ECSS Paris 2023: CP-PN12
INTRODUCTION: Strength and combat sports are associated with marked hypertrophy of the trunk and cervical musculature. These structural adaptations may increase mechanical loading of the chest wall and upper airways, potentially altering respiratory system mechanics. Athletes with pronounced muscular development also appear to have an increased prevalence of sleep-disordered breathing, including obstructive sleep apnea (OSA). The functional implications of these adaptations, however, remain insufficiently defined. The aim of this study was to characterize respiratory system mechanics in strength-trained athletes using spirometry, static lung volume assessment (TLC and RV), and the forced oscillation technique (FOT), and to examine their relationship with nocturnal respiratory parameters. METHODS: Twenty athletes engaged in strength and/or combat sports and 20 matched controls were enrolled. All participants underwent spirometry, static lung volume measurements (including total lung capacity [TLC] and residual volume [RV]) using a mouthpiece-based plethysmographic system, and assessment of respiratory impedance with FOT. Overnight polygraphic sleep studies were performed in all subjects. Associations between respiratory mechanics parameters, body composition indices, and markers of sleep apnea severity were analyzed. RESULTS: Athletes with substantial muscular development demonstrated alterations in respiratory mechanics, particularly in FOT-derived resistance and reactance parameters. These abnormalities were not consistently reflected in conventional spirometric indices. Altered impedance parameters were associated with the presence and severity of sleep apnea. Static lung volumes showed no uniform spirometric pattern explaining these changes, suggesting functional rather than overt restrictive or obstructive impairment. CONCLUSION: Muscular hypertrophy characteristic of strength-based disciplines may modify respiratory system mechanics and contribute to early functional alterations that remain undetected by standard spirometry. FOT appears capable of identifying subclinical changes in airway resistance and elastic properties prior to overt spirometric abnormalities and potentially before the clinical manifestation of sleep apnea. These findings suggest a physiological trade-off between adaptation to high-intensity training and optimal respiratory function.
Read CV Szymon SiatkowskiECSS Paris 2023: CP-PN12
INTRODUCTION: Interoception, the perception of internal bodily signals, may play a key role in initiating, regulating, and maintaining physical activity. However, research on the relation between interoception and exercise mostly uses measures of interoception at rest while resting measures may not generalize to conditions under physiological load. Yet, assessment of interoception during progressive exercise remains understudied. The current study aims to address these gaps by assessing changes in interoceptive accuracy of heart rate and breathing frequency using a cardiopulmonary exercise test (CPET). As exercise intensity increases, interoceptive signals become more salient, but competing sensory and cognitive demands also increase. We therefore expect interoceptive accuracy to follow an inverted-U curve, improving from low to moderate intensities and then stabilizing or declining at high intensities. METHODS: Ninety-seven undergraduate students (63% female, age = 20.5 ± 1.4) from a human movement sciences bachelor's program at a Dutch university participated in the study. Heart rate (HR) and breathing frequency (BF) were assessed breath-by-breath during a CPET, which included one minute sitting stationary, three minutes warming-up, before workload increased. Interoceptive accuracy assessment during the CPET included estimation of HR and BF every three minutes, starting at minute one. Accuracy scores were on a scale from 0 to 1, with 1 being perfect accuracy. Two Linear Mixed Models (LMM) were specified with HR and BF interoceptive accuracy as outcome variables, continuous time as a predictor, random intercepts for each participant, and random slopes for time. RESULTS: Participants had a mean VO2max of 49.5 ± 8.1 mL/kg/min and a mean test duration of 14.9 ± 2.0 min. HR interoceptive accuracy increased progressively across timepoints from 0.79 ± 0.23 at minute one to 0.93 ± 0.07 at the end of the test, with a significant positive effect of time (b = 0.0085, SE = 0.0017, 95% CI = [0.0051, 0.0120], p < .001). BF accuracy fluctuated (minute 1: 0.58 ± 0.35; end of test: 0.67 ± 0.23) and showed no significant effect of time (b = 0.0028, SE = 0.0027, 95% CI = [-0.0025, 0.0080], p = .304). Interoceptive accuracy was significantly higher for heart rate (M = 0.861, SD = 0.078) than for breathing frequency (M = 0.602, SD = 0.237; t(85) = 9.94, p < .001). CONCLUSION: Contrary to hypotheses, interoceptive accuracy of heart rate and breathing frequency did not follow inverted-U curves during progressively increasing exercise intensities. Instead, heart rate interoceptive accuracy increased steadily throughout the CPET, approximating linear trends before plateauing toward the end of the test. In contrast, breathing frequency accuracy showed no consistent pattern and fluctuated across timepoints. These findings highlight the importance of assessing interoception during exercise rather than at rest and suggest relations between exercise intensity and interoceptive accuracy may be specific per bodily domain.
Read CV Jesper MulderECSS Paris 2023: CP-PN12
INTRODUCTION: Breathing is a critical pillar of physiological homeostasis and there is a growing public interest in breathing techniques, with trends such as mouth taping and nasal dilators. Nevertheless, the specific cardiorespiratory consequences of nasal versus oral breathing remain under-explored, particularly under environmental stressors like hypoxia and hypercapnia, which could exacerbate their physiological impact. METHODS: Twenty-three young adults participated in a randomized cross-over study. Participants performed 6-min trials of nasal, oral, and free breathing under three resting conditions: normoxia, poikilocapnic hypoxia (FiO₂ = 12%), and normoxic hypercapnia (FiCO₂ = 5%). We continuously monitored pulmonary gas exchange breath-by-breath using a metabolic cart, cardiac hemodynamics (cardiac output, heart rate, stroke volume) via impedance cardiography, and oxygen saturation (SpO₂) using pulse oximetry. Baroreflex sensitivity (BRS) and blood pressure were assessed using finger photoplethysmography and an automated cuff, respectively. RESULTS: In normoxia, breathing mode had minimal effects, though oral breathing was associated with reduced BRS compared to free breathing (P=0.04). In hypoxia, oral breathing elicited a higher respiratory frequency compared to free breathing (15.7 ± 2.8 vs 14.9 ± 2.8 breaths/min; P<0.01). Conversely, nasal breathing mitigated hypoxic tachycardia, maintaining a significantly lower heart rate compared to free breathing (70 ± 13 vs 74 ± 13 bpm; P=0.01). In hypercapnia, nasal breathing significantly reduced the metabolic cost of breathing (V̇O₂) compared to free breathing (324 ± 69 vs 360 ± 58 mL/min; P=0.02). Additionally, oral breathing in hypercapnia was associated with increased diastolic blood pressure compared to free breathing (75 ± 5 vs 72 ± 5 mmHg; P<0.01). CONCLUSION: The physiological impact of breathing mode is negligible at rest in normoxia but becomes significant under environmental stress (hypoxia/hypercapnia). Nasal breathing improves autonomic regulation and ventilatory efficiency, mitigating hypoxic tachycardia and reducing the metabolic cost of breathing in hypercapnia, whereas oral breathing alters cardiorespiratory control. These findings suggest that nasal breathing serves as a potent tool for optimizing health, enhancing cardiorespiratory stability, especially during contexts such as altitude exposure.
Read CV Tom CitherletECSS Paris 2023: CP-PN12