Inria launches an unprecedented data measurement experiment at the heart of the Moroccan desert

XtremLog - Capteurs dans le désert Ep4 Guillaume Chelius - © Inria

This year, the SULTAN MARATHON DES SABLES will welcome a new kind of runner. Guillaume Chelius, a junior research scientist in Inria’s DNET team and an ultra-marathon runner, will run 250 km over 7 days, kitted out with 16 sensors, which will, in real time and without any human intervention, measure numerous physiological, biomechanical and environmental variables. Once they have been sorted and analysed, the resulting data can be used to model the race and study the body’s movements, its performance levels, and the ways in which it adapts to the environment, weather conditions and fatigue.

X-Trem-Log: an unprecedented experiment tackling a threefold challenge

The X-Trem Log project is a first. As Guillaume Chelius explains, «No measurement experiment has ever been conducted like the one Inria will be conducting at the 25th SULTAN MARATHON DES SABLES. Other studies have already taken place, but they concerned a single physiological factor or were conducted over a short period. This time, many different parameters will be recorded simultaneously over a long period.»
In order to make a success of this experiment, the DNET research team, as well as the DEMAR team and engineers from the Inria experimentation and development department, have pooled their expertise to tackle three major challenges:

A technological challenge linked to the implementation of a wireless measurement system, which must be both ergonomic and high-performance, given the uncontrolled weather conditions and the long duration of the experiment. Furthermore, the sensors must have a long battery life and the equipment must be robust. Alone in the desert with no technical team around him, the runner will not be able to maintain the equipment or change the sensor batteries in the event of a failure.

A scientific challenge, due to the large quantity of data being recorded in complex conditions which make collection difficult. These data must then be analysed, segmented and classified in order to apply movement reconstruction and analysis algorithms.

A technical challenge due to the need to synchronise the data recorded. As they do not have the same temporal reference system, the sensors must be synchronised through radio communication between them. What is more, this need for constant synchronisation leads to additional energy consumption, which requires specific algorithms and analysis methods to be developed to reduce the amount of energy used. The miniaturisation of the sensors and the measurement architecture also constitute a real challenge in themselves, in terms of both ergonomics and robustness

Finally, it was also necessary to design light, non-intrusive equipment so as not to hinder the runner’s strides and movements. Salomon, a partner of the X-Trem Log project, has therefore developed a bespoke running outfit integrating all of the sensors. The challenge was to integrate the sensors in the runner's clothes and trail bag in such a way that they would remain pressed against the runner’s body without hindering his movements, and to develop instrumented trail shoes suitable for use in extreme conditions while keeping their weight down to a level acceptable to a runner looking to clock a good time.

An experiment with a number of points of scientific interest

The sensors are of such a type, and positioned in such a way on the runner’s body, that they are capable of collecting data on environmental factors (temperature, humidity, brightness), physiological factors (heart rate, skin temperature) and spatio-temporal factors (runner’s position). They also capture the movements of the different parts of the body (trunk, head, feet, shin, thigh, arms) in order to be able to accurately reconstruct the runner's movements during the race. These data can be used to combine and analyse different parameters, such as movement sequences (walking, running), the nature of the terrain (sandy, rocky, inclines), heart rate, fatigue or brightness (day/night).
The aim of the experiment conducted during the SULTAN MARATHON DES SABLES is to validate the human movement analysis system in extreme conditions. Several fields of application are already envisaged:

In biomechanics, the wireless sensors will make it possible to reconstruct the movements and posture of subjects in natural conditions and over long periods.

In physiology, researchers interested in the reactions of the body to great fatigue and prolonged effort will be able to measure changes in the behaviour of the runner’s body, such as running pace, recovery time, and the impacts of heat and fatigue.

In the field of practical assistance for people with motor disabilities, researchers need flexible, simple and light systems for analysing patient movements in a clinical or private environment. These sensors can also be integrated in the control systems of functional rehabilitation or compensation devices (splints, prosthetic limbs, assistance robots, etc.). Inria’s DEMAR team (Artificial movement and gait restoration) is already using these solutions as part of its research work to artificially control deficient movements (functional electrical stimulation), particularly in cases of paraplegia and hemiplegia.

In the monitoring of animals’ migratory movements, it is common to study a population of animals, such as penguins, by fitting some of them with sensors. The work done on the miniaturisation and robustness of the sensors as part of the SULTAN MARATHON DES SABLES experiment is therefore of interest to biologists.

During the development of elite sporting equipment, manufacturers need to collect data about the sensations experienced by athletes in order better to analyse the physiological responses and neuromuscular adaptations that occur during walking or running, impacts, variations in temperature or perspiration, for example. As Nicolas Horvais, R&D biomechanist at Salomon, explains, ‘This experiment will allow us to further improve our products and provide data for our anticipation cell. For over 50 years, we have built up unique know-how in innovation. On-the-ground observation of sports in extreme conditions lies at the heart of this innovation and allows us to develop and enrich our projects to develop the textiles, accessories and shoes of tomorrow.

In the preparation of elite athletes: the system developed may be of great value in the preparation and training of athletes. It allows a large number of parameters to be measured, such as the movement of the body or a given piece of equipment (e.g. a ski), physiological data, etc., in a real usage context. Analysing these measurements is a way of quantitatively studying a sporting practice and developing training programmes accordingly.

About

Inria

A public science and technology institution under the supervision of the ministries for Research and Industry. Management: Michel COSNARD, Inria CEO - Jean-Pierre VERJUS, Deputy CEO. Annual budget (2009): €217 million, 21% of which from its own resources. Regional research centres: Paris - Rocquencourt, Sophia Antipolis – Méditerranée, Grenoble – Rhône-Alpes, Nancy – Grand Est, Rennes – Bretagne Atlantique, Bordeaux – Sud Ouest, Lille – Nord Europe, Saclay – Île-de-France. 3,150 researchers, including more than 1,000 PhD students, working within more than 170 project-teams, the majority of which are shared with other bodies, Grandes Ecoles and universities. 80 associate teams around the world. Around 100 companies created since 1984.

Keywords: XtremLog – Sensors in the desert Guillaume Chelius Ep4 Project DNET Press release