ECSS Paris 2023: OP-PN25
INTRODUCTION: To identify phase-specific and cumulative multi-system adaptations during stepped altitude training in elite race walkers, and to determine performance-related monitoring markers supporting individualized altitude training regulation. METHODS: Ten national-level race walkers completed an 18-week stepped altitude training program including a moderate-altitude adaptation phase (1800 m), a sub-altitude intensification phase (2500 m), and a pre-competition adjustment phase (1800 m). Blood, urine, rating of perceived exertion (RPE), body composition, dietary intake, and training load were assessed at 11 predefined time points. Relative longitudinal changes (percent) in physiological markers were analyzed as predictors of performance improvement rate (percent) using Spearman correlation. RESULTS: Adaptation responses showed clear phase dependency. During the initial 1800 m phase, immune mobilization and stress regulation were primary determinants, with lymphocyte proportion and inflammatory ratios (NLR, PLR) associated with performance improvement. During the 2500 m phase, adaptation shifted from erythrocyte quantity toward functional quality and oxygen transport efficiency, reflected by mean corpuscular hemoglobin concentration, hemoglobin density indices, and hypothalamic-pituitary-adrenal axis activation. Vitamin D2 and B-vitamin markers were positively associated with performance during mid-to-late altitude exposure. After return to 1800 m, hematological variables stabilized, and pre-competition performance was characterized by secondary reticulocyte activation, controlled inflammatory status, and low cumulative creatine kinase responses. Non-blood measures showed inverse associations between RPE variability and performance improvement, greater body mass stability in better responders, and positive associations between late-phase carbohydrate intake adjustment and performance gains. Urinary markers indicated that early optimal hydration and consistently low renal stress were linked to superior adaptation quality. CONCLUSION: Performance enhancement during stepped altitude training in elite race walking results from a coordinated multi-system adaptive process integrating immune regulation, stress control, erythrocyte functional optimization, nutritional support, and fatigue management rather than isolated erythropoietic augmentation. Superior performance outcomes are associated with achieving effective physiological mobilization at lower systemic cost, providing a framework for precision monitoring and individualized altitude training strategies.
Read CV zihong HeECSS Paris 2023: OP-PN25
INTRODUCTION: Acute hypoxia is widely reported to compromise both maximal and submaximal endurance performance,(1,2) although a large variation exists between individuals. Sex and training status have been suggested to partly explain the interindividual differences in physiological responses to hypoxia,(1,3) but research remains limited. This study investigated the effects of acute normobaric hypoxia on submaximal endurance performance and whether the physiological responses, such as blood lactate (La), peripheral oxygen saturation (SpO2), and perceived exertion, are influenced by sex or training status. In addition, we assessed whether heart rate is sufficient for monitoring exercise intensity during submaximal exercise in acute hypoxia, as athletic training monitoring often relies on lactate threshold specific heart rates determined in normoxic conditions. METHODS: Endurance trained males (n=20; Age=30 ± 5) and females (n=20; Age=27 ± 7) were recruited for the study and classified as Recreational to Trained (Tier 1-2; M=10, F=8) and Highly Trained athletes (Tier 3-4; M=8, F=12).(4) All participants performed an incremental running test in normoxia, from which VO2max and heart rates at first (HRLT1) and second lactate thresholds (HRLT2) were determined. Two running interval sessions were then completed in a randomized, single-blind study design, with participants completing 2 x 4 min at HRLT1 and 5 x 4 min at HRLT2 in normoxia (NORM) and hypoxia (HYP). Running speed, rating of perceived exertion (RPE), and SpO2 were assessed during each interval. La was collected after the second interval at HRLT1 and second and fourth interval at HRLT2. RESULTS: During the interval sessions, no significant interactions between the environment and sex or training status were detected (p>0.05). Instead, hypoxia had significant effects on running speed, La, and SpO2 (F=100.1, p<0.001; F=32.7, p<0.001; F=420.0, p<0.001), while RPE remained unaffected. Running speed and SpO2 were 6.7 ± 5.3 % and 10.2 ± 4.8 % lower throughout the hypoxic interval session in all participants, while La increased by 30.0 ± 40.0 % across HRLT1 and HRLT2. CONCLUSION: The results of the present study demonstrated comparable physiological responses to submaximal exercise in acute hypoxia between training status groups and sex. Interestingly, the observed elevation in La during the hypoxic exercise may suggest an elevated relative exercise intensity when using normoxic lactate threshold heart rates to monitor training in acute hypoxia. As such, lactate, instead of heart rate, may be a preferred training intensity monitoring method for endurance athletes in acute hypoxic conditions. REFERENCES: 1. Deb et al. 2018. DOI: 10.1080/17461391.2017.1410233 2. Faulhaber et a. 2021. DOI: 10.3390/ijerph18147573 3. Raberin et al. 2024. DOI: 10.1123/ijspp.2021-0451 4. McKay et al. 2022. DOI: 10.1007/s40279-023-01954-6
Read CV Titta KuorelahtiECSS Paris 2023: OP-PN25
INTRODUCTION: The kidney is subject to conflicting processes during adaptation to elevated altitude (diuresis and natriuresis) and environmental heat (water and sodium retention). Athletes and military personnel who are transported rapidly from lower, cooler locations to hotter, higher settings may experience reduced physical performance and increased risk of acute kidney injury (AKI). Liver fatty acid-binding protein (L-FABP) is a novel AKI marker that rises with the severity of organ injury (1) in the heat and is also released with hypoxia (2); values >12.5 ng/mL indicate increased AKI risk (1). We tested the hypothesis that, under the combined climatic challenge of increased altitude and heat, urinary L-FABP would be relatively increased. METHODS: Twenty-seven military personnel were deployed, by air then road, from sea level in the UK to increased altitude (1947 m) and heat (daytime wet bulb globe temperature, WBGT, 24.4 ± 1.98 °C) in Kenya. They were rested upon arrival (Day 0), then commenced seven days of structured, progressive acclimatisation. Fluids were taken ad libitum. Urine was sampled at rest on Day 0, 2 and 7, for measurement of specific gravity (SG) and Point-of-Care (POC) assay of L-FABP (Renischem, Tokyo). Heart rate (HR) and peripheral oxygen saturations (SpO2) were sampled and urinary measures repeated following exercise on Day 2 (50 min walking at 6 km/h, WBGT 21.5 °C) and Day 7 (100 min at 6 km/h, additional 10 kg load carriage, WBGT 24.8 °C). RESULTS: Resting urinary values did not change for SG, whereas L-FABP increased from Day 0 to Day 2 and Day 7 (1.0 [0.3, 2.1] vs 2.7 [0.7, 3.6] vs 1.8 [0.8, 4.3], P=0.002). From Day 2 to Day 7, post-exercise HR and SpO2 decreased significantly (89 ± 14 vs 77 ± 14 bpm, P<0.001, and 96 ± 2 vs 94 ± 1 %, P=0.021). Main effects of exercise were evident for SG, which increased significantly from pre-to-post (P=0.009), and for L-FABP, which showed a significant reduction (P=0.002). The impact of exercise on L-FABP was consistent with acclimatisation (P=0.836), whereas the rise in SG on Day 2 (P=0.002) was not observed on Day 7 (P=0.721), with post-exercise SG on Day 7 lower than on Day 2 (P=0.036). L-FABP did not exceed the AKI risk threshold. CONCLUSION: Short-term acclimatisation associated with increased renal stress at rest. Despite increasing duration of exercise, additional load and higher WBGT, the impact of exercise on SG diminished, suggested improved water/electrolyte handling as an adaptive mechanism. Assay of L-FABP at POC provided assurance that structured acclimatisation to altitude and thermal stress associated with a low risk of AKI. REFERENCES: 1. Goto, et al. (2025) Liver fatty acid-binding protein point-of-care testing detects heat-induced organ damage: a pilot study in Japanese male self-defense force personnel. Sci Rep, 15: 7197. 2. Katagiri D, et al. (2023) Urinary L-Type Fatty Acid-Binding Protein Predicts Oxygen Demand of COVID-19 in Initially Mild Cases. Crit Care Explor. Mar 9;5:e0873.
Read CV Thomas PalinECSS Paris 2023: OP-PN25