age-adjusted hemodynamic variables including resting and maximal double product, heart rate reserve, double-product reserve, and 1-min recovery heart rate were more favorable across CRF quintiles ( P < 0.001 for all). Beginning at a referent value of 4.5 METs, a significant decreasing gradient of all-cause mortality exists across the CRF continuum, until a threshold of approximately 11 METs is reached. Although all women should be encouraged to work toward meeting public health guidelines for physical activity, it is especially important to target those at the low end of the CRF continuum.

Eating Habits among US Firefighters and Association with Cardiometabolic Outcomes.

Cardiovascular disease is the leading cause of on-duty mortality among firefighters, with obesity as an important risk factor. However, little is known regarding the dietary patterns which are characteristic in this population and how these patterns relate to cardiometabolic outcomes. The aim of this study was to identify the dietary patterns of US firefighters and examine their association with cardiometabolic outcomes. The participants (n = 413) were from the Indianapolis Fire Department, and were recruited for a Federal Emergency Management Agency (FEMA)-sponsored Mediterranean diet intervention study. All of the participants underwent physical and medical examinations, routine laboratory tests, resting electrocardiograms, and maximal treadmill exercise testing. A comprehensive food frequency questionnaire was administered, and dietary patterns were derived using principal component analysis. The mean body mass index (BMI) was 30.0 ± 4.5 kg/m2 and the percentage of body fat was 28.1 ± 6.6%. Using principal component analysis, two dietary patterns were identified, namely a Mediterranean diet and a Standard American diet. Following the adjustment for gender, BMI, maximal oxygen consumption (VO2 max), max metabolic equivalents (METS), age, and body fat percent, the Mediterranean diet was positively associated with high-density lipoprotein (HDL) cholesterol (β = 1.20, p = 0.036) in linear regression models. The Standard American diet was associated with an increase in low-density lipoprotein (LDL) cholesterol (β = −3.76, p = 0.022). In conclusion, the Mediterranean diet was associated with more favorable cardiometabolic profiles, whereas the Standard American diet had an inverse association. These findings could help in providing adequate nutrition recommendations for US firefighters to improve their health.

Exercise-induced expression of SARS-CoV-2 entry receptors: impact of mask modality, sex, and exercise intensity.

Wearing a facemask affects physiological responses to exercise. We explored how exercising with a facemask affects the expression of SARS-CoV-2 entry receptor (angiotensin-converting enzyme 2 [ACE2]) and some associated genes (angiotensin type-1 receptors [AT<inf>1</inf>R]; Mas receptor [MasR]; hypoxia-inducible factor 1α [HIF-1α]; endothelial nitric oxide synthase [eNOS]) among healthy males and females. One hundred forty-four apparently healthy individuals (72 females; age: 30±6) were allocated to three mask groups of 48 (N95, Surgical, No Mask) with two exercise subgroups for each mask for both sexes. Participants in each experimental group performed either a submaximal (walking with no grade) or maximal (a modified Bruce Protocol) treadmill exercise test. Blood samples were collected before and after each exercise test and used to analyze the mRNA expression of the genes studied. The post-exercise expression of genes examined were comparable between Surgical, N95, and No Mask (P>0.05). ACE2 was significantly greater in Surgical and N95 against No Mask at baseline and following moderate-intensity exercise (P<0.05). Whilst similar expressions were noted for MasR and eNOS (P>0.05), AT<inf>1</inf>R was greater in N95 than Surgical following high-intensity exercise (P<0.05). HIF-1α following either exercise intensity was significantly lower in N95 than Surgical (P<0.05). AT<inf>1</inf>R and HIF-1α were similar between Surgical and N95 against No Mask (P>0.05). ACE2 and AT<inf>1</inf>R were significantly higher in either mask modality than No Mask in males at baseline and postexercise (P<0.05). HIF-1α, MasR, and eNOS expressions were comparable between all mask groups in either sex (P<0.05). Our findings suggest that wearing a facemask does not differentiate the gene expression of SARS-CoV-2 entry receptor following exercise among both sexes.

Cardiorespiratory Fitness in Adults Aged 18 to 34 Years and Long-Term Pericardial Adipose Tissue (from the Coronary Artery Risk Development in Young Adults Study)

Pericardial adipose tissue (PAT), an ectopic adipose depot surrounding the coronary arteries, is a pathogenic risk marker for cardiometabolic disease; however, the association between cardiorespiratory fitness (CRF) and PAT is unclear. Young adults (n=2,614, mean age 25.1 years, 55.8% women, and 43.8% Black at baseline [1985 to 1986]) from the Coronary Artery Risk Development in Young Adults study were included. Maximal CRF was estimated at baseline, examination year 7 (1992 to 1993) and year 20 (2005 to 2006), using a symptom-limited maximal treadmill exercise test (duration in minutes) among those achieving ≥85% of age-predicted maximal heart rate. PAT volume (ml) was quantified at examination year 15 (2000 to 2001) and year 25 (2010 to 2011) using computed tomography. Multivariable linear and linear mixed regressions with covariates (sociodemographics, cardiovascular disease risk factors, inflammation, waist circumference) from baseline, year 7, and/or year 20 were used. Separate multivariable regression models revealed inverse associations of CRF at baseline, year 7, or year 20 with PAT at year 25 in fully adjusted models (all p <0.001). The linear mixed model showed that a 1-minute increase in treadmill exercise test duration over 20 years was associated with 1.49 ml lower subsequent PAT volume (p <0.001). In conclusion, findings suggest that higher CRF is inversely associated with subsequent PAT volume. Strategies to optimize CRF may be preventive against excessive PAT accumulation with age.

Aerobic exercise training improves endothelial function and attenuates blood pressure reactivity during maximal exercise in chronic kidney disease.

Patients with chronic kidney disease (CKD) have exaggerated increases in blood pressure during exercise that are associated with endothelial dysfunction. We hypothesized that aerobic exercise training would improve endothelial function and attenuate blood pressure reactivity during exercise in CKD. Sedentary individuals with CKD stages III-IV underwent 12 wk of aerobic cycling exercise (n = 26) or nonaerobic exercise (n = 22, control). Both interventions were performed 3 days/wk and matched for duration. Endothelial function was measured via peripheral arterial tonometry and quantified as reactive hyperemia index (RHI). Peak oxygen uptake (V̇o2peak) was assessed via maximal treadmill exercise testing with concomitant blood pressure monitoring. All measurements were performed at baseline and after the 12-wk intervention. A linear mixed model was used to compare the rate of increase in blood pressure during the test. RHI improved with exercise (Pre = 1.78 ± 0.10 vs. Post = 2.01 ± 0.13, P = 0.03) with no change following stretching (Pre = 1.73 ± 0.08 vs. Post = 1.67 ± 0.10, P = 0.69). Peak systolic blood pressure during the maximal treadmill exercise test was lower after exercise training (Pre = 186 ± 5 mmHg, Post = 174 ± 4 mmHg, P = 0.003) with no change after stretching (Pre = 190 ± 6 mmHg, Post = 190 ± 4 mmHg, P = 0.12). The rate of increase in systolic blood pressure during the V̇o2peak test tended to decrease after training for both groups (-2 mmHg/stage) with no differences between groups (P = 0.97). There was no change in V̇o2peak after either intervention. In conclusion, aerobic exercise training improves endothelial function and attenuates peak blood pressure reactivity during exercise in CKD.NEW & NOTEWORTHY Patients with chronic kidney disease (CKD) exhibit increased blood pressure reactivity during exercise that is associated with endothelial dysfunction. Twelve weeks of structured, aerobic, exercise training improves endothelial function and attenuates peak blood pressure responses during exercise in CKD stages III-IV.

Left Vocal Cord Paralysis, Lung Function and Exercise Capacity in Young Adults Born Extremely Preterm With a History of Neonatal Patent Ductus Arteriosus Surgery—A National Cohort Study

Background: Left vocal cord paralysis (LVCP) is a known complication of patent ductus arteriosus (PDA) surgery in extremely preterm (EP) born neonates; however, consequences of LVCP beyond the first year of life are insufficiently described. Both voice problems and breathing difficulties during physical activity could be expected with an impaired laryngeal inlet. More knowledge may improve the follow-up of EP-born subjects who underwent PDA surgery and prevent confusion between LVCP and other diagnoses.Objectives: Examine the prevalence of LVCP in a nationwide cohort of adults born EP with a history of PDA surgery, and compare symptoms, lung function, and exercise capacity between groups with and without LVCP, and vs. controls born EP and at term.Methods: Adults born EP (<28 weeks' gestation or birth weight <1,000 g) in Norway during 1999–2000 who underwent neonatal PDA surgery and controls born EP and at term were invited to complete questionnaires mapping voice-and respiratory symptoms, and to perform spirometry and maximal treadmill exercise testing. In the PDA-surgery group, exercise tests were performed with a laryngoscope positioned to evaluate laryngeal function.Results: Thirty out of 48 (63%) eligible PDA-surgery subjects were examined at mean (standard deviation) age 19.4 (0.8) years, sixteen (53%) had LVCP. LVCP was associated with self-reported voice symptoms and laryngeal obstruction during exercise, not with lung function or peak oxygen consumption (VO2peak). In the PDA-surgery group, forced expiratory volume in 1 second z-score (z-FEV1) was reduced compared to EP-born controls (n = 30) and term-born controls (n = 36); mean (95% confidence interval) z-FEV1 was −1.8 (−2.3, −1.2), −0.7 (−1.1, −0.3) and −0.3 (−0.5, −0.0), respectively. For VO2peak, corresponding figures were 37.5 (34.9, 40.2), 38.1 (35.1, 41.1), and 43.6 (41.0, 46.5) ml/kg/min, respectively.Conclusions: LVCP was common in EP-born young adults who had undergone neonatal PDA surgery. Within the PDA-surgery group, LVCP was associated with self-reported voice symptoms and laryngeal obstruction during exercise, however we did not find an association with lung function or exercise capacity. Overall, the PDA-surgery group had reduced lung function compared to EP-born and term-born controls, whereas exercise capacity was similarly reduced for both the PDA-surgery and EP-born control groups when compared to term-born controls.

Nedocromil sodium and diphenhydramine HCl ameliorate exercise-induced arterial hypoxemia in highly trained athletes.

IntroductionExercise‐induced arterial hypoxemia (EIAH) has been observed in highly trained endurance athletes during near maximal exercise, which may be influenced by a histamine‐mediated inflammatory response at the pulmonary capillary‐alveolar membrane. In order to test this hypothesis, we examined whether the mast cell stabilizer nedocromil sodium (NS) and H1‐receptor antagonist diphenhydramine HCL (DH) would ameliorate EIAH and mitigate the drop in arterial oxyhemoglobin saturation (SaO2) during intensive exercise.MethodsSeven highly trained male cross country runners (age, 21 ± 2 years; V̇O2max, 74.7 ± 3.5 ml·kg−1·min−1) participated in the study. All subjects completed a maximal exercise treadmill test to exhaustion, followed by three 5‐min constant‐load exercise bouts at 70%, 80%, and 90% V̇O2max. Prior to testing, subjects received either placebo (PL), NS, or DH.ResultsCompared to PL, there was a significant treatment effect on SaO2 (p < 0.001) for both NS and DH during both constant‐load exercise and at V̇O2max. Post hoc tests revealed SaO2 values, compared to PL, were significantly higher at V̇O2max and during DH trials and higher with NS at constant‐load intensities except at 70% (p = 0.13).ConclusionThe findings provide further evidence that histamine contributes directly or indirectly to the development of EIAH during intense exercise in highly trained athletes.

Abstract 11461: Women with Coronary Artery Disease and Higher Cardiorespiratory Fitness Have Lower Coronary Artery Calcium Scores

Introduction: Higher coronary artery calcium (CAC) scores have been associated with increased cardiovascular (CVD) events and mortality. Women develop coronary artery disease (CAD) on average 10-15 years older than men and have worse outcomes than men when CVD events occur. The effect of exercise capacity on CAC scores in women with CAD is unclear. Objective: To determine if exercise capacity is predictive of CAC scores in men and women with CAD. Methods: A total of 203 men and 38 women with known CAD had CAC scores measured using noncontrast multidetector coronary tomography. All subjects underwent maximal exercise treadmill testing with calculation of metabolic equivalents of task (METs) achieved as a measure of cardiorespiratory fitness. Results: Mean (SD) age was not different in men and women: 62.7 (7.9) and 64.4 (6.8) years, P=0.239, respectively. CAC scores were significantly lower in women compared to men: median [IQR]: 114.0 [27.5, 321.0] Agatston units vs 535.3 [182.9, 1367.4] respectively, (P&lt;0.001) and were lower in women than men at any given age (Fig 1A). Female CAC scores did not equal those of men until women were 20 years older (Fig 1A). After adjustment for age, METs were associated with CAC scores in both men and women (Fig 1B). However, after multivariate adjustment for age, LDL-cholesterol, waist circumference, diabetes status and hypertension,, METs remained an independent predictor of CAC score in women (P=0.011) but not in men (P=0.223). Conclusions: Despite having known CAD, female CAC scores did not equal those of men until women were 20 years older. The independent association of METs with CAC score in women supports counseling women to exercise to maximize their cardiorespiratory fitness to minimize CAC scores. Since higher CAC scores predict adverse CVD events and mortality, lower CAC scores should protect women from development of CVD events and possibly lower their worse outcome.