Place Pierre de Coubertin, 1-2
1348 Louvain-la-Neuve
Belgique
Téléphone : +32 10 47.44.32
Fax : +32 10 47.31.06
E-mail : Patrick.Willems@loco.ucl.ac.be
Staff
Academic staff
- Dominique DE JAEGER (lecturer)
- Norman C. HEGLUND (professor)
- Bénédicte SCHEPENS (lecturer)
- Patrick A. WILLEMS (professor)
Scientific Collaborators
- Giovanni CAVAGNA (Istituto di Fisiologia Umana - Universita di Milano - Italie)
- Christine DETREMBLEUR (Unité de Réadaptation - MD - UCL)
- Trevor DREW (Centre de Recherche en Sciences Neurologiques - Université de Montréal - Canada)
- Christian EUGENE (Unité d'électrotechnique et d'instrumentation - FSA - UCL)
- Pierre Y. WILLEMS (Unité d'automatique des systèmes - FSA - UCL)
Scientific Staff
- Guillaume BASTIEN
- Joakim GENIN
- Massimo PENTA
- Thierry GOSSEYE
Administrative and technical staff
- Sylviane DEDEURWAERDER
- Thierry QUERIAT
Pedagogical advisors
- Stéphane BEAUME
- Marc DELNEST
- Frédéric LEROY
- Sabine RENARD
Research
The principal domain of research of our lab is the physiology and the biomechanics of terrestrial locomotion. Movement in sports (particularly in gymnastic) are also studied.
Studies on terrestrial locomotion
At first glance, there are many different modes of terrestrial locomotion: some vertebrates move on Earth on two legs while others use four. They walk, amble, trot, pace, canter, gallop, hop, etc. In fact, this huge variety of locomotory types are all based on two basic mechanisms:
Intrinsic factors (morphology, development, pathologies...) or extrinsic factors (slope or softness of the terrain, carrying a load...) may modify the pattern of locomotion (stride length, step frequency, muscular power...). The aim of our research is to understand how the locomotory system adapts to these particular situations.
Equipements
- A force platform made of 10 plates (total length: 6 m.) measures the vertical and forward components of the ground reaction force during several walking or running steps. This platform is installed at the level in the middle of a 40 m long corridor.
- A of 16 plates (size of each plate: 1m x 1m) is under construction. This platform measures the ground reaction forces in the three directions of the space. It has a resolution of 3 N and a full scale of 50.000 N
- A piezo-electric force platform (KIESTLER®) measures the ground reaction forces in the three directions of the space.
- A motion analysis system with infrared cameras (SELSPOT®) records the movements of the body segments at 400 frames/s.
- Electromyographs (EMG) record the electrical activity of height muscular groups.
- A telemetric system allows to measure energy expenditure during various exercises (KOSMED K4®). More information : Norman HEGLUND
More information : Norman HEGLUND
Main research projects of the last five years :
The mechanics of walking and running in children during growth :
Three children run on the 6 m long force platform of the lab.
The aim of this study is to understand: (1) how the mechanisms of locomotion change during growth, (2) which are the factors that influence this evolution (change in morphology, increase of the weight and the size, maturation of the nervous system, modification of the muscular force...).
Three studies were realized these last years.
The energy expenditure in children during walking.
In this study, we measured the oxygen consumption during walking at different speeds in adults and in 3 to 12 years old children.
The mechanical work done by children during walking at different speeds.
The mechanical work can be divided into different parts: (1) the external work necessary to sustain the displacement of the center of mass of the body relative to the surroundings, (2) the internal work done to accelerate the body segments relative to the center of mass of the body and (3) the internal work done during the double contact phase of walking by the back leg which generates energy that will be absorbed by the front leg (see picture). This last part is not counted in the 'classic' measurements of the positive muscular work done during walking. Using force platforms, we studied the effect of speed and age (size) on the internal work done by one leg against the other. We also measured the total mechanical work done during walking at different speeds in adults and in 3-12 years old children (paper in preparation).
The bouncing mechanism of running in children.
The natural frequency of the body bouncing system depends on the body mass and the stiffness of the elastic structures responsible for the rebound. Between the age of initiation of running and adulthood, body mass increases more than five times, but the effect of growth on stiffness is unknown. In this study, we investigated the factors affecting the freely chosen step frequency, and measured the mechanical work done to move the center of mass of the body during running at various speeds in children of different age.
Mechanics and energetics of human locomotion on sand
The mechanics and energetics of locomotion have been thoroughly investigated only in the laboratory on hard, level, non-slippery surfaces, although these bear little resemblance to those actually occurring in nature. It could be that the energy-saving mechanisms utilized during locomotion on a hard surface are not functional on a soft surface, or that the muscles on a soft surface are in a condition such that they contract and do work at lower efficiency, or simply that the mechanical work required to walk or run on a soft surface is much greater since the foot does work on the substratum. The purpose of the present study was to quantify the increase in metabolic cost and the reason for that increase, in human walking and running on dry sand. A 50 m track containing 8 tons of sand was build (left picture). In order to evaluate muscular work during sand locomotion, a track was also build on the top of the force plate (right picture).
Physiology of load carrying
People in the Third World often carry prodigious loads supported by their heads. With the exception of African women, virtually nothing is known about the energetics and mechanics of carrying head supported loads.
In Nepal, load carrying is mostly done by humans. Porters use a bag (doko) supported by a strap on the head (naamlo). On the average, loads are equal to body weight (occasionally up to two times the body weight). We studied the energetics (oxygen consumption - right picture) and mechanics (mechanical work - left picture) of Sherpa carrying head supported loads in an effort to determine if this is a particularly economical means of portage, and if so, what mechanisms are used to minimize cost.
Effect of gravity on the mechanics of walking and running.
Professor Cavagna (University of Milan) walking at 0.4 g (like on Mars)
The aim of this study is to understand how gravity affects the mechanisms of locomotion. We measured the ground reaction forces during walking in reduced (0.4 g) or enhanced (1.5 g) gravity and during running in enhanced gravity (1.3 g). Hypo-gravity is obtained during parabolic flights while hyper-gravity is obtained during circular flight
List of the new research projects in the field of locomotion :
- Effect of exercise on the muscle and bone loss during extended weightlessness
- Mechanics of locomotion of the elephant
- Control of step frequency during running in children and in adults
Analysis of movement in gymnastics
In a first project, we analyze the movement of the center of mass of the body during a stationary backwards flip (see picture). This exercise requires one to take off and land at the same place. The aim of the work is to understand how the subject is able to induce a movement of rotation of the body without inducing a horizontal translation of its center of mass. We record the ground reaction forces and compute the trajectory of center of mass during that exercise (paper in preparation).
>> Publications
Scientific award
- B. SCHEPENS : Award of the Société de Biomécanique for the best Ph.D. these presented at the congress of Montreal: The mechanics of running in children.
Award of the Human Frontier Science Program 2000- 2001, 2001-2022 & 2002-2003
H.H. Jasper Fund 1999-2000, One year Fellowship, Canada
- M. PENTA : Award for the best poster of the 2nd World Congress of the International Society of Physical Rehabilitation Medicine, Prague, 2003
Services to Society
- Transfer of knowledge to the economical world
A Spin-Off, funded by the Région Wallonne, has been created. The aim of this company is to commercialize products that were designed for our research. These products are force platforms (all size and shape available), surface EMG and a software called OUTCOME©. OUTCOME© is a multi-langage, multi-test application that allows to track patient outcomes on a Palm PoweredTM handheld computer.
- Transfer of knowledge to the cultural world
Consultant for exhibitions on sports (Parc d'Aventure Scientifique) and on load carrying (Musée de la vie Wallonne).
- Participation to scientific live
N. HEGLUND Member of the editorial board of the European Journal of Applied Physiology The members of the lab are involved in different scientific societies:
- International Society of Biomechanics,
- Society of Experimental Biology,
- Society for Neurosciences,
- American Association for the Advancement of Science, American Physiological Society.
Teaching
Lessons
The Academic Staff of the lab is in charge of several lessons and thesis in the following programs: - Bachelor and Master in Physical Education,
- Bachelor and Master in Physiotherapy,
- Sports Medicine,
- Engineering.
The following subject are covered:
- physiology,
- biomechanics in sports and in rehabilitation,
- analysis of human walking,
- technology applied to rehabilitation,
- physiotherapy,
- ergonomics,
- gymnastic activities,
- methodology of research,
- motor learning.
Students in physiotherapy design a robot driven by the EMG of the biceps muscles.
Ph.D. Theses
- THIERRY LEJEUNE Ph.D. in Biomedical Sciences orientation: physiology, 1998, Energétique mécanique de la locomotion dans le sable
- BENEDICTE SCHEPENS Ph.D. in Physiotherapy, 1998, The mechanics of running in children
- GUILLAUME BASTIEN Ph.D. in Physiotherapy, project 2004, Physiology of load carrying in the Nepalese porters
- JOAKIM GENIN Ph.D. in Physiotherapy, project 2006, Mechanics of locomotion of large terrestrial vertebrates
