Cardiopulmonary Exercise Test Parameters in Athletic Population: A Review

Although still underutilized, cardiopulmonary exercise testing (CPET) allows the most accurate and reproducible measurement of cardiorespiratory fitness and performance in athletes. It provides functional physiologic indices which are key variables in the assessment of athletes in different disciplines. CPET is valuable in clinical and physiological investigation of individuals with loss of performance or minor symptoms that might indicate subclinical cardiovascular, pulmonary or musculoskeletal disorders. Highly trained athletes have improved CPET values, so having just normal values may hide a medical disorder. In the present review, applications of CPET in athletes with special attention on physiological parameters such as VO2max, ventilatory thresholds, oxygen pulse, and ventilatory equivalent for oxygen and exercise economy in the assessment of athletic performance are discussed. The role of CPET in the evaluation of possible latent diseases and overtraining syndrome, as well as CPET-based exercise prescription, are outlined.

Minute ventilation/carbon dioxide production in patients with dysfunctional breathing

Dysfunctional breathing refers to a multi-dimensional condition that is characterised by pathological changes in an individual's breathing. These changes lead to a feeling of breathlessness and include alterations in the biomechanical, psychological and physiological aspects of breathing. This makes dysfunctional breathing a hard condition to diagnose, given the diversity of aspects that contribute to the feeling of breathlessness. The disorder can debilitate individuals without any health problems, but may also be present in those with underlying cardiopulmonary co-morbidities. The ventilatory equivalent for CO2 (VeqCO2) is a physiological parameter that can be measured using cardiopulmonary exercise testing. This review will explore how this single measurement can be used to aid the diagnosis of dysfunctional breathing. A background discussion about dysfunctional breathing will allow readers to comprehend its multidimensional aspects. This will then allow readers to understand how VeqCO2 can be used in the wider diagnosis of dysfunctional breathing. Whilst VeqCO2 cannot be used as a singular parameter in the diagnosis of dysfunctional breathing, this review supports its use within a broader algorithm to detect physiological abnormalities in patients with dysfunctional breathing. This will allow for more individuals to be accurately diagnosed and appropriately managed.

Ventilation/carbon dioxide output relationships during exercise in health

“Ventilatory efficiency” is widely used in cardiopulmonary exercise testing to make inferences regarding the normality (or otherwise) of the arterial CO2 tension (PaCO2) and physiological dead-space fraction of the breath (VD/VT) responses to rapid-incremental (or ramp) exercise. It is quantified as: 1) the slope of the linear region of the relationship between ventilation (V′E) and pulmonary CO2 output (V′CO2); and/or 2) the ventilatory equivalent for CO2 at the lactate threshold (V′E/V′CO2) or its minimum value (V′E/V′CO2min), which occurs soon after but before respiratory compensation. Although these indices are normally numerically similar, they are not equally robust. That is, high values for V′E/V′CO2 and V′E/V′CO2min provide a rigorous index of an elevated VD/VT when PaCO2 is known (or can be assumed) to be regulated. In contrast, a high V′E–V′CO2 slope on its own does not, as account has also to be taken of the associated normally positive and small V′E intercept. Interpretation is complicated by factors such as: the extent to which PaCO2 is actually regulated during rapid-incremental exercise (as is the case for steady-state moderate exercise); and whether V′E/V′CO2 or V′E/V′CO2min provide accurate reflections of the true asymptotic value of V′E/V′CO2, to which the V′E–V′CO2 slope approximates at very high work rates.

Follow-Up Study of the Chest CT Characteristics of COVID-19 Survivors Seven Months After Recovery

Background: It has remained a concern whether any long-term pulmonary sequelae exist for COVID-19 survivors.Methods: Forty-one patients (22 men and 19 women, 50 ± 14 years) confirmed with COVID-19 performed follow-up chest CT and cardiopulmonary exercise testing at 7 months after discharge. Patients were divided into fibrosis group and non-fibrosis group according to the evidence of fibrosis on follow-up CT. The clinical data and the CT findings were recorded and analyzed.Results: The predominant CT patterns of abnormalities observed at 7 months after discharge were parenchymal band (41%), interlobular septal thickening (32%), and traction bronchiectasis (29%). Sixty-one percent of the patients achieved complete radiological resolution, and 29% of patients developed pulmonary fibrosis. Compared with the patients in the non-fibrosis group, the patients in the fibrosis group were older, with a longer hospital stay, a higher rate of steroid and mechanical ventilation therapy, lower levels of lymphocyte and T cell count, higher levels of D-dimer and lactic dehydrogenase, and higher quantitative CT parameters (opacity score, volume of opacity, and percentage of opacity) at discharge. Besides, oxygen consumption and metabolic equations were decreased and ventilatory equivalent for carbon dioxide was increased in patients in the fibrosis group. Logistic regression analyses revealed that age, steroid therapy, presence of traction bronchiectasis on chest CT at discharge, and opacity score at discharge, were independent risk factors for developing pulmonary fibrosis at 7 months after discharge. Receiver operating characteristic analysis revealed that the combined clinical-radiological model was better than the clinical-only model in the prediction of pulmonary fibrosis.Conclusions: The chest CT lesions could be absorbed without any sequelae for most patients with COVID-19, whereas older patients with severe conditions are more prone to develop fibrosis, which may further lead to cardiopulmonary insufficiency. The combined clinical-radiological model may predict the formation of pulmonary fibrosis early.

Effect of Running Velocity Variation on the Aerobic Cost of Running

The aerobic cost of running (CR), an important determinant of running performance, is usually measured during constant speed running. However, constant speed does not adequately reflect the nature of human locomotion, particularly competitive races, which include stochastic variations in pace. Studies in non-athletic individuals suggest that stochastic variations in running velocity produce little change in CR. This study was designed to evaluate whether variations in running speed influence CR in trained runners. Twenty competitive runners (12 m, VO2max = 73 ± 7 mL/kg; 8f, VO2max = 57 ± 6 mL/kg) ran four 6-minute bouts at an average speed calculated to require ~90% ventilatory threshold (VT) (measured using both v-slope and ventilatory equivalent). Each interval was run with minute-to-minute pace variation around average speed. CR was measured over the last 2 min. The coefficient of variation (CV) of running speed was calculated to quantify pace variations: ±0.0 m∙s−1 (CV = 0%), ±0.04 m∙s−1 (CV = 1.4%), ±0.13 m∙s−1(CV = 4.2%), and ±0.22 m∙s−1(CV = 7%). No differences in CR, HR, or blood lactate (BLa) were found amongst the variations in running pace. Rating of perceived exertion (RPE) was significantly higher only in the 7% CV condition. The results support earlier studies with short term (3s) pace variations, that pace variation within the limits often seen in competitive races did not affect CR when measured at running speeds below VT.

Carbon dioxide output

This chapter describes how carbon dioxide is produced from metabolism and also from buffering of lactic acid. The volume of carbon dioxide exhaled (VCO2) is calculated from the concentration in exhaled gas and minute ventilation. If the lungs are less efficient than normal, with a high dead space, the amount of ventilation needed to achieve any given VCO2 is much higher. This index, known as the ventilatory equivalent for carbon dioxide, is an important prognostic marker. Early on in a cardiopulmonary exercise test (CPET), VCO2 is slightly less than the oxygen uptake (VO2). As exercise reaches its maximum, VCO2 increases more quickly when acidaemia starts to stimulate ventilation.

Effect of training on the development of exercise-induced arterial hypoxemia in volleyball players

Background and Study Aim. The purpose of this study was to examine the effect of volleyball training on the development of exercise-induced arterial hypoxemia during incremental exercise in male competitive volleyball players. Material and Methods. Eight male amateur volleyball players (age 21±1.3 years) participated in a 6-week volleyball training program three times a week in the pre-season preparatory period. Before and after the training period, all players performed an incremental treadmill test to determine maximal oxygen uptake (VO2max), and oxyhemoglobin saturation (SaO2) was continuously measured using a pulse oximeter during the test. Maximal values of minute ventilation (VEmax), respiratory exchange ratio (RERmax), ventilatory equivalent for oxygen (VE/VO2) and carbon dioxide (VE/VCO2) were determined. Exercise-induced arterial hypoxemia (EIAH) was defined as a SaO2 decreased by at least 4% (ΔSaO2≤ −4%) from resting level. Results. All the players exhibited exercise-induced arterial hypoxemia before (ΔSaO2= –8.8±3.3%) and after (ΔSaO2= –8.31.5%) the training period. SaO2 was significantly decreased from 97.6±1% at rest to 88.7±2.7% at exhaustion before the training period, and from 97.2±1.1% at rest to 88.8±2.1% at exhaustion after training period (p < 0.001). There was no significant difference in resting and lowest SaO2 values by comparison between the before and after training (p > 0.05). There were no significant changes in VO2max, VEmax, RERmax, VE/VO2 and VE/VCO2 after training period (p > 0.05). Conclusions. The results of this study showed that volleyball players with a history of anaerobic training may exhibit EIAH, but that 6-week volleyball training has no effect on the degree of exercise-induced arterial hypoxemia.

The role of testosterone in the respiratory and thermal responses to hypoxia and hypercapnia in rats

Many diseases of the respiratory system occur differently in males and females, indicating a possible role of gonadal hormones in respiratory control. We hypothesized that testosterone (T) is important for the ventilatory chemosensitivity responses in males. To test this hypothesis, we evaluated ventilation (V̇E), metabolic rate and body temperature (Tb) under normoxia/normocapnia, hypercapnia and hypoxia in orchiectomized (ORX), ORX with testosterone replacement (ORX+T) or flutamide (FL, androgen receptor blocker)-treated rats. We also performed immunohistochemistry to evaluate the presence of androgen receptor (AR) in the carotid body (CB) of intact males. Orchiectomy promoted a reduction V̇E and ventilatory equivalent (V̇E/V̇O2) under room-air conditions, which was restored with testosterone treatment. Moreover, during hypoxia or hypercapnia, animals that received testosterone replacement had a higher V̇E and V̇E/V̇O2 than control and ORX, without changes in metabolic and thermal variables. Flutamide decreased the hypoxic ventilatory response without changing the CO2-drive to breathe, suggesting that the testosterone effect on hypercapnic hyperventilation does not appear to involve the AR. We also determined the presence of AR in the CB of intact animals. Our findings demonstrate that testosterone seems to be important for maintaining resting V̇E in males. In addition, the influence of testosterone on V̇E, either during resting conditions or under hypoxia and hypercapnia, seems to be a direct and specific effect, as no changes in metabolic rate or Tb were observed during any treatment. Finally, a putative site of testosterone action during hypoxia is the CB, since we detected the presence of AR in this structure.

Absolute Accelerometer-Based Intensity Prescription Compared to Physiological Variables in Pregnant and Nonpregnant Women

Estimation of the intensity of physical activity (PA) based on absolute accelerometer cut points (Cp) likely over- or underestimates intensity for a specific individual. The purpose of this study was to investigate the relationship between absolute moderate intensity Cp and the first ventilatory threshold (VT1). A group of 24 pregnant and 15 nonpregnant women who performed a submaximal incremental walking test with measures of ventilatory parameters and accelerations from three different accelerometers on the wrist (ActiGraph wGT3X-BT, GENEActiv, Axivity AX3) and one on the hip (Actigraph wGT3X-BT) were analyzed. Cp were determined corresponding to 3 metabolic equivalents of task (MET), using the conventional MET definition (Cp3.5) (3.5 mL/kg×min) and individual resting metabolic rate (Cpind). The ventilatory equivalent (VE/VO2) was used to determine VT1. Accelerations at VT1 were significantly higher (p < 0.01) compared to Cp3.5 and Cpind in both groups. Cp3.5 and Cpind were significantly different in nonpregnant (p < 0.01) but not in pregnant women. Walking speed at VT1 (5.7 ± 0.5/6.2 ± 0.8 km/h) was significantly lower (p < 0.01) in pregnant compared to nonpregnant women and correspondent to 3.8 ± 0.7/4.9 ± 1.4 conventional METs. Intensity at absolute Cp was lower compared to the intensity at VT1 independent of the device or placement in pregnant and nonpregnant women. Therefore, we recommend individually tailored cut points such as the VT1 to better assess the effect of the intensity of PA.

Prognostic significance of compound physiology variables in oesophageal cancer

AimsObjective identification of patient risk profile in Oesophageal Cancer (OC) surgery is critical. This study aimed to evaluate to what extent cardiorespiratory fitness and select metabolic factors predict clinical outcome.MethodsConsecutive 186 patients were recruited (median age 69 yr. 160 male, 138 neoadjuvant therapy). All underwent pre-operative cardiopulmonary exercise testing to determine peak oxygen uptake , anaerobic threshold (AT), and ventilatory equivalent for carbon dioxide . Cephalic venous blood was assayed for serum C-reactive protein (CRP), albumin, and full blood count. Primary outcome measures were Morbidity Severity Score (MSS), and Overall Survival (OS).ResultsMSS (Clavien-Dindo >2) developed in 33 (17.7%) and was related to elevated CRP (AUC 0.69, p=0.001) and lower V·O2Peak (AUC 0.33, p=0.003). Dichotomisation of CRP (above 10mg/L) and V·O2Peak (below 18.6mL/kg/min) yielded adjusted Odds Ratios (OR) for MSS CD>2, of 4.01 (p=0.002) and 3.74 (p=0.002) respectively. OC recurrence occurred in 36 (19.4%) and 69 (37.1%) patients died. On multivariable analysis; pTNM stage (Hazard Ratio (HR) 2.20, p=0.001), poor differentiation (HR 2.20, p=0.010), resection margin positivity (HR 2.33, p=0.021), and MSS (HR 4.56, p<0.001) were associated with OS.ConclusionsCRP and V·O2Peak are collective independent risk factors that can account for over half of OC survival variance.