ECSS Paris 2023: OP-PN33
INTRODUCTION: Chronic fatigue can lead to inflammation, resulting in disruptions in tryptophan metabolism [1]. The majority of tryptophan is metabolized via the kynurenine pathway [2]. Increased kynurenine levels, observed under stress conditions, may contribute to mood deterioration and impaired psychophysiological function [1,2], significantly affecting the athletic performance of players. This study explored the potential role of tryptophan metabolites as biomarkers of fatigue in professional athletes. METHODS: Thirty male professional football players from the highest Polish league participated in the study. Blood samples were collected throughout the season: after transition (P1, P6), preparatory (P2, P7), and competitive periods of the Fall (P3–P5) and Spring Rounds (P8, P9). Tryptophan metabolites – kynurenine (KYN), 3-hydroxykynurenine (3HK), kynurenic acid (KA), xanthurenic acid (XANA), quinolinic acid (QA), picolinic acid (PA), anthranilic acid (AA), and 3-hydroxyanthranilic acid (3HAA) were quantified using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Data normality was assessed with the Shapiro-Wilk test, variance homogeneity with Levene’s test, and differences in tryptophan metabolite concentrations between different training periods were analyzed using Welch’s t-test. RESULTS: The study results indicated changes in the levels of pro-inflammatory tryptophan metabolites during the annual training cycle in football players. 3-HK levels were significantly higher during the competitive period compared to the transition period (8.4±3.2 nmol/L – P5 vs. 6.8±2.6 nmol/L – P1; p= 0.04). Similarly, QA reached its highest concentration during the competitive period and its lowest after the transition phase (157.6±57.6 nmol/L – P5 vs. 119.3±31.4 nmol/L – P1; p= 0.006). Furthermore, changes in the levels of anti-inflammatory tryptophan metabolites were observed throughout the training macrocycle. XANA concentrations were lowest at the end of the competitive period of the Fall Round (13.2±3.69 nmol/L – P5), while AA levels progressively decreased across training periods (94.0±22.6 nmol/L – P1 vs. 29.3±13.8 nmol/L – P9; p< 0.001). CONCLUSION: In conclusion, the study indicates an increase in pro-inflammatory and a decrease in anti-inflammatory tryptophan metabolites during the competitive period in football players. Elevated 3-HK and QA levels may result from intense physical exertion, contributing to fatigue. Further research is needed to confirm these associations and clarify kynurenine pathway regulation under prolonged physical effort. This study was funded by the National Science Centre, MINIATURA_7 grant no. 2023/07/X/NZ4/00199. References 1. Cervenka et al. Kynurenines: Tryptophans metabolites in exercise, inflammation, and mental health. Science. 2017;357(6349):eaaf97 2. Yamashita et al. Tryptophan circuit in fatigue: From blood to brain and cognition. Brain Res. 2017;1675:116-126.
Read CV Anna KsiążekECSS Paris 2023: OP-PN33
INTRODUCTION: An acute bout of 30 low-intensity (10% of maximal voluntary isometric contraction strength: MVC) eccentric contractions of the elbow flexors did not induce significant changes in indirect markers of muscle damage (1). However, lowering a dumbbell of 9% of MVC 1800 times resulted in significant changes in MVC, range of motion (ROM), upper arm circumference, delayed onset muscle soreness (DOMS) and plasma creatine kinase (CK) activity (2). These suggest that low-intensity eccentric contractions (LIECs) still induce muscle damage when the number of the contractions exceeds a certain level. However, the threshold number of contractions to induce muscle damage is unknown. The present study investigated how many LIECs would result in significant changes in muscle damage markers. METHODS: A pilot study to compare 30, 60, 120, 240, 480 and 960 LIECs using a dumbbell set at 10% MVC at 90o elbow flexion showed that 960 LIECs resulted in significant changes in all muscle damage markers, but no such changes by 30-480 LIECs. Thus, 52 sedentary young men performed a bout of 600, 720, 840 or 960 LIECs (n=13 per group) using their non-dominant arm consisting of many sets of six eccentric contractions per set until the total number reached to 600, 720, 840 or 960. The participants lowered a dumbbell from an elbow flexed (90°) to a fully extended position (0°) in 3 s, and the investigator removed the dumbbell at the extended position and the arm was returned to the flexed position without load. The interval was 10 s between contractions, and 2-min between sets. Changes in maximal voluntary concentric contraction torque (MVCcon), ROM, DOMS, plasma CK activity, and echo-intensity (EI) were assessed before, immediately after, 1, 2, 3, 4 and 5 days post-exercise. Changes in these variables over time were compared among the groups by a mixed-design of two-way ANOVA. RESULTS: All variables changed significantly (P<0.05) after 960 LIECs (MVCcon: –14%, ROM: –3% at 1-day post-exercise, peak DOMS: 21 mm in a 100-mm visual analogue scale, peak CK: 786 IU/L, peak EI increase: 10%), but they returned to the baseline by 3-4 days post-exercise. The 600, 720 and 840 LIECs showed a significant decreases in MVCcon and ROM at immediately post-exercise (–10 - –2%), without significant changes in DOMS, CK and EI. CONCLUSION: These results indicate that the threshold was 960 repetitions, but the magnitude of muscle damage was minor. Considering the fact that 30 maximal-intensity eccentric contractions of the elbow flexors induce large changes in the muscle damage markers (e.g., MVCcon: –49%, ROM: –11%, peak DOMS: 66 mm, peak CK: 6192 IU/L, peak EI increase: 39%) lasting for more than 10 days (3), the muscle damage etiology seems different between low-intensity and high-intensity eccentric contractions. 1. Chen et al. J Sci Med Sports 21:1068-72, 2018. 2. Nosaka et al. Med Sci Sports Exerc 34:920-7, 2002. 3. Chen et al. Appl Physiol Nutr Metab 37:680-9, 2012.
Read CV Trevor Chung-Ching ChenECSS Paris 2023: OP-PN33
INTRODUCTION: Many workers worldwide are exposed to prolonged and hazardous heat stress, physical activity, or a combination of both. Occupations such as mining, farm work, construction, and wildland firefighting involve various physical tasks that impose different degrees of metabolic, ergonomic, and cognitive stress, which can be worsened by adverse environmental conditions. The stress imposed by either the climate or the physical demands of these vocations can be dangerous, potentially limiting human productivity and performance and exacerbating pre-existing conditions like high blood pressure, obesity, and. One organ particularly at risk is the kidney. Numerous studies have documented that prolonged exposure to heat and physical activity can lead to acute kidney injury (AKI). Repeated episodes of AKI induced by such exposure have been linked to chronic kidney disease, particularly chronic kidney disease of unknown origin (CKDu). Research on effective strategies to reduce the incidence of AKI has explored various approaches, including heat acclimation, hydration and pre-cooling, and adjustments to physical work rates and durations (e.g., increasing rest periods or breaks). A novel and relatively low-cost strategy that has not been widely studied is using sodium bicarbonate (SB) to maintain hydration, and potentially improve exercise tolerance. While SB has traditionally been used in athletic settings to enhance performance, it has also been shown to increase plasma volume and reduce markers of oxidative and inflammatory stress. Given these effects, SB’s potential impact on kidney function under prolonged heat stress and physical activity merits further investigation. As such, this pilot study investigated whether SB supplementation could mitigate AKI during moderate-intensity outdoor work in a hot environment. METHODS: Fourteen healthy adults were randomized into SB or placebo (PLA) groups using a double-blind crossover design. Participants completed two experimental trials, during which they rotated through a circuit of five workstations over two hours. During the circuit, participants were encouraged to maintain a moderate intensity effort (e.g., 11 – 13 RPE (Borg 6 – 20)), and the stations consisted of digging, wheelbarrow pushing, cinderblock carry, and shoveling activities. All work was completed outdoors in the Sonoran Desert during June, with an average wet bulb globe temperature of 34.8°C. RESULTS: SB supplementation significantly increased blood bicarbonate (mean difference: 4.5 ± 0.7 mmol/L, p < 0.001) and base excess (mean difference: 4.5 ± 0.6 meq/L, p < 0.001). Core temperature increased slightly with SB compared to PLA (mean difference: 0.2 ± 0.1°C, p < 0.05), as did heart rate (mean difference: 9 ± 3 bpm, p < 0.01). However, as measured by urine-specific gravity, hydration status and fluid intake did not differ significantly between conditions (p = 0.72). No significant differences were found between SB and PLA for kidney stress markers, including IGFBP-RP1 (condition p = 0.51; time p = 0.74; interaction p = 0.87), TIMP-2 (condition p = 0.13; time p = 0.11; interaction p = 0.81), and NGAL (condition p = 0.64; time p = 0.88; interaction p = 0.54). CONCLUSION: These preliminary findings suggest that while SB improved buffering capacity, there was no influence on markers of kidney injury across the two-hour work session in the heat. This study integrated mitigation strategies (e.g., ensuring hydration, following NIOSH work-to-rest guidelines for working in the heat, etc.) that may be present in a standard work environment which could have contributed to the lack of changes in markers of kidney injury. As multiple factors contribute to the development of AKI, future research should explore the relationship between duration and intensity.
Read CV Brooke ButterickECSS Paris 2023: OP-PN33