VO2max Research Articles

Physical Activity Component of the Greek Interventional Geriatric Study to Prevent Cognitive Impairment and Disability (GINGER): Protocol Development and Feasibility Study

Background/Objectives: Individuals with subjective cognitive decline (SCD) have an increased risk of developing dementia, while non-pharmacological multicomponent lifestyle interventions are recommended for prevention/management. The Greek Interventional Geriatric Initiative to Prevent Cognitive Impairment and Disability (GINGER) is such a multicomponent approach, encompassing simultaneous interventions (cognitive training, depression and sleep management, etc.). Exercise/Physical activity (PA) is suggested as one such intervention. This study (i) presents the exercise protocol developed for GINGER and (ii) explores its feasibility (acceptability, applicability, adherence, users’ satisfaction and reliability). Methods: Exercise/PA protocol development, targeting SCD individuals aged > 55 years, utilized relevant guidelines/literature followed by focus group involving exercise specialists. Data were synthesized through consensus to design optimal exercise interventions prescribed on participant’s physical capacity (heart rate, exertion, etc.), comprising 6-month combined aerobic, strengthening, balance and dual-task exercises, delivered 3 times/weekly in two group-based supervised sessions (in-person and online) and one home-based session. Physical outcomes include balance, aerobic capacity [2-Minute Walk Test (2 MWT), IPAQ-7], strength [Hand Grip Strength (HGS), Sit-to-Stand], fear of falling. Eligibility for entering intervention is low IPAQ-7, 2 MWT or HGS scoring. Feasibility was explored with adherence (exercise diaries and Exercise Adherence Rating Scale) and satisfaction (Patient Satisfaction Questionnaire) Results: Intervention was easily delivered with good reliability across testers’ assessments on 13 SCD participants (ICCs = 0.62–0.99), and improved physical outcomes, whereas users’ adherence and satisfaction scored highly. Conclusions: The exercise protocol for SCD was feasible, acceptable, applicable, reliable, demonstrating adherence and satisfaction, while improving physical parameters. It is thus integrated in the GINGER study, where multiple simultaneous interventions will take place to prevent/enhance cognitive function.

Impact of New York City's 4-year multi-component natural experiment to improve elementary school physical education on student cardiorespiratory fitness.

School physical education is an important population-level health intervention for improving youth fitness. This study estimated the impact of New York City's PE Works program - which included providing PE teachers, training for classroom teachers, and administrative/ teacher support for PE - on student cardiorespiratory fitness as measured by the FitnessGram's 15-meter PACER test for aerobic capacity. This longitudinal study (2014/15-2018/19) includes 581 elementary schools (n = 315,999 4th /5th -grade students; 84% non-white; 74% who qualify for free or reduced-price meals, a proxy for socioeconomic status). We apply the parametric g-formula to address schools' time-varying exposure to intervention components and time-varying confounding. After four years of staggered PE Works implementation, 49.7% of students/school (95% CI: 42.6%, 54.2%) met age/sex-specific Healthy Fitness Zone (HFZ) aerobic capacity standards set by the FitnessGram. Had PE Works not been implemented, we estimate 45.7% (95% CI: 36.9%, 52.1%) would have met aerobic capacity HFZ standards. Had PE Works been fully implemented in all schools from the program's inception, we estimate 57.4% (95% CI: 49.1%, 63.3%) would have met aerobic capacity HFZ standards. Adding a PE teacher, alone, had the largest impact (6.4% (95% CI: 1.0, 12.0) increase). PE Works positively impacted student cardiorespiratory fitness. Mandating and funding multicomponent PE programs is an important public health intervention to increase children's cardiorespiratory fitness.

Greater improvement in aerobic capacity after a polarized training program including cycling interval training at low cadence (50-70 RPM) than freely chosen cadence (above 80 RPM).

This study compared the impact of two polarized training programs (POL) on aerobic capacity in well-trained (based on maximal oxygen uptake and training experience) female cyclists. Each 8-week POL program consisted of sprint interval training (SIT) consisting of 8-12 repetitions, each lasting 30 seconds at maximal intensity, high-intensity interval training (HIIT) consisting of 4-6 repetitions, each lasting 4 minutes at an intensity of 90-100% maximal aerobic power, and low-intensity endurance training (LIT) lasting 150-180 minutes with intensity at the first ventilatory threshold. Training sessions were organized into 4-day microcycles (1st day-SIT, 2nd day-HIIT, 3rd day-LIT, and 4th day-active rest), that were repeated throughout the experiment. In the first POL program, exercise repetitions during SIT and HIIT training were performed with freely chosen cadence above 80 RPM (POLFC group, n = 12), while in the second POL program with low cadence 50-70 RPM (POLLC group, n = 12). Immediately before and after the 8-week POL intervention, participants performed an incremental test to measure maximal aerobic power (Pmax), power achieved at the second ventilatory threshold (VT2), maximal oxygen uptake (VO2max), maximal pulmonary ventilation (VEmax), and gross efficiency (GE). Moreover, participants performed VO2max verification test. Analysis of variance showed a repeated measures effect for Pmax (F = 21.62; η2 = 0.5; p = 0.00), VO2max (F = 39.39; η2 = 0.64; p = 0.00) and VEmax (F = 5.99; η2 = 0.21; p = 0.02). A repeated measures x group mixed effect was demonstrated for Pmax (F = 4.99; η2 = 0.18; p = 0.03) and VO2max (F = 6.67; η2 = 0.23; p = 0.02). Post-hoc Scheffe analysis showed that increase in Pmax were statistically significant only in POLLC group. The Friedman test showed that VT2 differed between repeated measures only in the POLLC group (χ2 = 11; p = 0.001; W = 0.917). In conclusion, it was found that POL program where SIT and HIIT were performed at low cadence was more effective in improving aerobic capacity in well-trained female cyclists, than POL with SIT and HIIT performed at freely chosen cadence. This finding is a practical application for athletes and coaches in cycling, to consider not only the intensity and duration but also the cadence used during various interval training sessions.

Changes in Cardiorespiratory Fitness Following Exercise Training Prescribed Relative to Traditional Intensity Anchors and Physiological Thresholds: A Systematic Review with Meta-analysis of Individual Participant Data.

It is unknown whether there are differences in maximal oxygen uptake ( O2max) response when prescribing intensity relative to traditional (TRAD) anchors or to physiological thresholds (THR). The present meta-analysis sought to compare: (a) mean change in O2max, (b) proportion of individuals increasing O2max beyond a minimum important difference (MID) and (c) response variability in O2max between TRAD and THR. Electronic databases were searched, yielding data for 1544 individuals from 42 studies. Two datasets were created, comprising studies with a control group ('controlled' studies), and without a control group ('non-controlled' studies). A Bayesian approach with multi-level distributional models was used to separately analyse O2max change scores from the two datasets and inferences were made using Bayes factors (BF). The MID was predefined as one metabolic equivalent (MET; 3.5 mLkg-1min-1). In controlled studies, mean O2max change was greater in the THR group compared with TRAD (4.1 versus 1.8 mLkg-1min-1, BF > 100), with 64% of individuals in the THR group experiencing an increase in O2max > MID, compared with 16% of individuals taking part in TRAD. Evidence indicated no difference in standard deviation of change between THR and TRAD (1.5 versus 1.7 mLkg-1min-1, BF = 0.55), and greater variation in exercise groups relative to non-exercising controls (1.9 versus 1.3 mLkg-1min-1, BF = 12.4). In non-controlled studies, mean O2max change was greater in the THR group versus the TRAD group (4.4 versus 3.4 mLkg-1min-1, BF = 35.1), with no difference in standard deviation of change (3.0 versus 3.2 mLkg-1min-1, BF = 0.41). Prescribing exercise intensity using THR approaches elicited superior mean changes in O2max and increased the likelihood of increasing O2max beyond the MID compared with TRAD. Researchers designing future exercise training studies should thus consider the use of THR approaches to prescribe exercise intensity where possible. Analysis comparing interventions with controls suggested the existence of intervention response heterogeneity; however, evidence was not obtained for a difference in response variability between THR and TRAD. Future primary research should be conducted with adequate power to investigate the scope of inter-individual differences in O2max trainability, and if meaningful, the causative factors.

Effects of high-intensity interval training on selected indicators of physical fitness among male team-sport athletes: A systematic review and meta-analysis.

Superior physical fitness and performance are essential in male team sports. Among a myriad of training methodologies, high-intensity interval training (HIIT) has gained popularity owing to its unparalleled efficiency and effectiveness. Previous studies have established that HIIT is a proven and effective approach for enhancing various physiological performance outcomes, particularly oxygen consumption capacity, in individual sports. Despite potential differences in training practices between male and female athletes, HIIT is recognized as an anaerobic training approach for team-sport athletes. This systematic review aimed to comprehensively and innovatively analyze the existing literature to examine the effectiveness of HIIT on oxygen consumption performance among male team-sport athletes. A comprehensive literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines across the PubMed, SCOPUS, Web of Science, and SPORTDiscus databases until December 31, 2023. The inclusion criteria for this review encompassed research articles published in peer-reviewed journals that specifically focused on the impact of HIIT on the oxygen consumption performance of male players engaged in team sports. The study population exclusively consisted of male participants. The collected data included study characteristics, participant demographics, intervention details, and outcomes. Methodological quality assessment was performed using standardized criteria. The effect sizes (ESs) were calculated, and a meta-analysis was conducted using a random-effects model. The literature search yielded 13 eligible studies encompassing 286 athletes aged 14-26 years. The meta-analysis showed statistically significant enhancements in maximal oxygen uptake (VO2max) in six studies (ES, 0.19-0.74; p < 0.005), Yo-Yo Intermittent Recovery Test (YYIRT) performance in six studies (ES, 0.20-2.07; p = 0.009), repeated-sprint ability total time (RSAtotal) in five studies (ES, 0.18-1.33; p < 0.001), and the best and average times for repeated-sprint ability (RSAbest and RSAmean, respectively) in four studies (ES, 0.47-1.50; p < 0.001). However, two studies did not report any significant differences in the outcomes of the Velocity in 30-15 Intermittent Fitness Test (VIFT) between the experimental and control groups (ES, -0.08 and -0.27; p = 0.87 and 0.443, respectively). Moreover, one study did not report any significant differences in the maximal aerobic speed (MAS) (ES, 0.41, p = 0.403). HIIT significantly improved VO2max, YYIRT, and RSA; however, it did not appear to enhance VIFT and MAS performance, irrespective of age or competition level. These findings indicate that HIIT could serve as a valuable method for improving oxygen consumption performance (VO2max, YYIRT, and RSA) in male team-sport athletes, offering a time-efficient alternative to the traditional training methods. Further research is warranted to investigate its impact on performance outcomes in competitive settings and identify optimal HIIT protocols tailored to specific team sports.

Changes in Exercise Performance in Patients During a 6-Week Inpatient Psychiatric Rehabilitation Program and Associated Effects on Depressive Symptoms

Background/Objectives: The impact of exercise on affective disorders has been demonstrated in various studies. However, almost no data are available on performance effects. Therefore, this study investigated exercise performance related to the severity of depression symptoms in a pre–post within-subjects design in a 6-week standard inpatient psychiatric rehabilitation program. Methods: A total of 53 individuals (20 female; mean age, 40.98 ± 11.33) with a primary diagnosis of depression performed a cardiopulmonary exercise test (CPX) to obtain maximal oxygen uptake (VO2max), maximal power output (Pmax), and the first and second ventilatory threshold (VT1, VT2) at the start and the end of the rehabilitation. Degree of depression was assessed by Becks Depression Inventory (BDI) and the Brief Symptom Inventory test (BSI). Overall activity was measured by accelerometer step-counts. Results: Mean total step-count per day during rehabilitation was high (12,586 ± 2819 steps/day). Patients’ BDI and BSI at entry were 21.6 ± 8.83 and 65.1 ± 6.8, respectively, and decreased significantly (p &lt; 0.001) following rehabilitation, to 10.1 ± 9.5 and 54.5 ± 11.3, respectively. Pmax and VO2max increased significantly (p &lt; 0.001) from entry values (182.6 ± 58.7 W, 29.74 ± 5.92 mL·kg−1·min−1) following rehabilitation: by 11.91 ± 12.09 W and 1.35 ± 2.78 mL·kg−1·min−1, respectively. VT1 and VT2 showed a similar behavior. An increase in physical performance could predict improvement in BDI (R2 = 0.104, F(1,48) = 5.582, p = 0.022) but not in BSI. Conclusions: The program was associated with improved mental health status in all patients and increased performance in the majority of patients, although increases were small. Since improvements in exercise performance may be positively related to depression symptoms and comorbidities, it is recommended to individualize and tailor exercise programs, which could yield larger effects.

Abstract 4122780: Muscle Quality Defines Sarcopenic Obesity in Older Adults In Association with Cardiac Function

Background: Obesity phenotypes are increasingly used to define cardiovascular diseases (CVD) risks. Age-related deteriorations in skeletal muscle function have ignited interest in the co-occurrence of sarcopenia and obesity in older adults. However, the traditional definition of sarcopenia (low appendicular skeletal mass [ASM] and handgrip strength [HGS]) may lead to underdiagnosis of sarcopenic obesity (SO) in overweight individuals (due to higher muscle mass). To address this enigma, we evaluated the use of muscle quality (MQ), as an alternative metric for SO, in association with cardiac function. Methods: Community older adults without CVD were prospectively annotated for skeletal mass, HGS and cardiac function via bioimpedance analysis, dynamometer, and simultaneous acquisition of echocardiography respectively. Sarcopenia was defined by low ASM and low HGS. Low MQ (HGS divided by upper body ASM) was defined by males&lt;5.76kg/kg and females&lt;5.475kg/kg. Aerobic capacity (VO2 max,ml/kg/min) was computed by a physical activity prediction model. Mitral early diastolic inflow velocity to early diastolic annular tissue velocity (E/e’) and early to late diastolic inflow velocity (E/A) ratios were recorded. Results: Overall, low MQ was prevalent (34.3%) in n=574 participants (59% females), but only 17.4% fulfilled sarcopenia diagnosis. Higher BMI correlated with higher ASM but lower MQ (Fig 1). Low MQ prevalence was higher in the obese compared to the non-obese (64.7% vs 30.2%, p&lt;0.0001). Low MQ group was significantly older (69.0±10.4 vs 64.8±14.0 years, p&lt;0.0001), had higher prevalence of dyslipidemia (49.2% vs 40.9% p=0.002) and hypertension (45.2% vs 39.3% p&lt;0.0001) than the normal MQ group. The low MQ group had greater left ventricular mass (129±45 vs 114±44, grams, p&lt;0.0001), left atrial volumes (37±14 vs 33±13, ml, p=0.001), and demonstrated a greater degree of diastolic dysfunction (lower E/A (0.89±0.28 vs 1.1±0.49, p&lt;0.0001 and higher E/e’(8.63±2.42 vs 8.00±2.58, p=0.005), compared to the high MQ. VO2 max was lower in low MQ group (33±5.7 vs 36±6.7, p&lt;0.0001). By regression, low MQ was associated with E/A (β=-0.119, adjusted p&lt;0.0001) and VO2 max (β=-0.137, p&lt;0.0001) (Table 1). Conclusion: Muscle quality is a useful metric of muscle function for sarcopenia in obese older adults. The associations between low MQ with diastolic dysfunction and reduced aerobic capacity corroborate the clinical impact of MQ as a defining metric of sarcopenia in obesity.

Abstract 4135001: Right Ventricular Function and Right Ventricular-Pulmonary Arterial Adaptations in Aging Older Adults

Background: Compared to our understanding of left ventricular (LV) dysfunction in cardiac aging, there is far less depiction of right heart function, especially right ventricular (RV) remodelling in response to pulmonary arterial (PA) changes with aging. Given the importance of cardio-respiratory function in declining aerobic capacity with age, identifying sensitive metrics of RV function would complete our understanding of RV and RV-PA conduit adaptations in aging. Methods: Community older adults without cardiovascular disease underwent prospective cardiac magnetic resonance (CMR) imaging that measured RV volumes (RV end-diastolic volume, EDV; end-systolic volume, ESV), RV function (RV ejection fraction, RVEF; RV global longitudinal strain, GLS) and RV-PA coupling (end-systolic elastance to arterial elastance, computed as ratio of LV stroke volume, SV to RVESV). A RV-PA coupling threshold of &gt;1.5 (based on prior literature) implies effective RV adaptation Aerobic capacity (VO 2 ) was calculated. Multivariable regression adjusted for significant covariates. Results: We studied 251 participants (54.5% female, 70.78±9.07 years) with normal LV and RV function (mean LVEF, 65.13±7.51 %, RVEF, 64.25±6.98 %). RV-PA threshold of &lt;1.5 defined poorer RV structure and function with lower RVEF (56.6 ± 3.95 vs. 67.5 ± 5.25, p &lt; 0.001), RVGLS (28.13± 4.55 vs. 32.8 ± 5.1, p = 0.0065) and higher RVEDV index (73.2 ± 15.15 vs. 63.34 ± 12.03, p &lt; 0.001), compared to those with RVPA &gt; 1.5. Predictors of better RVGLS were female sex (β=0.189, adj. p=0.019), independent of systolic and diastolic blood pressure while predictors of RVESV were female sex (β=-0.433, adj. p&lt;0.00), age (β=-0.195, adj. p&lt;0.001) and body mass index (β=0.264, adj. p&lt;0.001). Overall, women had better RVEF and RVGLS but lower RVSV and VO 2 (30.1±4,5 vs 37.7±5.1, ml/kg/min) compared to men (all p&lt;0.001) (Table 1). Lower VO 2 among women compared to men was accompanied by higher RV-PA (2.1±0.7 vs 1.8±0.7, p&lt;0.001). Female sex (β=0.233, 95% CI [0.158, 0.506, adj. p&lt;0.001) was independently associated with RV-PA coupling on multivariable analyses. Conclusions: Novel CMR-derived right heart parameters defined RV function and RV adaptations as depicted by RV-PA interactions in older adults. Superior RV functions and RV-PA coupling in women may represent hemodynamic adaptations in women, despite lower aerobic capacities.

Abstract 4137678: Maximal Oxygen Uptake Prediction From Resting and Submaximal Variables of Cardiopulmonary Exercise Testing by Using Machine Learning Methods

Background: Cardiorespiratory fitness, as measured by maximal oxygen consumption (VO2max) during a cardiopulmonary exercise test (CPET), is a prognostic indicator for longevity and adverse cardiovascular event prevention. This study aims to formulate a regression model utilizing resting and submaximal variables during CPET evaluation in the general population to predict VO2max. Methods: We used 13,535 CPET results on cycle ergometer collected by the UCLA Exercise Physiology Research Laboratory over eight years. Patients were divided into a normal group (NG; n=1,400) and an other group (OG; n=12,135). The inclusion criteria for the NG were: the absence of any known clinical diagnosis, BMI &lt;30, no current use of beta blocker, and VO2max &gt;85% of the predicted value for age and sex (Wasserman equation). OG refers to all other patients not in NG. Models were trained and evaluated for each group using stratified 5-fold cross-validation. We also trained different models using only resting variables (R-VARS) and resting and submaximal exercise variables (R+S-VARS). Feature importance was assessed using Shapely additive explanations (SHAP) values to identify how the feature related to the VO2max prediction. Results: The regression models were trained on the NG, OG, and total (N+OG) groups. The optimal models were Bayesian Ridge for the NG and Light Gradient Boosting Machine for the other two groups. The mean (standard deviation) R2 when using only R-VARS was 0.67(0.037) for the NG, 0.54 (0.014) for the OG, and 0.55 (0.009) for the N+OG. When using R+S-VARS, performance increased to 0.82 (0.014) for the NG, 0.80 (0.010) for the OG, and 0.8 (0.008) for the N+OG. Chronotropic index (ci), body mass index (BMI), VO2 at the first ventilatory threshold (VO2h1kg), minute ventilation at the second ventilatory threshold (VEH2), and forced expiratory volume (FEV1) were important features across the models trained with R+S-VARS. CI, BMI, and VEH2 had a negative effect, while VO2h1kg, FEV1 had positive effect on VO2max prediction. Conclusion: Our VO2max prediction model demonstrated remarkable accuracy in this dataset representing a generally healthy, non-athlete population using R+S-VARS. Particularly noteworthy was the enhanced performance within subgroups exhibiting a lower VO2max. This methodology offers a means to assess VO2max for individuals who might not achieve maximal exhaustion during CPET due to non-cardiopulmonary reasons.

Long-Term Physiological Adaptations Induced by Short-Interval High-Intensity Exercises: An RCT Comparing Active and Passive Recovery

Background: High-intensity interval training (HIIT) is one of the most debated methods involving several parameters that could be modulated, but the long-term adaptations it induces are still unclear. This investigation aimed to evaluate the efficacy of running and whole-body exercises with high-intensity (&gt;80% heart rate) short intervals (30 s) in body composition and physical performance and compare the effects between groups with active (AR) or passive recovery (PR), both in males and females. Methods: Eighteen trained young adults (55.56% ♀) were randomly allocated to the PR (n = 9, 23.09 ± 2.56 years, 163.69 ± 9.88 cm, 68.96 ± 14.62 kg) or AR (n = 9, 22.05 ± 1.54 years, 170.61 ± 11.5 cm, 68.78 ± 12.45 kg) group. Both groups performed eight weeks of HIIT, with an equal progression, training, and volume load (TL: F = 1.55, p = 0.214; VL: F = 0.81, p = 0.505). Body fat (BF), fat-free mass (FFM), upper and lower limb fat (UFI, LFI) and muscle areas (UMA, LMA), handgrip strength (HGS), power (countermovement jump, CMJ), agility (5-0-5), and maximal oxygen consumption (V˙O2p) were tested before and after treatments. Results: The proposed HIIT reduced BF by 9.57% and increased FFM by 2.09%. Females reported better adaptations in LMA (8.34 times higher than males), while both sexes’ upper limb mass distribution was better affected by PR (♀: UFI g = 1.851, 95% CI: 0.51, 3.14; ♂: UFI g = 2.456, 95% CI: 0.336, 4.487). Concerning conditioning, the protocol increased V˙O2p by 6.47%. Females showed better adaptations in CMJ (RR = 1.8), while males showed better adaptations in agility (RR = 3.76). The interaction effects were significant for PR females (right = +6.28%; left = +9.28%) and for AR males (right = +19.21%; left = +19.04%) in HGS. Conclusions: Short-interval HIIT with different exercise recovery types may be a practical solution in training where several physiological improvements are needed. Coaches and trainers can take advantage of the versatile nature of HIIT, relying on desired movement patterns and long-term responses in both male and female individuals.

Abstract 4134460: Application of Principal Component Analysis to Heterogenous Fontan Registry Data to Identify Independent Contributing Factors to Decline

Introduction: Single ventricle heart disease is a severe and life-threatening illness, and improvements in clinical outcomes of those with Fontan circulation have not yet yielded acceptable survival over the past two decades. Patients are at risk of developing a diverse variety of Fontan-associated comorbidities that may ultimately require heart transplant. Goal: Our study goal was to determine if principal component analysis (PCA), which determines unique directions of data variance, applied to data collected from a pediatric Fontan cohort can predict functional decline (N=140). Methods: Heterogeneous data broadly consisting of measures of cardiac and vascular function, exercise (VO 2max ), lymphatic biomarkers, and blood biomarkers were collected over 9 years at a single site as part of a prospectively applied clinical care pathway; in that time, 16 events occurred that are considered here in a composite adverse outcome measure. After standardization and PCA, principal components (PCs) representing &gt;5% of total variance were thematically labeled based on their constituents and tested for association with the composite outcome. Results: Our main findings suggest that the 6 th PC (PC6), representing 7.1% percent of the total variance in the set, is greatly influenced by albumin, alkaline phosphatase, total protein, BUN and BNP max and is a superior measure of proportional hazard compared to EF; it displayed the greatest accuracy for classifying Fontan patients as determined by AUC. In bivariate hazard analysis, we found that models combining systolic function (EF or PC5) and blood biomarkers (PC6) were most predictive, with the former having the greatest AIC, and the latter having the highest c-statistic. Conclusion: Our findings support the hypothesis that a broad, prospectively collected, multiorgan system model analyzed by way of unsupervised machine learning methods will improve prognosis of adverse outcomes in a Fontan cohort.

Abstract 4122257: Inhibition of Neutrophil Extracellular Traps Prevents Heart Failure by Preserving Mitochondrial Function of Cardiomyocytes in Mice

Background: We have previously demonstrated that neutrophil extracellular traps (NETs) in myocardial tissue are associated with cardiac dysfunction and adverse outcomes in patients with heart failure with reduced ejection fraction. Here, we aimed to elucidate the underlying mechanisms and to clarify whether inhibiting NETs could rescue the cardiac phenotype using ex vivo and in vivo models. Methods and Results: Given that peptidyl arginine deiminase 4 (PAD4) is essential for the formation of NETs, PAD4 knockout mice were used for this study. First, we assessed the mitochondrial function of cardiomyocytes by conducting real-time measurements of the oxygen consumption rate in ex vivo . Extracellular flux analysis revealed that NETs-containing conditioned medium from wild-type neutrophils or purified NET components led to impaired mitochondrial oxygen consumption of adult mouse cardiomyocytes, while these effects were abolished when PAD4 in neutrophils was genetically ablated (Figure 1). In a murine model of pressure overload-induced heart failure, transverse aortic constriction (TAC) operation was performed on wild-type and PAD4 knockout mice. Immunohistological analysis demonstrated that TAC induced the formation of NETs in the myocardium, with the greatest number of NETs occurring at 1 day, persisting into the failing stage at 4 weeks in wild-type mice, while PAD4-deficient hearts displayed no presence of NETs in the heart tissue (Figure 2). Four weeks after TAC, left ventricular ejection fraction was reduced in wild-type mice, whereas PAD4 knockout mice displayed preserved left ventricular ejection fraction (Figure 2). Finally, we investigated the bioenergetics of cardiomyocytes isolated from PAD4 knockout mice after TAC. Maximal mitochondrial oxygen consumption rate in cardiomyocytes isolated from TAC-operated PAD4 knockout mice was significantly higher than in those from TAC-operated wild-type mice (Figure 3). Conclusion: Our data suggest that NETs directly derived impairment of mitochondrial function in cardiomyocytes. Inhibiting NETs represents a potential therapeutic approach for heart failure, preventing mitochondrial dysfunction of cardiomyocytes.

The whole-body and skeletal muscle metabolic response to 14 days of highly controlled low energy availability in endurance-trained females.

This study investigated the effects of 14 days low energy availability (LEA) versus optimal energy availability (OEA) in endurance-trained females on substrate utilization, insulin sensitivity, and skeletal muscle mitochondrial oxidative capacity; and the impact of metabolic changes on exercise performance. Twelve endurance-trained females (V̇O2max 55.2 ± 5.1 mL × min-1 × kg-1) completed two 14-day randomized, blinded, cross-over, controlled dietary interventions: (1) OEA (51.9 ± 2.0 kcal × kg fat-free mass (FFM)-1 × day-1) and (2) LEA (22.3 ± 1.5 kcal × kg FFM-1 × day-1), followed by 3 days OEA. Participants maintained their exercise training volume during both interventions (approx. 8 h × week-1 at 79% heart rate max). Skeletal muscle mitochondrial respiratory capacity, glycogen, and maximal activity of CS, HAD, and PFK were unaltered with LEA. 20-min time trial endurance performance was impaired by 7.8% (Δ -16.8 W, 95% CI: -23.3 to -10.4, p < .001) which persisted following 3 days refueling post-LEA (p < .001). Fat utilization was increased post-LEA as evidenced by: (1) 99.4% (p < .001) increase in resting plasma free fatty acids (FFA); (2) 270% (p = .007) larger reduction in FFA in response to acute exercise; and (3) 28.2% (p = .015) increase in resting fat oxidation which persisted during submaximal exercise (p < .001). These responses were reversed with 3 days refueling. Daily glucose control (via CGM), HOMA-IR, HOMA-β, were unaffected by LEA. Skeletal muscle O2 utilization and carbohydrate availability were not limiting factors for aerobic exercise capacity and performance; therefore, whether LEA per se affects aspects of training quality/recovery requires investigation.

Strength Training Among Male Master Cyclists—Practices, Challenges, and Rationales

Background: Cycling performance declines with age due to reduced aerobic capacity, along with reductions in muscle mass and bone density. Strength training can help counter these effects. This study aims to explore the strength training practices, challenges, and decision-making rationale of male master cyclists to optimize performance and health as they age. Methods: A total of 555 male master cyclists aged 35 and above completed an online questionnaire, distributed via social media platforms, that included Likert-type, single- and multiple-selection, and open-ended questions. Participants were then divided into two age groups: 35–49 years (n = 359) and ≥50 years (n = 196). Analyses involved descriptive statistics, Wilcoxon signed-rank tests, Mann–Whitney U-tests, and chi-square tests, with qualitative data analyzed using content analysis. Results: More cyclists engaged in strength training during the off-/pre-season, with a significant reduction in both frequency and the number of cyclists engaging in strength training during the race season. The strength training practice was focused mainly on core and lower body, employing hypertrophy and maximal strength training methods. Key challenges included fatigue induced by strength training and limited time to perform strength training. The main rationale for the strength training revolved around improving cycling performance, reducing injury risk, and the health benefits of strength training. Both age categories, but the older group in particular, reported bone health as a primary rationale for strength training. Conclusions: While strength training offers performance and health benefits, issues of fatigue and time constraints remain substantial, suggesting the need for tailored training programs to improve adherence and effectiveness.

Abstract 4124293: Exercise Capacity in Patients with Fontan Physiology

Introduction/Background: In the absence of a sub-pulmonary ventricle in the Fontan circulation, augmentation of pulmonary blood flow and filling of the systemic ventricle during exercise are limited. Cardiopulmonary exercise testing (CPET) is a reliable method for evaluation of aerobic capacity, gas exchange, and other physiologic parameters used for risk stratification in this population. Despite the ubiquitous use of CPET, reference ranges for patients with Fontan physiology are limited. The purpose of this study is to describe exercise characteristics and their relationship with different characteristics of Fontan physiology, imaging, and hemodynamics. Methods/Approach: In this retrospective cohort study, CPET results were reviewed for adult Fontan patients at the University of Washington between May 2021 and February 2024. Demographics, comorbidities, medications, type of Fontan conduit, imaging characteristics, hemodynamics, and exercise characteristics were included. Results were compared to a large previously published cohort of Fontan patients. Univariate linear regression was used to identify associations between demographics, cardiac anatomy, and exercise parameters. A p-value of less than 0.05 was considered statistically significant. Results/Data: Baseline demographics were notable for an older patient population (31±7 years) with lower indexed peak VO 2 (20.5±5.6 mL/kg/min) and greater V E /VCO 2 slope (37±7) compared to the historic cohort. Indexed peak VO2 was associated with age, BMI, type of Fontan conduit, FEV1, FVC, resting oxygen saturation, peak systolic blood pressure, and peak heart rate. Indexed peak VO 2 was notably not significantly associated with sex, systemic ventricular morphology, ventricular systolic function, Fontan pressure, or the presence of conventional heart failure medical therapy. Conclusions: In the growing population of older patients with Fontan physiology, development of age-specific population normative data may increase the clinical utility of CPET. Further investigation of the relationship between imaging characteristics, hemodynamics, and exercise parameters is needed in the Fontan population.

Impact of VO2 Max Capacity And Application of Training Methods on the Effectiveness of Endurance Ability

This research aims to see the effectiveness of training methods and aerobic capacity (VO2 Max) to increase endurance capacity (aerobic capacity). The method used in this research is an experimental method, with the research sample being Karawang district football players. The independent variables of this research are interval training and vo2 max, while the dependent variable is general endurance (aerobic capacity). In carrying out research, the interval method will be given taking into account the high and low aerobic capacity. The results of the research show that the interval method has a significant influence on increasing endurance (aerobic capacity), and the interval method has an interdependence with the level of aerobic capacity in increasing endurance. Extensive intervals are suitable for athletes who have low aerobic capacity and have not been in the process for long. Intensive interval training is suitable for athletes who have moderate aerobic capacity and have been in the training process for quite a long time. And short intervals are suitable for athletes who have a high aerobic capacity and have been training for a long time. Providing the interval method needs to take into account the high and low levels of aerobic capacity, because the interval method is a fairly heavy training method which needs to take into account the aerobic capacity capital of the athlete who will be trained and whether or not they have been involved in the training process for a long time. Keywords: extensive intervals, intensive and short intervals, VO2 Max, Speed ​​Endurance

The effect of vo2max on muscle oxygen saturation (SMO2) in University Badminton Athletes

Muscle oxygen saturation (SmO2) is an additional physiological parameter that helps identify the transition from aerobic to anaerobic workload. Additionally, it can be used to predict performance by calculating Vo2 and energy expenditure. Muscle oxygen saturation (SmO2) is a measure of oxygen saturation in muscle tissue that can be used to evaluate metabolic zones, training intensity, and athlete performance. An athlete's muscle oxygen saturation (SMO2) is a measure of how well their muscles use oxygen, which is important for evaluating performance and creating training programs. This research is a week-long experimental study with a one-shot case study design, research intends to look at the effect of Vo2Max on muscle oxygen saturation (SMO2) in university badminton athletes. The subjects of this research are student athletes who actively practice badminton. There were 6 respondents who were willing to be research subjects and had met the specified criteria, namely actively exercising three times a week and being in good health. Then the author took data on athletes who had the highest and lowest Vo2Max to analyze SMO2 optimization, which was the focus of this research. The results of the analysis show that there is a significant influence between Vo2max and SMO2 optimization; this can be seen by the difference through the t test with a sig (2-tailed) value of 0.000 &lt; 0.05. Another finding is that athletes with higher Vo2max show better SMO2 recovery results. better than athletes with low Vo2max; in this study, athletes with higher Vo2max showed a 37% increase in SMO2 over two minutes, while athletes with lower Vo2max showed a 21% increase. This is an interesting finding for coaches and athletes regarding the importance of Vo2 max capacity in optimizing SMO2.

Aerobic and anaerobic poise of white swimming muscles of the deep-diving scalloped hammerhead shark: comparison to sympatric coastal and deep-water species

Scalloped hammerhead sharks (Sphyrna lewini) routinely perform rapid dives to forage on mesopelagic prey. These deep dives consist of intensive swimming followed by recovery periods in the surface mixed layer. Swimming muscle temperature profiles suggest that S. lewini suppresses gill function as a means to reduce convective heat loss during dives into cool water. Such intensive swimming behavior coupled with reduced respiration prompted us to test whether the aerobic and anaerobic metabolic capacities of the white swimming muscle tissue of this species are greater than those of other shark species from the same region. The activities of key enzymes used in aerobic and anaerobic metabolism provide an indirect indicator of the metabolic potential (“poise”) of a tissue. Here we measured the maximal activities [international units (µmol substrate converted to product per min, U) per gram of wet tissue mass at 10°C] of the citric acid cycle enzymes citrate synthase (CS) and malate dehydrogenase (MDH) and glycolytic enzymes pyruvate kinase (PK) and lactate dehydrogenase (LDH) from white swimming muscle of S. lewini. Enzyme activities, and ratios of these enzyme activities that indicate relative indexes of aerobic to anaerobic capacity, were compared to those measured in three sympatric coastal carcharhinid sharks and two deep-dwelling species, Echinorhinus cookei and Hexanchus griseus. This is the first report of swimming-muscle enzyme activity for these deep-dwelling species. In comparison to the other species, S. lewini had significantly higher activities of both LDH and MDH in the white muscle, and a higher MDH/CS ratio. The high LDH activities suggest that the white muscle of S. lewini relies on relatively high rates of anaerobic ATP production, with would result in build up of high lactate levels, during deep foraging dives. High MDH activity in S. lewini white muscle suggests the potential for lactate levels to be rapidly reduced when aerobic conditions are restored while in the surface mixed layer between dives. These biochemical characteristics may enable S. lewini to swim rapidly while suppressing gill function during deep dives and thereby exploit a very different ecological niche from sympatric shark species (e.g., coastal carcharhinids) and hunt more rapidly via faster swimming for deep-water prey compared to species that permanently inhabit deep depths.

Prescribing submaximal training based on the lactate threshold improved aerobic fitness in dogs with preclinical myxomatous mitral valve disease

Abstract Exercise intolerance may be a primary symptom of myxomatous mitral valve disease (MMVD) and a significant factor in reducing the quality of a dog’s life. Aerobic training effectively improves oxygen uptake and life expectancy in human patients with chronic heart failure. Lactate threshold (LT) is used to prescribe training programs. We conducted a study with dogs diagnosed with asymptomatic MMVD (stage B1), using the velocity corresponding to the visual lactate threshold (VLTv) and an eight-week submaximal training program (STP), three times a week, with each session lasting 30 min, to improve their aerobic fitness. The dogs were assigned into two groups: a healthy control group and a MMVD group (stage B1). The treadmill-based graded exercise test (GXT) was used to determine the lactate-velocity curve (LVC) inflexion point. We utilised the velocity corresponding to 70% VLTv as the external load STP, representing a training zone between 145 and 157 bpm. Before the STP, VLTv and maximum velocity (Vmax) were lower in B1 dogs compared with the healthy group. The VLTv increased in the B1 dogs, resulting in rightward shifts of the LVC. The VLT values for healthy dogs were 3.62 ± 0.90 m/s and 4.75 ± 0.6 m/s; for B1 dogs were 3.03 ± 0.6 m/s and 3.8 ± 0.75 m/s in the pre-STP and post-STP. The Vmax values were 4.50 ± 0.70 m/s and 4.75 ± 1.04 m/s for healthy dogs, and 4.0 ± 0.53 m/s and 4.66 ± 0.74 m/s for B1 dogs. In both groups, changes in the relationship between lactatemia and exercise work may indicate improvements in aerobic and anaerobic capacities. VLTv, as an external training loading, should be considered when prescribing tailored training programs for dogs with asymptomatic myxomatous mitral valve disease to improve their muscular and cardiovascular function and exercise tolerance.

Evaluating the athletics Athletes' Physical Fitness for PON XXI/2024 Qualification

Maluku's achievements can grow when the human resources of the coaches are enhanced to promote professionalism in the development of the science and technology of sports. Thus, the training process is not solely based on experience but on the science of training, which is studied in depth to support the better development of training athletes in the future. This study aims to determine how well Maluku athletic athletes' physical fitness is prepared for the PON XXI/2024 qualification round held in Solo, Central Java. This study used saturation sampling to study all the population samples. The instruments utilized in this study are the VO2 Max test, local muscle endurance test, biomotor ability test, speed and power tests, and local muscular stamina tests. The results revealed that the athletes' physical fitness to face a national event, in this case, the PON XXI/2024 qualification, is still considered medium, and the physiological condition belongs to the category of good based on the running time achievement that is close to the time achieved on the PON XXI qualification. The results of the study indicate that Maluku's athletic athletes have improved. However, the improvement has not surpassed the PB PASI time record. Despite the improvement in performance during training, the athletes had not reached the target to pass into the PON XXI Qualification. Keywords: evaluation, physical fitness, athletes’ achievement.