Peak Oxygen Research Articles

Effects of water-based Liuzijue exercise on peak exercise capacity, functional exercise capacity, and quality of life in people with COPD.

This study was conducted to investigate the effect of water-based Liuzijue exercise on peak exercise capacity, functional exercise capacity, and quality of life in people with COPD. The study included 50 participants randomly divided into three groups: a control group (CG = 17), a land-based Liuzijue exercise group (LG = 17), and a water-based Liuzijue exercise group (WG = 16). The LG and WG performed Liuzijue exercise in different environments, and the CG had no exercise intervention. All participants received prescribed medical treatment. Liuzijue exercise was performed according to the description of Health Qigong Liuzijue compiled by Chinese Health Qigong Association for 60minutes, two times per week, for 12weeks. After intervention, peak oxygen uptake and peak working rate were significantly improved in WG (P=.02). The results of the 6minutes walking test (6MWT) and 30 seconds sit-to-stand test were significantly improved in both WG and LG (P<.05), and significant difference was found between WG and CG in 6MWT (P=.03). The St. George's Respiratory Questionnaire (SGRQ) activity score increased significantly in the CG (P=.03), while all domains of SGRQ significantly decreased in both training groups (P<.01). All SGRQ scores showed a significant difference between LG and CG (P<.05) and, except for the activity score, between WG and CG (P<.05). Water-based Liuzijue exercise can effectively improve peak exercise capacity, functional exercise capacity, and quality of life in people with COPD, especially with respect to increasing peak VO2 and 6MWD.

Polysomnography parameters as predictors of respiratory adverse events following adenotonsillectomy in children

The first-line treatment of obstructive sleep apnea syndrome in children is adenotonsillectomy, but this may result in perioperative respiratory adverse events (PRAEs). The primary aim of this study is to examine whether the McGill oximetry score (MOS) and other polysomnography parameters can predict major PRAEs following adenotonsillectomy. We secondarily evaluated the MOS interrater reliability and correlation with other polysomnography parameters. This retrospective study included all children aged 0-18 years who underwent preoperative polysomnography between June 2010 and January 2016 prior to adenotonsillectomy at a tertiary pediatric institution. Oximetries from polysomnograms were assigned an MOS. Univariable and multivariable models for prediction of major PRAEs were constructed. MOS was correlated with polysomnography parameters and interrater reliability was evaluated. This study included 106 children; 15 had a major PRAE. A multivariable prediction model that combined MOS and age showed evidence for the ability to predict major PRAEs with an area under the receiver operating characteristic curve of 0.68 (95% confidence interval: 0.52, 0.84), whereby increased MOS and younger age were associated with PRAEs, but apnea-hypopnea index was not. MOS had excellent interrater reliability (κ = 0.95) and was highly correlated with oxygen saturation nadir and cumulative time percentage with oxygen saturation less than 90%. A prediction model including MOS and age may predict PRAEs following adenotonsillectomy. This suggests that nocturnal oximetry provides the most essential information of polysomnography measures to direct postoperative monitoring following adenotonsillectomy. Xiao L, Barrowman N, Momoli F, etal. Polysomnography parameters as predictors of respiratory adverse events following adenotonsillectomy in children. J Clin Sleep Med. 2021;17(11):2215-2223.

Physiological responses and cycle characteristics during double-poling versus diagonal-stride roller-skiing in junior cross-country skiers

PurposeThis study aimed to compare physiological factors and cycle characteristics during cross-country (XC) roller-skiing at matched inclines and speeds using the double-poling (DP) and diagonal-stride (DS) sub-techniques in junior female and male XC skiers.MethodsTwenty-three well-trained junior XC skiers (11 women, 12 men; age 18.2 ± 1.2 yr.) completed two treadmill roller-skiing tests in a randomized order using either DP or DS. The exercise protocols were identical and included a 5 min warm-up, 4 × 5 min submaximal stages, and an incremental test to exhaustion, all performed at a 5° incline.ResultsNo significant three-way interactions were observed between sex, submaximal exercise intensity, and sub-technique. For the pooled sample, higher values were observed for DP versus DS during submaximal exercise for the mean oxygen uptake kinetics response time (33%), energy cost (18%), heart rate (HR) (9%), blood lactate concentration (5.1 versus 2.1 mmol·L−1), rating of perceived exertion (12%), and cycle rate (25%), while cycle length was lower (19%) (all P < 0.001). During the time-to-exhaustion (TTE) test, peak oxygen uptake (dot{V}O2peak), peak HR, and peak oxygen pulse were 8%, 2%, and 6% lower, respectively, for DP than DS, with a 29% shorter TTE during DP (pooled data, all P < 0.001).ConclusionIn well-trained junior XC skiers, DP was found to exert a greater physiological load than DS during uphill XC roller-skiing at submaximal intensities. During the TTE test, both female and male athletes were able to ski for longer and reached markedly higher dot{V}O2peak values when using DS compared to DP.

Can wearable technology be used to approximate cardiopulmonary exercise testing metrics?

BackgroundConsumer wrist-worn wearable activity monitors are widely available, low cost and are able to provide a direct measurement of several markers of physical activity. Despite this, there is limited data on their use in perioperative risk prediction. We explored whether these wearables could accurately approximate metrics (anaerobic threshold, peak oxygen uptake and peak work) derived using formalised cardiopulmonary exercise testing (CPET) in patients undergoing high-risk surgery.MethodsPatients scheduled for major elective intra-abdominal surgery and undergoing CPET were included. Physical activity levels were estimated through direct measures (step count, floors climbed and total distance travelled) obtained through continuous wear of a wrist worn activity monitor (Garmin Vivosmart HR+) for 7 days prior to surgery and self-report through completion of the short International Physical Activity Questionnaire (IPAQ). Correlations and receiver operating characteristic (ROC) curve analysis explored the relationships between parameters provided by CPET and physical activity.Device selectionOur choice of consumer wearable device was made to maximise feasibility outcomes for this study. The Garmin Vivosmart HR+ had the longest battery life and best waterproof characteristics of the available low-cost devices.ResultsOf 55 patients invited to participate, 49 (mean age 65.3 ± 13.6 years; 32 males) were enrolled; 37 provided complete wearable data for analyses and 36 patients provided full IPAQ data.Floors climbed, total steps and total travelled as measured by the wearable device all showed moderate correlation with CPET parameters of peak oxygen uptake (peak VO2) (R = 0.57 (CI 0.29–0.76), R = 0.59 (CI 0.31–0.77) and R = 0.62 (CI 0.35–0.79) respectively), anaerobic threshold (R = 0.37 (CI 0.01–0.64), R = 0.39 (CI 0.04–0.66) and R = 0.42 (CI 0.07–0.68) respectively) and peak work (R = 0.56 (CI 0.27–0.75), R = 0.48 (CI 0.17–0.70) and R = 0.50 (CI 0.2–0.72) respectively).Receiver operator curve (ROC) analysis for direct and self-reported measures of 7-day physical activity could accurately approximate the ventilatory equivalent for carbon dioxide (VE/VCO2) and the anaerobic threshold. The area under these curves was 0.89 for VE/VCO2 and 0.91 for the anaerobic threshold. For peak VO2 and peak work, models fitted using just the wearable data were 0.93 for peak VO2 and 1.00 for peak work.ConclusionsData recorded by the wearable device was able to consistently approximate CPET results, both with and without the addition of patient reported activity measures via IPAQ scores. This highlights the potential utility of wearable devices in formal assessment of physical functioning and suggests they could play a larger role in pre-operative risk assessment.EthicsThis study entitled “uSing wearable TEchnology to Predict perioperative high-riSk patient outcomes (STEPS)” gained favourable ethical opinion on 24 January 2017 from the Welsh Research Ethics Committee 3 reference number 17/WA/0006. It was registered on ClinicalTrials.gov with identifier NCT03328039.

The new theory CPET guides the overall plan of individualized precision exercise to effectively improve the overall functional status of "frailty"

Objective: Under the guidance of the new theory of holistic integrated physiology and medicine, the effect of individualized accurate exercise program on the overall functional state was studied according to cardiopulmonary exercise testing (CPET). Methods: Li xx, female, 31 years old, has a fast heart rate since childhood (90~100 bpm), usually feel cold, especially in autumn and winter, and general health good. CPET was performed after signing the informed consent form at Fuwai Hospital in September 2019. Peak oxygen uptake, anaerobic threshold (AT), and peak cardiac output were (69~72)% pred, respectively, and the oxygen uptake ventilation efficiency and carbon dioxide exhaust ventilation efficiency were basically normal (96~100)% pred. The resting heart rate was fast, the blood pressure was low, the blood pressure response was weak during exercise, and the heart rate was mainly increased. The holistic integrated physiology medical theory pointed out that she was in weak health and heart weakness was the main manifestation. CPET was used to guide individualized precise exercise intensity titration, combine continuous beat-by-beat blood pressure, ECG, pulse and blood glucose dynamic monitoring to formulate an holisticplan of individualized quantitative exercise .Reexamine CPET after 8 weeks' strengthening management. Results: After 8 weeks of intensive holistic management, the limbs were warm and the cold symptoms disappeared. Re-examination of CPET peak oxygen uptake, AT and peak cardiac output were (90~98)% pred, which increased by (30~36)% respectively, and the holistic weak functional status was significantly improved; basically normal oxygen uptake ventilation efficiency and carbon dioxide exhaust ventilation efficiency also increased by (10~37)% respectively; resting heart rate and blood pressure basically returned to normal, and blood pressure and heart rate response during exercise were normal. Continuous ambulatory blood glucose monitoring indicated that the average blood glucose level decreased slightly and became more stable. Repeated measurement results of continuous ECG and beat-to-beat blood pressure also indicated a decrease in heart rate and an increase in blood pressure during rest, exercise and during sleep, and radial pulse wave. The amplitude of the dicrotic wave increases and becomes more pronounced. Conclusion: The new theoretical system to guide CPET to formulate an holistic plan for individualized precision exercise can safely and effectively enhance myocardial contractility, increase stroke volume, increase blood pressure, lower heart rate, stabilize and slightly lower blood glucose, and improve holistic functional status.

Chronotropic incompetence is more frequent in obese adolescents and relates to systemic inflammation and exercise intolerance

BackgroundAdults with obesity may display disturbed cardiac chronotropic responses during cardiopulmonary exercise testing, which relates to poor cardiometabolic health and an increased risk for adverse cardiovascular events. It is unknown whether cardiac chronotropic incompetence (CI) during maximal exercise is already present in obese adolescents and, if so, how that relates to cardiometabolic health. MethodsSixty-nine obese adolescents (body mass index standard deviation score = 2.23 ± 0.32, age = 14.1 ± 1.2 years; mean ± SD) and 29 lean adolescents (body mass index standard deviation score = –0.16 ± 0.84, age = 14.0 ± 1.5 years) performed a maximal cardiopulmonary exercise testing from which indicators for peak performance were determined. The resting heart rate and peak heart rate were used to calculate the maximal chronotropic response index. Biochemistry (lipid profile, glycemic control, inflammation, and leptin) was studied in fasted blood samples and during an oral glucose tolerance test within obese adolescents. Regression analyses were applied to examine associations between the presence of CI and blood or exercise capacity parameters, respectively, within obese adolescents. ResultsCI was prevalent in 32 out of 69 obese adolescents (46%) and 3 out of 29 lean adolescents (10%). C-reactive protein was significantly higher in obese adolescents with CI compared to obese adolescents without CI (p = 0.012). Furthermore, peak oxygen uptake and peak cycling power output were significantly reduced (p < 0.05) in obese adolescents with CI vs. obese adolescents without CI. The chronotropic index was independently related to blood total cholesterol (standardized coefficient β = –0.332; p = 0.012) and C-reactive protein concentration (standardized coefficient β = –0.269; p = 0.039). ConclusionCI is more common in the current cohort of obese adolescents, and is related to systemic inflammation and exercise intolerance.

Effect of different work and recovery settings during high-intensity intermittent training on maximal oxygen uptake and session volume responses

Summary Objectives The aim of the present study was to verify the training session volume and the time spent at or above 90% of maximal oxygen uptake (t90VO2max) under different work and recovery settings during high-intensity intermittent training. Equipment and methods After having the maximal oxygen uptake (VO2max) and peak velocity (Vpeak) determined, eleven male runners (age: 25.45 ± 4.13 years; VO2max: 55.88 ± 1.43 ml.kg−1.min−1 and personal best in urban 5 km: 18 min: 30s ± 01 min: 25s) completed three short HIIT (30s/30s, 40s/40s e 40s/20s) at 110% of Vpeak until exhaustion. The time sustained in oxygen fractions above 90% of VO2max, total exercise time (TT), number of complete series performed (NS) and time of exercise (TE) were quantified and compared between the different sessions. Results The t90VO2max was not different between sessions (P > 0.05); in turn, the 30s/30s protocol was greater than both 40s/40s and 40s/20s at the volume variables (30s/30s, TT (s): 1463 ± 86.14, NS (n): 24.18 ± 1.48 and TE (s): 737.36 ± 41.9–40s/40s, TT (s): 1043 ± 69.39, NS (n): 12.91 ± 0.87 and TE (s): 526.45 ± 34.72–40s/20s, TT (s): 415.55 ± 30.08, NS (n): 6.72 ± 0.51 and TE (s): 281 ± 20.01). For the prescription of training sessions, the 30s/30s protocol being the most appropriate when there is the goal to increase the volume session. On the other hand, protocol 40s/20s may optimize training time when the purpose is to stimulate high oxygen fractions, as its results are like those of other protocols in t90VO2max with time reduced up to four times.

The impacts of outpatient vs inpatient holistic management based on exercise training on cardiac rehabilitation efficacy among patients with chronic heart failure

Objective: To evaluate the impacts of outpatient vs inpatient exercise training (ET) on cardiac rehabilitation efficacy among patients with chronic heart failure (CHF). Methods: Thirty six patients who were diagnosed with CHF in Beijing Rehabilitation Hospital from September 2015 to September 2018, were randomly divided into three groups: control group (n=12), outpatient ET group (n=12) and inpatient ET group (n=12). Patients in control group were treated with conventional cardiac rehabilitation without ET, patients in outpatient and inpatient ET groups were treated with holistic cardiac rehabilitation with the core of ET according to individualized exercise prescription based on cardiopulmonary exercise testing (CPET). Exercise intensity of cycle ergometer was Δ50% power above anaerobic threshold (AT), 30 min/d, 5 d/week, for 12 weeks. General information, CPET parameters, echocardiogram, 6 minute walking distance (6MWD) and quality of life (QoL) score of three groups of patients before and after treatment were recorded. Results: All patients in 3 groups finished symptom-limited CPET and patients in ET groups finished 12 weeks - ET safely without complications. Before treatment, there were no significant differences in CPET parameters, echocardiogram results, 6MWD and QoL score among 3 groups (P>0.05). After treatment, AT (ml/min, ml/(min·kg), %pred), peak oxygen uptake (VO2) (ml/min, ml/(min·kg), %pred), peak oxygen pulse(ml/beat), peak workload(W/min, %pred), left ventricular ejection fraction (LVEF) and 6MWD of patients in outpatient and inpatient ET groups were significantly higher than those of patients in control group (P<0.05), QoL score of patients in outpatient and inpatient ET groups was lower than that of patients in control group(P<0.05). To be noted, there were no obvious differences in CPET indexes, echocardiogram results, 6MWD and QoL score in patients between outpatient ET group and inpatient ET group (P>0.05). For patients in control group, there were no significant differences in above parameters before and after treatment (P>0.05). AT(ml/min, ml/(min·kg)), Peak VO2 (ml/min, ml/(min·kg), %pred), peak oxygen pulse(ml/beat, %pred), peak workload(W/min, %pred), LVEF and 6MWD of patients in outpatient and inpatient ET groups were significantly higher than those before treatment (P<0.05), QoL score of patients in outpatient and inpatient ET groups after treatment was significantly lower than that before treatment (P<0.05). Conclusion: Outpatient ET can improve the cardiopulmonary function, exercise tolerance and QoL of CHF patients, which has no significant difference compared with inpatient ET, indicating that outpatient cardiac rehabilitation, as an effective rehabilitation mode, is deserved to be applied widely.

Prediction of peak oxygen consumption by incremental 6minutes walking test in patients with Ischemic heart disease after cardiac rehabilitation

For ischemic heart disease patients (IHD), Cardiac rehabilitation (CR) helps to recover the functional capacity. Stress test with oxygen peak consumption (VO2 max at peak) at CR discharge is a key point to determine physical capacity. There was no regression equation available to predict oxygen peak consumption (VO2 max at peak) at discharge. The aim of our study was to develop an equation to predict VO2 peak values at discharge. It is a retrospective study including 68 patients with IHD admitted for CR. They all had of 6 minutes walking Test before and after CR and also underwent a stress test with Ergospirometry at the beginning of CR. The study end point was to develop an equation to predict VO2 max at peak at their discharge using only the results of the two six minutes walking tests (entry and at discharge) and the VO2max at peak exercice at the beginning of their Cardiac rehab. The average age of patients was 52,14 ± 10,1 years with male predominance (80%), they had more than three cardiovascular risk factors dominated by smoking and hypertension. After 20 sessions of CR, they significantly increase 6 minutes walking test (from 488,18 ± 101,29 m to 560,61 ± 100,20 m) and their VO2max(from 20,74 ± 5,41 ml/kg/min to 23,52 ± 6,46 ml/kg/min). Using linear regression analysis, we developed an equation to calculate the Final VO2 max at peak (predicted) = 1,167 + (0,95x initial VO 2 peak) + (0,002x initial 6MWT) + (0,003x final 6MWT). There was no statistically significant difference between the VO2 peak measured directly and the predicted one with our equation. This study showed that cardiac rehabilitation, can avoid a final stress test with VO2max using our predicted equation. This new method to predict the VO2max at peak at discharge from CR is easy to use and can be cost effective saving a whole test with ergospirometry at discharge. This study needs to be confirmed by a larger number of patients included.

Protein supplementation increases adaptations to endurance training: A systematic review and meta-analysis

Trials that assessed the impact of protein supplementation on endurance training adaptations have reported conflicting findings. To determine the impact of protein supplementation during chronic endurance training on aerobic capacity, body composition and exercise performance in healthy and clinical populations. A systematic database search was conducted for randomised controlled trials addressing the effects of protein supplementation during endurance training on aerobic capacity, body composition and exercise performance in PubMed, Embase, Web of Science, and CINAHL. Meta-analyses were performed to outline the overall effects of protein supplementation with all studies containing endurance training components. The effects of endurance training and add-on effects of protein supplementation were evaluated by the meta-analyses with endurance training-focused studies. Nineteen studies and 1162 participants contributed to the analyses. Compared with the control group, the protein supplementation group demonstrated greater improvements in aerobic capacity measured by mixed peak oxygen uptake (V̇O2peak) and peak workload power (Wpeak) (standardised mean difference [SMD]=0.36, 95% confidence interval [CI]: 0.05 to 0.67), and V̇O2peak (mean difference [MD]=0.89mL‧kg-1‧min-1, 95% CI: 0.07 to 1.70); had a greater lean mass gain (MD=0.32kg, 95% CI: 0.07 to 0.58); and had a greater improvement in time trial performance (MD=-29.1s, 95% CI:-55.3 to-3.0). Secondary analyses showed that, in addition to the substantial improvement in V̇O2peak (MD=3.67mL‧kg-1‧min-1, 95% CI: 2.32 to 5.03) attributed to endurance training, protein supplementation provided an additional 26.4% gain in V̇O2peak (MD=0.97mL‧kg-1‧min-1, 95% CI:-0.03 to1.97). Protein supplementation further increased aerobic capacity, stimulated lean mass gain, and improved time trial performance during chronic endurance training in healthy and clinical populations. PROSPERO REGISTRATION NUMBER: (CRD42020155239).

Sustainable Trend in Mitigating Fuel Emissions and Load Performance of Internal Combustion Engine Empirical Research

As technology strives with increase in energy demand, there is need of adopting reliable techniques towards maintaining green environment without affecting production. Knowing fossil and biomaterial feedstock with different percentages of NOx emissions generation. This research reviews the effective ways of reducing the various pollutants (NOx, CO, HC and smoke) emissions from different fuel types (petroleum and biodiesel). This centered on some factors on high generation of NOx emissions from biofuel and fossil which include flame adiabatic temperature, molecular structure of the bio-material (biofuel)and fossil, load conditions and ignition delay time. The paper further stated the adequate methods for reduction of NOx, HC, smoke and others for both in pre and post combustion approaches. However, the observed results from the adopted technologies indicates that EGR introduced, reduced the NOx emissions at about 5-25% EGR rate when used with bio-fueled engine. This is achievable via controlling the combustion peak temperature and oxygen content, also shows significant drop in CO and HC emissions. Finally, with this techniques and modifications, the fuel emissions will be greatly minimized for better environment for operational activities.

Synthesis and characterization of reduced graphene oxide using the aqueous extract of Eclipta prostrata.

In this study, biological deoxygenation of graphene oxide (GO) using an Eclipta prostrata phytoextract was performed via the infusion method. The presence of oxide groups on the surface of graphene and removal of oxides groups by reduction were characterized through morphological and structural analyses. Field emission scanning electron microscopy images revealed that the synthesized GO and rGO were smooth and morphologically sound. Transmission electron microscopy images showed rGO developing lattice fringes with smooth edges and transparent sheets. Atomic force microscopy images showed an increase in the surface roughness of graphite oxide (14.29nm) compared with that of graphite (1.784nm) due to the presence of oxide groups after oxidation, and the restoration of surface roughness to 2.051nm upon reduction. Energy dispersive X-ray analysis indicated a difference in the carbon/oxygen ratio between GO (1.90) and rGO (2.70). Fourier-transform infrared spectroscopy spectrum revealed peak stretches at 1029, 1388, 1578, and 1630cm-1 for GO, and a decrease in the peak intensity after reduction that confirmed the removal of oxide groups. X-ray photoelectron microscopy also showed a decrease in the intensity of oxygen peak after reduction. In addition, thermogravimetric analysis suggested that rGO was less thermally stable than graphite, graphite oxide, and GO, with rGO decomposing after heating at temperatures ranging from room temperature to 600°C.

Long-lasting exercise involvement protects against decline in V̇O2max and V̇O2 kinetics in moderately active women.

We studied the effects of age on different physiological parameters, including those derived from (i) maximal cardiopulmonary exercise testing (CPET), (ii) moderate-intensity step transitions, and (iii) tensiomyography (TMG)-derived variables in moderately active women. Twenty-eight women (age, 19 to 53 years), completed 3 laboratory visits, including baseline data collection, TMG assessment, maximal oxygen uptake test via CPET, and a step-transition test from 20W to a moderate-intensity cycling power output (PO), corresponding to oxygen uptake at 90% gas exchange threshold. During the step transitions, breath-by-breath pulmonary oxygen uptake, near infrared spectroscopy derived muscle deoxygenation (ΔHHb), and beat-by-beat cardiovascular response were continuously monitored. There were no differences observed between the young and middle-aged women in their maximal oxygen uptake and peak PO, while the maximal heart rate (HR) was 12 bpm lower in middle-aged compared with young (p = 0.016) women. Also, no differences were observed between the age groups in τ pulmonary oxygen uptake, ΔHHb, and τHR during on-transients. The first regression model showed that age did not attenuate the maximal CPET capacity in the studied population (p = 0.638), while in the second model a faster τ pulmonary oxygen uptake, combined with shorter TMG-derived contraction time (Tc) of the vastus lateralis (VL), were associated with a higher maximal oxygen uptake (∼30% of explained variance, p = 0.039). In conclusion, long lasting exercise involvement protects against a maximal oxygen uptake and τpulmonary oxygen uptake deterioration in moderately active women. Novelty: Faster τ pulmonary oxygen uptake and shorter Tc of the VL explain 33% of the variance in superior maximal oxygen uptake attainment. No differences between age groups were found in τ pulmonary oxygen uptake, τΔHHb, and τHR during on-transients.

The Effect of Different Cadence on Paddling Gross Efficiency and Economy in Stand-Up Paddle Boarding.

Background: Due to the importance of energy efficiency and economy in endurance performance, it is important to know the influence of different paddling cadences on these variables in the stand-up paddleboarding (SUP). The purpose of this study was to determine the effect of paddling at different cadences on the energy efficiency, economy, and physiological variables of international SUP race competitors. Methods: Ten male paddlers (age 28.8 ± 11.0 years; height 175.4 ± 5.1 m; body mass 74.2 ± 9.4 kg) participating in international tests carried out two test sessions. In the first one, an incremental exercise test was conducted to assess maximal oxygen uptake and peak power output (PPO). On the second day, they underwent 3 trials of 8 min each at 75% of PPO reached in the first test session. Three cadences were carried out in different trials randomly assigned between 45–55 and 65 strokes-min−1 (spm). Heart rate (HR), blood lactate, perceived sense of exertion (RPE), gross efficiency, economy, and oxygen uptake (VO2) were measured in the middle (4-min) and the end (8-min) of each trial. Results: Economy (45.3 ± 5.7 KJ·l−1 at 45 spm vs. 38.1 ± 5.3 KJ·l−1 at 65 spm; p = 0.010) and gross efficiency (13.4 ± 2.3% at 45 spm vs. 11.0 ± 1.6% at 65 spm; p = 0.012) was higher during de 45 spm condition than 65 spm in the 8-min. Respiratory exchange ratio (RER) presented a lower value at 4-min than at 8-min in 55 spm (4-min, 0.950 ± 0.065 vs. 8-min, 0.964 ± 0.053) and 65 spm cadences (4-min, 0.951 ± 0.030 vs. 8-min, 0.992 ± 0.047; p < 0.05). VO2, HR, lactate, and RPE were lower (p < 0.05) at 45 spm (VO2, 34.4 ± 6.0 mL·kg−1·min−1; HR, 161.2 ± 16.4 beats·min−1; lactate, 3.5 ± 1.0 mmol·l−1; RPE, 6.0 ± 2.1) than at 55 spm (VO2, 38.6 ± 5.2 mL·kg−1·min−1; HR, 168.1 ± 15.1 beats·min−1; lactate, 4.2 ± 1.2 mmol·l−1; RPE, 6.9 ± 1.4) and 65 spm (VO2, 38.7 ± 5.9 mL·kg−1·min−1; HR, 170.7 ± 13.0 beats·min−1; 5.3 ± 1.8 mmol·l−1; RPE, 7.6 ± 1.4) at 8-min. Moreover, lactate and RPE at 65 spm was greater than 55 spm (p < 0.05) at 8-min. Conclusion: International male SUP paddlers were most efficient and economical when paddling at 45 spm vs. 55 or 65 spm, confirmed by lower RPE values, which may likely translate to faster paddling speed and greater endurance.

Limited usefulness of resting hemodynamic assessments in predicting exercise capacity in hypertensive patients.

Reliable assessments of reduced exercise capacity based on resting tests are one of the major challenges in clinical practice. The aim of this study was to evaluate the relationship between hemodynamic parameters obtained via resting tests (echocardiography and impedance cardiography (ICG)) and objective parameters of exercise capacity assessed via cardiopulmonary exercise testing and exercise ICG in patients with controlled arterial hypertension (AH). The left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), diastolic function parameters (e', E/A, E/e'), cardiac output (CO), stroke volume (SV), and systemic vascular resistance index were evaluated for any correlations with selected parameters of exercise capacity, such as peak oxygen uptake (VO2) and peak CO in 93 people with AH (mean age 54 years, 47 women). Statistically relevant correlations occurred between indices of exercise capacity (peak VO2; peak CO) and only the following hemodynamic parameters: diastolic blood pressure (R = 0.23, p = 0.026; R = 0.24, p = 0.021; respectively), e' (R = 0.32, p = 0.002; R = 0.24, p = 0.027), E/e' (R = 0.35, p < 0.001; ns), E/A (R = 0.23, p = 0.030; R = 0.21, p = 0.047), SV at rest (ns; R = 0.24, p = 0.019), and CO at rest (ns; R = 0.21, borderline p = 0.052). No significant correlations between the exercise capacity parameters and either LVEF or GLS were observed. No hemodynamic parameter proved to be an independent correlate of either peak VO2 or peak CO. The association between hemodynamic parameters at rest and parameters of exercise capacity was weak and limited to selected parameters of diastolic function. Exercise capacity assessment in patients with AH based on resting tests alone is insufficiently reliable and should be supplemented with exercise tests.

Long-term changes of exercise hemodynamics and physical capacity in chronic thromboembolic pulmonary hypertension after pulmonary thromboendarterectomy

BackgroundA substantial number of chronic thromboembolic pulmonary hypertension (CTEPH) patients experience dyspnea on exertion and limited exercise capacity despite surgically successful pulmonary endarterectomy (PEA). We sought to prospectively evaluate resting and peak exercise hemodynamics before, 3 and 12 months after PEA in consecutive CTEPH-patients and correlate it to physical functional capacity. Methods and resultsTwenty consecutive CTEPH-patients were examined. Twelve months after PEA, 75% of patients with severely increased pre-PEA mean pulmonary arterial pressure (mPAP) at rest had normal or mildly increased mPAP. However, mPAP reduction was less pronounced during exercise where only 45% had normal or mildly increased mPAP at 12 months. Hemodynamic changes during exercise were tested using the pressure-flow relationship (i.e. mPAP/cardiac output (CO) slope). The average mPAP/CO slope was 7.5 ± 4.2 mm Hg/L/min preoperatively and 3.9 ± 3.0 mm Hg/L/min at 12 months (p < .005). CO reserve (CO increase from rest to peak exercise) was increased (5.7 ± 2.9 L/min) 12 months after PEA compared with pre-PEA (2.5 ± 1.8 L/min), p < .0001. However, 12 months after PEA, the CO reserve was only 49% of that of healthy controls, p < .0001. Changes in cardiac output (∆CO), calculated as the difference between CO before PEA and 12 months later, were significantly correlated with six-minute-walk-test and peak oxygen uptake (VO2), both at rest and peak exercise. ConclusionInvasive exercise hemodynamic examination in CTEPH-patients demonstrates that after otherwise successful PEA surgery, >50% of patients have a significant increase in exercise mPAP, and the CO reserve remains compromised 12 months after PEA. Improvement in physical capacity is correlated with ∆CO.

TEM Studies on Antibacterial Mechanisms of Black Phosphorous Nanosheets.

PurposeRecently, two-dimensional (2D) nanomaterials are gaining tremendous attention as novel antibacterial platforms to combat against continuously evolving antimicrobial resistance levels. Among the family of 2D nanomaterials, black phosphorus (BP) nanosheets have demonstrated promising potential for biomedical applications. However, there is a need to gain nanoscale insights of the antibacterial activity of BP nanosheets which lies at the center of technical challenges.MethodsUltra-large BP nanosheets were synthesized by liquid-exfoliation method in the eco-friendly deoxygenated water. Synthesized BP nanosheets were characterized by TEM, AFM, and Raman spectroscopy techniques and their chemical stability was evaluated by EDS and EELS elemental analysis. The antibacterial activity of BP nanosheets was evaluated at nanoscale by the ultramicrotome TEM technique. Further, HAADF-STEM image and EDS elemental line map of the damaged bacterium were utilized to analyze the presence of diagnostic ions. Supportive SEM and ATR-FTIR studies were carried out to confirm the bacterial cell wall damage. In vitro colony counting method was utilized to evaluate the antibacterial performance of ultra-large BP nanosheets.ResultsElemental EELS and EDS analysis of BP nanosheets stored in deoxygenated water confirmed the absence of oxygen peak. TEM studies indicate the various events of bacterial cell damage with the lost cellular metabolism and structural integrity. Colony counting test results show that as-synthesized BP nanosheets (100 μg/mL) can kill ~95% bacteria within 12 hours.ConclusionTEM studies demonstrate the various events of E. coli membrane damage and the loss of structural integrity. These events include the BP nanosheets interaction with the bacterial cell wall, cytoplasmic leakage, detachment of cytoplasm from the cell membrane, reduced density of lipid bilayer and agglomerated DNA structure. The EDS elemental line mapping of the damaged bacterium confirms the disrupted cell membrane permeability and the lost cellular metabolism. SEM micrographs and ATR-FTIR supportive results confirm the bacterial cell wall damage.

Ventricular arrhythmias not meeting criteria for terminating cardiopulmonary exercise testing stratify prognosis and disease severity in heart failure of preserved, midrange, and reduced ejection fraction.

BackgroundContinued high mortality in heart failure patients indicates the need for additional methods of risk stratification and phenotyping.HypothesisWe hypothesized that ventricular arrhythmias that do not meet test‐termination criteria (non‐terminating ventricular arrhythmias [NTVA]) during cardiopulmonary exercise testing (CPET) may help in phenotyping disease severity and prognosis in heart failure with reduced (HFrEF) and midrange (HFmrEF)/preserved (HFpEF) left ventricular ejection fraction (LVEF).MethodsAbout 319 patients with heart failure (199 HFrEF; 80 HFmrEF; 41 HFpEF) underwent CPET. Tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PASP) were measured by echocardiography. B‐type natriuretic peptide (BNP) at rest and peak exercise was also determined. The patients were tracked for primary (cardiac death) and secondary composite outcomes (all‐cause death, heart transplantation/left ventricular assist device implantation, hospitalization for cardiac reasons).ResultsForty‐seven (15%) of the patients demonstrated NTVA during CPET, regardless of coronary artery disease prevalence. Patients without arrhythmias had a significantly higher LVEF (P < .05), TAPSE/PASP ratio (P < .001), peak oxygen consumption (P < .01), lower resting and peak BNP (P < .001), and the minute ventilation/carbon dioxide production slope (P < .001) compared to those with NTVA. Seventy‐one patients died during the tracking period, 54 for cardiac reasons. NTVA during CPET was a significant predictor of primary and secondary outcomes in the total heart failure cohort (HR: 5.3, 3.7; 95% CI: 3.1‐9.1, 2.4‐5.5; P < .001, respectively), as well as in subgroups categorized according to reduced and middle‐range/preserved LVEF (P < .001).ConclusionExercise‐induced ventricular arrhythmias that do not reach test‐termination criteria are nonetheless indicative of an advanced disease severity phenotype and worse prognosis.

Cardio-Respiratory Fitness and Autonomic Function in Patients with Major Depressive Disorder.

Patients with major depressive disorder (MDD) have an augmented risk of cardiovascular morbidity and mortality. Although a link between depression and autonomic dysfunction as well as reduced cardio-respiratory fitness (CRF) is well documented, the underlying cause is a matter of debate. Therefore, we studied the interplay between autonomic function, body composition and severity of the disease to disentangle possible physiological factors influencing the assumed lack of CRF in MDD patients. We investigated seventeen patients suffering from MDD and seventeen control subjects matched with respect to age, sex, body-mass-index, and smoking habits. A resting baseline assessment and a cardiopulmonary exercise test including a prolonged recovery period were performed to study autonomic function (i.e., heart rate responses and heart rate variability) during rest, exercise and recovery as well as CRF. Most investigated autonomic indices were significantly different at rest, during exercise as well as during recovery indicating altered autonomic modulation. Nevertheless, none of our participants was classified as chronotropically incompetent. As expected, a reduced CRF (i.e., peak oxygen uptake and peak power output, p < 0.01) was observed in patients compared to controls. In addition, a correlation of baseline heart rate and of heart rate during recovery with the ventilatory threshold 1 (p < 0.05) was found in patients only, indicating a relation to the lack of CRF. Furthermore, we observed a positive correlation of the severity of the disease with the weekly sitting time (p < 0.01) as well as a negative correlation with the activity time in the intensity domain walking (p < 0.001) and with the total score of the International Physical Activity Questionnaire (p < 0.01) for patients. This study shows that patients with MDD have altered autonomic function not only during resting conditions but also during exercise as well as recovery from exercise. Intervention studies are needed to evaluate how the described autonomic alterations can be influenced by increasing CRF due to appropriate exercise training programs.

Comparison of Acute Responses to Two Different Cycling Sprint Interval Exercise Protocols with Different Recovery Durations.

Background: Knowledge of acute responses to different sprint interval exercise (SIE) helps to implement new training programs. The aim of this study was to compare the acute physiological, metabolic and perceptual responses to two different SIE cycling protocols with different recovery durations. Methods: Twelve healthy, active male participants took part in this study and completed four testing sessions in the laboratory separated by a minimum of 72h. Two SIE protocols were applied in randomized order: SIE6×10”/4’—six “all-out” repeated 10-s bouts, interspersed with 4-min recovery; and SIESERIES—two series of three “all-out” repeated 10-s bouts, separated by 30-s recovery and 18-min recovery between series. Protocols were matched for the total work time (1 min) and recovery (20 min). Results: In SIESERIES, peak oxygen uptake and peak heart rate were significantly higher (p < 0.05), without differences in peak blood lactate concentration and mean rating of perceived exertion compared to SIE6×10”/4’. There were no differences in peak power output, peak oxygen uptake and peak heart rate between both series in SIESERIES. Conclusions: Two series composed of three 10-s “all-out” bouts in SIESERIES protocol evoked higher cardiorespiratory responses, which can provide higher stimulus to improve aerobic fitness in regular training.