The Need for Testing—The Exercise Challenge Test to Disentangle Causes of Childhood Exertional Dyspnea

Exertional dyspnea is a common symptom in childhood which can induce avoidance of physical activity, aggravating the original symptom. Common causes of exertional dyspnea are exercise induced bronchoconstriction (EIB), dysfunctional breathing, physical deconditioning and the sensation of dyspnea when reaching the physiological limit. These causes frequently coexist, trigger one another and have overlapping symptoms, which can impede diagnoses and treatment. In the majority of children with exertional dyspnea, EIB is not the cause of symptoms, and in asthmatic children it is often not the only cause. An exercise challenge test (ECT) is a highly specific tool to diagnose EIB and asthma in children. Sensitivity can be increased by simulating real-life environmental circumstances where symptoms occur, such as environmental factors and exercise modality. An ECT reflects daily life symptoms and impairment, and can in an enjoyable way disentangle common causes of exertional dyspnea.

L-Carnitine Tartrate Supplementation for 5 Weeks Improves Exercise Recovery in Men and Women: A Randomized, Double-Blind, Placebo-Controlled Trial

L-carnitine tartrate has been shown to improve relatively short-term recovery among athletes. However, there is a lack of research on the longer-term effects in the general population. Objective: The primary objectives of this randomized double-blind, placebo-controlled trial were to evaluate the effects of daily L-carnitine tartrate supplementation for 5 weeks on recovery and fatigue. Method: In this study, eighty participants, 21- to 65-years-old, were recruited. Participants were split into two groups of forty participants each, a placebo, and a L-carnitine Tartrate group. Seventy-three participants completed a maintenance exercise training program that culminated in a high-volume exercise challenge. Results: Compared to placebo, L-carnitine tartrate supplementation was able to improve perceived recovery and soreness (p = 0.021), and lower serum creatine kinase (p = 0.016). In addition, L-carnitine tartrate supplementation was able to blunt declines in strength and power compared to placebo following an exercise challenge. Two sub-analyses indicated that these results were independent of gender and age. Interestingly, serum superoxide dismutase levels increased significantly among those supplementing with L-carnitine tartrate. Conclusions: These findings agree with previous observations among healthy adult subjects and demonstrate that L-carnitine tartrate supplementation beyond 35 days is beneficial for improving recovery and reducing fatigue following exercise across gender and age.

Clinical evaluation of a novel subcutaneous lactate monitor

Lactate levels are commonly used as an indirect measure to assess metabolic stress in clinical conditions like sepsis. Dynamic lactate measurements are recommended to assess and guide treatment in patients with shock and other critical care conditions. A minimally invasive, continuous lactate monitor has potential to improve clinical decisions and patient care. The purpose of the study was to evaluate continuous lactate measurements of a novel enzymatic Continuous Lactate Monitor (CLM) developed in our laboratory. Lactate levels were monitored during incremental cycling exercise challenges as a tool for hyperlactatemia. Six healthy individuals 18–45 y/o (4 males, 2 females) participated in the study. CLM devices were inserted subcutaneously in the postero-lateral trunk below the renal angle, one hour before the exercise challenge. Each exercise challenge consisted of a 3 to 12-min warm up period, followed by up to 7, 4-min incremental workload bouts separated by rest intervals. Continuous lactate measurements obtained from CLM were compared with commercial lactate analyzer (Abbott iSTAT) measurements of venous blood (plasma) drawn from the antecubital vein. Blood was drawn at up to 25 time points spanning the duration of before exercise, during exercise, and up to 120 min post exercise. Area under the curve (AUC), and delay time were calculated to compare the CLM readings with plasma lactate concentration. Average plasma lactate concentration increased from 1.02 to 16.21 mM. Ratio of AUC derived from CLM to plasma lactate was 1.025 (0.990–1.058). Average dynamic delay time of CLM to venous plasma lactate was 5.22 min (2.87–10.35). Insertion sites examined 48 h after CLM removal did not show signs of side effects and none required medical attention upon examination. The newly developed CLM has shown to be a promising tool to continuously measure lactate concentration in a minimally invasive fashion. Results indicate the CLM can provide needed trends in lactate over time. Such a device may be used in the future to improve treatment in clinical conditions such as sepsis.

Exercise-Induced Alterations in Phospholipid Hydrolysis, Airway Surfactant and Eicosanoids and their Role in Airway Hyperresponsiveness in Asthma

The mechanisms responsible for driving endogenous airway hyperresponsiveness (AHR) in the form of exercise-induced bronchoconstriction (EIB) are not fully understood. We examined alterations in airway phospholipid hydrolysis, surfactant degradation, and lipid mediator release in relation to AHR severity and changes induced by exercise challenge. Paired induced sputum (n=18) and bronchoalveolar lavage (BAL) fluid (n=11) were obtained before and after exercise challenge in asthmatic subjects. Samples were analyzed for phospholipid structure, surfactant function and levels of eicosanoid and secreted phospholipase A2 group 10 (sPLA2-X). A primary epithelial cell culture model was used to model effects of osmotic stress on sPLA2-X. Exercise challenge resulted in increased surfactant degradation, phospholipase activity, and eicosanoid production in sputum samples of all patients. Subjects with EIB had higher levels of surfactant degradation and phospholipase activity in BAL fluid. Higher basal sputum levels of cysteinyl leukotrienes (CysLTs) and prostaglandin D2 (PGD2) were associated with direct AHR and both the post-exercise and absolute change in CysLTs and PGD2 levels were associated with EIB severity. Surfactant function was either abnormal at baseline or became abnormal after exercise challenge. Baseline levels of sPLA2-X in sputum and the absolute change in amount of sPLA2-X with exercise were positively correlated with EIB severity. Osmotic stress ex vivo resulted in movement of water and release of sPLA2-X to the apical surface. In summary, exercise challenge promotes changes in phospholipid structure and eicosanoid release in asthma, providing two mechanisms that promote bronchoconstriction, particularly in individuals with EIB who have higher basal levels phospholipid turnover.

89 Effects of Saccharomyces cerevisiae fermentation product on fecal microbiota populations of dogs subjected to exercise challenge

Previously, a Saccharomyces cerevisiae fermentation product (SCFP) was demonstrated to positively alter fecal microbiota, fecal metabolites, and circulating immune cell functionality in adult dogs. The objective of this study was to determine the fecal characteristics, microbiota, and metabolites of trained dogs subjected to an exercise challenge. All procedures were approved by the Four Rivers Kennel IACUC prior to experimentation. Thirty-six adult dogs (mean age: 7.1 y; mean BCS: 4.9) were used. Dogs were randomly assigned to control or SCFP-supplemented (250 mg/d) diets, trained, and fed for a few mo prior to exercise challenge. Fresh fecal samples were collected for the measurement of fecal characteristics, microbiota, and metabolites before and after an exercise challenge (10 mile run). Fecal microbiota data were evaluated using QIIME2. All other data were analyzed using the Mixed Models procedure of SAS, with treatment and exercise as fixed effects, dog as random effect, and P < 0.05 considered significant. For both treatments, fecal scores and butyrate and propionate concentrations were lower and fecal pH and ammonia, isobutyrate, isovalerate, and total BCFA concentrations were higher after exercise challenge. SCFP did not affect fecal scores, pH, dry matter, or fermentative end-product concentrations after exercise challenge. Alpha-diversity or beta-diversity (unweighted PCoA plot) were not affected by SCFP before or after exercise challenge. The weighted PCoA plot, however, showed clustering of dogs before exercise and after exercise, regardless of treatment. Fecal Collinsella, Slackia, Turicibacter, Blautia, Dorea, Ruminococcus, Faecalibacterium, Catenibacterium, Clostridium (Erysipelotrichaceae family), and Eubacterium relative abundances were higher, while fecal Bacteroides, Parabacteroides, Prevotella (Prevotellaceae family), Phascolarctobacterium, Fusobacterium, Suttella and Anaerobiospirillum relative abundances were lower after exercise challenge. SCFP increased fecal Lactobacillus compared to controls. Our data demonstrate that exercise and SCFP alter fecal microbiota in dogs. Higher SCFP dosages may provide greater changes and may be of interest in future studies.