ECSS Paris 2023: OP-PN15
INTRODUCTION: While ultra-endurance sports are growing in popularity, the prerequisites for successful participation and adaptation to such training remain vague. The aim of the study was to compare physiological profile between ultra-distance runners and long-distance runners. METHODS: Road runners competing in 24-h races (ULTRAs, n=13) or distances 10 km to marathon (LDRs, n=12) arrived to the laboratory in an overnight fasted condition and performed resting metabolic rate measurement followed by oral glucose tolerance test. Anthropometric, muscle and tendon ultrasonography as well as muscle force and power tests were then conducted, after which athletes performed a progressive 4-min step treadmill test to exhaustion to assess the lactate curve, heart rate response, running economy, and fat oxidation, as well as to determine maximal oxygen uptake (VO₂max). Additionally, blood volume, plasma volume and total hemoglobin (Hb) mass were measured using the CO rebreathing. RESULTS: Despite being of similar competitive level (personal bests for IAAF scores), age, training experience and body weight (p>0.05 for all), ULTRAs had more body fat (mainly due to larger upper body skinfold thickness, p<0.001), even if they had been training by substantially larger volume in terms of distance run and hours spent training (p<0.01 for both). Both absolute and relative to body weight plasma volume (p<0.01) and blood volume (p<0.05) were larger in LDRs, while Hb concentration, total Hb mass and Hb mass per body weight did not differ between the groups (p>0.05 for all). Resting metabolic rate was similar and relative fat oxidation identical between the groups. There were no obvious differences in glucose handling and associated lactate disposal rate between the groups during oral glucose tolerance test. Heart rate and lactate response to exercise were the same for the two groups, while maximal oxygen uptake was larger in LDRs (66.7 (5.1) vs. 59.1 (6.4) ml/kg/min, p=0.004). In our conditions, neither maximal fat oxidation rate, nor the associated running speed differ between ULTRAs and LDRs. Running economy was comparable between the groups (206 (19) and 214 (22) ml/kg/km in ULTRAs and LDRs, respectively, p=0.347). Contractile properties of knee extensors and muscle power measured as different vertical jump parameters did not differ between the groups. Achilles tendon and calf muscle structural properties as well as passive stiffness of plantar flexors were also similar between the groups. CONCLUSION: Ultra-distance runners exhibit largely similar physiological profile as long-distance runners, but do not have that large maximal oxygen uptake, at least to some extent due lower total blood volume and higher percentage of upper body fat.
Read CV Tomas VenckunasECSS Paris 2023: OP-PN15
INTRODUCTION: Ultramarathon events represent an extreme challenge for the human body and its physiological systems. Their impact on the red blood cell (RBC) system is underexplored and in particular changes in RBC deformability and aggregation, both critical for blood flow in the microcirculation, remain poorly understood. Additionally, the role of modifiers such as nitric oxide (NO) metabolism in these processes has not been fully elucidated. This study aimed to investigate changes in hematological and hemorheological parameters, as well as markers of the NO pathway, during a 230 km non-stop ultramarathon. METHODS: Twelve participants (3f/8m; 48±8 years, 71±14 kg, 176.7±8.1 cm) finished the ultramarathon race. Blood samples were taken before and 5 minutes after the race and parameters were either analyzed immediately or processed and frozen at the appropriate temperature until measurement. Data were tested for normal distribution using the Shapiro-Wilk test and pre-post differences were calculated using either the paired t-test or the Wilcoxon matched-pairs signed rank test. RESULTS: Results revealed significant changes in RBC properties post-race. The osmoscan curve, representing deformability under an osmotic gradient, showed a distinct left-shift (p<0.001) and the mean cellular volume (p<0.001) and intracellular water content (p=0.08) both decreased, while the mean cellular hemoglobin concentration increased (p<0.01). These findings might be related to dehydration which causes cell shrinkage, mimicking increased fragility. However, haptoglobin levels and RBC count were not significantly altered which might indicate that cell lysis might not acutely be relevant in this setting. RBC deformability, measured using ektacytometry, increased (p<0.05) and correlated moderately with elevated RBC nitrite levels (r=0.41, p<0.001), suggesting a shear stress-dependent activation of NO production and its positive influence on deformation. RBC aggregation, obtained from a syllectogram, increased (p<0.001), and the time to half-maximal aggregation was reduced (p<0.001). These changes were independent of hemoconcentration, as hematocrit remained unaltered post race. Levels of free reactive oxygen and nitrogen species (ROS/RNS) and S-nitrosylation of RBC cytoskeletal spectrins decreased significantly (p<0.05), raising questions about the interplay between oxidative stress and NO metabolism. Remaining hematological variables remained unaltered. CONCLUSION: In summary, the data indicate that ultramarathon participation exerts profound effects on RBC properties and its potential effect on microcirculatory blood flow. This study thus contributes to understanding the hemorheological adaptations to extreme endurance challenges and underscores the need for longitudinal studies to evaluate their long-term impact on RBC properties.
Read CV Marijke GrauECSS Paris 2023: OP-PN15
INTRODUCTION: The relation between muscle fatigue and marathon running is well established [1], but not all individuals respond to it in the same way. Overall fatigue, muscle fatigue, and muscle soreness are commonly experienced by marathoners. This analysis aimed to observe whether perceived overall muscle fatigue and soreness ratings over 8 weeks would differ in marathoners responding or not to a muscle fatigue protocol. METHODS: Data from 17 habitual marathoners (15 males, aged: 38±12 y, height: 1.81±0.09 m, weight: 70±9 kg, VO2max: 64±12 ml/kg/min) were analyzed. Training workload was measured using a chest strap. HR was used to compute total TRIMP (tTRIMP), composed of anaerobic TRIMP (anTRIMP) and aerobic TRIMP (aTRIMP), where (aTRIMP = z1+z2; anTRIMP = z3+z4+ z5). Runners kept a diary where they self-reported on a 0 to 10 scale overall fatigue, muscle fatigue and soreness every morning, evening, and before and after each training. Prior to the 8-week observation period (W38-45), they visited our laboratory twice for VO2max and muscle fatiguability tests. The fatiguability tests consisted of a 10-minute baseline submax run and baseline maximal voluntary contractions (MVCs), then 100 drop jumps from a 40 cm height step with a 20-second rest between each jump, followed by an isometric contraction to muscle failure at 30% MVC output. This fatigue protocol was immediately followed by post-MVCs and a 10-minute run at the same speed as baseline. RESULTS: Runners were divided into responders (R) who showed an MVC drop ≥20% and non-responders (NR) who did not. Pre- and post-fatigue MVCs, as well as pre- post-fatigue submax run HR, differ between R and NR (ΔMVC for R was -38%, and for NR=-2%, ΔHR for R was 10 bpm and for NR 4 bpm). During the 8 weeks a difference was found between the R and NR groups in overall fatigue ratings (F(1,382)=10.34, p<0.001); once followed-up it revealed differences at: W40 F(1,53)=4.88 p<0.05; W42 F(1,53)=4.27 p<0.05; W43 F(1,51)=7.01 p<0.011. Muscle soreness ratings showed a significant effect of group R vs. NR (F(1,382)=9.89 p=0,002); when followed up, there were not significant effects. Muscle fatigue ratings showed a significant difference between R and NR (F(1,382) =20.43 p<0.05), and follow-up showed differences at W38, W40, and W43 (F(1,41)=7.29 p=0.01; F(1,53)=9.91 p=0.003; F(1,51)=4.57 p<0.05). Overall (r=0.40, r =0.26, p<0.001), muscle fatigue (r=0.40, r =0.37, p<0.001), and muscle soreness ratings (r=0.40, r =0.24, p<0.001) significantly (within-subject) correlated with tTRIMP and anTRIMP, but not with aTRIMP. CONCLUSION: This study confirms that not all athletes respond to muscle fatigue equally. Interestingly, those who did not respond in the lab had higher overall fatigue and muscle fatigue ratings in training, while muscle soreness did not differ from responders. Future studies should investigate the reasons behind these differences and whether they differ in competition results. 1. Del Coso et al., (2017)
Read CV Matteo FerroECSS Paris 2023: OP-PN15