Incremental Treadmill Exercise Test Research Articles

Changes in red blood cell parameters during incremental exercise in highly trained athletes of different sport specializations.

During physical exercise, the level of hematological parameters change depending on the intensity and duration of exercise and the individual's physical fitness. Research results, based on samples taken before and after exercise, suggest that hematological parameters increase during incremental exercise. However, there is no data confirming this beyond any doubt. This study examined how red blood cell (RBC) parameters change during the same standard physical exertion in athletes representing different physiological training profiles determined by sport discipline. The study included 39 highly trained male members of national teams: 13 futsal players, 12 sprinters, and 14 triathletes. We used multiple blood sampling to determine RBC, hemoglobin (Hb), hematocrit value (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and red blood cell distribution width (RDW) before, during (every 3 min), and after (5, 10, 15, 20, and 30 min) an incremental treadmill exercise test until exhaustion. There were no significant exercise-induced differences in RBC parameters between athletic groups. No significant changes were recorded in RBC parameters during the low-intensity phase of exercise. RBC, Hb, and Hct increased significantly during incremental physical exercise, and rapidly returned to resting values upon test termination. The general pattern of exercise-induced changes in RBC parameters is universal regardless of the athlete's physiological profile. The changes in RBC parameters are proportional to the intensity of exercise during the progressive test. The increase in hemoglobin concentration associated with the intensity of exercise is most likely an adaptation to the greater demand of tissues, mainly skeletal muscles, for oxygen.

Within-breath oscillometry for identifying exercise-induced bronchoconstriction in pediatric patients reporting symptoms with exercise.

Evaluating oscillometry parameters separately for the inspiratory and expiratory breath phases and their within-breath differences can help to identify exercise-induced bronchoconstriction (EIB) in pediatric outpatients disclosing exercise-induced symptoms (EIS). To assess the response in impedance parameters following an exercise challenge in patients reporting EIS. Sixty-eight patients reporting EIS (34 asthmatics and 34 suspected of asthma, age mean = 10.8 years, range = 6.0-16.0) underwent an incremental treadmill exercise test. Spirometry was performed at baseline and 1, 5-, 10-, 15-, and 20-min post exercise. Oscillometry was performed at baseline and at 3- and 18-min post exercise. Bronchodilator response to 200 µg albuterol was then assessed. EIB was defined as a forced expiratory volume in 1 s (FEV1) fall ≥10% from baseline. Expiratory and inspiratory resistance (Rrs) and reactance (Xrs), their z-score (Ducharme et al. 2022), and their mean within-breath differences (ΔRrs = Rrsexp-Rrsinsp, ΔXrs = Xrsexp-Xrsinsp) were calculated. Receiver operating characteristic (ROC) curves and their areas (AUCs) were used to evaluate impedance parameters' performances in classifying EIB. Asthmatic patients developed EIB more frequently than those suspected of asthma [18/34 (52.9%) vs. 2/34 (5.9%), p < 0.001]. In the 20 subjects with EIB, Rrsinsp, Rrsexp, Xrsinsp, and Xrsexp peaked early (3'), and remained steady except for Xrsinsp, which recovered faster afterward. ΔXrs widened 18 min following the exercise and reversed sharply after bronchodilation (BD) (-1.81 ± 1.60 vs. -0.52 ± 0.80 cmH2O × s/L, p < 0.001). Cutoffs for EIB leading to the highest AUCs were a rise of 0.41 in z-score Rrsinsp (Se: 90.0%, Sp: 66.7%), and a fall of -0.64 in z-score Xrsinsp (Se: 90.0%, Sp: 75.0%). Accepting as having "positive" postexercise oscillometry changes those subjects who had both z-scores beyond respective cutoffs, sensitivity for EIB was 90.0% (18/20) and specificity, 83.3% (40/48). Oscillometry parameters and their within-breath differences changed markedly in pediatric patients presenting EIB and were restored after the bronchodilator. Strong agreement between z-scores of inspiratory oscillometry parameters and spirometry supports their clinical utility, though larger studies are required to validate these findings in a broader population.

Attenuated peripheral oxygen extraction and greater cardiac output in women with posttraumatic stress disorder during exercise.

Posttraumatic stress disorder (PTSD) is associated with an increased risk of developing cardiovascular disease, especially in women. Evidence indicates that men with PTSD exhibit lower maximal oxygen uptake (V̇o2max) relative to controls; however, whether V̇o2max is blunted in women with PTSD remains unknown. Furthermore, it is unclear what determinants (i.e., central and/or peripheral) of V̇o2max are impacted by PTSD. Therefore, we evaluated the central (i.e., cardiac output; Q̇c) and peripheral (i.e., arteriovenous oxygen difference) determinants of V̇o2max in women with PTSD; hypothesizing that V̇o2max would be lower in women with PTSD compared with women without PTSD (controls), primarily due to smaller increases in stroke volume (SV), and therefore Q̇c. Oxygen uptake (V̇o2), heart rate (HR), Q̇c, SV, and arteriovenous oxygen difference were measured in women with PTSD (n = 14; mean [SD]: 43 [11] yr,) and controls (n = 17; 45 [11] yr) at rest, and during an incremental maximal treadmill exercise test, and the Q̇c/V̇o2 slope was calculated. V̇o2max was not different between women with and without PTSD (24.3 [5.6] vs. 26.4 [5.0] mL/kg/min; P = 0.265). However, women with PTSD had higher Q̇c [P = 0.002; primarily due to greater SV (P = 0.069), not HR (P = 0.285)], and lower arteriovenous oxygen difference (P = 0.002) throughout exercise compared with controls. Furthermore, the Q̇c/V̇o2 slope was steeper in women with PTSD relative to controls (6.6 [1.4] vs. 5.7 [1.0] AU; P = 0.033). Following maximal exercise, women with PTSD exhibited slower HR recovery than controls (P = 0.046). Thus, despite attenuated peripheral oxygen extraction, V̇o2max is not reduced in women with PTSD, likely due to larger increases in Q̇c.NEW & NOTEWORTHY The current study indicates that V̇o2max is not different between women with and without PTSD; however, women with PTSD exhibit blunted peripheral extraction of oxygen, thus requiring an increase in Q̇c to meet metabolic demand during exercise. Furthermore, following exercise, women with PTSD demonstrate impaired autonomic cardiovascular control relative to sedentary controls. We interpret these data to indicate that women with PTSD demonstrate aberrant cardiovascular responses during and immediately following fatiguing exercise.

The inorganic NItrate and eXercise performance in Heart Failure (iNIX-HF) phase II clinical trial: Rationale and study design

BackgroundHeart failure (HF) is a debilitating and often fatal disease that affects millions of people worldwide. Diminished nitric oxide synthesis, signaling, and bioavailability are believed to contribute to poor skeletal muscle function and aerobic capacity. The aim of this clinical trial (iNIX-HF) is to determine the acute and longer-term effectiveness of inorganic nitrate supplementation on exercise performance in patients with HF with reduced ejection fraction (HFrEF). MethodsThis clinical trial is a double-blind, placebo-controlled, randomized, parallel-arm design study in which patients with HFrEF (n = 75) are randomized to receive 10 mmol potassium nitrate (KNO3) or a placebo capsule daily for 6 wk. Primary outcome measures are muscle power determined by isokinetic dynamometry and peak aerobic capacity (VO2peak) determined during an incremental treadmill exercise test. Endpoints include the acute effects of a single dose of KNO3 and longer-term effects of 6 wk of KNO3. The study is adequately powered to detect expected increases in these outcomes at P < 0.05 with 1-β>0.80. DiscussionThe iNIX-HF phase II clinical trial will evaluate the effectiveness of inorganic nitrate supplements as a new treatment to ameliorate poor exercise capacity in HFrEF. This study also will provide critical preliminary data for a future ‘pivotal’, phase III, multi-center trial of the effectiveness of nitrate supplements not only for improving exercise performance, but also for improving symptoms and decreasing other major cardiovascular endpoints. The potential public health impact of identifying a new, relatively inexpensive, safe, and effective treatment that improves overall exercise performance in patients with HFrEF is significant.

High‐Resistance Inspiratory Muscle Strength Training‐Associated Increases in Exercise Tolerance in Midlife/Older Adults are Related to Circulating Acylcarnitines

BackgroundAge‐related declines in cardiorespiratory fitness (CRF) and exercise tolerance are major independent risk factors for cardiovascular diseases and mortality in midlife/older adults (ML/O; ≥50 years). Aerobic exercise is a well‐established strategy to improve CRF and exercise tolerance; however, adherence to time‐intensive physical activity (PA) guidelines is poor. High‐resistance inspiratory muscle strength training (IMST; 30 breaths/day against resistance, ~5 min/day) is a time‐efficient, highly adherable form of physical training but the effects of high‐resistance IMST on CRF and exercise tolerance in ML/O adults are unknown. We investigated if high‐resistance IMST would increase CRF and exercise tolerance and, if so, whether the improvements would be related to changes in circulating metabolites.MethodsThirty‐five ML/O adults performed 6 weeks of high‐resistance IMST (75% maximal inspiratory pressure [PIMAX], n=17, 9F/8M) or Sham training (15% PIMAX, n=18, 8F/10M). Peak oxygen uptake (VO2peak) was determined with an incremental treadmill exercise test to exhaustion (modified Balke protocol). Exercise tolerance was defined as treadmill time to exhaustion (TTE). Metabolic pathways modulated by high‐resistance IMST were assessed using mass spectrometry‐based plasma metabolomics.ResultsAdherence was high to both IMST and Sham training (IMST=94% of training sessions completed; Sham=90%). Body weight, body mass index (BMI), and leisure time PA levels remained stable in both groups across the intervention (all p&gt;0.05). VO2peak was unchanged after 6 weeks of either high‐resistance IMST (pre=27.7±1.2 ml/kg/min, post=27.9±1.2 ml/kg/min; p=0.75) or Sham training (pre=27.2±1.7 ml/kg/min, post=26.7±1.6 ml/kg/min; p=0.20). However, high‐resistance IMST increased TTE by 12%, with no change after Sham (IMST: pre=540±42 sec, post=606±33 sec; Sham: pre=562±39 sec, post=553±44 sec; group*time: p=0.03). TTE increases were related to changes in 18 metabolites (all p&lt;0.05), predominantly plasma acylcarnitines, which play key roles in energy production and fatty acid metabolism. Indeed, of the 19 carnitines measured, 11 were positively associated with TTE change post‐IMST. The strongest relations to TTE were seen with acyl‐C14:1 (R2=0.57; p&lt;0.01), acyl‐C10 (R2=0.54; p&lt;0.01), and acyl‐C12 (R2=0.52; p=0.01). These relations were not seen in the Sham group (all p&gt;0.05).ConclusionsIn ML/O adults, high‐resistance IMST does not increase CRF, but does improve TTE independent of changes in body weight, BMI, or PA. Improved TTE was related to changes in circulating metabolites, particularly increases in plasma acylcarnitines. These preliminary findings suggest 5 min/day of high‐resistance IMST is a promising, highly adherable mode of physical training that increases exercise tolerance and modulates metabolic pathways in ML/O adults.

Association of Innate and Acquired Aerobic Capacity With Resilience in Healthy Adults: Protocol for a Randomized Controlled Trial of an 8-Week Web-Based Physical Exercise Intervention.

BackgroundPhysical activity alleviates chronic stress. The latest research suggests a relationship between resilience and physical fitness. Beneficial adaptations of the hypothalamic-pituitary-adrenal axis, sympathetic nervous system, endocannabinoid system, and tryptophan pathway, which are induced by an active lifestyle, are considered to be conducive to resilience. However, detailed knowledge on the molecular link between the effects of acute and chronic physical exercise and improved resilience to stress in humans is missing. Moreover, the relationship between innate and acquired aerobic capacity and resilience is poorly understood.ObjectiveThe aim of this study is to implement a human exercise intervention trial addressing the following main hypotheses: a high innate aerobic capacity is associated with high resilience to stress, and web-based physical exercise training improves aerobic capacity of physically inactive adults, which is accompanied by improved resilience. In this setting, we will analyze the relationship between resilience parameters and innate and acquired aerobic capacity as well as circulating signaling molecules.MethodsA total of 70 healthy, physically inactive (<150 minutes/week of physical activity) adults (aged 18-45 years) will be randomly assigned to an intervention or control group. Participants in the intervention group will receive weekly training using progressive endurance and interval running adapted individually to their remotely supervised home training performance via web-based coach support. A standardized incremental treadmill exercise test will be performed before and after the intervention period of 8 weeks to determine the innate and acquired aerobic capacity (peak oxygen uptake). Before and after the intervention, psychological tests and questionnaires that characterize parameters implicated in resilience will be applied. Blood and saliva will be sampled for the analysis of cortisol, lactate, endocannabinoids, catecholamines, kynurenic acid, and further circulating signal transducers. Statistical analysis will provide comprehensive knowledge on the relationship between aerobic capacity and resilience, as well as the capacity of peripheral factors to mediate the promoting effects of exercise on resilience.ResultsThe study was registered in October 2019, and enrollment began in September 2019. Of the 161 participants who were initially screened via a telephone survey, 43 (26.7%) fulfilled the inclusion criteria and were included in the study. Among the 55% (17/31) of participants in the intervention group and 45% (14/31) of participants in the control group who completed the study, no serious adverse incidents were reported. Of 43 participants, 4 (9%) withdrew during the program (for individual reasons) and 8 (19%) have not yet participated in the program; moreover, further study recruitment was paused for an indeterminate amount of time because of the COVID-19 pandemic.ConclusionsOur study aims to further define the physiological characteristics of human resilience, and it may offer novel approaches for the prevention and therapy of mental disorders via an exercise prescription.International Registered Report Identifier (IRRID)DERR1-10.2196/29712

Increased body fat content in horses alters metabolic and physiological exercise response, decreases performance, and increases locomotion asymmetry.

ABSTRACTThis study examined the effect of altered body weight (BW) and body fat content on exercise performance and recovery. Nine horses were divided into two groups, and changes in BW and fat content were induced by feeding a high (HA) or restricted (RA) energy allowance for 36 days in a cross‐over design. In the last week of each treatment, BW and body condition score (BCS) were recorded, body fat percentage was estimated using ultrasound, and a standardized incremental treadmill exercise test (SET) and competition‐like field test were performed (scored by judges blinded to treatments). Blood samples were collected, and heart rate (HR), rectal temperature (RT), and respiratory rate (RR) were also recorded. Objective locomotion analyses were performed before and after the field test. Body weight, body fat percentage, and BCS were higher (5–8%) in HA than in RA horses (p < 0.05). In SET, HA horses showed higher HR, plasma lactate concentration, RR, and RT than RA horses (p < 0.05), and lower VLa4, hematocrit (Hct), plasma glucose, and plasma NEFA concentrations (p < 0.05). Hct was also lower in HA horses in the field test, while RA horses showed higher scores (p < 0.05). After both tests, resting plasma lactate concentrations were reached faster in RA than in HA horses (p < 0.05). Objective locomotion asymmetry was higher in HA than in RA (p < 0.05). These results clearly show that increased BW and body fat content in horses lower physiological fitness in terms of VLa4, plasma lactate removal, Hct levels, plasma glucose availability and reduce true performance evaluated by blinded judges.

Hypercapnia and hyperlactatemia were positively associated with higher-grade arrhythmias during peak exercise in horses during poor performance evaluation on a high-speed treadmill

Cardiac arrhythmias are common in horses during exercise, especially immediately post-exercise. The objectives of this study were to: (1) describe the frequency and type of cardiac arrhythmias detected in horses during incremental high-speed treadmill exercise testing (ITET); (2) determine if arterial blood gas (ABG) changes at peak and immediately post-exercise were associated with arrhythmias; and (3) determine whether upper or lower airway disease was associated with exercising cardiac arrhythmias. Horses (n = 368) presenting for an ITET underwent resting and exercising upper airway endoscopy, resting, exercising and post-exercise electrocardiography, resting and post-exercise echocardiography and exercising ABG. Arrhythmias were graded by the most severe arrhythmia present. Grade 1 arrhythmias were defined as one or two atrial (APCs) or ventricular premature complexes (VPCs), or one APC and one VPC, detected in 6.9% at peak and 16% at 0-2 min post exercise.. Grade 2 arrhythmias were >2 APCs or VPCs, or both, detected in 5.8% at peak and 16.6% at 0-2 min post exercise. Grade 3 included complex arrhythmias (couplets, triplets, R on T, multiform complexes or paroxysmal atrial or ventricular tachycardia), detected in 4.4% at peak and 7.3% at 0-2 min post exercise.Both partial pressure of arterial CO2 (PaCO2; P = 0.008) and lactate (P = 0.031) were significantly associated with arrhythmias occurring at peak exercise, but not immediately post-exercise. As PaCO2 and lactate increased, arrhythmia severity increased. Blood pH was significantly associated with grades 2 and 3 arrhythmias at 0–2 min post ITET (OR = 0.0002; P < 0.001). There was no significant association between grades 2 and 3 cardiac arrhythmias, inflammatory airway disease (IAD), or exercise-induced pulmonary hemorrhage (EIPH). When adjusted for lactate concentration (P = 0.06), higher PaCO2 concentrations in horses with and without exercising upper respiratory tract (URT) obstruction were associated with higher likelihood of grades 2 and 3 arrhythmias (P < 0.01). This study demonstrated that at peak exercise, with severe hypercapnia and hyperlactatemia, there was increased risk for grades 2 or 3 cardiac arrhythmias and, as the PaCO2 and lactate values increased further, the severity of those arrhythmias increased.

Lung abnormalities do not influence aerobic capacity in school children born preterm.

Children born preterm have impaired lung function and altered lung structure. However, there are conflicting reports on how preterm birth impacts aerobic exercise capacity in childhood. We aimed to investigate how neonatal history and a diagnosis of bronchopulmonary dysplasia (BPD) impact the relationship between function and structure of the lung, and aerobic capacity in school-aged children born very preterm. Preterm children (≤ 32 w completed gestation) aged 9-12years with (n = 38) and without (n = 35) BPD, and term-born controls (n = 31), underwent spirometry, lung volume measurements, gas transfer capacity, a high-resolution computer tomography (CT) scan of the chest, and an incremental treadmill exercise test. Children born preterm with BPD had an elevated breathing frequency to tidal volume ratio compared to term controls (76% vs 63%, p = 0.002). The majority (88%) of preterm children had structural changes on CT scan. There were no differences in peak V̇O2 (47.1 vs 47.7mL/kg/min, p = 0.407) or oxygen uptake efficiency slope when corrected for body weight (67.6 vs 67.3, p = 0.5) between preterm children with BPD and term controls. There were no differences in any other exercise outcomes. The severity of structural lung disease was not associated with exercise outcomes in this preterm population. Children born preterm have impaired lung function, and a high prevalence of structural lung abnormalities. However, abnormal lung function and structure do not appear to impact on the aerobic exercise capacity of preterm children at school age.

Hit Effects On Substrates Oxidation Rates Of Women In Different Phases Of Monthly Ovarian Cycle

The metabolic inflexibility (limitation to respond or adapt to conditional changes in metabolic demand due to dietary patterns, energy availability, or circulating energy substrates) may be associated with variations in estrogen concentrations observed during the monthly ovarian cycle, whereas that apparently healthy women of childbearing age exhibit variation in substrates oxidation rates that may lead to overweight, type II diabetes and other associated conditions. PURPOSE: The aims of this study were to verify and compare the influence of eight treadmill high-intensity interval training (HIT) sessions on carbohydrate and lipid oxidation rates (CHOox and LIPox, respectively) and intensities of ventilatory anaerobic thresholds (VATs) of women in different phases of monthly ovarian cycle. METHODS: Eleven irregularly active women performed incremental treadmill exercise testing followed by submaximal work-rate running for 45min to determine VATs, VO2peak, peak velocity (Vpeak), and substrate oxidation rates, before and after training period, in different phases of their monthly ovarian cycle (“Follicular” phase group, FPG, n=6; “Luteal” phase group, LPG, n=5). The training period consisted of eight HIT sessions, composed each one of eight sets of 60s running at 100%Vpeak interspersed by 75s recovery, every 48h. RESULTS: Our results showed no significant differences in VATs intensities between groups. The comparison between groups showed significant differences in relative energy derived from CHOox pre-post training of the -61.4% and -59.3% respectively, and LIPox pre-post training of the 27.5% and 34.4% respectively. The relative energy derived from CHOox after the training period were 18.9% and 25.5% higher to FPG and LPG, respectively; consequently, the relative energy derived from LIPox after the training period were 8,45% and 3.46% lower to FPG and LPG, respectively. Over the training period, Vpeak was ~13.5 km/h, which produced the relative intensities of ~89%VO2peak e ~93%HRpeak for both groups. CONCLUSION: The monthly ovarian cycle phases promote significant changes on substrates oxidation rates leading to decrease of CHOox. High intensity interval training can minimize the differences observed and constitute an alternative intervention.

High-intensity training in normobaric hypoxia enhances exercise performance and aerobic capacity in Thoroughbred horses: A randomized crossover study.

We examined the effects of high‐intensity training in normobaric hypoxia on aerobic capacity and exercise performance in horses and the individual response to normoxic and hypoxic training. Eight untrained horses were studied in a randomized, crossover design after training in hypoxia (HYP; 15.0% inspired O2) or normoxia (NOR; 20.9% inspired O2) 3 days/week for 4 weeks separated by a 4‐month washout period. Before and after each training period, incremental treadmill exercise tests were performed in normoxia. Each training session consisted of 1 min cantering at 7 m/s and 2 min galloping at the speed determined to elicit maximal oxygen consumption ( V˙O2max) in normoxia. Hypoxia increased significantly more than NOR in run time to exhaustion (HYP, +28.4%; NOR, +10.4%, p = .001), V˙O2max (HYP, +12.1%; NOR, +2.6%, p = .042), cardiac output ( Q˙; HYP, +11.3%; NOR, −1.7%, p = .019), and stroke volume (SV) at exhaustion (HYP, +5.4%; NOR, −5.5%, p = .035) after training. No significant correlations were observed between NOR and HYP for individual changes after training in run time (p = .21), V˙O2max (p = .99), Q˙ (p = .19), and SV (p = .46) at exhaustion. Arterial O2 saturation during exercise in HYP was positively correlated with the changes in run time (r = .85, p = .0073), Q˙ (r = .72, p = .043) and SV (r = .77, p = .026) of HYP after training, whereas there were no correlations between these parameters in NOR. These results suggest that high‐intensity training in normobaric hypoxia improved exercise performance and aerobic capacity of horses to a greater extent than the same training protocol in normoxia, and the severity of hypoxemia during hypoxic exercise might be too stressful for poor responders to hypoxic training.

Change in Lactate, Ammonia, and Hypoxanthine Concentrations in a 1-Year Training Cycle in Highly Trained Athletes: Applying Biomarkers as Tools to Assess Training Status.

Włodarczyk, M, Kusy, K, Słomińska, E, Krasiński, Z, and Zieliński, J. Change in lactate, ammonia, and hypoxanthine concentrations in a 1-year training cycle in highly trained athletes: applying biomarkers as tools to assess training status. J Strength Cond Res 34(2): 355-364, 2020-The aim was to determine changes in biomarker (LA, NH3, purine metabolites) blood concentration during graded exercise and recovery throughout an annual training cycle in highly trained athletes of different training profiles. The study included 12 sprinters (SP, 21-30 years), 11 triathletes (TR, 20-31 years), 12 futsal players (FU, 19-31 years), and 13 amateur runners (AM, 20-33 years). Purine metabolite (hypoxanthine, xanthine, uric acid), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes postexercise) in 4 phases of an annual training cycle. Purine metabolite concentration was determined from plasma, whereas LA and NH3 from whole blood. For LA during exercise and recovery, certain significant differences between training phases within groups were observed for FU, TR, and SP but not for AM. For NH3, the greatest differences between examination points were observed for SP and TR near maximal exercise and in the first few stages of recovery. For hypoxanthine (Hx), the largest amount of differences between examination points was observed for FU, TR, and FU throughout the entire exercise spectrum. Biomarker concentration dynamics change during an incremental exercise test and postexercise in an annual training cycle. Biomarker responses differ depending on training type and magnitude of training loads used in various phases of an annual training cycle. When assessing training status using an incremental exercise test throughout an annual training cycle, NH3 and Hx concentration changes are more sensitive compared with LA.

The Inorganic NItrate For eXercise In Heart Failure (INIX-HF) Trial: Rationale, Design, And Preliminary Data

Peak oxygen uptake (VO2peak) and muscle contractile function are both impaired in patients with heart failure with reduced ejection fraction (HFrEF), with these deficits significantly contributing to the diminished quality of life and possibly even early mortality of such individuals. In previous pilot studies, however, we have reported that these deleterious changes can be ameliorated by acute ingestion of nitrate (NO3-), which in vivo can be converted to nitric oxide (NO) via the enterosalivary NO3- → nitrite (NO2-) → NO pathway. PURPOSE Based on these studies, the INIX-HF trial is a proposed multi-center (i.e., 8 site), randomized control trial of the effects of acute (i.e., single dose) and chronic (i.e., 2 wk) dietary NO3- supplementation (in the form of KNO3) on VO2peak and muscle contractility in patients with HFrEF. We are presently performing the work that is necessary and sufficient to set up this trial, including determining the optimal dose of KNO3 to utilize. METHODS Using a double-blind, crossover design, six patients with HFrEF (5 men, 1 woman; age = 49±4 y; EF = 32±3%) were studied 2-3 h after acute ingestion of either 10 or 20 mmol KNO3. On each occasion, VO2peak was measured during an incremental treadmill exercise test (modified Naughton protocol) and muscle function was determined using isokinetic dynamometry. RESULTS The increase in plasma NO3- was greater following ingestion of 20 vs. 10 mmol KNO3 (Δ = 430±51 vs. 218±19 μmol/L; P=0.002). However, plasma NO2- increased to a similar degree in both trials (Δ = 0.219±0.078 vs. 0.169±0.044 μmol/L; P=0.67). Presumably as a result, VO2peak did not differ between treatments (i.e., 18.0±1.5 vs. 17.7±1.3 mL.min-1.kg-1; P=0.74). There was also no difference in maximal knee extensor power (4.52±0.56 vs. 4.25±0.59 W/kg; P=0.69) across trials. 27% of subjects experienced moderate-to-severe nausea and/or vomited after ingesting the higher dose KNO3, vs. only 9% after the lower dose. CONCLUSION There was no difference in the efficacy of 10 vs. 20 mmol KNO3 in influencing VO2peak or muscle power in patients with HFrEF. The higher dose, however, was associated with a greater frequency of gastrointestinal distress. Based on these preliminary data, it appears that 10 mmol KNO3 is the preferred dose for a larger, multicenter trial. Supported by award R34HL138253 from the NHLBI

Six Hit Treadmill Training Sessions Improves Lipid Oxidation and Ventilatory Thresholds Intensities

The high-intensity interval training (HIT) has been used as alternative to cardiorespiratory training performed continuously with submaximal intensity and prolong time. PURPOSE: The aims of this study were to propose a treadmill HIT protocol and verify the influence of six HIT sessions on intensities of ventilatory anaerobic thresholds (VATs) and substrate oxidation rates during submaximal continuous exercise (SCE). METHODS: Fifteen irregularly active men performed incremental treadmill exercise testing followed by submaximal work-rate running for 45min to determine VATs, VO2peak, peak velocity (Vpeak), and substrate oxidation rates, before and after training period. The training period consisted of six HIT sessions, composed each one of eight sets of 60s running at 100%Vpeak interspersed by 75s recovery, every 48h. RESULTS: Our results showed increases in VATs intensities of 4.4% for VAT1 and 8.8% for VAT2, reduction of 12.8% for carbohydrate oxidation (CHOox) and increase of 23.7% for lipid oxidation (LIPox); as a result, the relative energy derived from LIPox was 20.3% higher after the training period. Vpeak was ~15 km/h, which produces the relative intensities of ~84%VO2peak e ~91%FCpeak during the training period. CONCLUSION: The proposed protocol promoted similar adaptations and intensities which were described by the literature; but unlike others, it can be applied in irregularly active individuals.

Changes in Blood Concentration of Adenosine Triphosphate Metabolism Biomarkers During Incremental Exercise in Highly Trained Athletes of Different Sport Specializations.

Włodarczyk, M, Kusy, K, Słomińska, E, Krasiński, Z, and Zieliński, J. Changes in blood concentration of adenosine triphosphate metabolism biomarkers during incremental exercise in highly trained athletes of different sport specializations. J Strength Cond Res 33(5): 1192-1200, 2019-We hypothesized that (a) high-level specialized sport training causes different adaptations that induce specific biomarker release dynamics during exercise and recovery and (b) skeletal muscle mass affects biomarker release. Eleven sprinters (21-30 years), 16 endurance runners (18-31 years), 12 futsal players (18-29 years), and 12 amateur runners as controls (22-33 years) were examined. Hypoxanthine (Hx), xanthine (X), uric acid (UA), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes after exercise). Hx, X, and UA concentration was determined from plasma, while LA and NH3 from whole blood, and muscle mass was assessed using dual X-ray absorptiometry method. At rest, during incremental exercise, and up to 30 minutes into the postexercise recovery period, sprinters had lowest Hx, X, and UA concentrations, and endurance athletes had lowest NH3 concentrations. For LA during exercise, the lowest concentrations were noted in endurance athletes, except when reaching maximum intensity, where the differences between groups were not significant. There were no significant correlations observed between skeletal muscle mass and biomarker concentration at maximal intensity and recovery in any group. In conclusion, the magnitude of exercise-induced biomarker concentration is only related to training adaptations through specific training profile but not to muscle mass. In addition, the results suggest that combined measuring of LA, NH3, and Hx concentration in blood is useful in indirectly reflecting key changes in exercise- and training-induced energy status. Further research should focus on studying how specific training sessions affect individual biomarker response in highly trained athletes.

Lactate and glucose thresholds and heart rate deflection points for Beagles during intense exercise.

OBJECTIVE To determine whether the lactate threshold of dogs could be determined by a visual method and to assess the extent of agreement and bias among treadmill velocities for the lactate threshold as determined by visual (LTv) and polynomial (LTp) methods, glucose threshold as determined by visual (GTv) and polynomial (GTp) methods, and heart rate deflection point (HRdp) as a method for estimating the aerobic capacity of dogs. ANIMALS 18 healthy adult Beagles. PROCEDURES Each dog underwent a standardized incremental treadmill exercise test once. The test ended when the dog began to show signs of fatigue. Plasma lactate and glucose concentrations and heart rate (HR) were plotted against exercise intensity (treadmill velocity) for the duration of the test, and the LTv, GTv, and HRdp were determined visually. The LTp and GTp were determined by means of a second-order polynomial function. One-way ANOVA, Pearson correlation, Bland-Altman analyses, and ordinary least products regression were used to assess the extent of agreement and bias among the various threshold velocities. RESULTS Mean velocity did not differ significantly among the thresholds evaluated. There was a strong positive correlation between the LTv velocity and the velocity for GTv (r = 0.91), LTp (r = 0.96), GTp (r = 0.94), and HRdp (r = 0.95). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that LTv could be determined for dogs undergoing intense exercise on a treadmill, and the treadmill velocity corresponding to the LTv was associated with the velocity for the other hallmarks of endurance. Thus, that method may be useful for prescription and evaluation of conditioning programs for dogs.

Increased prevalence of expiratory flow limitation during exercise in children with bronchopulmonary dysplasia.

Evidence regarding the prevalence of expiratory flow limitation (EFL) during exercise and the ventilatory response to exercise in children born preterm is limited. This study aimed to determine the prevalence of EFL as well as contributing factors to EFL and the ventilatory response to exercise in preterm children with and without bronchopulmonary dysplasia (BPD).Preterm children (≤32 weeks gestational age) aged 9–12 years with (n=64) and without (n=42) BPD and term controls (n=43), performed an incremental treadmill exercise test with exercise tidal flow–volume loops.More preterm children with BPD (53%) had EFL compared with preterm children without BPD (26%) or term controls (28%) (p<0.05). The presence of EFL was independently associated with decreased forced expiratory volume in 1 s/forced vital capacity z-score and lower gestational age (p<0.05). There was no difference in peak oxygen uptake between preterm children with BPD and term controls (48.0 versus 48.4 mL·kg−1·min−1; p=0.063); however, children with BPD had a lower tidal volume at peak exercise (mean difference −27 mL·kg−1, 95% CI −49– −5; p<0.05). Children born preterm without BPD had ventilatory responses to exercise similar to term controls.Expiratory flow limitation is more prevalent in children born preterm with BPD and is associated with airway obstruction and a lower gestational age.

The effects of recovery duration on physiological and perceptual responses of trained runners during four self-paced HIIT sessions

ObjectivesThis study aimed to examine the effects of different recovery durations on self-selected running velocities, physiological responses, and ratings of perceived exertion (RPE) in a commonly used high intensity interval training (HIIT) protocol. Design & methodsTwelve trained runners performed an incremental treadmill exercise test to determine maximal oxygen uptake (V˙O2max) and heart rate (HRmax). In four subsequent visits, participants performed a HIIT session comprising six 4-min work intervals, in which the recovery duration between work intervals equalled either a fixed (1MIN, 2MIN, 3MIN) or a self-selected duration (ssMIN). HIIT sessions were run on a non-motorized treadmill, and were performed under isoeffort conditions. ResultsMean running velocity was significantly higher in 3MIN compared with all other protocols, and higher in ssMIN compared with 2MIN. No significant differences in time spent ≥90% and 95% V˙O2max, or ≥90% and 95% HRmax were evident between the four protocols. RPE responses were similar across and within the protocols showing a gradual increase with each progressive interval. ConclusionIn a self-paced HIIT session of six 4-min work intervals, the length of recovery durations had a limited effect on the total physiological strain endured in the training. However, running velocities were higher when participants received the longest recovery period (3MIN). Longer recovery durations may facilitate a higher external training load (faster running), whilst maintaining a similar internal training load (physiological stimulus), and may therefore allow for greater training adaptations.

Exercise-induced arterial hypoxemia in aerobic and anaerobic trained athletes during incremental exercise

Purpose: The purpose of this study was to examine and compare the occurrence of exercise-induced arterial hypoxemia (EIAH) in aerobic and anaerobic trained athletes during an incremental treadmill exercise test. Material: International level male junior skiers including ten cross-country skiers and ten alpine skiers took part in the study. All participants performed an incremental treadmill exercise test to determine maximal oxygen uptake (VO2max), and oxyhemoglobin saturation (SaO2) was continuously measured using a pulse oximetry. Maximal minute ventilation (VEmax), maximal heart rate (HRmax), ventilatory equivalent for oxygen (VE/VO2) and carbon dioxide (VE/VCO2) were determined during the last stage of the incremental exercise test. EIAH was assumed to have developed when SaO2 decreased by at least 4% (ΔSaO2 ≤ −4%) from the baseline values. Results: VO2max, VE, maximal running speed and test time were higher in the cross-country skiers than in the alpine skiers (p &lt; 0.01), whereas HRmax, VE/VO2 and VE/VCO2 showed similar values in both group (p &gt; 0.05). All the athletes in both groups exhibited EIAH. SaO2 was significantly decreased from 97.5 ± 0.9% at rest to 89 ± 2% at exhaustion in alpine skiers and from 97.8 ± 0.7% at rest to 88.1 ± 2.4% at exhaustion in cross-country skiers (p &lt; 0.001). There were no differences in resting and lowest %SaO2 values between two groups (p &gt; 0.05). Conclusions: EIAH may occur in endurance athletes as well as anaerobic trained athletes. Well-trained athletes who have different aerobic fitness levels may exhibit similar EIAH during the incremental maximal exercise.

Superior Effects of High-Intensity Interval Training vs. Moderate Continuous Training on Arterial Stiffness in Episodic Migraine: A Randomized Controlled Trial.

Background: Migraine is associated with increased cardiovascular risk and vascular dysfunction. Since aerobic exercise can reduce cardiovascular risk, the present randomized controlled trail aimed at investigating the effects of high-intensity interval training (HIT) vs. moderate continuous exercise training (MCT) on arterial stiffness in migraine patients.Methods: Forty-eight episodic migraineurs were initially enrolled in the study. 37 patients [female: 30; age: 37 (SD: 10); BMI: 23.1 (5.2); Migraine days per month: 3.7 (2.5)] completed the intervention. Central blood pressure, pulse wave reflection, and aortic pulse wave velocity (PWV) were obtained by an oscillometric monitor. Incremental treadmill exercise testing yielded maximal and submaximal fitness parameters. Participants were randomly assigned to either HIT, MCT, or a control group (CON). The intervention groups trained twice a week over a 12-week intervention period.Results: After adjustment for between-group baseline differences, a moderate meaningful overall reduction of the augmentation index at 75 min−1 heart rate (AIx@75) was observed [partial eta squared () = 0.16; p = 0.06]. With 91% likely beneficial effects, HIT was more effective in reducing AIx@75 than MCT [HIT: pre 22.0 (9.7), post 14.9 (13.0), standardized mean difference (SMD) = 0.62; MCT: pre 16.6 (8.5), post 21.3 (10.4), SMD −0.49]. HIT induced a relevant reduction in central systolic blood pressure [cSBP: pre 118 (23) mmHg, post 110 (16) mmHg, SMD = 0.42] with a 59% possibly beneficial effect compared to CON, while MCT showed larger effects in lowering central diastolic blood pressure [pre 78 (7) mmHg, post 74 (7) mmHg, SMD = 0.61], presenting 60% possibly beneficial effects compared to CON. Central aortic PWV showed no changes in any of the three groups. Migraine days were reduced more successfully by HIT than MCT (HIT: SMD = 1.05; MCT: SMD = 0.43).Conclusion: HIT but not MCT reduces AIx@75 as a measure of pulse wave reflection and indirect marker of systemic arterial stiffness. Both exercise modalities beneficially affect central blood pressure. HIT proved to be an effective complementary treatment option to reduce vascular dysfunction and blood pressure in migraineurs.