Relative VO2 Research Articles

Efficacy of a Community- and Family-Based Intervention on Cardiovascular Fitness and Cardiometabolic Disease Risk Factors Among Primarily Latino Families.

Targeting cardiovascular fitness (CVF), rather than weight loss, may be a more acceptable and feasible outcome among Latinos. The purpose of this study was to test the short-term efficacy of Athletes for Life (AFL), a fitness- and lifestyle-focused behavioral intervention to improve CVF and performance among Latino families. Latino parent-child dyads (n = 137) were randomized to either AFL program or a waitlist control condition. AFL consisted of 24 group family-based, nutrition and sport/fitness oriented 90-minute sessions (twice-weekly). Measures included 1-mile run/walk time, three-minute step test, accelerometer-measured physical activity, body mass index (BMI), waist circumference, DEXA-measured % body fat, cardiometabolic risk biomarkers, and sociodemographic characteristics. Group differences at post-intervention were tested using ANCOVA analyses adjusting for outcome values at baseline and demographic variables. Parents were primarily female (93%), aged 38.3 ± 6.9 years, and 96% Latino and children were 8.8 ± 1.7 years old and 58% female. Intervention participants showed significantly faster adjusted post-intervention 1-mile run/walk times compared to control group participants (difference of -76.6 seconds P < 0.01 and -44 seconds P = 0.04, respectively). Parents also showed a significantly higher adjusted relative VO2 max (ml/kg/min) compared to control group parents (43.91, SE = 0.41 vs 42.93, SE = 0.44, respectively, P < 0.01). There were no significant post-intervention group differences on physical activity, BMI, waist circumference, % body fat or cardiometabolic biomarkers P > 0.05. The AFL program successfully improved aerobic performance among underserved Latino families with no observable changes in adiposity. These results support that fitness may be a more viable and acceptable outcome among Latino families than weight loss.

Thoracic load carriage impairs the acute physiological response to hypoxia in healthy males.

To assess the impact of thoracic load carriage on the physiological response to exercise in hypoxia. Healthy males (n = 12) completed 3 trials consisting of 45 min walking in the following conditions: (1) unloaded normoxia (UN; FIO2:20.93%); (2) unloaded hypoxia (UH; FIO2:~13.0%); and (3) loaded hypoxia (LH; 29.5 kg; FIO2:~13.0%). Intensity was matched for absolute VO2 (2.0 ± 0.2 L·min-1) across conditions and relative VO2 (64.0 ± 2.6 %VO2max) across hypoxic conditions. With LH versus UH, there were increases in breathing frequency (5-11 breaths·min-1; p < 0.05) and decreases in tidal volume (10%-18%; p < 0.05) throughout exercise due to reductions in end inspiratory lung volumes (p < 0.05). Consequently, deadspace (11%-23%; p < 0.05) and minute ventilation (7%-11%; p < 0.05) were increased starting at 20 and 30 min, respectively. In addition, LH increased perceived exertion/dyspnea and induced inspiratory (~12%; p < 0.05 vs. UN) and expiratory (~10%; p < 0.05 vs. pre-exercise) respiratory muscle fatigue. Expiratory flow limitation was present in 50% of subjects during LH. Cardiac output and muscle oxygenation were maintained during LH despite reduced stroke volume (6%-8%; p < 0.05). Finally, cerebral oxygenated/total hemoglobin were elevated in the LH condition versus UH starting at 15 min (p < 0.05). Thoracic load carriage increases physiological strain and interferes with the compensatory response to hypoxic exposure.

Enhancing Heart Rate-Based Estimation of Energy Expenditure and Exercise Intensity in Patients Post Stroke.

Indirect calorimetry is the gold standard field-testing technique for measuring energy expenditure and exercise intensity based on the volume of oxygen consumed (VO2, mL O2/min). Although heart rate is often used as a proxy for VO2, heart rate-based estimates of VO2 may be inaccurate after stroke due to changes in the heart rate-VO2 relationship. Our objective was to evaluate in people post stroke the accuracy of using heart rate to estimate relative walking VO2 (wVO2) and classify exercise intensity. Moreover, we sought to determine if estimation accuracy could be improved by including clinical variables related to patients' function and health in the estimation. Sixteen individuals post stroke completed treadmill walking exercises with concurrent indirect calorimetry and heart rate monitoring. Using 70% of the data, forward selection regression with repeated k-fold cross-validation was used to build wVO2 estimation equations that use heart rate alone and together with clinical variables available at the point-of-care (i.e., BMI, age, sex, and comfortable walking speed). The remaining 30% of the data were used to evaluate accuracy by comparing (1) the estimated and actual wVO2 measurements and (2) the exercise intensity classifications based on metabolic equivalents (METs) calculated using the estimated and actual wVO2 measurements. Heart rate-based wVO2 estimates were inaccurate (MAE = 3.11 mL O2/kg/min) and unreliable (ICC = 0.68). Incorporating BMI, age, and sex in the estimation resulted in improvements in accuracy (MAE Δ: -36.01%, MAE = 1.99 mL O2/kg/min) and reliability (ICC Δ: +20, ICC = 0.88). Improved exercise intensity classifications were also observed, with higher accuracy (Δ: +29.85%, from 0.67 to 0.87), kappa (Δ: +108.33%, from 0.36 to 0.75), sensitivity (Δ: +30.43%, from 0.46 to 0.60), and specificity (Δ: +17.95%, from 0.78 to 0.92). In people post stroke, heart rate-based wVO2 estimations are inaccurate but can be substantially improved by incorporating clinical variables readily available at the point of care.

Comparative Analysis of Respiratory and Functional Outcomes in Children Post-Fontan Procedure Versus Healthy Peers.

Studies have shown that respiratory muscle training enhances functional capacity and pulmonary function in Fontan patients. However, diaphragm muscle characteristics in Fontan children have not been fully elucidated. The aim of this study was to compare respiratory function, maximal and submaximal functional capacities, and quality of life, as well as to assess diaphragm mobility and thickness, between Fontan patients aged 8 to 12years and healthy individuals. This cross-sectional study included 45 children-27 Fontan patients, Fontan Group (FG) and 18 healthy control Group (CG) subjects. Different examinations were performed: spirometry was used to analyze pulmonary volume and capacity; manovacuometry was used to determine respiratory muscle strength; chest ultrasound was used to determine diaphragm muscle characteristics; cardiopulmonary exercise and the six-minute walk test (6MWT) wereused to determine functional capacity; the AUQEI questionnaire was used to determine quality of life. Descriptive analysis and intergroup comparisons were performed for all the data. Compared with the CG, the FG exhibited impaired pulmonary function and reduced functional capacity. Significant differences in median values were noted for forced expiratory volume in one second (FEV1): 2.39L/min, p = 0.002; forced vital capacity (FVC): 1.73 vs. 3.06L/min, p = 0.002; maximal inspiratory pressure: - 73 vs. - 117cmH2O, p = 0.007; absolute peak VO2: 1.09 vs. 1.51L/min, p < 0.001; relative peak VO2: 31.9 vs. 42.5mL/kg/min, p = 0.003; and 6MWT distance: 420 vs. 586m, p < 0.001. Diaphragmatic thickness, mobility and quality of life were similar between the groups. Despite the reduced functional capacity, impaired pulmonary volume and capacity, and respiratory muscle weakness of the FG compared to those of the CG, the diaphragm characteristics and quality of life were similar between the groups.

Aerobic capacity and respiratory indices of junior cross-country skiers and biathletes during incremental exercise testing.

The present study compared the isocapnic buffering phase (ICB), hypocapnic hyperventilation phase, ventilatory threshold (VT), respiratory compensation point (RCP), and maximum oxygen uptake (VO2max) among biathlon and cross-country ski athletes during an incremental exercise test. 37 male and 33 female Turkish National Team athletes volunteered to participate in the research. Body fat percentage, lean mass, and fat mass values of athletes were measured using the bioelectrical impedance analysis method, and oxygen consumption (VO2) was measured with a portable cardiopulmonary exercise test system with a ramp protocol on the treadmill. In VT, RCP, and VO2max phases, male athletes had higher VO2 and speed values than female athletes (p < 0.05). In contrast, they had similar values across different categories of sports (biathlon and cross-country skiing) (p > 0.05). Additionally, XC skiers and males had higher absolute (Abs) VO2 and mass-normalized (Rel) VO2 values than biathletes and females in exhaustion times and ICBs (p < 0.05). In contrast, they had similar Abs VO2 and Rel VO2 values in hypocapnic hyperventilation phases (p > 0.05). In addition, XC skiers and males had higher absolute (Abs) VO2 and relative (Rel) VO2 values than biathletes and females in exhaustion times and ICBs (p < 0.05). In contrast, they had similar Abs VO2 and Rel VO2 values in hypocapnic hyperventilation phases (p > 0.05). These results indicate significant differences in physiological profiles between male and female athletes and between XC skiers and biathletes.

An intermittent recovery test for soccer players: a validation study.

Soccer is an intermittent team sport that demands high aerobic capacity. On field, soccer players' aerobic capacity, assessed through the maximal oxygen uptake (VO<inf>2</inf>max), is usually determined by an intermittent recovery test. The aim of this study was to obtain a construct validity of a new intermittent recovery test (IRT) with a fixed speed and a progressive decrement of rest period. Twenty-five male soccer players were recruited to perform an incremental continuous test (ICT) and the new IRT, to compare their physiological data. Fifteen male soccer players were involved to perform a test-retest of IRT to assess its reliability. VE<inf>peak</inf>, absolute VO<inf>2</inf>max, relative VO<inf>2</inf>max and VCO<inf>2</inf>peak registered during ICT and IRT correlated strongly (Pearson's correlation coefficient ranges from 0.75 to 0.80, with very large as magnitude of effects and with P<0.001). IRT showed reliability from good to excellent regarding VE<inf>peak</inf>, absolute VO<inf>2</inf>max, relative VO<inf>2</inf>max, VCO<inf>2</inf>peak and covered distance (ICC values ranged from 0.82 to 0.95). These findings and its underlying physiological and muscular demands, suggest that IRT can be considered as a valid and reliable test to assess aerobic capacity in soccer players during the competitive period.

Comparison of Cardiopulmonary Exercise Test Variables to Predict Adverse Events in Patients with Heart Failure.

Given the rising burden of heart failure (HF), stratification of patients at increased risk for adverse events is critical. We aim to compare the predictive value of various maximal and submaximal cardiopulmonary exercise test (CPET) variables for adverse events in patients with HF. 237 patients with HF (66 [58-73] years, 30% women, 70% HF with reduced ejection fraction) completed a CPET and had five years of follow-up. Baseline characteristics and clinical outcomes (all-cause mortality, major adverse cardiovascular events, and cardiovascular-related hospitalization) were extracted from electronic patient files. Receiver operating characteristics curves for maximal (e.g. peak VO2) and submaximal CPET variables (e.g. VE/VCO2 slope, cardiorespiratory optimal point (COP), VO2 at anaerobic threshold) were compared using the Akaike Information Criterion (AIC) method, whereas their calibration was assessed. 103 participants (43%) reached the composite endpoint, and 55 (23%) died. Percent predicted peak VO2 was the best predictor for adverse outcomes (AIC: 302.6) followed by COP (AIC: 304.3), and relative peak VO2 (mL/(kg·min), AIC: 304.4). Relative peak VO2 (AIC: 217.1) and COP (AIC: 224.4) were also among the three best predictors for mortality, together with absolute peak VO2 (ml/min, AIC: 220.5). A good calibration between observed and predicted event rate was observed for these variables. Percent predicated and relative peak VO2 had the best predictive accuracy for adverse events and mortality, but the submaximal COP had a non-inferior predictive accuracy for adverse events in patients with HF. These findings highlight the potential of submaximal exercise testing in patients with HF.

Caffeine has no effect on submaximal running in hypoxia in low caffeine consuming males and females.

Exposure to hypoxia immediately challenges a variety of physiologic systems that limit exercise capacity. Under normoxia, caffeine (CAFF) increases ventilation and subsequent oxygenation of hemoglobin (SpO<inf>2</inf>) and skeletal muscle (SmO<inf>2</inf>). CAFF improves exercise performance at altitude. However, little attention has been given to submaximal exercise in hypoxia, particularly regarding low CAFF consumers and female participants. The aim of this study was to determine the effect of CAFF on pulmonary, metabolic, and perceptual variables in response to submaximal running in hypoxia in low CAFF consuming males and females. In a double blinded, counterbalanced design, 14 (6 females) individuals (24.1±5.1 years; VO<inf>2max</inf>: 40.6±5.6 mL × kg-1 × min-1; 20.8±8.0% body fat), who habitually consumed ≤150 mg/day of CAFF performed treadmill running at workloads of 25%, 40%, 60%, and 75% of sea level VO<inf>2max</inf> in normobaric hypoxia (F<inf>I</inf>O<inf>2</inf>=0.15) on two separate occasions: 1) 60 minutes after 6 mg/kg of CAFF; or 2) placebo. CAFF had no effect on any variable measured. Specifically, V<inf>E</inf> (condition: P=0.12; interaction: P=0.19), V<inf>T</inf> (condition: P=0.16; interaction: P=0.57), and Ve:VO<inf>2</inf> (condition: P=0.07; interaction: P=0.69) were similar between groups. Further, CAFF had no effect on relative VO<inf>2</inf> (condition: P=0.84; interaction: P=0.95), HR (condition: P=0.28; interaction: P=0.35), SmO<inf>2</inf> (condition: P=0.66; interaction: P=0.82), or SpO<inf>2</inf> (condition: P=0.16; interaction: P=0.97). Finally, rating of perceived exertion (RPE; P=0.92) and acute mountain sickness scores (P=0.29) were similar across conditions. These data demonstrate that CAFF provides no physiologic advantage to submaximal exercise in acute, normobaric hypoxia with low CAFF consuming males and females.

Impact of a 12-wk physical conditioning program on the aerobic capacity of aviation cadets.

Flight cadets need to have good physical fitness to cope with the challenges of flying missions. The continuous development of science and technology has led to the constant upgrading of fighter jets and the improvement of their performance, which has resulted in new and higher requirements for the physical fitness of flight personnel. The traditional physical training mode, method, and assessment have been used for many years and do not meet current fitness needs. To investigate the impact of a 12-wk comprehensive anti-G fitness training program on the aerobic capacity of aviation cadets and to evaluate its effectiveness. Fifty-five cadets were randomly assigned to control and experimental groups using a randomized, single-blind design. The control group maintained their existing training regimen, while the experimental group participated in a 12-wk comprehensive training intervention. The training program comprised strength training twice per week, high-intensity interval training three times per week, and supplemental nutritional and psychological support. Maximal oxygen uptake (VO2max), lower limb strength, and hemoglobin levels were measured at baseline, at 6 wk and 12 wk post-intervention. Repeated measures analysis of variance revealed significant differences of both VO2max and relative VO2 in both groups across time points (P < 0.05). However, no significant time-group interaction was observed (P > 0.05). Paired t-tests comparing baseline and 12-wk results showed that VO2max and relative VO2 were significantly higher in the experimental group than the control group (P < 0.05). This suggests that the training program effectively enhanced the aerobic capacity of the experimental group. Key indicators of aerobic capacity, bilateral lower limb strength and hemoglobin levels, were also significantly different over time and between groups (P < 0.05). No significant differences were noted in heart-rate metrics (P > 0.05). A 12-wk comprehensive anti-G fitness training program significantly improved the aerobic capacity of aviation cadets, thereby enhancing their overall capacity and laying a physiological foundation for enduring high-G flights.

Association of Sarcopenia and Oxygen Uptake Efficiency Slope in Male Patients With Heart Failure.

Sarcopenia, the loss of muscle mass and function, is a common comorbidity in patients with heart failure (HF). The skeletal muscle modulates the respiratory response during exercise. However, whether ventilatory behavior is affected by sarcopenia is still unknown. We enrolled 169 male patients with HF. Muscle strength was measured by a handgrip dynamometer. Body composition was measured with dual-energy X-ray absorptiometry. Sarcopenia was defined by handgrip strength <27 kg and appendicular lean mass divided by height squared (ALM/height 2 ) <7.0 kg/m 2 . Oxygen uptake efficiency slope (OUES), ventilation (VE), oxygen uptake (VO 2 ), and carbon dioxide output (VCO 2 ) were measured by a cardiopulmonary exercise test. Sarcopenia was identified in 29 patients (17%). At the first ventilatory threshold, VE/VO 2 (36.9±5.9 vs 32.7±6.5; P =.003) and VE/VCO 2 (39.8±7.2 vs 35.3±6.9; P =.004) were higher in patients with sarcopenia compared to those without sarcopenia. At the exercise peak, compared to patients without sarcopenia, patients with sarcopenia had lower OUES (1186±295 vs 1634±564; P <.001), relative VO 2 (16.2±5.0 vs 19.5±6.5 mL/kg/min; P =.01), and VE (47.3±10.1 vs 63.0±18.2L/min; P <.0001), while VE/VCO 2 (42.9±8.9 vs 38.7±8.4; P =.025) was increased. OUES was positively correlated with ALM/height 2 ( r =0.36; P <.0001) and handgrip strength ( r =0.31; P <.001). Hemoglobin (OR=1.149; 95% CI, 0.842-1.570; P =.038), ALM/height 2 (OR=2.166; 95% CI, 1.338-3.504; P =.002), and VO 2peak (OR=1.377; 95% CI, 1.218-1.557; P <.001) were independently associated with OUES adjusted by cofounders. Our results suggest that sarcopenia is related to impaired ventilatory response during exercise in patients with HF.

Examining and Comparing the Energy Expenditure of Two Modes of a Virtual Reality Fitness Game (Supernatural): Indirect Calorimetry Study.

The effectiveness of virtual reality (VR) fitness games as a form of moderate to vigorous physical activity has yet to be thoroughly quantified through gold standard energy expenditure measures. The purpose of this study was to examine the energy expenditure of 2 medium-intensity modes ("Flow and "Boxing") of a VR fitness game, Supernatural, using indirect calorimetry. Indirect calorimetry was used to examine relative and objective maximal oxygen consumption (VO2 max), metabolic equivalents of task (METs), and calories burned during medium-intensity bouts of both Flow and Boxing gameplay modes in young (mean age 25.42, SD 3.25 years), active individuals (n=12 female and n=11 male). METs and calories were also compared using a triaxial waist-worn accelerometer, an Apple smartwatch, and a VR headset. Mood states were assessed pre- and postbout using the shortened Profile of Mood States Questionnaire. Paired 2-tailed t tests were used to examine differences in game modes, between sexes, and pre-post exercise sessions. Objective and relative VO2 max averaged 1.93 (SD 0.44) L/min and 27.61 (SD 5.60) mL/kg/min, respectively, between modes. Flow (mean 8.2, SD 1.54 METs) and Boxing (mean 7.6, SD 1.66 METs) are both classified as high energy expenditure, vigorous activities. Calorie expenditure data of the accelerometer and VR headset differed significantly from the metabolic cart. Mood changes pre- to post exercise were consistent with expected values for moderate- to vigorous-intensity physical activity, with participants reporting that they felt more "active," "full of pep," "vigorous," and "lively" (P<.05) following bouts. Male individuals reported higher objective oxygen consumption (VO2) for both Flow and Boxing modes; no other sex-specific differences were observed. Both Flow and Boxing gameplay modes of Supernatural classify as vigorous physical activity and demonstrate the potential to promote mental and physical health benefits. Supernatural may be an effective exercise modality in a VO2 training program.

The impact of repeat opioid use (ROU) on fentanyl-induced respiratory depression

Objective: Repeat opioid use (ROU) is a primary driver for the ongoing opioid epidemic, and while a substantial understanding exists for the impact of ROU on behavioral neurophysiology, the consequences of ROU on respiratory-related physiology including opioid-induced respiratory depression (OIRD) remain poorly understood. Hypothesis: ROU leads to respiratory tolerance to fentanyl that is characterized by the blunting of respiratory depression and improvement of O2 consumption (VO2). Methods: We utilized a pre-clinical rodent model. Breathing was measured via whole body-plethysmography in freely behaving adult mice (P&gt;90) prior to and immediately following fentanyl administration. A single dose of fentanyl (0.7 mg/kg, i.p.) was given for up to 6 consecutive days. In a subset of experiments, O2 consumption was measured simultaneously using whole-body plethysmography. Results: We identified two distinct respiratory phenotypes in response to OIRD following ROU. Type 1 phenotype (n=18) adapted over time where breathing during OIRD is greater on day 5 versus day 1. In contrast, the Type 2 phenotype (n=5) showed no such adaptation, with unchanged or worsened breathing by day 5. In a subset of animals (n=12) the relationship between breathing (i.e. minute ventilation (Ve)) and oxygen consumption (VO2) was examined before and following ROU. Under baseline conditions the Ve to VO2 relationship positively correlated on day 1 and 5. During OIRD on day 1 this correlation became negative, but began to normalize by day 5, resembling the baseline relationship. These phenomena also coincided with an increase in the ventilatory drive observed at the whole-animal level and in the isolated preBötzinger complex following ROU. Conclusions: ROU leads to two distinct respiratory phenotypes in response to OIRD, where the majority of subjects show a blunted respiratory depression. Additionally, ROU improves the relationship between breathing and oxygen consumption and enhances inspiratory drive in the presence of fentanyl. These findings suggest that fentanyl-induced hypoxia experienced by repeat opioid users vastly differ from naïve users. Such differences may contribute to the unpredictable occurrence of overdose amongst repeat users. This work was supported by NIH: R01 HL163965 and DA057767. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Is the ICP pulse waveform P2/P1 ratio during -6° head-down tilt associated with relative VO2 peak? A non-invasive intracranial compliance monitoring approach

BackgroundSpaceflights influence intracranial compliance (ICC). P2/P1 ratio, from the intracranial pressure (ICP) waveform, provides information about ICC. Additionally, non-invasive methods for ICC monitoring are needed for spaceflights. Furthermore, astronauts try to maintain good levels of cardiorespiratory fitness before and during spaceflights, not only to sustain exploratory missions, but also to prevent diseases in extreme environments. Objectiveto correlate cardiorespiratory fitness levels with the P2/P1 ratio during a microgravity analog [-6° head-down tilt (HDT)]. Method34 individuals (11 women), mean age of 31.7 (±6.3) years and BMI 24.2 (±3.2) performed a cardiopulmonary exercise testing (CPET) with an incremental protocol on a cycle ergometer to determine the cardiopulmonary fitness through peak relative oxygen uptake (VO2 peak) of each individual. On the second test, which was conducted in an interval of 15 days of the CPET, participants remained for 30 min at HDT with P2/P1 ratio acquired using a non-invasive strain gauge sensor. The average of the last 5 min was used for analysis. The mean P2/P1 ratio and relative VO2 peak were correlated using the Spearman test. ResultsVolunteers presented 1.05 ± 0.2 of P2/P1 ratio and VO2 peak of 47.5 ± 7.6 mL/kg/min. The Spearman test indicated a negative and low correlation between the P2/P1 ratio and VO2 peak (ρ = -0.388; p = 0.023). ConclusionThe study suggests that the better the cardiorespiratory fitness, the better ICC in a weightlessness simulation.

Abstract 18949: Bariatric Surgery is Associated With Improved Coronary Microvascular Function and Cardiorespiratory Fitness in Patients With Ischemia and Non-Obstructive Coronary Arteries (INOCA)

Introduction - Severe obesity is associated with cardiometabolic disease and coronary microvascular dysfunction, as reflected by impaired coronary flow reserve (CFR). Bariatric surgery promotes sustained weight loss and lower incidence of diabetic microvascular complications, but its effect on the coronary microcirculation is unclear. In this ongoing pilot study, we aimed to investigate the impact of bariatric surgery on CFR, endothelial function, and cardiorespiratory fitness in patients with severe obesity and INOCA. Methods - Consecutive patients (N=19) with severe obesity (BMI≥35 kg/m 2 ), exertional dyspnea and planned bariatric surgery were enrolled. Patients underwent cardiac stress positron emission tomography (PET), peripheral arterial tonometry (PAT), echocardiogram and cardiopulmonary exercise testing (CPET) at baseline and after a median of 6.2 months post-surgery (N=9 completed to date). CFR was quantified as stress/rest myocardial blood flow (MBF) from PET. Reactive hyperemia index (RHI), a marker of endothelial function, was calculated as the ratio between PAT signal post and pre-occlusion in the corresponding arm. Results - Median age was 50 (Q1-Q3 42-54) years and 63% were female. At baseline, median BMI was 43 (40-54), LVEF was 0.62, and %LV visual ischemia was 0. Higher BMI inversely correlated with CFR (r= -0.53, p=0.02). As compared to baseline, patients post-surgery (78% sleeve gastrectomy, 22% gastric bypass) had significantly decreased BMI (45.2 vs. 34.3, p=0.008) and improved stress MBF [1.8 (1.3-2.2) vs. 2.4 (1.8-2.8), p&lt;0.02], CFR [2.3 (1.9-2.6) vs. 3.1 (2.4-3.6), p&lt;0.02] and peripheral endothelial function [RHI 1.5 (1.4-1.8) vs. 2.4 (1.8-2.8) vs. p=0.04]. These changes were accompanied on CPET by significantly higher exercise workload [112 (84.2-146) vs. 124.5 (90.5-149) W, p=0.046] and relative peak VO 2 [12.5 (11.9-14) vs. 15.2 (12.6-17) mL/kg/min, p=0.028]. Higher stress MBF directly correlated with relative peak VO 2 (r=0.53, p=0.04). Conclusion - In this pilot clinical study, bariatric surgery was associated with significant improvements in coronary microvascular function, peripheral endothelial function, and cardiorespiratory fitness in symptomatic patients with severe obesity after six months.

35 Impact of Cardiorespiratory Fitness and White Matter Lesions on Processing Speed with Age

Objective:Processing speed declines with age and is a strong predictor of age-related cognitive decline in other domains, and in predicting who will need help with tasks of daily living in later years. Higher cardiorespiratory fitness (CRF) reflects better cardiopulmonary health and is related to maintenance of processing speed and cognition into late life. On the other hand, white matter lesions (WML) are reflective of age-related brain network disconnections from damage to white matter tracts in the brain. Lower CRF and higher WML burden have each been related to poorer cognitive performance. Although higher CRF provides a protective effect on cognition, the combined effects of CRF and WML on processing speed have yet to be determined. Specifically, whether CRF and WML independently affect processing speed or if WML moderates the effect of CRF on processing speed is yet to be established. We predicted WML may moderate CRF benefits on cognitive aging if CRF-related cognitive benefits are weakened by high WML load. Here, we test this question with the gold-standard measure of CRF, maximal exercise oxygen uptake (relative VO2 max, mL/kg/min) during a graded exercise test, and a validated neuropsychological measure of processing speed, the Digit Symbol Substitution Test (DSST).Participants and Methods:CRF, DSST scores, and WML volumes of cognitively normal adults (n=91) aged 55-80 years were included in this analysis. The WML data was corrected for total intracranial volume and was log transformed. A linear regression model included the number of accurately completed items on the DSST as the dependent variable and age, sex, relative VO2 max, WML volumes and the interaction between relative VO2 max and WML volume as the predictor variables.Results:Main effects of age, sex, VO2 max and WML volume on the DSST were observed. Greater age, higher WML volume, and lower relative VO2 max were associated with poorer performance on the DSST. In addition, females (n=55) performed better than males (n=36) on the DSST. No significant interaction was observed between VO2 max and WML volume on DSST scores.Conclusions:Our results show that 1) WML and relative VO2 max independently contribute to processing speed performance in older adults as measured by the DSST, and 2) WML do not moderate the relation between VO2 max and the DSST. Strengths of this study include gold-standard measurement of CRF and WML volumes as predictors of performance on the DSST in older adults. Further research is warranted to understand how vascular aging and brain health indicators interactively or interdependently impact cognition in aging.

The Impact of a 10-Week Military Training Course on Saudi Medical Recruits' Fitness and Physical Activity Levels.

Background In preparation for military service, new recruits undergo a physical transformation. We aimed to determine the fitness outcomes and self-reported activity levels of Saudi medical recruits after a 10-week initial military training course (IMTC). Methods The cohort comprised 104 recruits aged 25-29 years. Anthropometric variables, including height, body mass index (BMI), body weight (BW), percent body fat (%BF), lean body mass (LBM), waist circumference (WC), and waist-to-height ratio (WtHR), were assessed pre-IMTC and post-IMTC. Physical fitness assessments, including a one-minute sit-up test, push-up test, Cooper's 12-minute run/walk test, and relative maximal oxygen consumption (VO2 max), were also evaluated. The International Physical Activity Questionnaire (IPAQ) was used to assess self-reported physical activity. Results We found a significant decrease in anthropometric variables following the course, including BW (P = 0.01), BMI (P = 0.01), %BF (P = 0.002), LBM (P = 0.01), WC (P = 0.005), and WtHR (P = 0.003). They also showed significant improvements in the push-up test(P = 0.001), one-minute sit-up test (P = 0.001), 12-minute test (P = 0.001), and relative VO2 max(P = 0.001). The comparison of pre-IPAQ with post-IPAQ demonstrated a percentage improvement in walking activity (15%-82%) and vigorous physical activity (17%-49%) after joining the IMTC. Conclusions These findings demonstrate that Saudi medical recruits who partake in the IMTC can attain significant improvements in their body composition, physical fitness, and physical activity levels.

Sex differences in hemodynamic response to high-intensity interval exercise.

Sex differences in the cardiorespiratory and hemodynamic response to exercise exist due to differences in heart size, blood volume, and hemoglobin mass, eliciting higher maximal oxygen uptake (VO2max ) in men versus women. Data are equivocal whether sex differences in training responsiveness occur. This study investigated potential sex differences in the hemodynamic response (stroke volume (SV) and cardiac output (CO)) to high-intensity interval exercise (HIIE). Habitually active men (n = 15) and women (n = 13) underwent VO2max testing, followed by three HIIE sessions consisting of the 4 × 4, 10 × 1, and reduced exertion high-intensity training (REHIT), whose order was randomized. During exercise, oxygen uptake (VO2 ) and hemodynamic responses were determined. Results showed no sex difference in peak relative VO2 (p = 0.263), CO (p = 0.277), or SV (p = 0.116), although absolute values were higher in men (p < 0.05). Peak absolute (127.3 ± 20.6 vs. 115.2 ± 16.6 mL/beat, p = 0.004, d = 0.66) and relative SV (111.0 ± 15.5 vs. 100.7 ± 11.1% max, p = 0.005, d = 0.78) were higher with REHIT versus 4 × 4. No sex differences in mean relative VO2 , CO, or SV occurred (p > 0.05). Data showed lower mean VO2 during REHIT versus 4 × 4 (59.3 ± 6.8 vs. 65.8 ± 5.8 %VO2max , p < 0.001, d = 1.05) and 10 × 1 (59.3 ± 6.8 vs. 69.1 ± 7.4 %VO2max , p < 0.001, d = 1.4). Mean CO was lower in REHIT than 10 × 1 (79.8 ± 8.6 vs. 84.0 ± 7.4% max, p = 0.012, d = 0.53). Previously reported differences in VO2max response to HIIE may not be due to unique hemodynamic responses.

Physiological and Energetic Demands During Still-Rings Routines of Elite Artistic Gymnasts.

The aim of the study was to analyze physiological and energetic demands of elite gymnasts during still-rings routines (SRRs). Eleven male gymnasts (mean [SD] 23.6 [3.9]y, 65.9 [5.6]kg, 171.1 [6.7]cm) performed a maximal graded exercise test and an individual SRR, during which respiratory gas and heart rate (HR) were measured using a mobile spiroergometer and a paired HR sensor. Metabolic energy and the energy contribution in terms of aerobic, anaerobic lactic, and anaerobic alactic were determined by oxygen uptake (VO2) during exercise, net lactate production, and the fast component of postexercise VO2 kinetics. Mean routine duration of the SRRs was 48.3 (4.5)seconds. VO2 and HR during SRRs were shown to be 86.9% (5.9%) and 91.0% (3.3%), respectively, of the maximal values measured during the graded exercise test. The anaerobic alactic, aerobic, and anaerobic lactic systems provided 50.9% (6.6%), 28.6% (4.8%), and 20.5% (5.2%), respectively, of the total energy required during SRRs. The energy contribution of the anaerobic lactic system correlated negatively with individual anaerobic threshold (r = -.715) and maximal VO2 (r = -.682). The anaerobic alactic system is the predominant energy source for ATP resynthesis during SRRs. The high relative VO2 and HR values reached during SRRs showthat these routines strongly stress the cardiovascular system.

A slightly adapted treadmill protocol for the determination of maximal oxygen uptake in adults with Down syndrome.

The VO2 max test is the gold standard measure for aerobic fitness. A standardised treadmill protocol was developed years ago for individuals with Down syndrome but with variations in terms of starting speed, load increases and time spent at each stage. However, we realised that the most widely used protocol for adults with Down syndrome, trouble participants with high treadmill speeds. Consequently, the purpose of the current study was to determine whether an adapted protocol provided improved maximal test performance. Twelve adults (33 ± 6 years) randomly performed two variations of the standardised treadmill test. The protocol that added another incremental incline stage increase yielded a significant improvement in absolute and relative VO2 peak, time to exhaustion, minute ventilation and heart rate max. A treadmill protocol with the addition of an incremental incline stage allowed for a significant improvement in maximal test performance.

Oxygen vacancies in the Spotlight: On the engineering of intrinsic defects in highly defective TiO2 photocatalysts

Nanostructured oxide semiconductors are widely used in energy conversion, catalysis, sensing and environmental applications, due to their high stability, commercial availability, efficiency and low cost. Despite its crucial importance for the design of more efficient materials, the interplay between intrinsic and extrinsic defects is yet to be clarified. For example, oxygen vacancies (VO’s) can be either beneficial or detrimental to the desired performances, depending on a variety of factors. Here, we synthesize TiO2-x samples by the addition of three different N chemical sources (NH3, triethylamine, urea). X-ray absorption spectroscopy, confocal microscopy, UV–vis absorbance and fluorescence, are employed to explore the occurrence and location of VO’s both in real and energy spaces. High–grade bulk DFT simulations complement the experimental picture. Synergy between theory and experiment, on the one hand, estimates the relative VO’s content in the different samples from local structural information. On the other hand, a sharp optical transition at ≈2.7 eV serves an unequivocal spectral signature of bulk VO’s, allowing a semi-quantitative analysis by confocal microscopy. Surface oxygen vacancies do not display fluorescence features under UV pumping, possibly due to the reaction of surface defects with atmospheric O2. Thus, the comparison between local structure and confocal microscopy can discriminate surface-localized and bulk VO’s. Concurrently, UV-induced photochromism and visible light photodegradation shed light on the most effective reactive defects. Eventually, surface-localized oxygen vacancies are predominant where actual N substitutional doping occurs, leading to materials exhibiting visible-light activity and characteristic photochromic behaviour. Implications on strategies for concomitant VO engineering and extrinsic doping are discussed.