Incremental Exercise Test Research Articles

Time- and Frequency-Domain Analysis of Stroke Volume Variability Using Indoor Cycling to Evaluate Physical Load of Body

A potential myocardial injury can be induced by intensive sporting activities, which may be due to ventricular tachycardia or fibrillation when individuals continue to exercise during the maximum physical loading period (the aerobic capability plateau, ACP). Herein, we conducted an incremental exercise test with the RR-interval and SV-series measurements as the input and output of the circulatory system. Through time and frequency analyses, we aimed to identify the indicators for distinguishing the normal stage (S1), last stage before ACP (S2), and ACP stage (S3) during different incremental physical loads. The cross-correlation results of the RR interval and SV series showed that the maximum coefficient of S2 was significantly greater (p < 0.05) than that of S1 (median 0.91 to 0.87), and also significantly lower (p < 0.05) than that of S3 (median 0.87 to 0.60). The corresponding spectrum shows that the decreasing correlation coefficient of SVV and Heart rate variability can be used to assess whether the body has reached the ACP. These findings can be used as a guide for exercise healthcare. Pausing or reducing the exercise load before entering the ACP could effectively reduce the risk of myocardial injury.

Role of Blood Pressure Responses to Exercise and Vascular Insulin Sensitivity with Nocturnal Blood Pressure Dipping in Metabolic Syndrome

Introduction: Nocturnal systolic blood pressure (SBP) dipping is independently related to cardiovascular disease risk, but it is unclear if vascular insulin sensitivity associates with SBP dipping in patients with metabolic syndrome (MetS). Methods: Eighteen adults with MetS (ATP III criteria 3.3 ± 0.6; 53.2 ± 6.5 years; body mass index 35.8 ± 4.5 kg/m²) were categorized as “dippers” (≥10% change in SBP; n = 4 F/3 M) or “non-dippers” (<10%; n = 9 F/2 M). Twenty-four-hour ambulatory blood pressure was recorded to assess SBP dipping. A euglycemic-hyperinsulinemic clamp (40 mU/m²/min, 90 mg/dL) with ultrasound (flow mediated dilation) was performed to test vascular insulin sensitivity. A graded, incremental exercise test was conducted to estimate sympathetic activity. Heart rate (HR) recovery after exercise was then used to determine parasympathetic activity. Metabolic panels and body composition (DXA) were also tested. Results: Dippers had greater drops in SBP (16.63 ± 5.2 vs. 1.83 ± 5.6%, p < 0.01) and experienced an attenuated rise in both SBP_slope (4.7 ± 2.3 vs. 7.2 ± 2.5 mm Hg/min, p = 0.05) and HR_slope to the incremental exercise test compared to non-dippers (6.5 ± 0.9 vs. 8.2 ± 1.7 bpm/min, p = 0.03). SBP dipping correlated with higher insulin-stimulated flow-mediated dilation (r = 0.52, p = 0.03), although the relationship was no longer significant after covarying for HR_slope (r = 0.42, p = 0.09). Conclusion: Attenuated rises in blood pressure and HR to exercise appear to play a larger role than vascular insulin sensitivity in SBP dipping in adults with MetS.

12 Inflammatory Response Following a Single Bout of Exercise Is More Prominent Is Young Horses Compared to Older Horses

Abstract Horses experience a post-exercise inflammatory response to damaged tissues that is part of the mechanism of recovery and is indicated by heat and muscle soreness (MS). Further, old horses (OH) are at a greater risk of prolonged MS, lameness, and injury than are young horses (YH). Therefore, the objective of this study was to compare heat and MS of unconditioned young (14-16 months) and old (19-24 years) Quarter Horses after the completion of an incremental exercise test (IET: counterclockwise at 3 min at 6.44 kph, 10 min at 16.09 kph, 2 min each at 19.31 and 22.53 kph). MS evaluations were performed on neck, shoulder, back, and hip for both sides at pre, 12, 36, 60, and 84 hours post IET. FLIR images of the shoulder, forearm, back, hip, and gaskin were taken on the left side at day 0, pre-IET, 15 min, and 12, 24, 48, 72 h post-IET. Data were analyzed by repeated measures ANOVA using the MIXED procedure of SAS. There was a main effect of age on gaskin temperature, whereby YH (32.3±17.5°C) had higher temperatures than OH (31.4±17.5°C; P = 0.043). There was a tendency for an interaction of age and time for shoulders (P = 0.063) and an interaction for forearm (P = 0.03) and back (P = 0.046). At 12 h post IET, YH shoulders were higher (34.6±17.1°C) than OH (31.8±17.1°C), YH forearms were higher (34.1±17.3°C) than OH (30.4±17.1°C), and YH backs (33.4±17.3°C) were higher than OH (32±17.3°C). Necks were sorer on the right side 36 h post-IET compared to pre-exercise (P = 0.033) and 60 hours compared to 12 hours post IET (P = 0.033). Muscle soreness increased in the right hip from pre-IET to 36 h post-IET (P = 0.037). No other differences were observed. Our results suggest that YH have higher surface temperatures than OH but this was not associated with MS.

15 Potential Benefits of Rice Bran Oil for Lightly Worked Young Horses

Abstract Rice bran (RICE) and flax (FLAX) oils contain omega-3 fatty acids with the potential to reduce post-exercise muscle damage. This study compared plasma essential fatty acid profiles, creatine kinase (CK) activity, and lactic acid (LA) concentrations in lightly worked young horses undergoing a 16 min incremental exercise test (IET; 16.1, 19.3, 22.5, and 25.7 kph) after 60 d of supplementation. Treatments consisted of none (CON; n = 4), FLAX (n = 4), or RICE (n = 4) oil. Horses received their energy requirement as 40% from concentrate and 60% from hay, with oil replacing 25% of concentrate calories. Blood was obtained before, 1, and 30 min post-IET. Data were analyzed by repeated measures ANOVA. On d60, alpha-linolenic acid was greater in FLAX (2.3±0.2 g/100g) than RICE (1.5±0.2 g/100g; P = 0.01), and docosahexaenoic acid was higher in CON (1.4±0.3 g/100g) and RICE (0.9±0.3 g/100g) than FLAX (0±0.3 g/100g; P &amp;lt; 0.01). In CON horses, CK activity was increased on both IET days at 30min post (1.9±0.4 U/L; P &amp;lt; 0.01). In FLAX and RICE horses, CK activity increased 30 min post IET on d0 only (FLAX=2.2±0.1 U/L; P=0.02; RICE=1.9±0.06 U/L; P = 0.01), with no increase on d60 (P &amp;gt; 0.06). For CON, LA concentrations were not different at 1 min post-IET between d0 and 60 (P &amp;gt;0.7) but were different at 30min post (d0=1.0±0.1 mmol/L; d60=0.4±0.1 mmol/L; P = 0.04), In FLAX, LA was greater at 1min post-IET on d60 (2.8±0.1 mmol/L) than d0 (1.5±0.1 mmol/L; P = 0.057), with no differences between days at 30min post-IET (P &amp;gt;0.07). In RICE horses, LA was not different at 1min post IET across days (P &amp;gt;0.1), however was lower at 30min post-IET on d60 (d0=1.7±0.1 mmol/L; d60=0.2±0.1 mmol/L; P &amp;lt; 0.01). Sixty days of rice oil supplementation may benefit lightly worked horses by reducing post-exercise lactic acid concentrations, CK activity, and increasing docosahexaenoic acid.

Changes in the skin characteristics associated with dehydration and rehydration

ABSTRACT The present study aimed to test the hypothesis that changes in the dermal tissue dielectric constant (TDC) and biomechanical properties of the skin would be correlated with the indicators related to dehydration. Ten healthy adult men were enrolled in three trials: no fluid intake (DEH), ad libitum fluid intake (AL-HYD), and programmed fluid intake (P-HYD) after exercise in a randomised crossover design. The participants performed a pedalling exercise at 60% heart rate reserve until 2% body mass loss. At 120 min after exercise, an incremental exercise test was carried out. Aerobic capacity, body composition, TDC, biomechanical properties of the skin (pliability, viscoelasticity, and total recovery), and indicators related to dehydration in the serum and urine were measured before and 120 min after exercise. Higher values of the pliability and viscoelasticity, and lower value of the total recovery on the hand were demonstrated in the P-HYD trial compared to the DEH trial (all P < 0.05). Changes in the TDC were significantly correlated with changes in body mass, total body water, serum osmolarity, and hematocrit (all P < 0.05). Changes in the biomechanical properties of the hand were significantly correlated with changes in body mass, hematocrit, and urine specific gravity (all P < 0.05). The present study showed that the changes in skin characteristics correlated with the body water and dehydration-associated indicators in the serum and urine, thus suggesting that skin characteristics may be useful in the assessment of dehydration. Highlights This study was the first to investigate the effect of dehydration and rehydration on the TDC and biomechanical properties of the skin upon instrumental measure, and not manual testing. This study confirmed the decline in aerobic capacity by dehydration and immediate recovery with sufficient rehydration. Changes in the TDC and the biomechanical properties of the skin correlated with the body water and dehydration-associated indicators in the serum and urine. Skin characteristics may be useful in the assessment of dehydration.

Dietary Nitrate Supplementation Does Not Alter Exercise Efficiency at High Altitude - Further Results From the Xtreme Alps Study.

IntroductionNitrate supplementation in the form of beetroot juice (BRJ) ingestion has been shown to improve exercise tolerance during acute hypoxia, but its effect on exercise physiology remains unstudied during sustained terrestrial high altitude exposure. We hypothesized that performing exercise at high altitude would lower circulating nitrate and nitrite levels and that BRJ ingestion would reverse this phenomenon while concomitantly improving key determinants of aerobic exercise performance.MethodsTwenty seven healthy volunteers (21 male) underwent a series of exercise tests at sea level (SL, London, 75 m) and again after 5–8 days at high altitude (HA, Capanna Regina Margherita or “Margherita Hut,” 4,559 m). Using a double-blind protocol, participants were randomized to consume a beetroot/fruit juice beverage (three doses per day) with high levels of nitrate (∼0.18 mmol/kg/day) or a nitrate-depleted placebo (∼11.5 μmoles/kg/day) control drink, from 3 days prior to the exercise trials until completion. Submaximal constant work rate cycle tests were performed to determine exercise efficiency and a maximal incremental ramp exercise test was undertaken to measure aerobic capacity, using breath-by-breath pulmonary gas exchange measurements throughout. Concentrations of nitrate, nitrite and nitrosation products were quantified in plasma samples collected at 5 timepoints during the constant work rate tests. Linear mixed modeling was used to analyze data.ResultsAt both SL and HA, plasma nitrate concentrations were elevated in the nitrate supplementation group compared to placebo (P < 0.001) but did not change throughout increasing exercise work rate. Delta exercise efficiency was not altered by altitude exposure (P = 0.072) or nitrate supplementation (P = 0.836). V̇O2peak decreased by 24% at high altitude (P < 0.001) and was lower in the nitrate-supplemented group at both sea level and high altitude compared to placebo (P = 0.041). Dietary nitrate supplementation did not alter other peak exercise variables or oxygen consumption at anaerobic threshold. Circulating nitrite and S-nitrosothiol levels unexpectedly rose in a few individuals right after cessation of exercise at high altitude.ConclusionWhilst regularly consumed during an 8 days expedition to terrestrial high altitude, nitrate supplementation did not alter exercise efficiency and other exercise physiological variables, except decreasing V̇O2peak. These results and those of others question the practical utility of BRJ consumption during prolonged altitude exposure.

Accelerated Muscle Deoxygenation in Aerobically Fit Subjects During Exhaustive Exercise Is Associated With the ACE Insertion Allele.

IntroductionThe insertion/deletion (I/D) polymorphism in the gene for the major regulator of vascular tone, angiotensin-converting enzyme-insertion/deletion (ACE-I/D) affects muscle capillarization and mitochondrial biogenesis with endurance training. We tested whether changes of leg muscle oxygen saturation (SmO2) during exhaustive exercise and recovery would depend on the aerobic fitness status and the ACE I/D polymorphism.MethodsIn total, 34 healthy subjects (age: 31.8 ± 10.2 years, 17 male, 17 female) performed an incremental exercise test to exhaustion. SmO2 in musculus vastus lateralis (VAS) and musculus gastrocnemius (GAS) was recorded with near-IR spectroscopy. Effects of the aerobic fitness status (based on a VO2peak cutoff value of 50 ml O2 min−1 kg−1) and the ACE-I/D genotype (detected by PCR) on kinetic parameters of muscle deoxygenation and reoxygenation were assessed with univariate ANOVA.ResultsDeoxygenation with exercise was comparable in VAS and GAS (p = 0.321). In both leg muscles, deoxygenation and reoxygenation were 1.5-fold higher in the fit than the unfit volunteers. Differences in muscle deoxygenation, but not VO2peak, were associated with gender-independent (p > 0.58) interaction effects between aerobic fitness × ACE-I/D genotype; being reflected in a 2-fold accelerated deoxygenation of VAS for aerobically fit than unfit ACE-II genotypes and a 2-fold higher deoxygenation of GAS for fit ACE-II genotypes than fit D-allele carriers.DiscussionAerobically fit subjects demonstrated increased rates of leg muscle deoxygenation and reoxygenation. Together with the higher muscle deoxygenation in aerobically fit ACE-II genotypes, this suggests that an ACE-I/D genotype-based personalization of training protocols might serve to best improve aerobic performance.

Maximal Aerobic Power Using the Modified Heck Protocol: Prediction Models.

The purpose of this study was to develop prediction models based on an incremental treadmill test to volitional exhaustion utilizing the modified Heck protocol. A total of 598 professional and youth athletes participating in different sports were recruited for this study. Specifically, the study enrolled professional male soccer players (n=380), professional male futsal players (n=24), elite male basketball players (n=27), professional male soccer referees (n=50), elite female soccer players (n=19), youth male basketball players (13-14 yrs n=15, 15-17 yrs n=20) and youth male soccer players (15 yrs n=28, 16-17 yrs n=35). Anthropometric measurements included stature, body mass, and body fat. Furthermore, all participants performed incremental cardiopulmonary exercise testing on a treadmill using the modified Heck protocol. Through multiple regression analysis, a separate prediction model was developed for each of the athletic populations. Results demonstrated that a significant (p=0.001) proportion of the variation observed in VO2max was explained by the variation in running time. The generated VO2max regression equations would allow athletes and coaches to predict VO2max in a relatively short time without the need for expensive and sophisticated equipment. To our knowledge, this is the first study that provides regression models for different athletic populations using the modified Heck protocol.

Phenotyping Cardiopulmonary Exercise Limitations in Chronic Obstructive Pulmonary Disease.

BackgroundExercise limitation in chronic obstructive pulmonary disease (COPD) is commonly attributed to abnormal ventilatory mechanics and/or skeletal muscle function, while cardiovascular contributions remain relatively understudied. To date, the integrative exercise responses associated with different cardiopulmonary exercise limitation phenotypes in COPD have not been explored but may provide novel therapeutic utility. This study determined the ventilatory, cardiovascular, and metabolic responses to incremental exercise in patients with COPD with different exercise limitation phenotypes.MethodsPatients with COPD (n = 95, FEV1:23–113%pred) performed a pulmonary function test and incremental cardiopulmonary exercise test. Exercise limitation phenotypes were classified as: ventilatory [peak ventilation (VEpeak)/maximal ventilatory capacity (MVC) ≥ 85% or MVC-VEpeak ≤ 11 L/min, and peak heart rate (HRpeak) < 90%pred], cardiovascular (VEpeak/MVC < 85% or MVC-VEpeak > 11 L/min, and HRpeak ≥ 90%pred), or combined (VEpeak/MVC ≥ 85% or MVC-VEpeak ≤ 11 L/min, and HRpeak ≥ 90%pred).ResultsFEV1 varied within phenotype: ventilatory (23–75%pred), combined (28–90%pred), and cardiovascular (68–113%pred). The cardiovascular phenotype had less static hyperinflation, a lower end-expiratory lung volume and larger tidal volume at peak exercise compared to both other phenotypes (p < 0.01 for all). The cardiovascular phenotype reached a higher VEpeak (60.8 ± 11.5 L/min vs. 45.3 ± 15.5 L/min, p = 0.002), cardiopulmonary fitness (VO2peak: 20.6 ± 4.0 ml/kg/min vs. 15.2 ± 3.3 ml/kg/min, p < 0.001), and maximum workload (103 ± 34 W vs. 72 ± 27 W, p < 0.01) vs. the ventilatory phenotype, but was similar to the combined phenotype.ConclusionDistinct exercise limitation phenotypes were identified in COPD that were not solely dependent upon airflow limitation severity. Approximately 50% of patients reached maximal heart rate, indicating that peak cardiac output and convective O2 delivery contributed to exercise limitation. Categorizing patients with COPD phenotypically may aid in optimizing exercise prescription for rehabilitative purposes.

Return to Play after SARS-CoV-2 Infection in Competitive Athletes of Distinct Sport Disciplines in Italy: A FMSI (Italian Federation of Sports Medicine) Study.

Background: SARS-CoV-2 can lead to several systemic complications, including myocardial injuries; these might be worsened by heavy physical activity. The optimal approach to cardiac risk stratification following SARS-CoV-2 infection in athletes for a safe return to play (RTP) still needs defining. The aim of this study was to assess the prevalence of abnormal RTP test results, according to the protocol of Italian Federation of Sport Medicine (FMSI), which was endorsed by the Italian Ministry of Health, potentially representing COVID-19-associated cardiac injuries. Methods: This was a prospective, multicenter, observational study. All consecutive competitive athletes who underwent COVID-19 RTP testing protocol from 1 May to 31 July 2021, across 60 Italian Centers of Sports Medicine, were enrolled in the study. Athletes were tested at least 30 days after negativization of the nasopharyngeal swab (or immediately after negativization in professional athletes or Probable Olympians). A 12-lead electrocardiography at rest and during maximal incremental exercise test with continuous O2 saturation monitoring and an echocardiographic examination were part of the protocol. In athletes with “moderate” disease (NHI classification), 24 h ECG monitoring (to be performed on a training day) and Magnetic Resonance Imaging (MRI) were also performed. Results: A total of 4143 athletes (67.8% males and 32.2% females) (53% > 18 years, 20% 18–35 years and 16% > 35 years), from more than 40 different sport disciplines, were included in the study. The mean age was 22.5 ± 13.3 years, with ages ranging from 8 to 80 years. Of these athletes, 52.3% were asymptomatic, 46.4% manifested mild symptoms, 1.1% and 0.14% had moderate or severe symptoms, respectively, while critical illness was evident in one athlete. Abnormal echocardiographic findings were detected in 80 cases (1.9%), and pericarditis in 7 cases (0.2%); all were from mildly symptomatic athletes. Arrhythmic events were recorded in 239 athletes, with 224 (5.4%) in the exercise test and 15 (0.4%) during 24 h ECG monitoring. Ventricular arrhythmias were observed in 101 (2.4%) athletes from the total population (mostly isolated or couples of premature ventricular beats): 91 in the exercise test and 10 during 24 h ECG monitoring. Cardiac magnetic resonance was performed in 34 athletes; the presence of myocarditis was confirmed in 5 athletes (0.12% of the total population, 14.7% of athletes in which MRI was performed). Conclusions: According to our results, cardiac complications from SARS-CoV-2 in asymptomatic or mildly symptomatic competitive athletes are rare, and an RTP assessment based on symptoms and ECG-monitored exercise test would ensure a safe RTP in these athletes.

Prediction and types of dead-space fraction during exercise in male chronic obstructive pulmonary disease patients.

A high dead space (VD) to tidal volume (VT) ratio during peak exercise (VD/VTpeak) is a sensitive and consistent marker of gas exchange abnormalities; therefore, it is important in patients with chronic obstructive pulmonary disease (COPD). However, it is necessary to use invasive methods to obtain VD/VTpeak, as noninvasive methods, such as end-tidal PCO2 (PETCO2peak) and PETCO2 adjusted with Jones’ equation (PJCO2peak) at peak exercise, have been reported to be inconsistent with arterial PCO2 at peak exercise (PaCO2peak). Hence, this study aimed to generate prediction equations for VD/VTpeak using statistical techniques, and to use PETCO2peak and PJCO2peak to calculate the corresponding VD/VTpeaks (i.e., VD/VTpeakETVD/VTpeakJ).A total of 46 male subjects diagnosed with COPD who underwent incremental cardiopulmonary exercise tests with PaCO2 measured via arterial catheterization were enrolled. Demographic data, blood laboratory tests, functional daily activities, chest radiography, two-dimensional echocardiography, and lung function tests were assessed.In multivariate analysis, diffusing capacity, vital capacity, mean inspiratory tidal flow, heart rate, and oxygen pulse at peak exercise were selected with a predictive power of 0.74. There were no significant differences in the PCO2peak values and the corresponding VD/VTpeak values across the three types (both p = NS).In subjects with COPD, VD/VTpeak can be estimated using statistical methods and the PETCO2peak and PJCO2peak. These methods may have similar predictive power and thus can be used in clinical practice.

Exercise duration: Independent effects on acute physiologic responses and the need for an individualized prescription.

An individualization of exercise prescription is implemented mainly in terms of intensity but not for duration. To survey the need for an individualized exercise duration prescription, we investigated acute physiologic responses during constant‐load exercise of maximal duration (t max) and determined so‐called duration thresholds. Differences between absolute (min) and relative terms (% t max) of exercise duration were analyzed. Healthy young and trained male and female participants (n = 11) performed an incremental exercise test and one t max constant‐load exercise test at a target intensity of 10% of maximal power output below the second lactate turn point (LTP2). Blood lactate, heart rate, and spirometric data were measured during all tests. t max was markedly different across subjects (69.6 ± 14.8 min; range: 40–90 min). However, distinct duration phases separated by duration thresholds (DTh) were found in most measured variables. These duration thresholds (except DTh1) were significantly related to t max (DTh2: r 2 = 0.90, p < 0.0001; DTh3: r 2 = 0.98, p < 0.0001) and showed substantial interindividual differences if expressed in absolute terms (DTh2: 24.8 ± 6.0 min; DTh3: 47.4 ± 10.6 min) but not in relative terms (DTh2: 35.4 ± 2.7% t max; DTh3: 67.9 ± 2.4% t max). Our data showed that (1) maximal duration was individually different despite the same relative intensity, (2) duration thresholds that were related to t max could be determined in most measured variables, and (3) duration thresholds were comparable between subjects if expressed in relative terms. We therefore conclude that duration needs to be concerned as an independent variable of exercise prescription.

Can Non-invasive Ventilation Modulate Cerebral, Respiratory, and Peripheral Muscle Oxygenation During High-Intensity Exercise in Patients With COPD-HF?

AimTo evaluate the effect of non-invasive positive pressure ventilation (NIPPV) on (1) metabolic, ventilatory, and hemodynamic responses; and (2) cerebral (Cox), respiratory, and peripheral oxygenation when compared with SHAM ventilation during the high-intensity exercise in patients with coexisting chronic obstructive pulmonary disease (COPD) and heart failure (HF).Methods and ResultsOn separate days, patients performed incremental cardiopulmonary exercise testing and two constant-work rate tests receiving NIPPV or controlled ventilation (SHAM) (the bilevel mode—Astral 150) in random order until the limit of tolerance (Tlim). During exercise, oxyhemoglobin (OxyHb+Mb) and deoxyhemoglobin (DeoxyHb+Mb) were assessed using near-infrared spectroscopy (Oxymon, Artinis Medical Systems, Einsteinweg, The Netherlands). NIPPV associated with high-intensity exercise caused a significant increase in exercise tolerance, peak oxygen consumption ( in mlO2·kg−1·min−1), minute ventilation peak ( in ml/min), peak peripheral oxygen saturation (SpO2, %), and lactate/tlim (mmol/s) when compared with SHAM ventilation. In cerebral, respiratory, and peripheral muscles, NIPPV resulted in a lower drop in OxyHb+Mb (p < 0.05) and an improved deoxygenation response DeoxyHb+Mb (p < 0.05) from the half of the test (60% of Tlim) when compared with SHAM ventilation.ConclusionNon-invasive positive pressure ventilation during constant work-rate exercise led to providing the respiratory muscle unloading with greater oxygen supply to the peripheral muscles, reducing muscle fatigue, and sustaining longer exercise time in patients with COPD-HF.

Responses to incremental exercise and the impact of the coexistence of HF and COPD on exercise capacity: a follow-up study

Our aim was to evaluate: (1) the prevalence of coexistence of heart failure (HF) and chronic obstructive pulmonary disease (COPD) in the studied patients; (2) the impact of HF + COPD on exercise performance and contrasting exercise responses in patients with only a diagnosis of HF or COPD; and (3) the relationship between clinical characteristics and measures of cardiorespiratory fitness; (4) verify the occurrence of cardiopulmonary events in the follow-up period of up to 24 months years. The current study included 124 patients (HF: 46, COPD: 53 and HF + COPD: 25) that performed advanced pulmonary function tests, echocardiography, analysis of body composition by bioimpedance and symptom-limited incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer. Key CPET variables were calculated for all patients as previously described. The {dot{text{V}}}E/{dot{text{V}}}CO2 slope was obtained through linear regression analysis. Additionally, the linear relationship between oxygen uptake and the log transformation of {dot{text{V}}}E (OUES) was calculated using the following equation: {dot{text{V}}}O2 = a log {dot{text{V}}}E + b, with the constant ‘a’ referring to the rate of increase of {dot{text{V}}}O2. Circulatory power (CP) was obtained through the product of peak {dot{text{V}}}O2 and peak systolic blood pressure and Ventilatory Power (VP) was calculated by dividing peak systolic blood pressure by the {dot{text{V}}}E/{dot{text{V}}}CO2 slope. After the CPET, all patients were contacted by telephone every 6 months (6, 12, 18, 24) and questioned about exacerbations, hospitalizations for cardiopulmonary causes and death. We found a 20% prevalence of HF + COPD overlap in the studied patients. The COPD and HF + COPD groups were older (HF: 60 ± 8, COPD: 65 ± 7, HF + COPD: 68 ± 7). In relation to cardiac function, as expected, patients with COPD presented preserved ejection fraction (HF: 40 ± 7, COPD: 70 ± 8, HF + COPD: 38 ± 8) while in the HF and HF + COPD demonstrated similar levels of systolic dysfunction. The COPD and HF + COPD patients showed evidence of an obstructive ventilatory disorder confirmed by the value of %FEV1 (HF: 84 ± 20, COPD: 54 ± 21, HF + COPD: 65 ± 25). Patients with HF + COPD demonstrated a lower work rate (WR), peak oxygen uptake ({dot{text{V}}}O2), rate pressure product (RPP), CP and VP compared to those only diagnosed with HF and COPD. In addition, significant correlations were observed between lean mass and peak {dot{text{V}}}O2 (r: 0.56 p < 0.001), OUES (r: 0.42 p < 0.001), and O2 pulse (r: 0.58 p < 0.001), lung diffusing factor for carbon monoxide (DLCO) and WR (r: 0.51 p < 0.001), DLCO and VP (r: 0.40 p: 0.002), forced expiratory volume in first second (FEV1) and peak {dot{text{V}}}O2 (r: 0.52; p < 0.001), and FEV1 and WR (r: 0.62; p < 0.001). There were no significant differences in the occurrence of events and deaths contrasting both groups. The coexistence of HF + COPD induces greater impairment on exercise performance when compared to patients without overlapping diseases, however the overlap of the two diseases did not increase the probability of the occurrence of cardiopulmonary events and deaths when compared to groups with isolated diseases in the period studied. CPET provides important information to guide effective strategies for these patients with the goal of improving exercise performance and functional capacity. Moreover, given our findings related to pulmonary function, body composition and exercise responses, evidenced that the lean mass, FEV1 and DLCO influence important responses to exercise.

Disturbance of desire-goal motivational dynamics during different exercise intensity domains.

PurposeThe desire‐goal motivational conflict helps explain endurance performance; however, the physiological concomitants are unknown. The present study examined disturbances in desire to reduce effort and performance goal value across moderate, heavy, and severe exercise intensity domains, demarcated by the first (LT1) and second (LT2) lactate thresholds. In addition, the within‐person relationships among blood lactate concentration, heart rate, and desire‐goal conflict were examined.MethodsThirty participants (53% female, Mage = 21.03 years; SD = 2.06 years) completed an incremental cycling exercise test, in which work rate was increased by 25 watts every four minutes, until voluntary exhaustion or sufficient data from the severe intensity domain had been collected. Desire to reduce effort, performance goal value, blood lactate concentration (for determination of LT1 and LT2), and heart rate were measured at the end of each stage and analyzed using multilevel models.ResultsThe desire to reduce effort increased over the exercise test with additional shifts and accelerations after each lactate threshold. The performance goal did not show general declines, nor did it shift at LT1. However, the performance goal value shifted at LT2, and the rate of change increased at both thresholds. Within‐person variation in blood lactate concentration positively correlated with the desire to reduce effort and negatively correlated with the performance goal. Within‐person variation in heart rate correlated with desire to reduce effort but not the performance goal.ConclusionTransitioning through both lactate thresholds is important phases for motivation during progressive exercise, particularly for the desire to reduce effort. Within‐person variation in blood lactate concentration is more influential for motivation, compared with heart rate.

The Effect of Different Periodization and Modes of Concurrent Strength and Endurance Training on Double Poling Performance and Body Composition in Adolescent Cross-Country Skiers.

The aim of the study was to compare the effects of different types and periodization of strength training on body composition and maximal aerobic performance in 10-week training period in adolescent XC skiers. Twenty-eight adolescent competitive cross-country skiers, including 10 females (age 17.9 ± 1.8 years; body mass 69.6 ± 9.7 kg; height 1.77 ± 0.1 m; training experience 8.6 ± 3.2 years) took part in this study. Pre-and post-intervention performance was measured with the incremental exercise test (Pmax) on a double poling ski ergometer. Changes in body composition were measured with DXA. In addition to regular endurance training, experimental group one (EXP1) performed maximal and explosive strength training two times per week, experimental group two (EXP2) performed maximal and explosive strength training 1–3 times per week, and the traditional (TRAD) group performed low intensity–high volume strength training 2 times per week. Increases in arm, trunk, and overall lean mass were found in TRAD (p < 0.05). Increases in arm lean-mass was found in EXP1 (p < 0.05), while no changes in body composition occurred in EXP2 (p ≥ 0.05). Pmax improved significantly in all groups (p < 0.05). Changes in body mass, overall and arm lean mass was related to changes in absolute performance (W; p < 0.05), while no relationships were found between changes in body composition parameters and relative performance (W/kg; p ≥ 0.05). In conclusion, different periodization of strength training led to similar improvements in double poling ergometer performance, but resulted in different changes in body composition (lean mass) in adolescent cross-country skiers.

CHANGES IN METABOLIC EFFICIENCY IN SKILLED ATHLETES DURING INTENSE EXERCISE

The body’s predominant choice of substrates and the rate of their oxidation in the working muscle are largely influenced by physical activity intensity. The higher the intensity of work, the more important role in energy supply processes are played by carbohydrates. It is suggested that the ability to most effectively use fat as an energy substrate at rest and during exercise allows athletes to save carbohydrates to perform high-intensity work. This study investigated the efficiency of metabolism in skilled athletes at rest and during the exercise of increasing intensity. 99 body composition assessments (via bioelectrical impedance) and 99 incremental exercise tests using a gas analysis system were performed in 90 male national- and international-level athletes (age 16-35 y.o.) of sports related to endurance and combat sports. The respiratory exchange ratio in skilled athletes at rest significantly correlates with the values of respiratory exchange ratio when reaching the anaerobic threshold ((r = 0.52, р ≤ 0,05)) and respiratory exchange ratio when reaching the maximum oxygen consumption ((r = 0.52, р ≤ 0,05)) and with the maximum oxygen consumption (r = -0.26, р ≤ 0,05). The oobtained data shows that efficient resting metabolism creates the preconditions for more efficient use of energy substrates during intense muscle activity. The respiratory exchange ratio is an informative indicator of the efficiency of metabolism, which can be used in the complex control of the functional condition of the athlete.

Monitoring Performance in Show Jumping Horses: Validity of Non-specific and Discipline-specific Field Exercise Tests for a Practicable Assessment of Aerobic Performance

Show jumping is a highly specialized equestrian discipline that requires technical skill but also power and fitness. Monitoring the horses’ aerobic performance is therefore essential in order to verify whether the training has induced the desired cardiovascular and muscular adaptations. This study therefore aimed at evaluating the validity of non-specific and discipline-specific field exercise tests for objective evaluation of aerobic performance in show jumpers. For this purpose, data obtained from horses competing at Junior and Young Rider level during show jumping competitions as well as field exercise tests were retrospectively analyzed. The effect of the level of difficulty, the horses’ age, the penalty score and the horses’ previous level of performance on blood lactate concentrations after show jumping competitions (100 observations in 49 horses) was evaluated by linear mixed effects models (horse as random effect). Estimated marginal means significantly increased from 140 (4.1 mmol/L) to 150 cm (5.2 mmol/L) classes (P = 0.02). Furthermore, post-exercise lactate values significantly increased with the horses’ age (P = 0.001). Another group of 12 horses performed a standardized incremental field exercise test on a track (SETtrack), a standardized show jumping course (SETcourse) and a standardized grid exercise (SETgrid) each on three consecutive days. Indices of aerobic performance, derived from the SETtrack [velocity at a heart rate of 140 bpm (V140) and at a lactate concentration of 2 mmol/L (VLa2)] were highly correlated with heart rate (V140: r = −0.75, P = 0.005; VLa2: r =−0.66, P = 0.02) and lactate (V140: r = −0.73, P = 0.02; VLa2: r = −0.72, P = 0.02) in response to SETcourse as well as heart rate during SETgrid (V140: r = −0.73, P = 0.02; VLa2: r = −0.76, P = 0.01). Subjective rating of muscular fatigue was significantly correlated to the mean heart rate during SETcourse (r = −0.64, P = 0.05) and SETgrid (r = −0.74, P = 0.02) but not to the aerobic indices calculated from SETtrack. Besides non-specific incremental field tests, performance monitoring in show jumpers should therefore also include discipline-specific tests that more closely reflect the internal load induced by show jumping competitions.

Time-dependent cortical plasticity during moderate-intensity continuous training versus high-intensity interval training in rats.

The temporal pattern of cortical plasticity induced by high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) is required to clarify their relative benefits to prevent neurological disorders. The purpose of this study is to define the time-dependent effects of work-matched HIIT and MICT on cortical plasticity, endurance, and sensorimotor performances over an 8-week training period in healthy rats. Adult healthy rats performed incremental exercise tests and sensorimotor tests before and at 2, 4, and 8 weeks of training. In parallel, cortical markers related to neurotrophic, angiogenic, and metabolic activities were assessed. Results indicate that HIIT induced an early and superior endurance improvement compared to MICT. We found significant enhancement of speed associated with lactate threshold (SLT) and maximal speed (Smax) in HIIT animals. MICT promoted an early increase in brain-derived neurotrophic factor and angiogenic/metabolic markers but showed less influence at 8 weeks. HIIT upregulated the insulin-like growth factor-1 (IGF-1) as well as neurotrophic, metabolic/angiogenic markers at 2 and 8 weeks and downregulated the neuronal K-Cl cotransporter KCC2 that regulates GABAA-mediated transmission. HIIT and MICT are effective in a time-dependent manner suggesting a complementary effect that might be useful in physical exercise guidelines for maintaining brain health.

Effect of protocol on peak power output in continuous incremental cycle exercise tests.

Peak power output ([Formula: see text]peak) in an incremental exercise test (EXT) is considered an important predictor of performance for cyclists. However, [Formula: see text]peak is protocol dependent. The purpose of this study was to model the effect of EXT design on [Formula: see text]peak. An adapted version of a previously developed mathematical model was used. For the purpose of validity testing, we compared predicted [Formula: see text]peak differences (predicted Δ[Formula: see text]peak) with actual Δ[Formula: see text]peak found in sports science literature. The model quantified Δ[Formula: see text]peak between 36 EXT designs with stage durations in the range 1-5min and increments in the range 10-50W. Predicted Δ[Formula: see text]peak and actual Δ[Formula: see text]peak across a wide range of performance levels of cyclists were in good agreement. Depending on the specific combination of increment and stage duration, [Formula: see text]peak may be widely different or equivalent. A minimum difference in increment (5W) or in stage duration (1min) already results in significantly different [Formula: see text]peak. In EXTs having the same ratio between increment and stage duration, [Formula: see text]peak in the EXT with the shortest stage duration or the greatest increment is significantly higher. Tests combining 15W, 25W or 40W increments with 2, 3 and 4min stage durations, respectively, are 'special' in that their [Formula: see text]peak approximates the power output associated with maximal oxygen uptake ([Formula: see text]). The modeling results allow comparison of [Formula: see text]peak between widely different EXT designs. Absolute performance level does not affect Δ[Formula: see text]peak. [Formula: see text]peak15/2, [Formula: see text]peak25/3 and [Formula: see text]peak40/4 constitute a practical physiologic reference for performance diagnostics and exercise intensity prescription.