Submaximal Exercise Test Research Articles

The prognostic value of the cardiorespiratory optimal point during submaximal exercise testing in heart failure

IntroductionPeak oxygen consumption (pVO2) is a key parameter for assessing the prognosis of heart failure with reduced ejection fraction (HFrEF). However, it is less reliable when the cardiopulmonary exercise test (CPET) is not maximal. ObjectiveTo compare the prognostic power of various exercise parameters in submaximal CPET. MethodsAdult patients with HFrEF undergoing CPET in a tertiary center were prospectively assessed. Submaximal CPET was defined as a respiratory exchange ratio ≤1.10. Patients were followed for one year for the primary endpoint of cardiac death and urgent heart transplantation (HT). Various CPET parameters were analyzed as potential predictors of the combined endpoint and their prognostic power (area under the curve [AUC]) was compared using the Hanley-McNeil test. ResultsCPET was performed in 442 HFrEF patients (mean age 56±12 years, 80% male), of whom 290 (66%) had a submaximal CPET. Seventeen patients (6%) reached the primary endpoint. The cardiorespiratory optimal point (COP) had the highest AUC value (0.989, p<0.001), and significantly higher prognostic power than other tested parameters, with pVO2 presenting an AUC of 0.753 (p=0.001). COP ≥36 had significantly lower survival free of HT during follow-up (p<0.001) and presented a sensitivity of 100% and a specificity of 89% for the primary endpoint. ConclusionCOP had the highest prognostic power of all parameters analyzed in a submaximal CPET. This parameter can help stratify HFrEF patients who are physiologically unable to reach a maximal level of exercise.

Cardiorespiratory Optimal Point Is a Submaximal Exercise Test Variable and a Predictor of Mortality Risk: THE BALL STATE ADULT FITNESS LONGITUDINAL LIFESTYLE STUDY (BALL ST).

The cardiorespiratory optimal point (COP) is the minimum ventilatory equivalent for oxygen. The COP can be determined during a submaximal incremental exercise test. Reflecting the optimal interaction between the respiratory and cardiovascular systems, COP may have prognostic utility. The aim of this investigation was to determine the relationship between COP and all-cause mortality in a cohort of apparently healthy adults. The sample included 3160 apparently healthy adults (46% females) with a mean age of 44.0 ± 12.5 yr who performed a cardiopulmonary exercise test. Cox proportional hazards models were performed to assess the relationship between COP and mortality risk. Prognostic peak oxygen uptake (V˙ o2peak ) and COP models were compared using the concordance index. There were 558 deaths (31% females) over a follow-up period of 23.0 ± 11.9 yr. For males, all Cox proportional hazards models, including the model adjusted for traditional risk factors and V˙ o2peak , had a positive association with risk for mortality ( P &lt; .05). For females, only the unadjusted COP model was associated with risk for mortality ( P &lt; .05). The concordance index values indicated that unadjusted COP models had lower discrimination compared with unadjusted V˙ o2peak models ( P &lt; .05) and V˙ o2peak did not complement COP models ( P ≥ .13). Cardiorespiratory optimal point is related to all-cause mortality in males but not females. These findings suggest that a determination of COP can have prognostic utility in apparently healthy males aged 18-85 yr, which may be relevant when a maximal exercise test is not feasible or desirable.

Mean Six Minute Walk Distance of Healthy Healthcare Workers of a Tertiary Care Centre: A Descriptive Cross-sectional Study.

The six-minute walk test is a sub-maximal exercise test used in clinical populations to determine functional exercise capacity. It is a safe, simple, and inexpensive test. There are a number of reference equations described for estimating six-minute walk distance in healthy subjects in different countries. However, there is a lack of standard reference value for six minute walk distance in healthy Nepalese population. The aim of the study was to find the mean six minute walk distance of healthy healthcare workers of a tertiary care centre. A descriptive cross-sectional study was conducted among healthy health care workers of a tertiary care centre from 1 August 2021 to 30 November 2021 after taking ethical approval from Institutional Review Committee (Reference number: 1507202105). Convenience sampling was done. Point estimate and 95% Confidence Interval were calculated. The mean six-minute walk distance of the 162 healthy health care workers was 486.74±74.73 (475.23-498.24, 95% Confidence Interval) m. Men walked 519.61±79.19 m and women walked 474.12±75.62 m. The mean age of the participants was 29.25±8.25 years. The mean six-minute walk distance was found to be lower when compared to similar studies conducted in similar settings. exercise test; health personnel; healthy volunteer; walk test.

Octanoic Acid-Enrichment Diet Improves Endurance Capacity and Reprograms Mitochondrial Biogenesis in Skeletal Muscle of Mice.

Background: Medium Chain Fatty Acids (MCFAs) are a dietary supplement that exhibit interesting properties, due to their smaller molecular size. The acute consumption of MCFAs is expected to enhance exercise performance. However, the short-term effects of MCFAs on endurance performance remains poorly understood. The aim of our study is to evaluate the octanoic acid (C8)-rich diet effect on endurance capacity, and to explore their molecular and cellular effects. Methods: C57BL/6J mice were fed with a chow diet (Control group) or an octanoic acid-rich diet (C8 diet) for 6 weeks. Spontaneous activity, submaximal and maximal exercise tests were carried out to characterize the exercise capacities of the mice. Beta-oxidation and mitochondrial biogenesis pathways were explored in skeletal muscle by RT-qPCR, Western Blot (Quadriceps) and histochemical staining (Gastrocnemius). Results: Mice fed with a C8-rich diet presented a higher spontaneous activity (p < 0.05) and endurance capacities (p < 0.05) than the control, but no effect on maximal effort was observed. They also presented changes in the skeletal muscle metabolic phenotype, with a higher number of the oxidative fibers, rich in mitochondria. At the molecular level, the C8-diet induced an AMPK activation (p < 0.05), associated with a significant increase in PGC1a and CS gene expression and protein levels. Conclusion: Our study provided evidence that C8-enrichment as a food supplementation improves endurance capacities and activates mitochondrial biogenesis pathways leading to higher skeletal muscle oxidative capacities.

Intraocular Pressure Fluctuation during Aerobic Exercise at Different Exercise Intensities.

Few studies have examined the effects of different aerobic-exercise intensities on intraocular-pressure (IOP) changes. This may be important for eye diseases that are impacted by IOP or its fluctuation, including glaucoma, and diabetes that is complicated by diabetic retinopathy. We investigated the effects of low-, moderate-, and high-intensity exercise on IOP in healthy subjects. A submaximal cardiopulmonary exercise test was performed in 18 healthy male subjects, and the maximal oxygen uptake was calculated. The subjects then exercised for 20 min at 30%, 50%, and 70% ·VO2 of maximal oxygen uptake, and their IOP was measured at rest and every 5 min during exercise. Oxygen uptake was monitored using an expiratory gas analyzer during exercise to maintain accurate exercise intensity and adjust exercise load. Oxygen uptake during exercise was significantly higher at all intensities from 5 to 20 min than at rest. IOP was significantly lower at 70% exercise intensity from 5 to 20 min than at rest. A negative correlation existed between IOP and ·VO2. IOP remained unchanged during low- and moderate-intensity exercise but significantly declined during high-intensity exercise compared with that at rest. Although various factors, such as β-blockers, are involved in IOP decline at rest, a different mechanism is involved in IOP decline during exercise.

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.

Validity of Estimated Cardiorespiratory Fitness in Patients With Primary Breast Cancer

BackgroundEstimated peak oxygen consumption (Vo2peak) is widely used in oncology; however, estimated Vo2peak equations were developed in noncancer settings. ObjectivesThe aim of this study was to evaluate the validity of estimated Vo2peak in women with primary breast cancer and to develop oncology-specific estimated Vo2peak equations. MethodsVo2peak was directly measured (TrueOne 2400, Parvo Medics) during 380 cardiopulmonary exercise tests in women previously treated for breast cancer (mean age: 59 ± 10 years; 3.1 ± 1.2 years post-therapy). The American College of Sports Medicine (ACSM), the Fitness Registry and the Importance of Exercise National Database (FRIEND), and heart failure (HF)-FRIEND equations were used to estimate Vo2peak. New equations were developed using patient and peak (Oncpeak) or submaximal (Oncsub) exercise test characteristics. ResultsThe median differences between measured and estimated Vo2peak were 7.0 mL O2·kg−1·min−1, 3.9 mL O2·kg−1·min−1, and −0.2 mL O2·kg−1·min−1 for ACSM, FRIEND, and HF-FRIEND, respectively. The number of estimated Vo2peak values within ±3.5 mL O2·kg−1·min−1 of the measured values was 70 (18%), 164 (43%), and 306 (81%) for ACSM, FRIEND, and HF-FRIEND, respectively. The Oncpeak and OncSub models included body mass index, age, a history of chemotherapy or radiation, the peak measured heart rate, and the treadmill grade and/or speed. The median differences between measured and estimated Vo2peak were 0.02 mL O2·kg−1·min−1 (Oncpeak) and −0.2 mL O2·kg−1·min−1 (Oncsub). Eighty-six percent (n = 325) and 76% (n = 283) estimated Vo2peak values were within ±3.5 mL O2·kg−1·min−1 of the measured Vo2peak values for Oncpeak and Oncsub, respectively. ConclusionsHF-FRIEND or oncology-specific equations could be applied to estimate Vo2peak in patients previously treated for breast cancer in settings where cardiopulmonary exercise tests are not available. (Trial Comparing the Effects of Linear Versus Nonlinear Aerobic Training in Women With Operable Breast Cancer [EXCITE]; NCT01186367

Submaximal Walking Tests: A Review of Clinical Use

ABSTRACT Though graded exercise testing is the gold standard for assessing cardiorespiratory fitness, submaximal exercise testing is also useful to assess cardiorespiratory status and functional capacity when maximal testing is not feasible. Submaximal walking tests are advantageous as they have less risk, lower cost, require less time and equipment, and walking is a familiar activity that is easy to do in most environments. A number of submaximal walking tests exist for both overground and treadmill walking. Regression equations to predict V̇o2max values based on walking time, distance, and other variables that influence exercise tolerance have been developed for some submaximal tests, including the Rockport Fitness Walking Test and the Single-Stage Treadmill Walk Test. The 6-Minute Walk Test is a common test used in clinical populations to predict prognosis and assess change in functional capacity after intervention. Determining which submaximal walking test to use depends on purpose and setting, subject characteristics, equipment availability, space, and time. This review will provide clinicians with an overview of submaximal walking test protocols and provide reference equations and minimal clinically important difference values to interpret results.

Community based cross sectional study on the patterns of blood pressures and aerobic capacity among young adult smokers

Introduction : India is home to about 12% of the world’s smokers. More than 1 million people die every year due to tobacco related illnesses. smokers have tendencies to be less physically active than nonsmokers . We hypotheses that there was a significant relation between smoking and decrease in cardiovascular fitness. The purpose of this study was to examine the chronic effects of smoking on cardiovascular fitness and Blood pressure in young and adult smokers. Methods: This was a community based cross sectional study conducted in a span of 6 months with prior consent. 100 Subjects chosen for the study (50 smokers &amp; 50 non-smokers) involving both the genders , aged 18 years to 25 years and all classes of socio economic strata. 100 male participant were recruited &amp; divided into two groups. BP &amp; Heart rate (HR) were non-invasively measured in young non-smoking and smoking subjects at rest, during the accomplishment of a submaximal exercise test and recovery period. Smoking status of smokers was analyzed by three parameters, i.e., years of smoking, number of cigarettes smoke per day, and pack year. Results: There was no significant difference between both groups regarding to age, weight and height.

An Examination and Critique of Subjective Methods to Determine Exercise Intensity: The Talk Test, Feeling Scale, and Rating of Perceived Exertion.

Prescribing exercise intensity is crucial in achieving an adequate training stimulus. While numerous objective methods exist and are used in practical settings for exercise intensity prescription, they all require anchor measurements that are derived from a maximal or submaximal graded exercise test or a series of submaximal or supramaximal exercise bouts. Conversely, self-reported subjective methods such as the Talk Test (TT), Feeling Scale (FS) affect rating, and rating of perceived exertion (RPE) do not require exercise testing prior to commencement of the exercise training and therefore appear as more practical tools for exercise intensity prescription. This review is intended to provide basic information on reliability and construct validity of the TT, FS, and RPE measurements to delineate intensity domains. The TT and RPE appear to be valid measures of both the ventilatory threshold and the respiratory compensation threshold. Although not specifically examined, the FS showed tendency to demarcate ventilatory threshold, but its validity to demarcate the respiratory compensation threshold is limited. Equivocal stage of the TT, RPE of 10-11, and FS ratings between fairly good (+ 1) and good (+ 3) are reflective of the ventilatory threshold, while negative stage of the TT, RPE of 13-15, and FS ratings around neutral (0) are reflective of the respiratory compensation threshold. The TT and RPE can effectively be used to elicit homeostatic disturbances consistent with the moderate, heavy, and severe intensity domains, while physiological responses to constant FS ratings show extensive variability around ventilatory threshold to be considered effective in demarcating transition between moderate and heavy intensity domains.

Impact of surgical mask on performance and cardiorespiratory responses to submaximal exercise in COVID-19 patients near hospital discharge: A randomized crossover trial

Background Wearing a surgical mask in hospitalized patients has become recommended during care, including rehabilitation, to mitigate coronavirus disease 2019 (COVID-19) transmission. However, the mask may increase dyspnoea and raise concerns in promoting rehabilitation activities in post-acute COVID-19 patients. Objective To evaluate the impact of the surgical mask on dyspnoea, exercise performance and cardiorespiratory response during a 1-min sit-to-stand test in hospitalized COVID-19 patients close to discharge. Methods COVID-19 patients whose hospital discharge has been planned the following day performed in randomized order two sit-to-stand tests with or without a surgical mask. Outcome measures were recorded before, at the end, and after two minutes of recovery of each test. Dyspnoea (modified Borg scale), cardiorespiratory parameters and sit-to-stand repetitions were measured. Results Twenty-eight patients aged 52 ± 10 years were recruited. Compared to unmasked condition, dyspnoea was significantly higher with the mask before and at the end of the sit-to-stand test (mean difference[95%CI]: 1.0 [0.6, 1.4] and 1.7 [0.8, 2.6], respectively). The difference was not significant after the recovery period. The mask had no impact on cardiorespiratory parameters nor the number of sit-to-stand repetitions. Conclusion In post-acute COVID-19 patients near hospital discharge, the surgical mask increased dyspnoea at rest and during a submaximal exercise test but had no impact on cardiorespiratory response or exercise performance. Patients recovering from COVID-19 should be reassured that wearing a surgical facemask during physical or rehabilitation activities is safe. These data may also mitigate fears to refer these patients in rehabilitation centres where mask-wearing has become mandatory.

Predictors of Submaximal Exercise Test Attainment in Adults Reporting Long COVID Symptoms.

Adults with long COVID often report intolerance to exercise. Cardiopulmonary exercise testing (CPET) has been used in many settings to measure exercise ability but has been conducted in a few long COVID cohorts. We conducted CPET in a sample of adults reporting long COVID symptoms using a submaximal cycle ergometer protocol. We studied pre-exercise predictors of achieving 85% of the age-predicted maximum heart rate (85%HRmax) using logistic regression. Eighty participants were included (mean age 46 years, range 25–78, 71% women). Forty participants (50%) did not reach 85%HRmax. On average, non-achievers reached 84% of their predicted 85%HRmax. No adverse events occurred. Participants who did not achieve 85%HRmax were older (p < 0.001), had more recent COVID-19 illness (p = 0.012) with higher frequency of hospitalization (p = 0.025), and had been more affected by dizziness (p = 0.041) and joint pain (p = 0.028). In the logistic regression model including age, body mass index, time since COVID-19, COVID-19-related hospitalization, dizziness, joint pain, pre-existing cardiopulmonary disease, and use of beta blockers, independent predictors of achieving 85%HRmax were younger age (p = 0.001) and longer time since COVID-19 (p = 0.008). Our cross-sectional findings suggest that exercise tolerance in adults with long COVID has potential to improve over time. Longitudinal research should assess the extent to which this may occur and its mechanisms. ClinicalTrials.gov identifier: NCT05027724 (TROPIC Study).

A Comparison of Substrate Utilization Profiles During Maximal and Submaximal Exercise Tests in Athletes.

BackgroundExercise is primarily sustained by energy derived from lipids (plasma free fatty acids and intramuscular triglycerides), and glucose (plasma glucose and muscle glycogen). Substrate utilization is the pattern by which these fuel sources are used during activity. There are many factors that influence substrate utilization. We aim to delineate the effect of exercise intensity and body composition on substrate utilization.ObjectiveThe objective of our study was to discern the differences in substrate utilization profiles during a maximal and submaximal graded exercise test, and to determine the extent to which body composition influences substrate utilization during the exercise tests.MethodsA total of 27 male athletes, 32.5 ± 11 years of age, were recruited for this study. Body composition was analyzed using a bioelectrical impedance analyzer. Maximal and submaximal exercise tests were performed on a treadmill. A novel graded submaximal treadmill protocol was used for the submaximal test.ResultsAverage percent body fat (PBF) was 15.8 ± 5%. Average maximal oxygen consumption (VO2max) was 47.6 ± 9 mL/kg/min, while the average exercise intensity (percent VO2max) at which participants were shifting to glucose predominance for energy during the maximal and submaximal tests were 76 ± 8.3% and 58.4 ± 21.1%, respectively. A paired-samples t-test was conducted to compare percent VO2max at crossover point in maximal and submaximal graded exercise tests. There was a significant difference in percent VO2max at the crossover point for maximal (76 ± 8.3%) and submaximal (58 ± 21.1%) tests (t = 4.752, p = 0.001). A linear regression was performed to elucidate the interaction between exercise intensity at the crossover point and body composition during a maximal and submaximal graded exercise test. There was a significant effect of PBF on percent VO2max at crossover point during the maximal graded exercise test [F(1,24) = 9.10, P = 0.006] with an R2 of 0.245. However, there was no significant effect of PBF on percent VO2max at crossover point during the submaximal graded exercise test (P > 0.05).ConclusionSubstrate utilization, represented by the crossover point, is dependent on the rate of increase in exercise intensity. At maximal efforts, the crossover to carbohydrates from fats as the predominant fuel source occurs at a significantly later stage of percent VO2max than at submaximal efforts. Furthermore, body composition represented by PBF is a significant predictor of substrate utilization during maximal efforts. Athletes with a relatively higher PBF are more likely to have increased lipid oxidation during high intensity exercises than those with a lower body fat percentage.

Effects of photobiomodulation and deep water running in patients with chronic non-specific low back pain: a randomized controlled trial.

Photobiomodulation therapy (PBM) is often used to treat musculoskeletal disorders such as chronic non-specific low back pain (NSCLBP) as it can have positive effects on biomarkers-creatine kinase (CK) and serum cortisol levels-related to stress caused by physical exercise, such as deep water running (DWR) or by pain. The aim of this study was to evaluate the effects of the combination of PBM and aquatic exercise (DWR) on the intensity of pain, disability, 6-min walk test adapted (6WTA), and on cortisol and creatine kinase (CK) levels in a population with NSCLBP. The participants were allocated into three groups: TGPBM (Photobiomodulation and Training Group), TGPLA (Placebo Photobiomodulation and Training Group), and the GPBM (Photobiomodulation Group). Information regarding anthropometric data, blood pressure, and heart rate were collected, and the questionnaires were applied: IPAQ-Short Form, Oswestry Disability Index, and the Visual Analog Scale for Pain. The submaximal exercise test (6WTA) was performed. Blood was collected for analysis of cortisol and CK levels. The training sessions were performed twice a week, for 4weeks. In the intragroup comparisons, there were statistically significant changes in the TGPBM and GPBM groups in the outcomes pain intensity, disability (reductions in both groups), and in cortisol (increased in the TGPBM and reduced in the GPBM); in the TGPLA group, there was a statistically significant reduction only in the outcome of pain intensity. In the intergroup comparison, in the comparison between TGPBM and TGPLA, there was a statistically significant difference in the level of cortisol, as well as in the comparison between TGPBM and GPBM, in which there was a statistically significant difference for this same outcome (cortisol) and for the 6WTA outcome. The effects of the combination of PBM and aquatic exercise have positive effects on reducing pain intensity, disability, and cortisol levels, but its effects on other variables (6WTA and CK) are too small to be considered significant. Trial registration number: NCT03465228-April 3, 2019; retrospectively registered (ClinicalTrials.gov).

Effects of surgical facemasks on perceived exertion during submaximal exercise test in healthy children.

Only a few data associated to wearability of facemask during exercise are available in children. The aim of the study was to evaluate the effect of wearing a facemask on perceived exertion (primary aim), dyspnea, physical performance, and cardiorespiratory response during a submaximal exercise test in children aged between 8 and 12 years. This study was performed in 2021 in healthy volunteer children from 8 to 12 years. They performed prospectively two 1-min sit-to-stand tests (STST), with or without a surgical facemask. The perceived exertion (modified Borg scale), dyspnea (Dalhousie scale), heart rate, and pulsed oxygen saturation were recorded before and after STST. The STST measured the submaximal performance. Thirty-eight healthy children were recruited (8–9 years: n = 19 and 10–11 years: n = 19). After the STST, the perceived exertion increased with or without a facemask (8–9 years group: + 1 [0.6; 1.4] and + 1.6 [1.0; 2.1] — 10–11 years group: + 1.3 [0.7; 1.8] and + 1.9 [1.3; 2.6]) and it was higher with the facemask. The difference between the two conditions in perceived exertion was not clinically relevant in any group (mBorgf: 0.56 pts and 0.68 pts, respectively). The different domains of dyspnea assessed with Dalhousie scale were not influenced by the facemask. The submaximal performance measured by the STST was not changed by the mask whatever the age group. The cardio-respiratory demand was not clinically modified.Conclusion: The surgical facemask had no impact on dyspnea, cardiorespiratory parameters, and exercise performance during a short submaximal exercise in healthy children. What is Known: • The use of facemask has been associated with breathing difficulties during physical activities in adults.• Before the COVID-19 pandemic, the facemasks were not recommended during exercise in children and the consequences have been poorly investigated. What is New: • The different domains of dyspnea assessed with Dalhousie scale, the cardiac demand, and the submaximal performance measured by the STST were not changed by the facemask whatever the age group in children.

High-intensity interval training improves fat oxidation during submaximal exercise in active young men

This study aimed to examine the effects of four-weeks high-intensity interval training (HIIT) on fat oxidation responses during submaximal exercise in active young men. For this purpose, 20 active young men (who participated in the exercise three times per week) were divided into two groups, including a training group (age: 19.3±0.48 years, V̇O2peak 2.9±0.35 l/min, n=10) and a control group (age: 19.7±0.67 years, V̇O2peak 2.7±0.26 l/min, n=10). The training group performed high-intensity interval training for three sessions per week. Specifically, each session included 8-11 intensive cycling efforts comprising of 60 s duration. A 75 s low pedalling rate (30 W) was used as an active recovery between the intervals. Furthermore, a V̇O2peak test was performed prior to, at the end of two weeks and after the training period. Also, a 60 min constant cycling protocol was performed at ~60% V̇O2peak, in addition to the V̇O2peak test, before and after the training protocol. To assess plasma free fatty acids and glucose, blood samples were taken during a 60-min aerobic exercise prior to and following the training period. An increase (17.8%) in V̇O2peak was observed for the HIIT group after the training period compared to the control group (P&lt;0.05). The HIIT group performed the 60 min sub-maximal exercise test at a lower percentage of V̇O2peak, and decreases in the respiratory exchange ratio were greater in the HIIT group than in the control group (P&lt;0.05). Compared to the pre-test values and control group results, the HIIT group used less carbohydrate and more lipid oxidation during submaximal exercise (P&lt;0.05). The present study’s results indicate that short-term low volume HIIT can increase aerobic capacity and fat oxidation during submaximal exercise.

Abstract EP48: Long Term Improvement In Cardiorespiratory Fitness Ameliorates Insulin Sensitivity Beyond The Response Of Visceral/Ectopic Fat In Viscerally Obese Men

Introduction: The SYNERGIE study has documented the effects on the cardiometabolic risk (CMR) profile of a 1-year lifestyle intervention targeting physical activity (PA) and diet followed by an additional 2-year maintenance period in a sample of 144 men with visceral obesity and an atherogenic dyslipidemia. Previously published results, following the 1-year intervention, had reported significant improvements in CMR markers and a decrease in intramuscular lipids assessed by computed tomography (CT) using the area of low attenuation muscle (LAM) as a marker. However, following the 2-year maintenance period, a slight deterioration of CMR markers including visceral adiposity (VAT) was observed, with the exception of circulating insulin levels. Hypothesis: In this secondary analysis, we tested the hypothesis that variations in cardiorespiratory fitness (CRF) and LAM could explain the long-term improvement in insulin sensitivity indices. Methods: Anthropometric measurements and an oral glucose tolerance test were performed at 0, 1 and 3 years, as well as a submaximal exercise test to assess CRF. Areas and volume of VAT and areas of LAM at mid-thigh and L4-L5 (psoas and core) were measured by CT. Participants were classified into two groups based on CRF changes observed during the 2-year maintenance period: CRF increased (CRF+) and CRF decreased (CRF-). Results: Complete data were available in a subsample of 72 men (52±8 years). Mean annual PA decreased from 143 min/week during the intervention to 103 min/week after the 2-year maintenance period (p&lt;0.05). CRF changes during the maintenance period were negatively correlated with changes in psoas LAM area (r=-0.31; p&lt;0.01) and core LAM area (r=-0.30; p&lt;0.05). Changes in psoas LAM area (r=0.29; p&lt;0.05) and core LAM area (r=0.35; p&lt;0.01) were also correlated with changes in insulin resistance (HOMA-IR). The CRF+ group showed a greater decrease in HOMA-IR than the CRF- group (p&lt;0.05). CRF was found to limit the deterioration of the CMR profile observed during the 2-year maintenance period (smaller gain in BMI, waist circumference, VAT volume, and LAM at the psoas; p&lt;0.05). Conclusion: Despite some gain in VAT observed during the 2-year maintenance period following the initial 1-year lifestyle intervention, participants who were able to maintain or even increase their CRF during the 2-year maintenance period were those whose insulin sensitivity continued to improve, regardless of the changes in LAM. In conclusion, these results are consistent with the importance of targeting CRF for the long-term management of CMR in men with visceral obesity.

Adding objectivity to submaximal exercise testing by assessment of heart rate recovery in healthy volunteers (SEARCH-II)

Submaximal exercise tests (SETs) offer a cheaper, easier to conduct, and better tolerated alternative to ‘maximal’ cardiopulmonary exercise testing as a preoperative risk assessment tool.1 Quantifying HR recovery (HRR) is a potentially objective method for assessing cardiopulmonary fitness after SETs. HRR1 and HRR2 (calculated as HR on exercise cessation minus HR at 1 and 2 min of rest) are commonly used methods for quantifying HRR. Impaired HRR1 after SETs has been shown to be an independent predictor of cardiovascular complications after thoracic surgery.

Abnormal Maximal and Submaximal Cardiopulmonary Exercise Capacity in Pediatric Stem Cell Transplant Recipients Despite Normal Standard Echocardiographic Parameters: A Pilot Study

Left ventricular systolic dysfunction is a known complication of stem cell transplantation (SCT). There has been minimal research to determine whether subclinical cardiac dysfunction exists in SCT patients using tools other than standard echocardiography, such as maximal and submaximal effort cardiopulmonary exercise testing (CPET) and vascular function studies. The objective of this study was to determine the rate of subclinical cardiac dysfunction in patients with normal ejection fraction after SCT, identified by abnormal values by CPET, tissue-Doppler imaging, and arterial stiffness measurements and to further describe submaximal exercise test measures in this population. A prospective cohort study of SCT survivors who were at least 3 years after SCT without prior anthracycline or radiation exposure and with preserved systolic function (left ventricular ejection fraction > 50%) was performed to evaluate for abnormalities in exercise, vascular function, and diastolic function in an effort to detect subclinical dysfunction in SCT patients. Eleven patients (12.4 ± 3.8 years old) were included in the study. No patients had diastolic dysfunction. All patients completed a maximal effort exercise test, and 73% (8/11) had abnormal peak oxygen consumption (Vo2 peak), which is a measure of aerobic fitness. However, during submaximal effort CPET, 45% (5/11) had an abnormal Vo2 at anaerobic threshold (i.e., the point in exercise where aerobic transitions to anaerobic metabolism and fatigue starts), and 64% (7/11) had an abnormal oxygen uptake efficiency slope (a measure that relates Vo2 peak to total ventilation). Eighty-six percent (6/7) of the patients with an abnormal oxygen uptake efficiency slope ultimately had an abnormal Vo2 peak. There were no vascular function abnormalities. Pediatric survivors of SCT often have abnormal maximal and submaximal exercise capacity without vascular or cardiac dysfunction.

No effect of oral ketone ester supplementation on exercise capacity in patients with McArdle disease and healthy controls: A randomized placebo-controlled cross-over study.

Patients with glycogen storage disease type V (GSDV), also known as McArdle disease, have blocked glycogen breakdown due to myophosphorylase deficiency, leading to exercise intolerance, muscle pain, and risk of muscle damage. Blood‐derived ketone bodies (KBs) constitute an alternative energy source that could fuel the muscle independent of glycogenolysis. However, except for long‐time fasting or ketogenic dieting, KBs are present in low quantities. This led us to explore the effects of a drink containing exogenously produced KBs in the form of D‐β‐hydroxybutyrate esters (KE) on exercise capacity and metabolism in patients with GSDV. Eight GSDV patients and four healthy controls (HC) were included in this placebo‐controlled, cross‐over study where subjects were randomized to receive a KE drink with 395 mgKE/kg or placebo drink on two separate days 25 min before a submaximal cycle exercise test. The primary outcome was exercise capacity as indicated by heart rate response (HR) to exercise. Secondary outcomes included perceived exertion (PE) and measures of KB, carbohydrate, and fat metabolism during exercise. In GSDV, the KE drink vs. placebo increased plasma KBs and KB oxidation (p ≤ 0.0001) but did not improve exercise capacity as judged from HR (p = 0.120) and PE (p = 0.109). In addition, the KE drink lowered plasma glucose, free fatty acids, and lowered lipolytic rate and glucose rate of appearance compared with placebo. Similar results were found in the HC group. The present study indicates that an increase in KB oxidation by oral KE supplementation does not improve exercise capacity in GSDV possibly because of KB‐induced inhibition of lipolysis and liver glucose output. Thus, oral KE supplementation alone cannot be recommended as a treatment option for patients with GSDV.