Cutaneous stimulation at the ankle: a differential effect on proprioceptive postural control according to the participants’ preferred sensory strategy

International audienc

A soft ankle brace increases soleus Hoffman reflex amplitude but does not modify presynaptic inhibition during upright standing

International audienc

Additional file 1: of Cutaneous stimulation at the ankle: a differential effect on proprioceptive postural control according to the participants’ preferred sensory strategy

Data sets of the study. (XLSX 53 kb

Foot strike pattern and impact continuous measurements during a trail running race: proof of concept in a world-class athlete

<p>Foot strike identification has become an important topic since it may be related to injury risk and performance. Due to step variability and the influence of environmental features on running biomechanics, it is relevant to assess as many steps as possible in field conditions. Our purpose was to apply a novel simple method to assess foot strike and impact from continuous acceleration measurements over a 45 km trail running race. Three wireless tridimensional accelerometers were set on the left tibia and shoe (at the heel and metatarsals) of the current best ultratrail runner. Vertical, antero-posterior and resultant peak tibial accelerations and median frequencies were measured. Step frequency (SF) was calculated from tibial acceleration. Foot strike was quantified from the time between heel and metatarsal peak accelerations (THM). Foot strike classification was performed according to THM criteria and expressed in percentages of rearfoot, midfoot and forefoot steps. Multiple linear regressions were computed to assess relationships between the impact magnitude and slope, SF and THM. Over the first 20 km, 5530 steps were analysed. The pattern classification revealed on average 18.5% of rearfoot strike, 32.6% of midfoot strike and 48.9% of forefoot strike over the ∼82 min analysed in the runner studied. The impact magnitude for him may be related to slope, also taking into account speed, SF and landing technique. The main findings of this study were that (1) portable accelerometers make possible the assessment of foot strike and shock acceleration <i>in situ</i>, (2) the antero-posterior and resultant components of tibial acceleration should not be neglected in the measurement of stress severity, and (3) the trail running world champion presents an atypical foot strike profile.</p

Study of the Kinetics of the Determinants of Performance During a Mountain Ultramarathon: Multidisciplinary Protocol of the First Trail Scientifique de Clécy 2021

International audienceBackground 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. Objective 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. Methods 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. Results 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. Conclusions 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. International Registered Report Identifier (IRRID) RR1-10.2196/3802