Standard Treadmill Exercise Test Research Articles

Propionyl-L-carnitine for intermittent claudication.

Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis. Intermittent claudication is a symptomatic form of PAD that is characterized by pain in the lower limbs caused by chronic occlusive arterial disease. This pain develops in a limb during exercise and is relieved with rest. Propionyl-L-carnitine (PLC) is a drug that may alleviate the symptoms of PAD through a metabolic pathway, thereby improving exercise performance. The objective of this review is to determine whether propionyl-L-carnitine is efficacious compared with placebo, other drugs, or other interventions used for treatment of intermittent claudication (e.g. exercise, endovascular intervention, surgery) in increasing pain-free and maximum walking distance for people with stable intermittent claudication, Fontaine stage II. The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and the ClinicalTrials.gov trials register to July 7, 2021. We undertook reference checking and contact with study authors and pharmaceutical companies to identify additional unpublished and ongoing studies. Double-blind randomized controlled trials (RCTs) in people with intermittent claudication (Fontaine stage II) receiving PLC compared with placebo or another intervention. Outcomes included pain-free walking performance (initial claudication distance - ICD) and maximal walking performance (absolute claudication distance - ACD), analyzed by standardized treadmill exercise test, as well as ankle brachial index (ABI), quality of life, progression of disease, and adverse events. Two review authors independently selected trials, extracted data, and evaluated trials for risk of bias. We contacted study authors for additional information. We resolved any disagreements by consensus. We performed fixed-effect model meta-analyses with mean differences (MDs) and 95% confidence intervals (CIs). We graded the certainty of evidence according to GRADE. We included 12 studies in this review with a total number of 1423 randomized participants. A majority of the included studies assessed PLC versus placebo (11 studies, 1395 participants), and one study assessed PLC versus L-carnitine (1 study, 26 participants). We identified no RCTs that assessed PLC versus any other medication, exercise, endovascular intervention, or surgery. Participants received PLC 1 grams to 2 grams orally (9 studies) or intravenously (3 studies) per day or placebo. For the comparison PLC versus placebo, there was a high level of both clinical and statistical heterogeneity due to study size, participants coming from different countries and centres, the combination of participants with and without diabetes, and use of different treadmill protocols. We found a high proportion of drug company-backed studies. The overall certainty of the evidence was moderate. For PLC compared with placebo, improvement in maximal walking performance (ACD) was greater for PLC than for placebo, with a mean difference in absolute improvement of 50.86 meters (95% CI 50.34 to 51.38; 9 studies, 1121 participants), or a 26% relative improvement (95% CI 23% to 28%). Improvement in pain-free walking distance (ICD) was also greater for PLC than for placebo, with a mean difference in absolute improvement of 32.98 meters (95% CI 32.60 to 33.37; 9 studies, 1151 participants), or a 31% relative improvement (95% CI 28% to 34%). Improvement in ABI was greater for PLC than for placebo, with a mean difference in improvement of 0.09 (95% CI 0.08 to 0.09; 4 studies, 369 participants). Quality of life improvement was greater with PLC (MD 0.06, 95% CI 0.05 to 0.07; 1 study, 126 participants). Progression of disease and adverse events including nausea, gastric intolerance, and flu-like symptoms did not differ greatly between PLC and placebo. For the comparison of PLC with L-carnitine, the certainty of evidence was low because this included a single, very small, cross-over study. Mean improvement in ACD was slightly greater for PLC compared to L-carnitine, with a mean difference in absolute improvement of 20.00 meters (95% CI 0.47 to 39.53; 1 study, 14 participants) or a 16% relative improvement (95% CI 0.4% to 31.6%). We found no evidence of a clear difference in the ICD (absolute improvement 4.00 meters, 95% CI -9.86 to 17.86; 1 study, 14 participants); or a 3% relative improvement (95% CI -7.4% to 13.4%). None of the other outcomes of this review were reported in this study. When PLC was compared with placebo, improvement in walking distance was mild to moderate and safety profiles were similar, with moderate overall certainty of evidence. Although In clinical practice, PLC might be considered as an alternative or an adjuvant to standard treatment when such therapies are found to be contraindicated or ineffective, we found no RCT evidence comparing PLC with standard treatment to directly support such use.

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.

Altitude Cardiomyopathy Is Associated With Impaired Stress Electrocardiogram and Increased Circulating Inflammation Makers

Many sea-level residents suffer from acute mountain sickness (AMS) when first visiting altitudes above 4,000 m. Exercise tolerance also decreases as altitude increases. We observed exercise capacity at sea level and under a simulated hypobaric hypoxia condition (SHHC) to explore whether the response to exercise intensity represented by physiological variables could predict AMS development in young men. Eighty young men from a military academy underwent a standard treadmill exercise test (TET) and biochemical blood test at sea level, SHHC, and 4,000-m altitude, sequentially, between December 2015 and March 2016. Exercise-related variables and 12-lead electrocardiogram parameters were obtained. Exercise intensity and AMS development were investigated. After exposure to high altitude, the count of white blood cells, alkaline phosphatase and serum albumin were increased (P < 0.05). There were no significant differences in exercise time and metabolic equivalents (METs) between SHHC and high-altitude exposures (7.05 ± 1.02 vs. 7.22 ± 0.96 min, P = 0.235; 9.62 ± 1.11 vs. 9.38 ± 1.12, P = 0.126, respectively). However, these variables were relatively higher at sea level (8.03 ± 0.24 min, P < 0.01; 10.05 ± 0.31, P < 0.01, respectively). Thus, subjects displayed an equivalent exercise tolerance upon acute exposure to high altitude and to SHHC. The trends of cardiovascular hemodynamics during exercise under the three different conditions were similar. However, both systolic blood pressure and the rate–pressure product at every TET stage were higher at high altitude and under the SHHC than at sea level. After acute exposure to high altitude, 19 (23.8%) subjects developed AMS. Multivariate logistic regression analysis showed that METs under the SHHC {odds ratio (OR) 0.355 per unit increment [95% confidence intervals (CI) 0.159−0.793], P = 0.011}, diastolic blood pressure (DBP) at rest under SHHC [OR 0.893 per mmHg (95%CI 0.805−0.991), P = 0.030], and recovery DBP 3 min after exercise at sea level [OR 1.179 per mmHg (95%CI 1.043−1.333), P = 0.008] were independently associated with AMS. The predictive model had an area under the receiver operating characteristic curve of 0.886 (95%CI 0.803−0.969, P < 0.001). Thus, young men have similar exercise tolerance in acute exposure to high altitude and to SHHC. Moreover, AMS can be predicted with superior accuracy using characteristics easily obtainable with TET.

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.

The use of heart rate variability analysis to detect arrhythmias in horses undergoing a standard treadmill exercise test.

BackgroundLittle is known about normal heart rate variability (HRV) in horses during exercise. It can be difficult to separate premature beats from normal beat‐to‐beat variation at higher heart rates.ObjectivesThe aim was to quantify HRV in healthy horses during a high‐speed treadmill‐standardized exercise test (HSET) and to compare with the HRV in horses observed to have arrhythmias during exercise.AnimalsThirteen healthy horses (Group H), 30 horses with arrhythmias (Group A), and 11 horses with poor performance but no observed arrhythmias (Group O).MethodsProspective, observational study. All horses performed a HSET with simultaneous electrocardiograph (ECG) recorded. The ECGs were corrected for artifacts, and arrhythmias noted. Percent instantaneous beat‐to‐beat cycle length variation (% R‐R variation) was calculated, and HRV analyses were performed on trot, canter, and recovery segments.ResultsGroup H showed between −4.4 and +3.8% R‐R variation during trot and between −6.1 and +5.4% R‐R variation during the canter phase of the HSET. Group A had significantly larger maximum and 1st percentile R‐R shortening and lengthening compared with Group H and Group O during the recovery phase where most arrhythmias were observed. During recovery, a cutoff of 6% maximum % R‐R shortening predicted the presence of arrhythmia with 88% sensitivity and 97% specificity and likelihood ratio of 26.Conclusions and Clinical ImportanceHealthy horses have little instantaneous R‐R variation during exercise. If a cardiac cycle shortens more than 6% from the previous cycle during the recovery phase, this R‐R interval is likely to represent an arrhythmic event.

Changes in Blood Parameters in Healthy Horses and Horses With Upper and Lower Respiratory Tract Diseases Undergoing Treadmill Exercise Tests

Exercise tests are useful tools to evaluate the fitness level of horses in training or with a history of poor performance. The aim of this study was to evaluate the differences in blood parameters in three groups of horses undergoing treadmill exercise tests, either to detect the cause of exercise intolerance or to evaluate the level of fitness before a competition. Blood samples were taken from 30 horses before, at the end of, and two hours after a standardized treadmill exercise test, to detect differences in hematological parameters between healthy horses (10, group N), horses with upper (10, group U), and lower airway diseases (10, group L). Packed cell volume, erythrocyte number, hemoglobin, glucose, and total and unconjugated bilirubin concentration were statistically different between the groups, because of increased oxygen demands in respiratory diseases and intravascular hemolysis. This could occur during exercise and is worsened by the increased breakdown of erythrocytes secondary to exercise-induced pulmonary hemorrhage, diagnosed in horses in group L.

Exercise test using dry air in random adolescents: Temporal profile and predictors of bronchoconstriction.

Guidelines recommend exercise tests using dry air to diagnose exercise-induced bronchoconstriction (EIB). Lung function changes subsequent to these tests have not been investigated in a general adolescent population, and it remains unknown whether signs of airway inflammation, measured using exhaled nitric oxide (FeNO), can predict a positive response. The aim of this study was to investigate the temporal aspect of decline in forced expiratory volume in 1 s (FEV1 ) after an exercise test using dry air, and to investigate predictors of EIB. From a cross-sectional study on adolescents aged 13-15 years (n = 3838), a random subsample of 146 adolescents (99 with and 47 without self-reported exercise-induced dyspnoea) underwent standardized treadmill exercise tests for EIB while breathing dry air. Of the adolescents, 34% had a positive EIB test (decline of ≥10% in FEV1 from baseline) within 30 min. Of the subjects with EIB, 53% showed the greatest decline in FEV1 at 5 to 10 min (mean decline 18.5%), and the remaining 47% of the subjects showed the greatest decline at 15 to 30 min (mean decline 18.9%) after exercise. Increased FeNO (>20 ppb), female gender and self-reported exercise-induced dyspnoea were independently associated with a positive EIB test. When assessing general adolescents for EIB with exercise test using dry air, there is a temporal variation in the greatest FEV1 decline after exercise. Therefore, lung function should be measured for at least 30 min after the exercise. Increased FeNO, female gender and self-reported exercise-induced dyspnoea can be predictors of a positive EIB test.

The effect of exercise on exhaled nitric oxide depends on allergic rhinoconjunctivitis in children

Objective: Fractional exhaled nitric oxide (FENO) and exercise testing are widely used for the evaluation of pediatric asthma. The evidence relating to the effects of strenuous exercise on FENO in children is conflicting. Little information is available on the association between exercise and FENO in relation to allergic rhinoconjunctivitis (AR). We aimed to investigate the effects of AR on children's FENO in response to a standardized treadmill exercise test. Methods: A total of 124 children with current asthma and 124 non-asthmatic children aged 8–16 years were studied. FENO was measured at baseline, at 1 and 30 min after an exercise challenge test using the single breath technique with EcoMedics Exhalyzer®. A structured parental interview, spirometry, serum allergen-specific IgE and skin prick tests were performed. Results: Baseline FENO was higher in both asthmatics and non-asthmatics with AR than without AR (both p < 0.001). The FENO time trend was dependent on AR (p = 0.039), irrespective of asthma (p = 0.876). In children with AR, FENO had declined at 1 min by a mean of 6.1 ppb with a 95% confidence level of 5.1–7.5 ppb; at 30 min, the reduction was 2.8 (2.5–3.3) ppb. In children without AR, at 1 min the decline in FENO was 2.7 (2.1–3.5) ppb and by 30 min post-exercise it was 1.6 (1.3–2.0) ppb. Conclusions: The impact of exercise on FENO was dependent on the allergic phenotype, regardless of asthma status. FENO decreased immediately after exercise, and did not return to baseline level within 30 min.

Abstract 12532: Left Ventricular Diastolic Dysfunction and Exercise Intolerance in Type 2 Diabetes Patients With Endothelial Dysfunction

Introduction: Endothelial dysfunction plays a central role in the pathogenesis of diabetic vascular disease. Hypothesis: Although resultant left ventricular diastolic dysfunction is hypothesized to reduce exercise capacity, limited data exist on the relation between endothelial function, left ventricular diastolic function and exercise capacity in patients with type 2 diabetes. Methods: We recruited 231 subjects with type 2 diabetes, a preserved ejection fraction, a negative stress test and a sodium-restricted diet. All subjects underwent a brachial artery flow-mediated dilation (FMD) measurement, a transthoracic echocardiography and a standard submaximal Bruce protocol treadmill exercise test during the hospitalization period for diabetes education program. Results: Impaired FMD (%FMD 8) were found in 193 subjects (84%) and 174 subjects (75%), respectively, of which 11 (5%) had diastolic dysfunction (E/E’ &gt;15). Mean E/E’ by quartile (Q) were: Q1 6.9, Q2 8.9, Q3 10.4, and Q4 14.0. E/E’ was inversely correlated with %FMD (2.9 ± 4.3%, r = -0.19, p = 0.003) and exercise duration (460 ± 150 sec, r = -0.30, p &lt;0.001). Compared with subjects in Q4, those in Q1, Q2 and Q3 had longer exercise duration (Q1 500 ± 150 sec, Q2 510 ± 140 sec, Q3 460 ± 140 sec and Q4 390 ± 140 sec, p &lt;0.001). After adjustment for potential confounders including age, gender, smoking, body mass index, medication for hypertension, diabetes duration of more than 5 years, HbA1c and systolic blood pressure, %FMD and exercise duration were significantly associated with E/E’ (β = -0.17 and -0.18, p = 0.006 and 0.014) in all subjects. Conclusions: Diabetes patients with impaired endothelial function have impaired left ventricular diastolic function potentially leading to exercise intolerance.

Effect of ramipril on walking times and quality of life among patients with peripheral artery disease and intermittent claudication: A randomized controlled trial. Journal of the American Medical Association 2013; 309: 453–460

The objective of the trial was to examine whether ramipril, an angiotensin-converting enzyme (ACE), improves walking distance and health-related quality of life in patients with peripheral artery disease (PAD) associated with claudication. The study enrolled 212 patients with risk factors and symptoms of PAD treated by conventional therapies at three centers in Australia. All patients had an ankle-brachial index (ABI) of less than 0.90 at rest and intermittent claudication in at least one leg, which were stable for at least 6 preceding months along with the medication regimen. The patients were excluded if blood pressure was not controlled (brachial blood pressure of 160/100 mmHg or greater); if there was current or recent use of either ACE inhibitors or angiotensin II receptor blockers, potassium-sparing diuretics, or potassium supplements; renal failure (serum creatinine level 2.3 mg/dL or greater [200 µmol/L]); renal artery stenosis; previous coronary or peripheral artery revascularizations, recent myocardial infarction and other health conditions other than PAD that could adversely influence walking ability at the time of screening and for 1 year thereafter. This was a randomized, placebo-controlled, triple blinded study of ramipril at the high daily dose (10 mg) for 6 months. Primary outcomes were pain-free and maximum walking times assessed by a standard treadmill exercise test. Secondary outcomes were ABI changes; symptoms and functional status assessed by the Walking Impairment Questionnaire (WIQ)(1); health-related quality of life assessed by the Short-Form 36 Health Survey (SF-36)(2); and stenosis severity assessed by duplex ultrasound of the lower limb arteries. At baseline and at follow-up, pain-free and maximum walking distances were assessed by the standard constant load treadmill exercise test performed at a speed of 3.2 km/h and a grade of 12%.(3) ABI was calculated in both legs. Duplex ultrasonography was used to determine stenosis in lower-limb vessel segments. Functional changes per WIQ, and perceived disability assessed on the Physical Component Summary and the Mental Component Summary of the SF-36 were self-reported. Sample size was calculated as 100 patients per each group needed to provide a power of 80% at an α of 0.05 to detect a 120-second change in walking time and a 65-second change in pain-free walking time. A two-sided p-value of less than 0.05 was considered significant. Baseline variables were compared using the χ(2) test and one-way analysis of variance. The analysis of covariance model with baseline and post-treatment values after 6 months used Kruskal-Wallis analysis of variance. Imputations for missing 6-month data were performed. Data were analyzed on the intention-to-treat basis. Of 921 potential participants screened, 212 eligible participants were randomized into equal-sized ramipril and placebo groups where baseline parameters were not different. Compliance was monitored by pill count and adverse effects were monitored through interval clinical assessments, laboratory tests, and telephone calls. There was a 100% adherence rate to the study medications among 200 patients who completed the study. Ramipril was associated with a 75-second increase in mean pain-free and a 255-second increase in maximum walking time. There was a modest (less than 5 mmHg) blood pressure reduction and a small (0.1) ABI increase at rest and after exercise compared to placebo. The maximum walking time increase after ramipril therapy compared to placebo was greater in the subgroup of patients with femoropopliteal disease (286 seconds) than in those with aortoiliac disease (127 seconds). Patients treated with ramipril showed improvement of the median distance, speed and stair climbing scores on the WIQ, as well as of the Physical, but not the Mental, Component Summary score on the SF-36. The most frequent side effect was dizziness, more common in the ramipril (8.5%) than in the placebo (2.8%) group. Persistent cough occurred in 6.6% of patients on ramipril, causing their withdrawal from the study.

Effect of Supervised Exercise Therapy for Intermittent Claudication in Patients With Diabetes Mellitus

Primary treatment for patients with intermittent claudication is exercise therapy. Diabetes mellitus (DM) is a frequently occurring comorbidity in patients with intermittent claudication, and in these patients, exercise tolerance is decreased. However, there is little literature about the increase in walking distance after supervised exercise therapy (SET) in patients with both intermittent claudication and DM. The objective of this study was to determine the effectiveness of SET for intermittent claudication in patients with DM. Consecutive patients with intermittent claudication who started SET were included. Exclusion criteria were Rutherford stage 4 to 6 and the inability to perform the standardized treadmill test. SET was administered according to the guidelines of the Royal Dutch Society for Physiotherapy. At baseline and at 1, 3, and 6 months of follow-up, a standardized treadmill exercise test was performed. The primary outcome measurement was the absolute claudication distance (ACD). We included 775 patients, of whom 230 had DM (29.7%). At 6 months of follow-up, data of 440 patients were available. Both ACD at baseline and at 6 months of follow-up were significantly lower in patients with DM (P < 0.001). However, increase in ACD after 6 months of SET did not differ significantly (P = 0.48) between the DM group and the non-DM group (270 m and 400 m, respectively). In conclusion, SET for patients with intermittent claudication is equally effective in improving walking distance for both patients with and without DM, although ACD remains lower in patients with DM.

Exhaled nitric oxide decreases during exercise in non‐asthmatic children

Exhaled nitric oxide (FENO) measurements are recommended to be performed before spirometry and exercise challenge tests because forced breathing might influence FENO values. Information on the effect of exercise on FENO is lacking in non-asthmatic children. To investigate the effect on FENO of a standardized exercise challenge test on a treadmill in non-asthmatic children with and without allergic rhinoconjunctivitis (AR) symptoms. From the case-control study 'Asthma and allergy among school children in Nordland', 330 non-asthmatic pupils age 8-16 years were enrolled. FENO was measured at baseline and at 1 min and 30 min after exercise challenge test by the single breath technique with EcoMedics Exhalazer® (Eco Physics, Duernten, Switzerland). Pair-wise comparison of FENO from baseline demonstrated a highly significant reduction in FENO post-exercise for all children at 1 min (27.4%) and at 30 min (16.1%) (P < 0.001). The AR group had a significantly higher decline in FENO value at 1 min post-exercise compared to the non-AR group, 4.2 parts per billion (ppb) vs 2.6 ppb (P < 0.001). Decline in FENO immediately post-exercise was more significant if baseline FENO was ≥ 20 ppb; mean reduction 9.9 (95% CI: 8.7-11.4) ppb. FENO is reduced by 27.4% immediately after a standardized treadmill exercise test in non-asthmatic children. Pupils reporting AR symptoms demonstrate a larger decline in FENO value at 1 min post-exercise compared to pupils without AR symptoms. These findings confirm that children should refrain from physical activity before FENO measurement.

Aerobic Capacity and Exercise Performance in Young People Born Extremely Preterm

The goal of this study was to compare aerobic capacity and exercise performance of children and adolescents born extremely preterm and at term, and to relate findings to medical history and lifestyle factors. Potential cohort effects were assessed by studying subjects born in different decades. Two area-based cohorts of subjects born with gestational age ≤28 weeks or birth weight ≤1000 g in 1982-1985 and 1991-1992 and matched control subjects born at term were compared by using standardized maximal treadmill exercise and pulmonary function tests. Background data were collected from questionnaires and medical records. Seventy-five of 86 eligible preterm subjects (87%) and 75 control subjects were assessed at mean ages of 17.6 years (n = 40 + 40) and 10.6 years (n = 35 + 35). At average, measures of aerobic capacity for subjects born preterm and at term were in the same range, whereas average running distance was modestly reduced for those born preterm. Leisure-time physical activity was similarly and positively associated with exercise capacity in preterm and term-born adolescents alike, although participation was lower among those born preterm. Neonatal bronchopulmonary dysplasia and current forced expiratory vol in 1 second was unrelated to exercise capacity. Differences between subjects born preterm and at term had not changed over the 2 decades studied. Despite their high-risk start to life and a series of potential shortcomings, subjects born preterm may achieve normal exercise capacity, and their response to physical training seems comparable to peers born at term.

Muscle glycogen resynthesis, signalling and metabolic responses following acute exercise in exercise-trained pigs carrying the PRKAG3 mutation

Hampshire pigs carrying the PRKAG3 mutation in the AMP-activated protein kinase (AMPK) γ3 subunit exhibit excessive skeletal muscle glycogen storage and an altered glycogen synthesis signalling response following exercise. AMPK plays an important role as a regulator of carbohydrate and fat metabolism in mammalian cells. Exercise-trained muscles are repeatedly exposed to glycogen degradation and resynthesis, to which the signalling pathways adapt. The aim of this study was to examine the effect of acute exercise on glycogen synthesis signalling pathways, and the levels of insulin and other substrates in blood in exercise-trained pigs with and without the PRKAG3 mutation. After 5 weeks of training, pigs performed two standardized treadmill exercise tests, and skeletal muscle biopsies were obtained immediately after exercise and 3 h postexercise in the first test, and 6 h postexercise in the second test. The PRKAG3 mutation carriers had higher glycogen storage, and resynthesis of glycogen was faster after 3 h but not after 6 h of recovery. Alterations in the concentrations of insulin, glucose, lactate and free fatty acids after exercise did not differ between the genotypes. The carriers showed a lower expression of AMPK and increased phosphorylation of Akt Ser(473) after exercise, compared with non-carriers. Acute exercise stimulated the phosphorylation of AS160 in both genotypes, and the phosphorylation of GSK3α Ser(21) and ACC Ser(79) in the non-carriers. In conclusion, exercise-trained pigs carrying the PRKAG3 mutation show an altered Akt and AMPK signalling response to acute exercise, indicating that glucose metabolism is associated with faster resynthesis of muscle glycogen in this group.

Serum concentration of surfactant protein D in horses with lower airway inflammation

Surfactant protein D (SP-D), mainly synthesised by alveolar type II cells and nonciliated bronchiolar cells, is one important component of innate pulmonary immunity. In man, circulating concentrations of SP-D are routinely used as biomarkers for pulmonary injury. To date, serum SP-D levels have only been investigated in horses in an experimental model of bacterial airway infection. To compare serum SP-D concentrations at rest and after exercise in horses with and without inflammatory airway disease (IAD). Venous blood samples were collected from 42 Standardbred racehorses at rest and 60 min after performing a standardised treadmill exercise test. Tracheal wash and bronchoalveolar lavage fluid (BALF) samples were collected after exercise. Based on BALF cytology, 22 horses were defined as IAD-affected and 20 classified as controls. Serum SP-D concentrations were assessed using a commercially available ELISA kit and statistically compared between groups of horses and sampling times. Serum concentrations of SP-D in IAD-affected horses were significantly higher than those of control horses, both at rest and after exercise. Within the IAD-affected group, no significant correlation was found between serum SP-D concentrations and BALF cytology. Within each group of horses (IAD and control), no significant influence of exercise was found on serum SP-D levels. This is the first study determining serum SP-D concentrations in a noninfectious, naturally occurring form of lower airway inflammation in horses. The results highlight that IAD is associated with a detectable, though moderate, increase of circulating SP-D levels. Serum concentration of surfactant protein D could represent a potentially valuable and readily accessible blood biomarker of equine lower airway inflammation.

Effects of short‐term training on thermoregulatory and sweat responses during exercise in hot conditions

There is evidence that extensive training in cool conditions results in improvements to heat dissipation that contribute to successful acclimatisation. In horses, the effects of a less extensive training regimen have not been determined. This study investigated whether 10 consecutive days of moderate intensity treadmill training in cool conditions would improve thermoregulatory and sweating responses of horses to exercise in the heat. Six unfit Thoroughbred horses completed a standardised treadmill exercise test (SET) in hot, dry conditions (32-34 °C, 45-55% RH) before (SET1) and after (SET2) 10 consecutive days of running at 55% VO2max for 60 min in cool conditions (19-21°C, 45-55% RH). Each SET consisted of a 5 min warm-up and cool down at a walk, 40 min of trotting (50% VO2max), 7 min at 75% VO2max and a 30 min standing recovery. Bodyweight was determined pre- and post SET. Heart rate, rectal, skin, pulmonary artery and muscle temperatures were measured throughout the SETs and sweating rate (SR) and sweat ion losses determined for each 5 min interval. Following training, mean VO2max increased by 8.9% (P < 0.05). In SET2, PCV was lower during the last 30 min of exercise and end-exercise rectal, muscle and pulmonary artery temperatures were decreased by 1.5 ± 0.2, 0.8 ± 0.1 and 1.0 ± 0.2 °C, respectively (P < 0.05). Peak SR and the pattern of sweat ion losses during exercise was unchanged post training whereas SR and sweat losses during recovery were decreased (P < 0.05). Similar SRs for a given core temperature during exercise but a more rapid decrease in recovery resulted in an overall reduction in sweat fluid losses with no change in sweat ion losses after training. The results provide insight into the extent to which short-term training can improve the capacity of horses to exercise in hot conditions.

Observer agreement for detection of cardiac arrhythmias on telemetric ECG recordings obtained at rest, during and after exercise in 10 Warmblood horses

Frequent supraventricular or ventricular arrhythmias during and after exercise are considered pathological in horses. Prevalence of arrhythmias seen in apparently healthy horses is still a matter of debate and may depend on breed, athletic condition and exercise intensity. To determine intra- and interobserver agreement for detection of arrhythmias at rest, during and after exercise using a telemetric electrocardiography device. The electrocardiogram (ECG) recordings of 10 healthy Warmblood horses (5 of which had an intracardiac catheter in place) undergoing a standardised treadmill exercise test were analysed at rest (R), during warm-up (W), during exercise (E), as well as during 0-5 min (PE(0-5)) and 6-45 min (PE(6-45)) recovery after exercise. The number and time of occurrence of physiological and pathological 'rhythm events' were recorded. Events were classified according to origin and mode of conduction. The agreement of 3 independent, blinded observers with different experience in ECG reading was estimated considering time of occurrence and classification of events. For correct timing and classification, intraobserver agreement for observer 1 was 97% (R), 100% (W), 20% (E), 82% (PE(0-5)) and 100% (PE(6-45)). Interobserver agreement between observer 1 vs. observer 2 and between observer 1 vs. 3, respectively, was 96 and 92.6% (R), 83 and 31% (W), 0 and 13% (E), 23 and 18% (PE(0-5)), and 67 and 55% (PE(6-45)). When including the events with correct timing but disagreement for classification, the intraobserver agreement increased to 94% during PE(0-5) and the interobserver agreement reached 83 and 50% (W), 20 and 50% (E), 41 and 47% (PE(0-5)), and 83.5 and 65% (PE(6-45)). The interobserver agreement increased with observer experience. Intra- and interobserver agreement for recognition and classification of events was good at R, but poor during E and poor-moderate during recovery periods. These results highlight the limitations of stress ECG in horses and the need for high-quality recordings and adequate observer training.

Successful Bone Marrow Transplantation Reveals the Lack of Endothelial Progenitor Cells Mobilization in a Patient With Critical Limb Ischemia: A Case Report

Restoring blood flow to ischemic tissue is a prerequisite for treatment of ischemic diseases. Cell-based therapy based on bone marrow transplantation is a promising option for patients with critical limb ischemia (CLI). The efficacy of cell therapies to augment neovascularization seems to involve endothelial progenitor cells (EPCs); however, the mechanisms underlying the efficacy have not been fully elucidated. Herein we have described the case of a young patient with severe CLI, who experienced a 24-month beneficial clinical response to autologous bone marrow transplantation. The exceptional amelioration enabled him to perform standardized maximal treadmill exercise test that demonstrated lack of exercise-induced EPC mobilization, despite adequate stromal-derived factor 1 and vascular endothelial growth factor responses. Therefore, tissue ischemia is not sufficient to promote the recruitment of EPCs that have been demonstrated to be involved in the recovery from ischemia. The local implantation of marrow-derived elements may provide cells and/or trophic factors, which have the capacity to augment angiogenesis, opening new approaches to the etiopathogenesis of the disease.

Dynamic obstructions of the equine upper respiratory tract. Part 1: Observations during high-speed treadmill endoscopy of 600 Thoroughbred racehorses

To review the prevalence of single and complex forms of dynamic airway obstructions within a large group of Thoroughbred horses in training referred for investigation of poor performance. Video-endoscopic recordings of the upper respiratory tract made during a standardised treadmill exercise test of 600 Thoroughbred racehorses were reviewed and analysed in real time and slow motion to identify dynamic collapse by the tissues bordering onto the pharyngeal and laryngeal airways. Dynamic collapse within the nasopharynx or larynx was confirmed in 471 of the 600 horses. Dorsal displacement of the soft palate (DDSP; 50%) and palatal instability (33%) were the disorders most frequently identified. It was concluded that deglutition is not a significant event in the triggering of DDSP. Complex forms of dynamic collapse were present in 30% of the horses with upper respiratory tract obstructions. A significant influence of age on the prevalence of DDSP and dynamic laryngeal collapse was identified. There was an increased risk of DDSP in younger horses, and of laryngeal collapse in older horses. No association with gender or format of racing was identified. Palatal instability and DDSP comprised the most frequently encountered forms of dynamic collapse within the upper respiratory tract of the Thoroughbred racehorses in this study and are probably expressions of the same nasopharyngeal malfunction. Complex obstructions, i.e. where more than one structure collapses into the airway, occur frequently and therefore treatments that address solitary disorders may often be unsuccessful. Younger horses were found to be at greater risk of sustaining DDSP while older horses seemed more at risk to vocal cord collapse but not to collapse of the arytenoid cartilage itself.