BACKGROUND:Ultra-trail running is increasingly popular, yet most research on biomechanics focuses on road running or treadmills. This study assesses changes in foot strike pattern (FSP), step frequency, and other biomechanical parameters over a 156-km ultra-trail race. METHODS:Fifty-five experienced runners participated in the Trail Scientifique de Clécy, a 156-km race with 6000 meters of elevation gain. Biomechanical data were collected at the end of each 26-km lap using video for FSP and Optojump for other parameters. Muscle strength was measured via maximal voluntary isometric contraction (MVIC) of the hip abductors and ankle plantar flexors. RESULTS:Forty-one runners completed the race. FSP remained consistent. Step frequency decreased initially (P=0.003) before stabilizing. Self-selected speed declined by 14.2% (P<0.001), and step length reduced by 12.6% (P<0.001). Ground contact time increased (+12.9%, P<0.001), while flight time remained stable. Leg stiffness showed a non-significant decreasing trend (P=0.048). MVIC for hip abductors and ankle plantar flexors slightly decreased late in the race (P=0.015 and P=0.004). CONCLUSIONS:Experienced ultra-trail runners maintain consistent FSP while strategically adapting other biomechanical parameters to manage fatigue, supporting sustained performance and injury prevention in ultra-endurance races.

AIMS:Participation in outdoor cold-water swimming (OCWS) events combines endurance exercise and cold exposure. Concerns have emerged about the potential risk of acute adverse cardiac events during OCWS, particularly during endurance events. We analysed the effect of prolonged OCWS on cardiac function in trained athletes. METHODS:The swimming event consisted of laps over a 1000-m course, for up to 6 h, in water at 15 °C. Twenty participants (11 males, 47.3 ± 8.6 years old) were included. Core temperature (Tcore) was monitored using an ingestible temperature sensor during and up to 1 h after the swim. Body composition, blood pressure, electrocardiogram (ECG), and transthoracic echocardiography were assessed 1 day before the event and within the first hour upon completion of the swim. RESULTS:Mean body mass index was 27.1 ± 5.1 kg/m2 and fat mass was 25.2 ± 9.1 %. Mean duration of swimming was 214 ± 115 min. Minimum Tcore was 35.6 ± 1.3 °C. A significant lengthening of the QT interval corrected (QTc) for heart rate was observed post-exercise (437.7 ± 27.7 vs. 457.2 ± 35.9 ms, p = 0.012), with 5 participants exhibiting post-exercise QTc >500ms. OCWS did not alter the biventricular systolic function and left ventricular relaxation. No correlation was observed between ΔQTc and ΔTcore. CONCLUSION:OCWS seemed to acutely delay post-exercise cardiac repolarization without alteration of cardiac function in a healthy trained population. Additional investigations would be warranted to explore the clinical implications of QT lengthening and its relationship with autonomic nervous system regulation during OCWS.

Pre-participation screening and management of congenital cardiac valvulopathy in competitive athletes can be challenging, particularly within the context of ultra-endurance disciplines. A 55-year-old female athlete without a reported history of cardiac disease exhibited clinical signs of cardiogenic pulmonary edema during a 156 km ultra-trail race. The echocardiographic assessment revealed the presence of a parachute mitral valve, with no evidence of mitral stenosis or regurgitation at rest, but it demonstrated severe dynamic mitral stenosis during exercise. In competitive athletes, the detection of rare valvulopathy should prompt a comprehensive cardiac evaluation aimed at assessing the potential for dynamic valvular dysfunction.

AbstractAcute kidneys injuries (AKIs) have been described in marathon and trail running. The currently available data allows assessment of before/after comparisons but does not allow an analysis of what happens during the race. A multidisciplinary assessment protocol was performed during the first trail of Clécy (Normandy France) in November 2021. This allowed an initial assay to be carried out, then at the end of each of the 6 loops of 26 km, and finally after 24 h of recovery. The race extends over 156 km in hilly terrain and 6000 m of elevation gain (D+). The level of impairment according to the RIFLE classification was defined for each runner at each assay. Fifty‐five runners were at the start, and the per protocol analysis involved 36 runners (27 men and 9 women, 26 finishers). Fifteen (41.7%) of the riders presented at least one result corresponding to a “RIFLE risk” level. After 24 h of rest, only one runner still had a “RIFLE Risk”. The distance around the marathon seems to be the moment of greatest risk. For the first time, we find an association between this renal risk and the probability of abandonment. Many runners are vulnerable to kidney damage during long‐duration exercise, which is why it's important to limit risk situations, such as the use of potentially toxic drugs or hydration disorders. The consumption of NSAIDs (nonsteroidal anti‐inflammatory drugs) before or during an ultra‐distance race should therefore be prohibited. Attention should be paid to hydration disorders.

Ultra-trail running races pose appreciable physiological challenges, particularly for glucose metabolism. Previous studies that yielded divergent results only measured glycaemia at isolated times. We aimed to explore the impact of an ultra-endurance race on continuously measured glycaemia and to understand potential physiological mechanisms, as well as the consequences for performance and behavioural alertness. Fifty-five athletes (78

This study aimed to assess the longitudinal changes in triceps surae muscle-tendon architecture during a mountain ultramarathon. Experienced trail runners [n = 55, 78% men, age: 45.2 (13.5) yr] participated in a 156-km trail run (6,000 m climbing) consisting of six 26-km laps. The resting architectural properties of triceps surae muscle-tendon were measured using ultrasound imaging for Achilles tendon cross-sectional area (AT CSA), medial gastrocnemius muscle pennation angle, thickness, length, and fiber length. Measurements were performed the day before the race (baseline), at 52 km (T1), at 104 km (T2), at 156 km (T3), and 12 h after the race (H12). Among finishers (n = 41), there was a significant biphasic change in AT CSA during the race (P = 0.001). First, a significant decrease in AT CSA occurred between baseline and T1 (P = 0.006), with a greater decrease for participants averaging speed >8 km/h (P = 0.014). Second, there was a significant increase in AT CSA especially between T2 and T3 (P = 0.006) that was correlated with a decrease in average speed (P = 0.001) and alteration of spaciotemporal running parameters (P < 0.05). Changes in muscle-tendon architecture were not significantly different between finishers (n = 41) and nonfinishers (n = 14). In 47 participants (85.5%) who completed the follow-up, AT CSA at H12 was greater compared with baseline (P = 0.010). The main finding is the significant and biphasic modification of the AT CSA during a 156-km mountain ultramarathon with an initial decrease corresponding to mechanical stress followed by a secondary increase suggesting adaptive mechanotransduction persisting after 12 h. NEW & NOTEWORTHY Achilles tendon cross-sectional area (AT CSA) demonstrated significant adaptive modifications during a 156 km mountain ultramarathon in trained athletes. Initially, a decrease in AT CSA, especially at higher running speeds, is consecutive to the biomechanical stress on the plantar flexor muscle-tendon unit (MTU). Subsequently, there is a significant increase in AT CSA persisting up to 12 h after the race, which likely corresponds to an adaptive process to limit the compressive and tensile load on the tendon.

PURPOSE:To assess the factors associated with continued cooling duration of core temperature (Tcore°) after prolonged outdoor cold-water swimming.METHODS:We designed a cohort study among swimmers participating in an outdoor cold-water swim during qualifying for the English Channel Swim. The day before the event, the participants completed a demographic questionnaire, and body composition was measured using bioelectrical impedance analysis (mBCA 525, Seca). The swimming event consisted of laps over a 1000-m course, for up to 6 hours, in water at 12.5 to 13 °C. Tcore° was measured using an ingestible temperature sensor (e-Celsius, BodyCap) during and up to 1 hour after the swim.RESULTS:A total of 14 participants (38 [11] y; N = 14, n = 11 males, n = 8 in swimming costume and n = 6 in wetsuit) were included. Before swimming, Tcore° was 37.54 (0.39) °C. The participants swam for an average of 194.00 (101.94) minutes, and mean Tcore° when exiting the water was 35.21 (1.30) °C. The duration of continued cooling was 25 (17) minutes with a minimum Tcore° of 34.66 (1.26) °C. Higher body mass index (r = .595, P = .032) and fat mass (r = .655, P = .015) were associated with longer continued cooling, independent of wetsuit wear. Also, the rate of Tcore° drop during swimming (-1.22 [1.27] °C/h) was negatively correlated with the rate of Tcore° gain after swimming (+1.65 [1.23] °C/h, r = -.682, P = .007).CONCLUSION:Increased body mass index and fat mass were associated with Tcore° continued cooling duration after prolonged outdoor cold-water swimming at 12.5 to 13 °C. The rate of Tcore° drop during swimming was negatively correlated with the rate of rewarming.

Depuis les années 60, il a été établi que le rythme endogène de l’horloge circadienne était d’environ 24,5 h en l’absence de tout donneur de temps. L’objectif de notre étude est de déterminer si un groupe de personne vivant hors du temps présentera le même rythme que précédemment observé et si ce groupe se synchronisera socialement ou non. Pendant 40 jours, 14 personnes (7 ♀ et 7 ♂) ont vécu isolés dans une grotte sans aucunes informations temporelles. Leurs cycles veille/sommeil ont été enregistrés en continue grâce à un actimètre (MotionWatch R, CamNTech®) 14 jours en dehors de la grotte (Pré), dans la grotte (Per) et 14 jours à la sortie de la grotte (Post). La température corporelle a été mesurée par une gélule électronique ingérable (eCelsius Performance, BodyCAP®). Pendant 40 jours, on enregistre en moyenne 29,25 ± 2,56 cycles veille/sommeil avec une durée moyenne de 31,7 h ± 8,0 par cycle (aucune différence entre les sexes). Le ratio temps de sommeil sur temps de veille reste similaire pour les 3 conditions Per-Pre-Post (35,9 %). Aucune synchronisation sociale n’est observée au sein du groupe. Les cycles de température sont tout d’abord désynchronisés des cycles veille/sommeil puis se synchronisent en fin de protocole sur une période de 30,25 h ± 6,14. Nous montrons pour la première fois que les personnes préfèrent suivre leur propre rythme interne plutôt que de se synchroniser au groupe lorsqu’elles sont isolées de toutes contraintes externes. La durée des cycles augmente sans pour autant changer le ratio veille/sommeil nécessaire à une bonne récupération.

Introduction: Spaceflight simulation studies like confinement in small volume habitat with limited physical activity have reported even after 60 days an abnormal arterial wall adaptation with increase thickness or stiffness. The purpose of the current study was to determine the effects on blood vessel and organ structure of 40 days of isolation in a huge habitat with intensive physical activity.Method: Data were collected from 14 individuals (7 male) who isolated in a cavern for 40-days while performing normal daily activities without time references. Ultrasound assessments were performed pre- and post-isolation using a teleoperated system with eight different acoustic windows to obtain 19 measurements on 12 different organ/vascular structures which included the common carotid artery, femoral artery, tibial artery, jugular vein, portal vein, bile duct, kidney, pancreas, abdominal aorta, cervical and lumbar vertebral distance, and Achilles tendon.Results: Common carotid artery measures, including the intima media thickness, stiffness index, and the index of reflectivity measured from the radiofrequency signal, were not changed with isolation. Similarly, no differences were found for femoral artery measurements or measurements of any of the other organs/vessels assessed. There were no sex differences for any of the assessments.Discussion: Results from this study indicate a lack of physiological effects of 40-days of isolation in a cavern, contrary to what observed in previous 60 days confinement. This suggests a potential protective effect of sustained physical activity, or reduced environmental stress inside the huge volume of the confined facility.

La privation de sommeil est un problème majeur chez les coureurs d’ultratrail. La majorité passe deux nuits sur le parcours, certains optant pour des siestes pendant la course, bien que les bénéfices soient très peu étudiés. Pour la première fois, nous avons pu enregistrer les siestes en polysomnographie et déterminer leur impact sur leur performance. Au total, 55 coureurs ont participé au Trail scientifique de Clécy, organisé en 6 boucles identiques de 26 kms et 1000 m D+ chacune, autour d’un centre scientifique. Les nuits pré et post course, ainsi que les siestes, ont été enregistrées avec un appareil de polysomnographie (SomFit, Compumedics®). Au total, 17 coureurs ont effectué des siestes, dont 11 étaient des « Finishers (F) » et 6 étaient des « non-Finishers (NF) ». Le temps de course diffère significativement entre les siesteurs (30,36 ± 5,05 h) et les non-siesteurs (25,22 ± 4,34 h, p < 0,005). Les siestes sont effectuées majoritairement entre 3 et 7 h et entre 13 et 14 h. Les F siestaient significativement moins longtemps que les NF (35,8 ± 7,8 min et 50,6 ± 15,8 min respectivement, p = 0,05), sans influence du temps passé dans la course. La répartition moyenne des stades de sommeil est comme suit : S1 = 0,3 %, S2 = 32,3 %, S3 = 3,6 %, REM = 0 %, éveil = 56,9 %, sans différence significative entre les F et les NF. Les données de pré et post course sont en cours d’analyses. Les siestes ne permettent pas de réduire le temps de course. Toutefois elles sont nécessaires aux coureurs de mi et fin-peloton afin de finir la course, contrairement à ceux de l’avant du peloton qui n’ont passé qu’une nuit en privation de sommeil.

Abstract Hingrand, C, Olivier, N, Combes, A, Bensaid, S, and Daussin, FN. Power is more relevant than ascensional speed to determine metabolic demand at different gradient slopes during running. J Strength Cond Res 37(11): 2298–2301, 2023—Trail running is characterized by successive uphill and downhill running sessions. To prescribe training intensity, an assessment of maximal running capacity is required. This study compared 2 uphill incremental tests using the same ascensional speed increment to identify the influence of the slope gradient on performance. Ten subjects (8 men and 2 women) performed 3 incremental exercises on various slope (1%: IT01, 10%: IT10, and 25%: IT25), and the ascensional speed increment was similar between IT10 and IT25 (100 m·h−1 every minute). Gas exchanges, heart rate, and power were monitored continuously during the tests. Similar V̇o 2max levels were observed in the 3 conditions: 68.7 ± 6.2 for IT01, 70.1 ± 7.3 for IT10, and 67.6 ± 7.0 for IT25. A greater maximal ascensional speed was reached in the IT25 (1760 ± 190 vs. 1,330 ± 106 for IT25 and IT10, respectively, p < 0.01). A significant relationship was observed between relative V̇o 2 levels and relative power without any effect of slope. Power should be the parameter used for prescribing training intensity compared with ascensional speed in trail.

The analysis of trail-running performance appears to be complex and cardio-respiratory and muscular factors could have a variable importance depending on the inclination. Our study aims to determine the role of these parameters in performance. 13 subjects with heterogeneous levels participated in the study. They carried out 7 visits including 3 maximal aerobic speed (MAS) test at 1, 10 and 25 reached at 1, 10 and 25 speeds (60-180-240 °/s). Gas exchange measured during the incremental tests. We were able to identify 2 groups, a performance and a recreational group. We observe a difference in VO2max, MAS at 1 and 10 maximal aerobic ascensional speed (MAaS) at 25 difference in VO2max and exhaustion time at 100 conditions (1-10-25 parameters, expressed as absolute or relative values, are similar between conditions (10-25 suggests that the measurement of ascensional speed is not as relevant as heart rate for controlling intensity given the variety of slope gradients in trail-running races.

The growing interest of the scientific community in trail running has highlighted the acute effects of practice at the time of these races on isolated aspects of physiological and structural systems; biological, physiological, cognitive, and muscular functions; and the psychological state of athletes. However, no integrative study has been conducted under these conditions with so many participants and monitoring of pre-, per-, and postrace variables for up to 10 days over a distance close to 100 miles. The aim of this study was to evaluate the kinetics of the performance parameters during a 156 km trail run and 6000 m of elevation gain in pre-, per-, and postrace conditions. The general hypothesis is based on significant alterations in the psychological, physiological, mechanical, biological, and cognitive parameters. The Trail Scientifique de Clécy took place on November 11, 2021. This prospective experimental study provides a comprehensive exploration of the constraints and adaptations of psychophysiological and sociological variables assessed in real race conditions during a trail running of 156 km on hilly ground and 6000 m of elevation gain (D+). The study protocol allowed for repeatability of study measurements under the same experimental conditions during the race, with the race being divided into 6 identical loops of 26 km and 1000 m D+. Measurements were conducted the day before and the morning of the race, at the end of each lap, after a pit stop, and up to 10 days after the race. A total of 55 participants were included, 43 (78%) men and 12 (22%) women, who were experienced in ultra–trail-running events and with no contraindications to the practice of this sport. The launch of the study was authorized on October 26, 2021, under the trial number 21-0166 after a favorable opinion from the Comité de Protection des Personnes Ouest III (21.09.61/SIRIPH 2G 21.01586.000009). Of the 55 runners enrolled, 41 (75%) completed the race and 14 (25%) dropped out for various reasons, including gastric problems, hypothermia, fatigue, and musculoskeletal injuries. All the measurements for each team were completed in full. The race times (ie, excluding the measurements) ranged from 17.8206 hours for the first runner to 35.9225 hours for the last runner. The average time to complete all measurements for each lap was 64 (SD 3) minutes. The Trail Scientifique de Clécy, by its protocol, allowed for a multidisciplinary approach to the discipline. This approach will allow for the explanation of the studied parameters in relation to each other and observation of the systems of dependence and independence. The initial results are expected in June 2022. RR1-10.2196/38027

Les protocoles de Michel Siffre entre 1962 et 1999, ont permis de mettre en évidence la composante endogène de l’horloge biologique en condition d’isolement temporel en solitaire. L’objectif de cette étude était de suivre les principaux marqueurs de la chronobiologie afin d’observer les effets des interactions sociales d’un groupe de 15 personnes sur leurs rythmes circadiens. Adaptation Institute présidé par Christian Clot a dirigé une mission scientifique : DeepTime (https://www.deeptime.fr) entre mars et avril 2021. 15 volontaires, se sont isolés de tout repère temporel dans la grotte de Lombrives en Arriège pendant une durée de 40 jours. Afin de suivre les principaux marqueurs de la chronobiologie, le rythme vieille sommeil, le rythme de la température centrale, le rythme des principales hormones ainsi que la structure du sommeil ont été enregistrés pendant toute la durée de la mission. L’analyse du rythme veille sommeil montre que tous les sujets se sont rapidement désynchronisés avec des cycles systématiquement supérieurs à 24 h. Au total entre 27 et 36 cycles ont été enregistrés sur 40 jours. Bien que la durée des cycles soient très instables, le ratio temps d’éveil sur temps de sommeil varie assez peu en fonction de la longueur des cycles. Le groupe entier ne s’est pas collectivement synchronisé sur le même rythme veille/sommeil. Concernant l’étude des rythmes biologiques, les premiers résultats montrent que ce groupe n’a pas réussi à se synchroniser sur un rythme commun.