Jem I. Arnold

Ozone (O ₃ ) is a photochemical air pollutant known to reduce lung function and induce respiratory symptoms. This study aimed to determine whether breathing route influences O ₃ ‐induced lung function changes during exercise. Thirteen recreationally active participants (6 females, V̇O ₂ peak = 45.8 ± 5.3 mL/kg/min), with no history of cardiovascular or pulmonary disease or exercise‐induced bronchoconstriction, completed a double‐blind crossover study with four experimental visits. Participants performed 30 min of low‐intensity cycling (90% of power at the first ventilatory threshold) while breathing exclusively nasally or orally under room air or 0.40 ppm O ₃ . Spirometry was assessed before and after each trial, and dyspnea (Multidimensional Dyspnea Profile) every 5 min during exercise. O ₃ exposure impaired pulmonary function, reducing FEV ₁ , FVC, PEF, FEF25–75, and FEV ₁ /FVC (all p < 0.05). Regardless of environmental condition, oral breathing produced modestly greater post‐exercise reductions in FEV ₁ , PEF, FEF25–75, and FEV ₁ /FVC than nasal breathing, but no breathing route × environment interaction was observed. Nasal breathing was associated with greater breathing effort and air hunger ( p < 0.05). Thus, O ₃ exposure impaired pulmonary function and increased dyspnea regardless of breathing route. Although nasal breathing slightly attenuated overall post‐exercise lung function decline, it did not protect against O ₃ ‐induced pulmonary impairment and increased breathing discomfort during exercise.

Diaphragmatic electromyogram (EMGdi) can be measured using esophageal multi-paired electrodes. Due to the proximity of the heart, a cardiac artifact is often present within the EMGdi signal. This study sought to compare multiple approaches to reduce cardiac artifact and to determine if they differ on the basis of sex. We also determined the relationship between EMGdi and diaphragmatic work (PTPdi). Young participants (N=7 F; N=9 M) performed inspiratory threshold loading until failure while instrumented with a multi-pair esophageal balloon catheter system and an independent ECG. EMGdi signals were filtered: (1) by selecting between QRS complexes (ECG-R), (2) using an independent component analysis (ICA), (3) using an ICA with a wavelet transform (ICA-W), and compared to (4) no mitigation of ECG artifact (RAW). Estimated marginal slopes for each artifact removal method did not meaningfully change slope or intercept between females and males. Slopes for ICA, ICA-W, and ECG-R were not different from RAW (p>0.05). However, the intercepts for ICA-W, ICA, and ECG-R were reduced from RAW (p<0.05). EMGdi and PTPdi were significantly associated across all removal methods in females and males. Although, the relationship was lower for ICA and ICA-W (p<0.05) in females, males did not exhibit differences in the relationship across methods. All methods appear suitable for mitigating ECG artifact during PTL when heart rate remains modest. If a simultaneous ECG recording is unavailable, ICA and ICA-W are appropriate alternative techniques. If the relationship between EMGdi and PTPdi is the primary objective, the ECG-R approach is recommended.

Read, process, and analyse data from muscle near-infrared spectroscopy (mNIRS) devices. Import raw data from .csv or .xls(x) files and return time-series data and metadata. Includes standardised methods for cleaning, filtering, and pre-processing mNIRS data for subsequent analysis. Also includes a custom plot theme and colour palette. Intended for mNIRS researchers and practitioners in exercise physiology, sports science, and clinical rehabilitation with minimal coding experience required.

Sex differences in respiratory responses to ventilatory stress may contribute to exercise tolerance and dyspnoea perception, with potential implications across health and respiratory disease. We hypothesized that dead space loading (DSL) normalized to 15% of forced vital capacity would increase exertional dyspnoea, exacerbate inherent sex‐based differences in the respiratory system's response to exercise, and elicit higher diaphragmatic and extra‐diaphragmatic respiratory muscle activity in females than in males. Forty healthy, non‐smokers (20 males, 20 females; 24 ± 5 years old; maximal O ₂ uptake: 96 ± 20% predicted) completed familiarization followed by two maximal incremental cycling tests on separate days with and without DSL in a randomized, single‐blinded and counter‐balanced order. Diaphragm activity was recorded using a multi‐pair electrode oesophageal catheter, while extra‐diaphragmatic inspiratory muscle activity was recorded with bipolar surface electrodes. DSL was 797 ± 114 mL in males and 585 ± 71 mL in females ( P  < 0.001). Dyspnoea ratings increased similarly in both sexes with DSL, with no sex differences during or after exercise. Minute ventilation was increased with DSL throughout exercise [peak‐males: Δ16 L·min ⁻¹ ·%peak work ⁻¹ , CI: (12,19), P  < 0.001; females: Δ11 L·min ⁻¹ ·%peak work ⁻¹ , CI: (8,15), P  < 0.001], as well as indices of mechanical ventilatory constraints (e.g. tidal volume, power of breathing) at peak exercise in both sexes, where males had a greater increase with DSL for most variables than females. Diaphragm and extra‐diaphragmatic activity were increased with DSL in both sexes, with a greater increase in extra‐diaphragmatic activity in females near maximal exercise. These findings suggest that while sex differences in respiratory function and respiratory muscle activation exist, they do not necessarily translate to sex differences in dyspnoea perception during maximal incremental cycling. image Key points: Sex differences in respiratory anatomy and function are known to influence dyspnoea perception during exercise; however, the effects of higher ventilatory demand and mechanical ventilatory constraints on these differences remain poorly understood. Using a simple‐randomization, single‐blinded and counter‐balanced study design, we stimulated minute ventilation () and increased mechanical ventilatory constraints during maximal incremental cycling using dead space loading (DSL) customized to 15% of each individual's forced vital capacity. Dyspnoea was assessed using a multidimensional approach during and immediately after exercise. Despite increases in the sensations of breathing work/effort, unsatisfied inspiration and unsatisfied expiration with DSL in both sexes, there were no sex differences in dyspnoea perception during exercise with DSL. DSL increased and indicators of mechanical ventilatory constraints in both sexes compared to control exercise. Both sexes experienced an increase in diaphragmatic and extra‐diaphragmatic muscle activity, where females had a greater increase in extra‐diaphragmatic activity with DSL than males.

During the coronavirus disease 2019 pandemic, numerous studies evaluated the effects of face masks on the physiological and perceptual responses to exercise. However, the symptoms of breathlessness and associated physiological mechanisms were largely neglected. In addition, our understanding of whether face masks affected males and females differently was particularly limited. We found that sex-specific physiological responses can guide exercise and face mask strategies to improve comfort and performance for individuals engaging in prolonged, intense workouts.

The mechanisms of sex-based differences in the sensation of unsatisfied inspiration (UI) in healthy humans during exercise are poorly understood. We found that females who selected UI at peak exercise had worse dyspnea intensity ratings throughout exercise. Both sexes who selected UI at peak exercise also reported more distressing dyspnea qualities post exercise. Psychosocial factors appeared to influence male dyspnea perception, whereas smaller absolute lung volumes correlated with worse UI ratings in females.

Previous studies based on animal models have raised concerns about salbutamol use in ozone air pollution with regard to ozone related lung injury. We conducted a double‐blind, randomized, placebo‐controlled crossover study including 18 subjects diagnosed with EIB by a eucapnic voluntary hyperpnea (EVH) test. Participants completed 30 min of standardized moderate to vigorous exercise in four conditions: ozone plus salbutamol; room air plus salbutamol; ozone plus placebo medication; and room air plus placebo medication. Spirometry, fraction of exhaled nitric oxide, and symptoms were measured before, immediately after, 30 min after and 1 h after exercise. Measurements between the four conditions were compared using percent change from pre to post exercise. There was a statistically significant difference between the salbutamol and placebo medication groups for spirometric variables including FEV1 (Estimate = 6.3, 95% CI: 4.23–8.37, p < 0.001). No differences were observed between ozone and room air exposures. There were no significant differences in FeNO response between experimental conditions. We found that salbutamol improved pulmonary function in individuals with EIB when exercising in ozone and did not increase eosinophilic airway inflammation as indicated by FeNO. This evidence suggests that it is safe for people with EIB to continue to use salbutamol as prescribed when ozone levels are elevated.

Background Flow limitations in the iliac arteries (FLIA) is a sport-related vascular condition increasingly recognised as an occupational risk for professional cyclists and other endurance athletes. Surgical reconstruction is the definitive treatment for athletes wishing to continue competition. However, less information has been published regarding conservative management options and return-to-sport (RTS) guidelines. Objective Our aim was to review the existing literature on conservative treatment of FLIA, identify knowledge gaps and propose an RTS framework for athletes returning to competition. Methods A comprehensive literature review was performed using the Ovid-MEDLINE, PubMed, Embase and PEDro databases for publications relevant to conservative management of FLIA. A scoping review was conducted following PRISMA-ScR guidelines. Original, peer-reviewed publications in English describing conservative or postoperative management for athletes with FLIA were included. Additional grey literature and clinical expertise were consulted to inform RTS guidelines. Results Overall, 62 studies were included in this review. In total, 11 categories of conservative modalities were extracted and presented qualitatively in terms of the information source (discussion or results statements) and perspective of the authors (positive, negative or mixed). We have proposed RTS guidelines covering pre-operative preparation and postoperative rehabilitation based on the available literature, clinical experience, and drawing from other areas of sports medicine research. Conclusion There is insufficient literature evaluating the effectiveness of conservative management options for FLIA to establish best practices. Considering the importance of RTS for competitive athletes, we proposed practical guidelines to help with clinician and patient decision making. Future consensus should be sought for RTS best practices.

Introduction: Wearable near-infrared spectroscopy (NIRS) can be used during dynamic exercise to reflect the balance of muscle oxygen delivery and uptake. This study describes the behaviour and reliability of postexercise reoxygenation with NIRS as a function of exercise intensity at four muscle sites during an incremental cycling test. We discuss physiological components of faster and slower reoxygenation kinetics in the context of sport science and clinical applications. We hypothesised that reoxygenation would be slower at higher intensity, and that locomotor muscles would be faster than accessory muscles. We quantified test-retest reliability and agreement for each site.Methods: Twenty-one trained cyclists performed two trials of an incremental cycling protocol with 5-min work stages and 1-min rest between stages. NIRS was recorded from the locomotor vastus lateralis and rectus femoris muscles, and accessory lumbar paraspinal and lateral deltoid muscles. Reoxygenation time course was analysed as the half-recovery time (HRT) from the end of work to half of the peak reoxygenation amplitude during rest. Coefficient of variability (CV) between participants, standard error of the measurement (SEM) within participants, and intraclass correlation coefficient (ICC) for test-retest reliability were evaluated at 50%, 75%, and 100% peak workloads. A linear mixed-effects model was used to compare differences between workloads and muscle sites.Results: HRT was slower with increasing workload in the VL, RF, and PS, but not DL. VL had the fastest reoxygenation (lowest HRT) across muscle sites at all workloads (HRT = 8, 12, 17 s at 50%, 75%, 100% workload, respectively). VL also had the greatest reliability and agreement. HRT was sequentially slower between muscle sites in the order of VL < RF < PS < DL, and reliability was lower than for the VL.Discussion: This study highlights the potential for using wearable NIRS on multiple muscle sites during exercise. Reoxygenation kinetics differ between local muscle sites with increasing intensity. Moderate-to-good reliability in the VL support its increasing use in sport science and clinical applications. Lower reliability in other muscle sites suggest they are not appropriate to be used alone, but may add information when combined to better reflect systemic intensity and fatigue during exercise at different intensities.

Background: A flow limitation in the iliac arteries (FLIA) in endurance athletes is notoriously difficult to diagnose with the currently available diagnostic tools. At present, a commonly used diagnostic measure is a decrease in ankle brachial index with flex hips (ABI_Flexed) following a maximal effort exercise test. Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures skeletal muscle oxygenation as reflected by the balance of O₂ delivery from microvascular blood flow and O₂ uptake by metabolic activity. Therefore, NIRS potentially serves as a novel technique for diagnosing FLIA. The purpose of this study is to compare the diagnostic accuracy of NIRS-derived absolute, amplitude, and kinetic variables in legs during and after a maximal exercise test with ABI_Flexed. Methods: ABI_Flexed and NIRS were studied in 33 healthy subjects and 201 patients with FLIA diagnosed with echo-Doppler. Results: After maximal exercise, NIRS kinetic variables, such as the half value time and mean response time, resulted in a range of 0.921 to 0.939 AUC for the diagnosis of FLIA when combined with ABI_Flexed. Conversely, ABI_Flexed measurements alone conferred significantly worse test characteristics (AUC 0.717, p < 0.001). Conclusions: NIRS may serve as a diagnostic adjunct in patients with possible FLIA.