Constant Work Rate Research Articles

Feasibility of Constant Work Rate Testing to Detect Exercise-Induced Laryngeal Obstruction.

Exercise-induced laryngeal obstruction (EILO) is a condition in which laryngeal structures inappropriately obstruct the upper airway during exercise. The standard diagnostic test for EILO is the continuous laryngoscopy during exercise (CLE) test, usually performed with an incremental work rate protocol regardless of the nature of the triggering event. Typically, laryngeal obstruction occurs only briefly at the end of an incremental test, near peak work capacity. We aimed to investigate constant work rate (CWR) protocols for CLE testing to expand diagnostic test modalities and improve the understanding of EILO. In this prospective, self-controlled feasibility study, 10 patients with EILO performed both an incremental and a CWR CLE test at 70%, 80%, and 90% of maximal exercise capacity. Laryngoscopic video data were recorded and compared, and we evaluated the ability of CWR to reproduce the symptoms and laryngeal obstruction seen in incremental testing. In 70%-90% of cases, CWR testing induced at least the same severity of obstruction as incremental testing and CLE scores remained comparable across test modalities. CWR at 70% allowed observation of laryngeal obstruction for a significantly longer duration than in incremental testing (158 s; 95% confidence interval, 25-291 s; P = 0.027). Dyspnea intensity appeared higher during CWR testing compared with incremental testing. Submaximal CWR CLE testing is feasible and able to induce EILO equivalent to the standard incremental CLE test. This is the first step toward tailored CLE exercise protocols, and further studies are now needed to establish the utility of CWR in clinical and research settings.

Signal Variability Comparative Analysis of Healthy Early- and Late-Pubertal Children during Cardiopulmonary Exercise Testing.

The kinetics of physiological responses to exercise have traditionally been characterized by estimating exponential equation parameters using iterative best-fit techniques of heart rate (HR) and gas exchange (respiratory rate, oxygen uptake (V̇O 2 ), carbon dioxide output, and ventilation). In this study, we present a novel approach to characterizing the maturation of physiological responses to exercise in children by accounting for response uncertainty and variability. Thirty-seven early-pubertal (17 females, 20 males) and 44 late-pubertal (25 females, 19 males) participants performed three multiple brief exercise bouts (MBEB). MBEB consisted of ten 2-min bouts of cycle ergometry at constant work rate interspersed by 1-min rest. Exercise intensity was categorized as low, moderate, or high, corresponding to 40%, 60%, and 80% of peak work rate, and performed in random order on 3 separate days. We evaluated sample entropy (SampEn), approximate entropy, detrended fluctuation analysis, and average absolute local variability of HR and gas exchange. SampEn of HR and gas-exchange responses to MBEB was greater in early- compared with late-pubertal participants (e.g., V̇O 2 early-pubertal vs late-pubertal, 1.70 ± 0.023 vs 1.41 ± 0.027; P = 2.97 × 10 -14 ), and decreased as MBEB intensity increased (e.g., 0.37 ± 0.01 HR for low-intensity compared with 0.21 ± 0.014 for high intensity, P = 3.56 × 10 -17 ). Females tended to have higher SampEn than males (e.g., 1.61 ± 0.025 V̇O 2 for females vs 1.46 ± 0.031 for males, P = 1.28 × 10 -4 ). Average absolute local variability was higher in younger participants for both gas exchange and HR (e.g., early-pubertal vs late-pubertal V̇O 2 , 17.48 % ± 0.56% vs 10.24 % ± 0.34%; P = 1.18 × 10 -21 ). The greater entropy in signal response to a known, quantifiable exercise perturbation in the younger children might represent maturation-dependent, enhanced competition among physiological controlling mechanisms that originate at the autonomic, subconscious, and cognitive levels.

Prediction of Exercise Tolerance in the Severe and Extreme Intensity Domains by a Critical Power Model.

This study aimed to assess the predictive capability of different critical power (CP) models on cycling exercise tolerance in the severe- and extreme-intensity domains. Nineteen cyclists (age: 23.0 ± 2.7 y) performed several time-to-exhaustion tests (Tlim) to determine CP, finite work above CP (W'), and the highest constant work rate at which maximal oxygen consumption was attained (IHIGH). Hyperbolic power-time, linear power-inverse of time, and work-time models with three predictive trials were used to determine CP and W'. Modeling with two predictive trials of the CP work-time model was also used to determine CP and W'. Actual exercise tolerance of IHIGH and intensity 5% above IHIGH (IHIGH+5%) were compared to those predicted by all CP models. Actual IHIGH (155 ± 30 s) and IHIGH+5% (120 ± 26 s) performances were not different from those predicted by all models with three predictive trials. Modeling with two predictive trials overestimated Tlim at IHIGH+5% (129 ± 33 s; p = 0.04). Bland-Altman plots of IHIGH+5% presented significant heteroscedasticity by all CP predictions, but not for IHIGH. Exercise tolerance in the severe and extreme domains can be predicted by CP derived from three predictive trials. However, this ability is impaired within the extreme domain.

Baseline dependent minimally important differences for clinical outcomes of pulmonary rehabilitation in people with COPD

IntroductionMinimally important differences (MIDs) for common outcomes of pulmonary rehabilitation are well documented for people with chronic obstructive pulmonary disease (COPD). It is not known whether MIDs differ based on COPD disease characteristics. This study aimed to estimate MIDs for clinical outcomes of pulmonary rehabilitation dependent upon baseline characteristics. MethodsA database containing 2791 people with COPD was split into derivation (n=2245; age 66±9 years; 50% males; FEV1 47±20% predicted) and comparator (n=546; age 66±9 years; 47% males; FEV1 46±21% predicted) cohorts. MIDs were estimated using 0.5 x SD (symmetrically distributed) or 0.5 x IQR (non-symmetrically distributed) for: 6-minute walk test (6MWT), constant work rate test (CWRT), COPD assessment test (CAT), St. George's respiratory questionnaire (SGRQ), hospital anxiety and depression scale (HADS), and fat-free mass index (FFMI). MIDs were estimated based on baseline outcome scores, lung function, modified medical research council (mMRC) grade and FFMI. ResultsMID estimates were comparable to previously reported values. MIDs for SGRQ domains (Symptom=8.7 points, Activity=7.1 points, Impact=8.1 points) and FFMI were produced (0.36kg/m2). There was greater variation of change in 6MWT, SGRQ-activity, SGRQ-impact, HADS and FFMI on which the MIDs were determined when categorising for baseline values (all, p<0.05). Greater variation of change in 6MWT on which the MIDs were determined was evident with COPD disease severity grouping (p<0.05). The magnitude of change in 6MWT, CAT, CWRT, SGRQ-activity, and FFMI with baseline mMRC score categorisation resulted in greater variation on which the MIDs were determined (all, p<0.05). Baseline stratification for FFMI resulted in greater variation of change in CWRT (p<0.001) and HADS-depression (p = 0.043) on which MIDs were determined. DiscussionFindings suggest that baseline presentation should be considered for people with COPD when assessing the efficacy of pulmonary rehabilitation. However, clinical significance of the variation underpinning MIDs is yet to be determined.

Agreement between left and right middle cerebral artery blood velocity responses to incremental and constant work-rate exercise in healthy males and females

Objective. To quantify the agreement between left and right middle cerebral artery blood velocity (MCAv) responses to incremental and constant work-rate exercise in adults. Approach Seventeen healthy adults (23.8 ± 2.4 years, 9 females) completed a ramp incremental test to exhaustion on a cycle ergometer, three 6-minute transitions at a moderate-intensity, and three at a heavy-intensity, all on separate days. Bilateral MCAv was measured throughout using transcranial Doppler ultrasonography, with left and right MCAv data analysed separately. Data were analysed at baseline, gas exchange threshold, respiratory compensation point and exhaustion during ramp incremental exercise. MCAv responses to constant work-rate exercise were analysed using a mono-exponential model, to determine time- and amplitude-based kinetic response parameters. Main Results Left and right MCAv responses to incremental and constant work-rate exercise were significantly, strongly and positively correlated (r ≥ 0.61, P < 0.01). Coefficient of variation (left versus right) ranged from 7.3%–20.7%, 6.4%–26.2% and 5.9%–22.5% for ramp, moderate and heavy-intensity exercise, respectively. The relative change in MCAv from baseline was higher in the right compared to left MCAv during ramp, moderate and heavy-intensity exercise (all P < 0.05), but the effect sizes were small (d ≤ 0.4). Small mean left–right differences were present during ramp incremental exercise at all time-points (<6 cm s−1; <4%), and for all kinetic parameters during moderate and heavy-intensity exercise (<3 cm s−1, <3%, <4 s). Significance These findings demonstrate similarities between left and right MCAv responses to incremental and constant-work rate exercise in adults on a group-level, but also highlight individual variation in the agreement between left and right MCAv exercise responses.

Cardiovascular responses of exercises performed within the extreme exercise domain.

Stroke volume (SV), heart rate (HR) and arterio-venous O2 difference (a-vO2diff) responses to heavy and severe-intensity exercise have been well documented; however, there is a lack of information on the SV, HR and a v-O2diff responses of work rates within extreme exercise domain. The aim of this study was, therefore, to focus on central and peripheral components of VO2 responses to exercises performed within the heavy, severe and extreme exercise domain. Eight well-trained male cyclists participated in this study. Maximal O2 consumption (VO2max) and corresponding work rate (P@VO2max) were determined by multisession constant work rate exercises. Cardiovascular responses to exercises were evaluated by nitrous-oxide rebreathing method with work rates from 40 % to 160 % of P@VO2max, VO2max corresponded to 324+/-39.4 W; however, maximal SV responses occurred at 205+/-54.3 W (p<0.01). Maximal cardiac output (Q), HR, and a vO2diff responses were revealed by the P@VO2max. VO2 response to exercise significantly decreased from severe-intense exercises to the first work rate of extreme exercise domain due to significant decreases in Q, SV, and HR responses (p<0.05), except a v-O2diff (p>0.05). Moreover, non-significant decreases in Q, SV, and a v-O2diff were evaluated as response to increase in work rate belonging to extreme work rates (p>0.05), except the HR (p<0.05). Work rates within the lower district of the extreme exercise domain have an important potential to improve peripheral component of VO2, while the P@VO2max seems the most appropriate intensity for aerobic endurance development as it maximizes the central component of VO2max.

Physical Activity, Exercise Capacity and Sedentary Behavior in People with Alpha-1 Antitrypsin Deficiency: A Scoping Review.

Alpha-1 antitrypsin deficiency (AATD) isa hereditary disorder and a genetic risk factor for chronic obstructive pulmonary disease (COPD). Physical activity (PA) is important for the prevention and treatment of chronic disease. Little is known about PA in people with AATD. Therefore, we aimed to map the research undertaken to improve and/or measure PA, sedentary behaviour (SB) or exercise in people with AATD. Searches were conducted in CINAHL, Medline, EMBASE and clinical trial databases for studies published in 2021. Databases were searched for keywords (physical activity, AATD, exercise, sedentary behavior) as well as synonyms of these terms, which were connected using Boolean operators. The search yielded 360 records; 37 records were included for review. All included studies (n = 37) assessed exercise capacity; 22 studies reported the use of the six-minute walk test, the incremental shuttle walk test and cardiopulmonary exercise testing were reported in three studies each. Other objective measures of exercise capacity included a submaximal treadmill test, the Naughton protocol treadmill test, cycle ergometer maximal test, endurance shuttle walk test, constant cycle work rate test, a peak work rate test and the number of flights of stairs a participant was able to walk without stopping. A number of participant self-reported measures of exercise capacity were noted. Only one study aimed to analyze the effects of an intensive fitness intervention on daily PA. One further study reported on an exercise intervention and objectively measured PA at baseline. No studies measured SB. The assessment of PA and use of PA as an intervention in AATD is limited, and research into SB absent. Future research should measure PA and SB levels in people with AATD and explore interventions to enhance PA in this susceptible population.

The minimal important difference of the constant work rate cycle test in severe COPD

BackgroundThe Constant Work Rate Cycle Test (CWRT) is a commonly used and sensitive test to detect treatment success in patients with Chronic Obstructive Pulmonary Disease (COPD). Earlier, the Minimal Important Difference (MID) of the CWRT was estimated at 101 s (or 34%) change from baseline based on one well executed study. However, this study was performed in a population of patients with mild-to-moderate COPD, and we have learned that MIDs might be quite different in patients with severe COPD. Therefore, we aimed to establish the MID of the CWRT in patients with severe COPD. MethodsWe included 141 patients with severe COPD, who underwent either pulmonary rehabilitation, bronchoscopic lung volume reduction with endobronchial valves, or a sham bronchoscopy as a control group. CWRT workload was set at 75% of the peak work capacity, as determined by an incremental cycle test. We used the change in 6-min walking test (6-MWT), forced expiratory volume in 1s (FEV1), residual volume (RV), and St. George's Respiratory Questionnaire (SGRQ) total score as anchors to calculate the MID. ResultsAll anchors had an association of ≥0.41 with change in CWRT. The MID estimates for the different anchors were: 6-MWT 278 s (95%), FEV1 273 s (90%), RV 240 s (84%), and SGRQ 208 s (71%). The average of these four MID estimates resulted in an MID of 250 s (or 85%). ConclusionWe established the MID for CWRT at 250 s (or 85%) change from baseline in patients with severe COPD.

Oxygen Uptake and Bilaterally Measured Vastus Lateralis Muscle Oxygen Desaturation Kinetics in Well-Trained Endurance Cyclists.

The aim of the present study was to compare and analyse the relationships between pulmonary oxygen uptake and vastus lateralis (VL) muscle oxygen desaturation kinetics measured bilaterally with Moxy NIRS sensors in trained endurance athletes. To this end, 18 trained athletes (age: 42.4 ± 7.2 years, height: 1.837 ± 0.053 m, body mass: 82.4 ± 5.7 kg) visited the laboratory on two consecutive days. On the first day, an incremental test was performed to determine the power values for the gas exchange threshold, the ventilatory threshold (VT), and V̇O2max levels from pulmonary ventilation. On the second day, the athletes performed a constant work rate (CWR) test at the power corresponding to the VT. During the CWR test, the pulmonary ventilation characteristics, left and right VL muscle O2 desaturation (DeSmO2), and pedalling power were continuously recorded, and the average signal of both legs' DeSmO2 was computed. Statistical significance was set at p ≤ 0.05. The relative response amplitudes of the primary and slow components of VL desaturation and pulmonary oxygen uptake kinetics did not differ, and the primary amplitude of muscle desaturation kinetics was strongly associated with the initial response rate of oxygen uptake. Compared with pulmonary O2 kinetics, the primary response time of the muscle desaturation kinetics was shorter, and the slow component started earlier. There was good agreement between the time delays of the slow components describing global and local metabolic processes. Nevertheless, there was a low level of agreement between contralateral desaturation kinetic variables. The averaged DeSmO2 signal of the two sides of the body represented the oxygen kinetics more precisely than the right- or left-leg signals separately.

Non-invasive ventilatory support accelerates the oxygen uptake and heart rate kinetics and improves muscle oxygenation dynamics in COPD-HF patients

BackgroundThe aim of this study was to explore the effects of non-invasive positive pressure ventilation (NIPPV) associated with high-intensity exercise on heart rate (HR) and oxygen uptake (V̇O2) recovery kinetics in in patients with coexistence of chronic obstructive pulmonary disease (COPD) and heart failure (HF). MethodsThis is a randomized, double blinded, sham-controlled study involving 14 HF-COPD patients, who underwent a lung function test and Doppler echocardiography. On two different days, patients performed incremental cardiopulmonary exercise testing (CPET) and two constant-work rate tests (80% of CPET peak) receiving Sham or NIPPV (bilevel mode - Astral 150) in a random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin and deoxyhemoglobin were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, Netherland). ResultsThe kinetic variables of both V̇O2 and HR during the high-intensity constant workload protocol were significantly faster in the NIPPV protocol compared to Sham ventilation (P < 0.05). Also, there was a marked improvement in oxygenation and lower deoxygenation of both peripheral and respiratory musculature in TLim during NIPPV when contrasted with Sham ventilation. ConclusionsNIPPV applied during high-intensity dynamic exercise can effectively improve exercise tolerance, accelerate HR and V̇O2 kinetics, improve respiratory and peripheral muscle oxygenation in COPD-HF patients. These beneficial results from the effects of NIPPV may provide evidence and a basis for high-intensity physical training for these patients in cardiopulmonary rehabilitation programs.

Bioenergetic changes and mitochondrial dysfunction in mania versus euthymia in bipolar disorder type I

IntroductionCurrent evidence has hypothesized the involvement of mitochondrial dysfunction during the acute episodes of BD compared to symptomatic remission. So far, no studies have compared mitochondrial and bioenergetic functions both in-vivo (respiratory parameters) and ex-vivo (cellular respiration) in different phases of the disease in the same individuals.ObjectivesThis multidisciplinary pilot study aims at assessing bioenergetic and mitochondrial intra-individual differences between manic and euthymic states.MethodsFour patients with a manic episode admitted to our acute psychiatric ward were recruited. Bioenergetic parameters were measured at admission (T0) and after symptomatic remission (T1).At admission (T0) and before discharge (T1), HAMD and YMRS total scores were obtained. For the assessment of cellular respiration, polymorphonuclear cells were obtained by a Ficoll density gradient centrifugation procedure. To determine oxygen consumption (at T0 and T1), a million of living peripheral blood mononuclear cells (PBMC) were used. High-resolution respirometry was performed at 37°C by polarographic oxygen sensors in a two-chamber Oxygraph-2k system.Specific oxygen uptakes (Routine: basal oxygen consumption; Proton Leak: oxygen consumption not coupled to ATP synthesis; and ETC: maximal capacity of the electron transport chain) rates were obtained using mitochondrial chain inhibitors and uncouplers. Oxygen consumption was normalized for protein concentration. Results are expressed as picomoles of oxygen per millilitre (pmol O2/s*μg prot).Also, a constant work rate exercise test was performed on a cycle ergometer and basal and effort respiratory variables were measured.Statistical analysis was performed with the SPSS v. 25.0 and GraphPad. Results were expressed as means and SD. Nonparametric tests (Mann–Whitney, Pearson) were used to determine differences (significant at p value &lt;0.05).ResultsOne patient was a man and three patients were women, with a mean age of 28 years old. HAMD initial and final mean scores were 11.0 and 7.0, and mean YMRS scores were 21.5 and 7.0 respectively.Results from mitochondrial oxygen consumption revealed that mean basal oxygen consumption tended to be higher in T1 (0.98±0.45) than in T0, and maximal respiratory capacity was significantly increased in T1 (2.26±0.33; p=0.028) compared to T0.Mean lactate levels and pH levels were similar in T0 and T1. Scales scores were not correlated to different pH or lactate changes after the effort task. Higher initial oxygen consumption was significantly correlated to higher maximal capacity (p&lt;0.05) in T0 and T1.Image:ConclusionsOur preliminary results suggest that mania could imply lower oxygen consumption capacity, which should be confirmed in future studies. A bigger study is planned to determine changes in bioenergetic patterns and capacity for aerobic response in manic and depressive episodes.Disclosure of InterestNone Declared

Metabolomic, oxidative, and inflammatory responses to acute exercise in chronic obstructive pulmonary disease

BackgroundThere is currently a need to identify metabolomic responses to acute exercise in chronic obstructive pulmonary disease (COPD). ObjectiveWe investigated the metabolomic, oxidative, and inflammatory responses to constant (CE) and intermittent (IE) work rate exercises in COPD. MethodsSixteen males with COPD performed a symptom-limited incremental cycle exercise test (ICE). Metabolomic, oxidative, and inflammatory responses to CE and IE (based on the performance of ICE) were analyzed in the plasma. ResultsFructose-6-phosphate, 3-phosphoglyceric acid, l-carnitine, and acylcarnitines levels were significantly decreased, whereas alpha-ketoglutaric, malic, 2-hydroxybutyric, and 3-hydroxybutyric acids were increased, after CE and IE (p<0.05). Increases in citric, isocitric, and lactic acids, as well as decreases in pyruvic and oxalic acids, were only present with IE (p<0.05). Isoleucine was decreased after both exercises (p<0.05). We observed an increase in inosine-5′-diphosphate, uric acid, ascorbic acid, and pantothenic acid, as well as a decrease in 5-hydroxymethyluridine, threonic acid, and dehydroascorbic acid, after IE (p<0.05). Catalase, reduced glutathione, and total antioxidant status difference values for both exercises were similar (p>0.05). The change in glutathione peroxidase (GPx) with CE was more significant than that with IE (p = 0.004). The superoxide dismutase change was greater with IE than with CE (p = 0.015). There were no significant changes in inflammatory markers after exercise (p>0.05). ConclusionCE and IE cause isoleucine, l-carnitine, and acylcarnitine levels to decrease, whereas ketone bodies were increased, thus indicating the energy metabolism shift from carbohydrates to amino acid utilization and lipid metabolism in COPD. Compared with CE, IE produces significant changes in more metabolomics in terms of carbohydrates, lipids, amino acids, nucleotides, and vitamins. Acute CE and IE alter circulating GPx levels in COPD.

Energy metabolism and muscle activation heterogeneity explain slow component and muscle fatigue of cycling at different intensities.

What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O2 cost per unit of work during high-intensity exercise? What is the main finding and its importance? Muscle fatigue happens before, and does not explain, the slow component ( ), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue and . Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes. This study aimed to explain the slow component ( ) and muscle fatigue during cycling at different intensities. The muscle fatigue of 16 participants was determined through maximal isokinetic effort lasting 3s during constant work rate bouts of moderate (MOD), heavy (HVY) and very heavy intensity (VHI) exercise. Breath-by-breath , near-infrared spectroscopy signals and EMG activity were analysed (thigh muscles). was higher during VHI exercise (∼70% vs. ∼28% of reserve in HVY). The deoxygenated haemoglobin final value during VHI exercise was higher than during HVY and MOD exercise (∼90% of HHb physiological normalization, vs. ∼82% HVY and ∼45% MOD). The muscle fatigue was greater after VHI exercise (∼22% vs. HVY ∼5%). There was no muscle fatigue after MOD exercise. The greatest magnitude of muscle fatigue occurred within 2min (VHI ∼17%; HVY ∼9%), after which it stabilized. No significant relationship between and muscle force production was observed. The τ of muscle was significantly related (R2 =0.47) with torque decrease for VHI. Type I and II muscle fibre recruitment mainly in the rectus femoris moderately explained the muscle fatigue (R2 =0.30 and 0.31, respectively) and the (R2 =0.39 and 0.27, respectively). The is also partially explained by blood lactate accumulation (R2 =0.42). In conclusion muscle fatigue and O2 cost seem to share the same physiological cause linked with a decrease in the muscle and a change in lactate accumulation. Muscle fatigue and are associated with muscle activation heterogeneity and metabolism of different muscles activated during cycling.

The Minimal Important Difference of the Constant Work Rate Cycle Test in Severe COPD

The Minimal Important Difference of the Constant Work Rate Cycle Test in Severe COPD

Respiratory Muscle Interval Training Improves Exercise Capacity in Obese Adolescents during a 3-Week In-Hospital Multidisciplinary Body Weight Reduction Program.

The purpose of this study was to determine whether a novel approach of interval training targeted to the respiratory muscles (RMIT; normocapnic hyperpnea with resistance) in addition to a multidisciplinary in-hospital body weight reduction program (BWRP) was able to improve the integrative response to exercise in young patients with obesity. Nine male patients (17.9 ± 4.9 (x ± SD) years; 113.8 ± 16.3 kg) underwent 12 sessions of RMIT and eight age-and sex-matched patients underwent 12 sessions of a sham protocol (CTRL) during the same 3-week BWRP. Before and after the interventions the patients performed an incremental and a heavy-intensity constant work-rate (CWR>GET) cycling exercise to voluntary exhaustion. Body mass decreased by ~4.0 kg after both RMIT (p = 0.0001) and CTRL (p = 0.0002). Peak pulmonary O2 uptake (V˙O2) increased after RMIT (p = 0.02) and CTRL (p = 0.0007). During CWR>GET at ISO-time, V˙O2 (p = 0.0007), pulmonary ventilation (p = 0.01), heart rate (p = 0.02), perceived respiratory discomfort (RPER; p = 0.03) and leg effort (p = 0.0003) decreased after RMIT; only RPER (p = 0.03) decreased after CTRL. Time to exhaustion increased after RMIT (p = 0.0003) but not after CTRL. In young patients with obesity, RMIT inserted in a 3-week BWRP reduced the cardiorespiratory burden, the metabolic cost, the perceived effort, and improved exercise tolerance during heavy-intensity cycling.

Exercise capacity and physical activity in COPD patients treated with a LAMA/LABA combination: a systematic review and meta-analysis

BackgroundPersistent airflow limitation and dyspnoea may reduce chronic obstructive pulmonary disease (COPD) patients exercise capacity and physical activity, undermining their physical status and quality of life. Long-acting muscarinic antagonists and long-acting beta-2 agonists (LAMA/LABA) combinations are amongst moderate-to-severe COPD recommended treatments. This article analyses LAMA/LABA combinations effect on COPD patients exercise capacity and physical activity outcomes.MethodsA systematic review and meta-analysis of double-blind randomized controlled trials comparing LAMA/LABA combinations against monotherapy or placebo was conducted.ResultsSeventeen articles were identified (N = 4041 patients). In endurance shuttle walk test and constant work rate cycle ergometry, LAMA/LABA combinations obtained better results than placebo, but not monotherapy, whereas in 6-min walking test, results favoured LAMA/LABA over monotherapy (four studies), but not over placebo (one study). Moreover, LAMA/LABA combinations obtained better results than placebo in number of steps per day, reduction in percentage of inactive patients and daily activity-related energy expenditure, and better than monotherapy when measuring time spent on ≥ 1.0–1.5, ≥ 2.0 and ≥ 3.0 metabolic equivalents of task activities.ConclusionsLAMA/LABA combinations in COPD patients provided better results than monotherapy or placebo in most exercise capacity and physical activity outcomes.

The effect of a pressure ventilatory support on quadriceps endurance is maintained after exercise training in severe COPD patients. A longitudinal randomized, cross over study.

Purpose: In severe chronic obstructive pulmonary disease (COPD) patients, the application of an inspiratory pressure support (IPS) during exercise increases exercise tolerance and the benefit of exercise training during pulmonary rehabilitation (PR). Moreover, it improves quadriceps endurance after a session of cycling exercise suggesting a reduced muscle fatigue. We looked for the persistence of this effect after PR and sought an association between the improved quadriceps endurance with IPS and the training load during PR. Patients and methods: We studied 20 patients with severe COPD (6 in stage 3and 14 in stage 4 of GOLD) before and after PR. As part of a PR program, patients completed 16 cycling sessions over 6 weeks with the addition of IPS during exercise. As a surrogate of muscular fatigue, quadriceps endurance was measured at 70% of maximal strength in a control condition, after a constant work rate exercise test (CWR) with IPS (TlimQ IPS) or with a sham ventilation (TlimQsham), in a random order. These tests were repeated similarly at the end of PR. Results: PR was associated with a significant increase in maximal power output, cycling endurance, quadriceps strength and endurance. Session training load (power output x duration of the session) increased by 142% during the course of the program. Before PR, CWR duration increases with IPS compared to sham ventilation (Δtime = +244s, p = 0.001). Compared to control condition, post-exercise TlimQ reduction was lower with IPS at isotime than at the end of CWR or than with sham ventilation (-9 ± 21%, -18 ± 16% and -23 ± 18%, respectively, p = 0.09, p < 0.0001 and p < 0.0001). After PR, the post-exercise decrease of TlimQ was reduced after IPS compared to sham (-9 ± 18% vs. -21 ± 17%, respectively, p = 0.004). No relationship was found between the prevention of quadriceps fatigue and the training load. Conclusion: In severe COPD patients, the beneficial effect of a ventilator support on quadriceps endurance persisted after PR with IPS. However, it was not related to the increase in training load, and could not predict the training response to non-invasive ventilation during exercise.

Abstract 10388: Impact Of Right Ventricular Function On Cardiopulmonary Exercise Capacity In Mitral Regurgitation Patients Undergoing Transcatheter Mitral Valve Repair

Background/Objectives: To investigate the role of right ventricular (RV) function on exercise capacity in patients undergoing transcatheter mitral valve repair (TMVR) we aimed to perform cardiopulmonary exercise testing (CPET) and to show a correlation between an improved RV function and maximal and submaximal exercise capacity. Methods: Constant work rate exercise time testing (CWRET) reflects submaximal/endurance exercise capacity, which is more likely to be relevant for daily life activities, and gives a more differentiated physiologic insight into the nature of exercise intolerance. Thus, 28 Patients with mitral regurgitation (MR) and symptomatic heart failure (NYHA≥II) underwent CPET by assessment of maximal oxygen uptake (peak VO 2 ) and submaximal exercise capacity (at 75% of maximal achieved work rate in the initial incremental exercise test) accompanied by echocardiography prior to TMVR and 3 months post-procedure. Results: Mean age of the patients was 75.0±8.7 years and 32.1% of them were female. One patient presented a reduction of MR &lt;2 grades. RV function (assessed with fractional area change, tricuspid annular plane systolic excursion, longitudinal strain of the RV free wall and S`) was at least moderately impaired in 25% of the patients. The submaximal exercise capacity of these patients was impaired, but did not significantly differ (416.4±359.6sec vs. 296.1 ±216.5sec; p=0.152) compared to patients without a deteriorated RV function. Three months after intervention, exercise time at 75% of maximal achieved work rate significantly improved (from 337.4±262.2sec to 517.4±393. sec p=0.006), reflecting a gain in submaximal exercise tolerance. peak VO 2 showed a positive trend, but no statistically significant difference (10.3±3.1ml/min/kg vs. 11.3±3.4ml/min/kg; p=0.056). RV function (at least 2 of 4 parameters) improved in 35.7% and these patients showed a significantly higher submaximal exercise time increasement (471.7±153.9sec vs. 82.7±47.0sec, p=0.003). Discussion/Conclusions: TMVR may have a beneficial effect on RV remodeling. Furthermore, submaximal exercise capacity is significantly increased, reflecting an improvement especially regarding daily life activities in MR patients and impaired RV function.

Respiratory Threshold as A New Threshold Determination Method based on Respiratory Responses and It’s Success to Indicate Critical Power

Yeni bir solunumsal eşik türü olarak ortaya atılan respirasyon eşiği (RE) kademeli bir rampa testinde dakika ventilasyonu bölü ekspirasyon sonu CO2 kısmi basıncı (VE/PETCO2) değerindeki zamana bağlı değişimlerin analizine dayanır. Ancak RE tekniğinin yaygın olarak kullanılan önemli bir eşik belirleme yöntemi olan kritik gücü (KG) hangi düzeyde işaret edebildiğine odaklanan bir araştırma bulgusu rapor edilmemiştir. Bu çalışmanın amacı, RE tekniği kullanılarak elde edilen egzersiz şiddetinin, KG’yi hangi düzeyde karşılayabildiğini araştırmaktır. Çalışmaya iyi antrene on erkek bisiklet sporcusu katılmıştır. Sporcuların gaz değişim eşiği (GDE), solunumsal kompanzasyon noktası (SKN) ve RE düzeyleri kademeli rampa testleriyle belirlenmiştir. Bu testlerde GDE ve SKN düzeyleri, Innocor sistemi yoluyla VCO2-VO2 ve VE-VCO2 ilişkilerinde saptanan kırılmalar tespit edilerek değerlendirilmiştir. RE düzeyi SegReg paket programı kullanılarak VE/PETCO2-zaman ilişkisindeki en güçlü kırılma noktası tespit edilerek bulunmuştur. Sonrasında KG’yi hesaplamak için farklı günlerde sabit iş oranlarında testler uygulanmıştır. Tüm eşik göstergelerinin birbirleriyle ilişkilerinin sınanması için geçerlik analizleri yapılmıştır. Bulgular, RE (328±35,5 W; 4,23±0,39 L·dk−1) ile SKN (324±34,3 W; 4,21±0,45 L·dk−1) güç çıktıları ve her birine ait VO2 yanıtları arasında yüksek bir ilişki ve uyum olduğunu göstermiştir (p&amp;gt;0,05; t= 1,19; r&amp;gt;0,96; % tahmini standart hata &amp;lt;5). Ancak hem RE hem de SKN güç çıktıları KG'den (298±32 W) yaklaşık %10 daha yüksek bulunmuştur (p&amp;lt;0,001). Çalışmamız, iyi antrene bisikletçilerde VE/PETCO2-zaman ilişkisinde oluşan en güçlü kırılmanın çok büyük bir başarı ile SKN’yi gösterdiğini, fakat KG’yi doğrudan belirlemede başarısız olduğunu ortaya koymuştur.

Variability in Cardiopulmonary Exercise Testing Biologic Controls.

Cardiopulmonary exercise testing is an increasingly common test and is considered the accepted standard for assessing exercise capacity. Quantifying variability is important to assess the instrument for quality control purposes. Though guidelines recommend biologic control testing, there are minimal data on how to do it. We sought to describe variability for oxygen consumption (V̇O2 ), carbon dioxide production (V̇CO2 ), and minute ventilation (V̇E) at various work rates under steady-state conditions in multiple subjects over a 1-y period to provide a practical approach to assess and perform biologic control testing. We performed a single-center, prospective study with 4 healthy subjects, 2 men and 2 women. Subjects performed constant work rate exercise tests for 6 min each at 25-100 W intervals on a computer-controlled cycle ergometer. Data were averaged over the last 120 s at each work rate to reflect stepwise steady-state conditions. Descriptive statistics, including the mean, median, range, SD, and coefficient of variation (CoV) are reported for each individual across the 4 work rates and all repetitions. As these data were normative, z-scores were utilized, and a value greater than ± 1.96 z-scores was used to define significant test variability. Subjects performed 16-39 biocontrol studies over 1-y. The mean CoV for all subjects in V̇O2 was 6.59%, V̇CO2 was 6.41%, and V̇E was 6.32%. The ± 1.96 z-scores corresponded to a 9.4-18.1% change in V̇O2 , a 9.6-18.1% change in V̇CO2 , and a 9-21.5% change in V̇E across the 4 workloads. We report long-term variability for steady-state measurement of V̇O2 , V̇CO2 , and V̇E obtained during biocontrol testing. Utilizing ± 1.96 z-scores allows one to determine if a result exceeds expected variability, which may warrant investigation of the instrument.