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Introduction Ultra-marathon races present a prolonged cardiopulmonary physiological stress but the magnitude, persistence, and impact of race environment on respiratory function are incompletely understood. The aim of this study is to observe the effect of ultra-marathon trail races on both lung function and airway impedance. Methods Fifty-seven individuals (49/8, M/F) participated in either the Courmayeur-Champex-Chamonix (CCC ® , 101.5km), Ultra Trail du Mont-Blanc (UMTB ® , 171.5 km), or the Hong Kong 100 (HK, 100 km) races. Participant demographics were measured pre-race and included: age (40.7±10.3 yrs); height (175.5±7.1 cm), body mass (69.7±8.3 kg). Spirometry, airway impedance (via forced oscillation technique, FOT), maximal inspiratory (MIP) and expiratory pressure (MEP), and exhaled nitric oxide (ExNO) were assessed before, immediately (18–4 hours after), and 188–24 hours post-race. Mixed effects analysis with Dunnett’s post-hoc correction were conducted to evaluate the effects of race and time. Results Results demonstrated significant effects of time for: forced vital capacity (FVC), forced expiratory flow over one second (FEV 1 ), peak expiratory flow (PEF), forced expiratory flow between 25-75% (FEF25-75), forced expiratory flow at 25% and at 50% (FEF 25 and FEF 50 , respectively), MIP, MEP, airway reactance (X) at all frequencies from FOT (X 5 , X 11 , X 19 ), respiratory rate, and ExNO (all p <0.05). A significant effect of race was also observed for ExNO ( p =0.002). Discussion Findings indicate declines in lung function and airway impedance immediately after ultra-marathon races, some of which, persisted up to 24 hours post-race. Further investigations are required to better understand the etiology of changes in lung function following ultra-endurance events.

ABSTRACT Introduction Endurance exercise at altitude can increase cardiac output and pulmonary vascular pressure to levels that may exceed the stress tolerability of the alveolar–capillary unit. This study examined the effect of ultramarathon trail racing at different altitudes (ranging from <1000 m to between 1500 and 2700 m) on alveolar–capillary recruitment and lung diffusion. Methods Cardiac and lung function were examined before and after an ultramarathon in 67 runners (age: 41 ± 9 yr, body mass index: 23 ± 2 kg·m −2 , 10 females), and following 12–24 h of recovery in a subset ( n = 27). Cardiac biomarkers (cTnI and BNP) were assessed from whole blood, whereas lung fluid accumulation (comet tails), stroke volume (SV), and cardiac output ( Q ) were quantified via echocardiography. Lung diffusing capacity for carbon monoxide (DLco) and its components, alveolar membrane conductance (Dm) and capillary blood volume (Vc), were determined via a single-breath method at rest and during three stages of submaximal semirecumbent cycling (20, 30, and 40 W). Results Average race time was 25 ± 12 h. From pre- to post-race, there was an increase in cardiac biomarkers (cTnI: 0.04 ± 0.02 vs 0.13 ± 0.03 ng·mL −1 , BNP: 20 ± 2 vs 112 ± 21 pg·mL −1 ; P < 0.01) and lung comet tails (2 ± 1 vs 7 ± 6, P < 0.01), a decrease in resting and exercise SV (76 ± 2 vs 69 ± 2 mL, 40 W: 93 ± 2 vs 88 ± 2 mL; P < 0.01), and an elevation in Q at rest (4.1 ± 0.1 vs 4.6 ± 0.2 L·min −1 , P < 0.01; 40 W: 7.3 ± 0.2 vs 7.4 ± 0.3 L·min −1 , P = 0.899). Resting DLco and Vc decreased after the race ( P < 0.01), whereas Dm was unchanged ( P = 0.465); however, during the three stages of exercise, DLco, Vc, and Dm were all reduced from pre- to post-race (40 W: 36.3 ± 0.9 vs 33.0 ± 0.8 mL·min −1 ·mm Hg −1 , 83 ± 3 vs 73 ± 2 mL, 186 ± 6 vs 170 ± 7 mL·min −1 ·mm Hg −1 , respectively; P < 0.01). When corrected for alveolar volume and Q , DLco decreased from pre- to post-race ( P < 0.01), and changes in DLco were similar for all ultramarathon events ( P > 0.05). Conclusions Competing in an ultramarathon leads to a transient increase in cardiac injury biomarkers, mild lung-fluid accumulation, and impairments in lung diffusion. Reductions in DLco are predominantly caused by a reduced Vc and possible pulmonary capillary de-recruitment at rest. However, impairments in alveolar–capillary recruitment and Dm both contribute to a fall in exertional DLco following an ultramarathon. Perturbations in lung diffusion were evident across a range of event distances and varying environmental exposures.

ABSTRACT Purpose Despite a growing body of literature on the physiological responses to ultramarathon, there is a paucity of data in females. This study assessed the female physiological response to ultramarathon and compared the frequency of perturbations to a group of race- and time-matched males. Methods Data were collected from 53 contestants of an ultramarathon trail race at the Ultra-Trail du Mont-Blanc (UTMB®) in 2018/19. Before and within 2 h of the finish, participants underwent physiological assessments, including blood sampling for biomarkers (creatine kinase–MB isoenzyme [CK-MB], cardiac troponin I [cTnI], brain natriuretic peptide [BNP], and creatinine [Cr]), pulmonary function testing (spirometry, exhaled NO, diffusing capacities, and mouth pressures), and transthoracic ultrasound (lung comet tails, cardiac function). Data from eight female finishers (age = 36.6 ± 6.9 yr; finish time = 30:57 ± 11:36 h:min) were compared with a group of eight time-matched males (age = 40.3 ± 8.3 yr; finish time = 30:46 ± 10:32 h:min). Results Females exhibited significant pre- to postrace increases in BNP (25.8 ± 14.6 vs 140.9 ± 102.7 pg·mL −1 ; P = 0.007) and CK-MB (3.3 ± 2.4 vs 74.6 ± 49.6 IU·L −1 ; P = 0.005), whereas males exhibited significant pre- to postrace increases in BNP (26.6 ± 17.5 vs 96.4 ± 51.9 pg·mL −1 ; P = 0.002), CK-MB (7.2 ± 3.9 vs 108.8 ± 37.4 IU·L −1 ; P = 0.002), and Cr (1.06 ± 0.19 vs 1.23 ± 0.24 mg·dL −1 ; P = 0.028). Lung function declined in both groups, but males exhibited additional reductions in lung diffusing capacities (DL CO = 34.4 ± 5.7 vs 29.2 ± 6.9 mL⋅min −1 ⋅mm Hg −1 , P = 0.004; DL NO = 179.1 ± 26.2 vs 152.8 ± 33.4 mL⋅min −1 ⋅mm Hg −1 , P = 0.002) and pulmonary capillary blood volumes (77.4 ± 16.7 vs 57.3 ± 16.1 mL; P = 0.002). Males, but not females, exhibited evidence of mild postrace pulmonary edema. Pooled effect sizes for within-group pre- to postrace changes, for all variables, were generally larger in males versus females ( d = 0.86 vs 0.63). Conclusions Ultramarathon negatively affects a range of physiological functions but generally evokes more frequent perturbations, with larger effect sizes, in males compared to females with similar race performances.

Background Exercise tolerance is strongly related the physiological components of the primary (PC) and slow components (SC) of oxygen uptake. Exercise tolerance is reduced in clinical populations and during acute exposure to altitude by factors affecting skeletal muscle oxygenation. The practice of ischemic preconditioning has been shown to improve exercise tolerance or performance in a variety of different testing methods, but the mechanisms behind the improvements in exercise tolerance following IPC are still unclear. Methods Thirteen men (age= 24 ± 4 years, V̇O 2 max= 63.1 ± 5.1 ml·kg −1 ·min −1 ) completed four randomized trials of each combination of hypoxia (F I O 2 = 0.16) or normoxia (F I O 2 = 0.21) with a resting pre‐exercise IPC protocol (4 × 5 min at 220 mmHg) or SHAM procedure. Following the IPC/SHAM protocol subjects completed two constant load cycling bouts at power outputs corresponding to 1) 15% below the normoxic gas exchange threshold (CL #1) and 2) 85% of normoxic V̇O 2 max (CL #2). Breath‐by‐breath V̇O 2 , oxyhemoglobin saturation, and skeletal muscle oxygenation/extraction (measured via near‐infrared spectroscopy) were continuously monitored throughout the trials. V̇O 2 and NIRS kinetics were quantified using a single (for CL#1) or double (for CL#2) exponential term equation with independent time delays for the V̇O 2 /NIRS primary and slow components. Results There was a significant effect of inspirate on deoxyhemoglobin time constant (τ) during CL#1 (Hypoxia: 5.58 ± 2.82 s vs. Normoxia: 8.01 ± 4.71s, P < 0.05) with no effect of IPC treatment (P = 0.84). During CL #2, there was a significant effect of inspirate on V̇O 2 primary amplitude (PC) (Normoxia: 3.13 ± 0.36 L/min vs. Hypoxia: 2.92 ± 0.39 L/min, P < 0.05). IPC did preserve microvascular oxygen extraction during high‐intensity cycling (CL #2) in Hypoxia (IPC: 21.3 ± 11.0 μM vs. SHAM: 19.9 ± 9.9 μM, P < 0.05), but did not affect any of the NIRS or V̇O 2 parameters in Normoxia. Conclusion Oxygen uptake and peripheral oxygen delivery are compromised during high‐intensity exercise in hypoxia. Ischemic preconditioning prior to high‐intensity bouts is effective at mitigating the declines in microvascular oxygen extraction seen during exercise in hypoxia, however the rates (τ) of microvascular extraction and oxygen uptake are not altered following treatment with IPC. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Environmental stressors, such as heat or altitude, elicit dissimilar physiological adaptations to endurance training programs. Whether these differences (i.e., increased hemoglobin mass vs plasma volume) differentially influence performance is debated. We review data in support of our novel hypothesis, which proposes altitude as the preferred environmental training stimulus for elite endurance athletes preparing to compete in temperate, sea-level climates (5°C–18°C).

ABSTRACT Introduction An adequate increase in minute ventilation to defend arterial oxyhemoglobin saturation (SpO 2 ) during hypoxic exercise is commonly viewed as an important factor contributing to large inter-individual variations in the degree of exercise performance impairment in hypoxia. Although the hypoxic ventilatory response (HVR) could provide insight into the underpinnings of such impairments, it is typically measured at rest under isocapnic conditions. Thus, we aimed to determine whether 1) HVR at rest and during exercise are similar and 2) exercise HVR is related to the degree of impairment in cycling time trial (TT) performance from normoxia to acute hypoxia (∆TT). Methods Sixteen endurance-trained men (V˙O 2peak , 62.5 ± 5.8 mL·kg −1 ·min −1 ) performed two poikilocapnic HVR tests: one during seated rest (HVR REST ) and another during submaximal cycling (HVR EX ). On two separate visits, subjects ( n = 12) performed a 10-km cycling TT while breathing either room air (F i O 2 = 0.21) or hypoxic gas mixture (F i O 2 = 0.16) in a randomized order. Results HVR EX was significantly ( P < 0.001) greater than HVR REST (1.52 ± 0.47 and 0.22 ± 0.13 L·min −1 ·%SpO 2 −1 , respectively), and these measures were not correlated ( r = −0.16, P = 0.57). ∆TT was not correlated with HVR REST ( P = 0.70) or HVR EX ( P = 0.54), but differences in ventilation and end-tidal CO 2 between hypoxic and normoxic TT and the ventilatory equivalent for CO 2 during normoxic TT explained ~85% of the variance in performance impairment in acute hypoxia ( P < 0.01). Conclusion We conclude that 1) HVR is not an appropriate measure to predict the exercise ventilatory response or performance impairments in acute hypoxia and 2) an adequate and metabolically matched increase in exercise ventilation, but not the gain in the ventilatory response to hypoxia, is essential for mitigating hypoxia-induced impairments in endurance cycling performance.