INFLUENCE OF CYCLIST SADDLE SETBACK ON KNEE JOINT FORCES

Despite the rapid development of bike fitting services, there is still a lack of scientific evidence on the effects of specific bicycle’s parameters on overuse injuries. The aim of this study was to investigate the influence of saddle setback on knee joint forces. Eleven cyclists experimented three saddle setback conditions while pedaling at a steady power output of 200 W and a cadence of 90 rpm. Using a static optimization procedure based on a musculoskeletal model, we estimated knee joint forces. As a first verification step, our preliminary results showed great similarity between muscle activations estimated from the modeling and experimental data (EMG) especially for the knee extensor muscles. Secondly, tibiofemoral joint forces tend to show that a forward sitting position increases tibiofemoral joint shear forces

LOWER LIMB MUSCLE LENGTHS IN ROWING: A PRELIMINARY STUDY

This study aimed to characterise the lower limb muscular coordination in rowing. A musculoskeletal model was developed to be used for movements exhibiting large joints range of motion. Maximum static muscle lengths computed from five static stretching tests were compared with muscle lengths extracted while rowing. Muscle lengths were derived from lower limb kinematics collected using a motion analysis system. Our results showed that classical stretching tests were suitable for a muscle group but must be more specific to target isolated muscle. During rowing trials, bi-articular muscle patterns were subject-dependant with hamstring lengths close to their maximum lengths. Asymmetries were observed for few muscles. Further studies are necessary to confirm these promising findings that may maximise rowing performance and minimise rowing injuries

Strength and Behavior of Spruce Pine Glulam Timber Moment Connections Using Glued-In Steel Rods

This paper presents experimental testing on glulam beam–column moment-resisting connections using glued-in rods (GiRod) and compares the results with model predictions. Three connection geometries and varying numbers of rods and member size were tested and compared. This experiment will be helpful in grounding research by bringing in new experimental results and proposing an innovative experimentation method. Experimental results showed the high efficiency of glued-in rod connections to transfer loads and bending moment between spruce pine glulam timber members. The observed limit states of the connections were failed steel rods in ductile tensile yielding or wood splitting around the anchorage installed perpendicularly to the grain in the column. It was found that the tested connections behaved as a semirigid moment-resisting connection and exhibited a ductile failure mode when wood splitting was avoided by design. Comparison of experimental results with model predictions showed good agreement, with a deviation under 15% for the moment capacity of the connection

A CONSISTENT MASS AND MOMENTUM FLUX COMPUTATION METHOD USING RUDMAN-TYPE TECHNIQUE WITH A CLSVOF SOLVER

ABSTRACT In this paper, a computational method is presented that addresses the problem of multiphase flow characterized by phases with significant density ratio accompanied by strong shearing. The Coupled Level-Set Volume-of-Fluid (CLSVOF) technique is used for interface tracking, while the momentum transfer is coupled to that of mass by means of momentum fluxes computed using a sub-grid. This is an extended adaptation of Rudman's volume tracking techniqu

Pull-out strength of glued-in steel rod perpendicular to the grain in spruce-pine glulam timber

This study presents pull-out tests of glued-in steel rod installed perpendicularly to the grain in Spruce-Pine glulam timber. The tested specimens indicate that the embedded length and the steel grade influence the anchorage behaviour and capacity. Results showed that a well design anchor can exhibit a ductile failure mode. Experimental results are also compared to theoretical models and to pull-out strength of glued-in steel rod parallel to the grain to investigate the relation between these pull-out strength capacities

Characterization of the energy dissipation of a landing mat for the study of landing strategies in artistic gymnastics

International audienc

Impact of osteopathic manipulative treatment on range of motion of the pelvis during the one-sided tilt test: a pilot study

International audienc

A comparative study on the enzymatic biodegradability of covalently functionalized double- and multi-walled carbon nanotubes

The assessment of the biodegradability potential of carbon nanotubes (CNTs) is a fundamental point towards their applications in materials science and biomedicine. Due to the continuous concerns about the fate of such type of nanomaterials, it is very important to understand if they can undergo degradation under certain conditions and if the morphology and structure of the nanotubes play a role in this process. For this purpose we have decided to undertake a comparative study on the enzymatic degradation of CNTs with concentric multilayers. Double-walled (DW) and multi-walled (MW) CNTs of various lengths, degrees of oxidation and functionalizations using different methods were treated with horseradish peroxidase (HRP). While all tested DWCNTs resulted resistant to the biodegradation, some of the MWCNTs were partially degraded by the enzyme. We have found that short oxidized multi-walled CNTs functionalized by amidation were reduced in length and presented a high amount of defects at the end of the period of treatment with HRP. This comparative study holds its importance in the understanding of the structural changes of different types of nanotubes towards the catalytic enzymatic degradation and will help to design safer CNTs for future applications

Effects of posture on performance and prevention of injury in cycling. Insights from a musculoskeletal modeling approach

La performance sportive et la prévention des blessures en cyclisme sont étroitement liées à l'amélioration des capacités physiques, de la technique gestuelle ainsi qu'à l'optimisation du matériel utilisé.Dans ce contexte, nous avons étudié l'influence du recul de selle sur l'efficacité du mouvement de pédalage ainsi que sur les efforts internes au niveau du genou. Une approche de modélisation musculo-squelettique a été développée afin de quantifier indirectement les forces musculaires et articulaires exercées à partir de mesures externes cinématiques et dynamiques. Un intérêt tout particulier a été porté sur l'adéquation entre les mesures des efforts extérieurs, le modèle anthropométrique et les mesures cinématiques afin de diminuer les incohérences dynamiques associées à un système surdéterminé.A partir de ces mesures, les effets du recul de la selle sur la performance ont été évalués à travers l'indice d'efficacité de la force produite à la pédale et un nouvel indice, basé sur le travail mécanique externe. Les résultats ont montré qu'un positionnement de la selle plus reculé augmente l'efficacité du mouvement de pédalage.Concernant la prévention des blessures, notre analyse s'est portée sur l'effet du recul de selle sur deux troubles musculo-squelettiques (TMS) fréquents en cyclisme : le syndrome fémoro-patellaire et le syndrome de la bandelette ilio-tibiale. Nos résultats ont montré que le recul de selle ne modifie pas les forces fémoro-patellaires communément incriminées dans la survenue de ce syndrome. Par ailleurs, une position plus reculée augmente les forces fémoro-tibiales de compression par le biais notamment de la contraction excentrique des muscles ischio-jambiers. Bien que le syndrome de la bandelette ilia-tibiale soit classiquement décrit comme un syndrome de friction (syndrome de l'essuie-glace), le calcul de la force d'interaction entre la bandelette iliotibiale et l'épicondyle fémoral a montré que la compression est le facteur discriminant dans le pathoméchanisme. L'approche méthodologique de simulation développée dans ce cadre possède par ailleurs un fort potentiel afin de corriger les défauts techniques, d'optimiser les réglages matériels et améliorer la prise en charge thérapeutique des TMS.Plus généralement, les développements méthodologiques et implications cliniques issus de ces travaux trouvent des applications directes dans le milieu du cyclisme mais aussi dans l'étude de nombreuses activités sportives (notamment sur ergomètre) du point de vue de la performance, de la prévention des blessures et de la rééducation.Performance and prevention of injuries in cycling are closely linked to the optimisation of individual's physical capacity and technique as weil as sport equipment.In this context, we have studied the influence of saddle setback on the effectiveness of pedalling and on knee joint loads. A musculoskeletal modelling was developed to estimate muscle and joint forces from experimental kinematic and dynamic measurements. We first focused on the adequacy between sensors data, anthropometrie model and kinematic measurements to obtain dynamically consistent input data.Then, the effect of sadd le setback on perforn1ance was evaluated through the index of pedal force effectiveness and a new index based on extemal mechanical work. Results have showed that a more backward sadd le position increases the effectiveness of pedalling.As regards to in jury prevention, our analysis focused on the effect of the saddle setback on two knee injuries commonly observed in cycling: the patellofemoral syndrome and iliotibial band syndrome. Our results showed that saddle setback do not influence patellofemoral joint forces that are usually linked to this syndrome. Moreover, a more backward saddle position increases tibiofemoral compression forces due to increasing eccentric contraction of the hamstrings.Commonly described as a friction syndrome, the computation of interaction force between iliotibial band and lateral femoral epicondyle have showed that the compression was the discriminating factor in the occurrence of the syndrome. The simulation approach developed here could be used as an additional tool to help correct potentially hartnful sport techniques, optimise equipment setup/design and improve the treatment of injuries.More generally, this thesis brings new methodological improvements and clinical implications that have broader applications on sport perfortnance, injury prevention and rehabilitation