Biomedical subjects

Gaspar Morey-Klapsing

Publications and source records attributed to Gaspar Morey-Klapsing.

15 recordsLinked to original sources

PubMed2006

Mechanical properties of the triceps surae tendon and aponeurosis in relation to intensity of sport activity.

The purpose of the present study was to investigate whether the mechanical properties (i.e. force strain relationship) of the triceps surae tendon and aponeurosis relate to the performed sport activity in an intensity-dependent manner. This was done by comparing sprinters with endurance runners and subjects not active in sports. Sixty-six young male subjects (26+/-5 yr; 183+/-6 cm; 77.6+/-6.7 kg) participated in the study. Ten of these subjects were adults not active in sports, 28 were endurance runners and 28 sprinters. All subjects performed isometric maximal voluntary plantar flexion contractions (MVC) on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) was visualised by ultrasound during the MVC. The results showed that only the sprinters had higher normalised stiffness (relationship between tendon force and tendon strain) of the triceps surae tendon and aponeurosis and maximal calculated tendon forces than the endurance runners and the subjects not active in sports. Furthermore, including the data of all 66 examined participants tendon stiffness correlated significantly (r=0.817, P<0.001) with the maximal tendon force achieved during the MVC. It has been concluded that the mechanical properties of the triceps surae tendon and aponeurosis do not show a graded response to the intensity of the performed sport activity but rather remain at control level in a wide range of applied strains and that strain amplitude and/or frequency should exceed a given threshold in order to trigger additional adaptation effects. The results further indicate that subjects with higher muscle strength possibly increase the margin of tolerated mechanical loading of the tendon due to the greater stiffness of their triceps surae tendon and aponeurosis.

Adaptation, Physiological↗

PubMed2006

Effect of contraction form and contraction velocity on the differences between resultant and measured ankle joint moments.

During a maximal isometric plantar flexion effort the moment measured at the dynamometer differs from the resultant ankle joint moment. The present study investigated the effects of contraction form and contraction velocity during isokinetic plantar/dorsal flexion efforts on the differences between resultant and measured moments due to the misalignment between ankle and dynamometer axes. Eleven male subjects (age: 31+/-6 years, mass: 80.6+/-9.6 kg, height: 178.4+/-7.4 cm) participated in this study. All subjects performed isometric-shortening-stretch-isometric contractions induced by electrical stimulation at three different angular velocities (25 degrees /s, 50 degrees /s and 100 degrees /s) on a customised dynamometer. The kinematics of the leg were recorded using the vicon 624 system with eight cameras operating at 250 Hz. The resultant moments at the ankle joint were calculated through inverse dynamics. The relative differences between resultant and measured ankle joint moments due to axis misalignment were fairly similar in all phases of the isometric-shortening-stretch-isometric contraction (in average 5-9% of the measured moment). Furthermore these findings were independent of the contraction velocity. During dynamic plantar/dorsal flexion contractions the differences between measured and resultant joint moment are high enough to influence conclusions regarding the mechanical response of ankle extensor muscles. However the relative differences were not increased during dynamic contractions as compared to isometric contractions.

Adult↗

PubMed2006

Influence of the muscle-tendon unit's mechanical and morphological properties on running economy.

The purpose of this study was to test the hypothesis that runners having different running economies show differences in the mechanical and morphological properties of their muscle-tendon units (MTU) in the lower extremities. Twenty eight long-distance runners (body mass: 76.8+/-6.7 kg, height: 182+/-6 cm, age: 28.1+/-4.5 years) participated in the study. The subjects ran on a treadmill at three velocities (3.0, 3.5 and 4.0 m s(-1)) for 15 min each. The V(O(2)) consumption was measured by spirometry. At all three examined velocities the kinematics of the left leg were captured whilst running on the treadmill using a high-speed digital video camera operating at 250 Hz. Furthermore the runners performed isometric maximal voluntary plantarflexion and knee extension contractions at eleven different MTU lengths with their left leg on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) and vastus lateralis (VL) were visualised by ultrasound during plantarflexion and knee extension, respectively. The morphological properties of the GM and VL (fascicle length, angle of pennation, and thickness) were determined at three different lengths for each MTU. A cluster analysis was used to classify the subjects into three groups according to their V(O(2)) consumption at all three velocities (high running economy, N=10; moderate running economy, N=12; low running economy, N=6). Neither the kinematic parameters nor the morphological properties of the GM and VL showed significant differences between groups. The most economical runners showed a higher contractile strength and a higher normalised tendon stiffness (relationship between tendon force and tendon strain) in the triceps surae MTU and a higher compliance of the quadriceps tendon and aponeurosis at low level tendon forces. It is suggested that at low level forces the more compliant quadriceps tendon and aponeurosis will increase the force potential of the muscle while running and therefore the volume of active muscle at a given force generation will decrease.

Adult↗

PubMed2005

Effect of different ankle- and knee-joint positions on gastrocnemius medialis fascicle length and EMG activity during isometric plantar flexion.

The purpose of this study was to provide evidence on the fact that the observed decrease in EMG activity of the gastrocnemius medialis (GM) at pronounced knee flexed positions is not only due to GM insufficiency, by examining muscle fascicle lengths during maximal voluntary contractions at different positions. Twenty-two male long distance runners (body mass: 78.5+/-6.7 kg, height: 183+/-6 cm) participated in the study. The subjects performed isometric maximal voluntary plantar flexion contractions (MVC) of their left leg at six ankle-knee angle combinations. To examine the resultant ankle joint moments the kinematics of the left leg were recorded using a Vicon 624 system with 8 cameras operating at 120 Hz. The EMG activity of GM, gastrocnemius lateralis (GL), soleus (SOL) and tibialis anterior (TA) were measured using surface electromyography. Synchronously, fascicle length and pennation angle values of the GM were obtained at rest and at the plateau of the maximal plantar flexion using ultrasonography. The main findings were: (a) identifiable differences in fascicle length of the GM at rest do not necessarily imply that these differences would also exist during a maximal isometric plantar flexion contraction and (b) the EMG activity of the biarticular GM during the MVC decreased at a pronounced flexed knee-joint position (up to 110 degrees ) despite of no differences in GM fascicle length. It is suggested that the decrease in EMG activity of the GM at pronounced knee flexed positions is due to a critical force-length potential of all three muscles of the triceps surae.

Ankle Joint↗

PubMed2005

Inevitable joint angular rotation affects muscle architecture during isometric contraction.

The purpose of this study was to quantify the influence of inevitable ankle joint motion during an isometric contraction on the measured change of the gastrocnemius medialis muscle (GM) architecture in vivo during the loading and the unloading phase. Sitting on a dynamometer subjects performed isometric maximal voluntary contractions as well as contractions induced by electrostimulation. Synchronous joint angular motion, plantarflexion moment, foot's centre of pressure and real-time ultrasonography of muscle architecture changes of the GM were obtained. During the contraction the ankle joint position altered and significantly affected the change in muscle architecture. At maximal tendon force (1094+/-323 N), the measured fascicle length overestimated the change in fascicle length due to the tendon force by 1.53 cm, while the measured pennation angle overestimated the change in pennation angle due to the tendon force by 5.5 degrees . At the same tendon force the measured fascicle length and pennation angle were significantly different between loading and unloading conditions. After correcting the values for the change in ankle joint angle no differences between the loading and the unloading phase at the same tendon force were found. Concerning the estimation of GM fascicle length-force and pennation angle-force curves during the loading and unloading phase of an isometric contraction, these findings indicate that not accounting for ankle joint motion will produce unreliable results.

Ankle Joint↗

PubMed2005

Strain and elongation of the vastus lateralis aponeurosis and tendon in vivo during maximal isometric contraction.

The strain and elongation of the vastus lateralis (VL) tendon, tendon plus aponeurosis, and aponeurosis were examined during maximal voluntary contractions on a Biodex-dynamometer (knee angle 115 degrees , hip angle 140 degrees ) in 12 sprinters. Following a warm-up phase, the subjects were instructed to perform a gradual maximal knee extension and hold it for about 3 s. The kinematics of the leg were recorded using a Vicon 512 system with eight cameras operating at 120 Hz. Ultrasonography images were taken simultaneously from the VL myotendinous junction and the mid lateral part of the VL muscle belly. During the maximal isometric knee extensions, the knee joint rotated (13.6+/-5.9 degrees ), leading to an overestimation of the elongation of the tendinous tissues. After correcting for this, the maximal elongation of the VL tendon examined at the myotendinous junction was lower (P<0.05) than the maximal elongation of the VL tendon plus aponeurosis examined at the muscle belly (15 vs. 27 mm, respectively). The maximal estimated strains of the tendon, tendon plus aponeurosis, and aponeurosis showed no statistical differences (8+/-2%, 8+/-1%, and 7+/-2%, respectively, P>0.05). It is concluded that the strains of the human VL tendon, VL tendon plus aponeurosis, and VL aponeurosis, as estimated in vivo by two dimensional ultrasound during maximal isometric contractions, do not differ from each other. The displacement measured at a cross point in the VL muscle belly is significantly greater than that measured at the VL myotendinous junction.

Adult↗

PubMed2005

Orthotic effect of a stabilising mechanism in the surface of gymnastic mats on foot motion during landings.

The purpose of this study was to examine two hypotheses: (a) mat hardness affects foot motion during landing; (b) the influence of a surface stabilising interface integrated in a mat on foot motion is detectable. Two studies were carried out: In the first one, six female gymnasts performed barefoot landings from different falling heights onto three mats having different hardness. In the second study, a stabilising mechanism was integrated in the surface of three new mats with different hardness. Three high speed video cameras (250Hz) captured the motion of the left leg and foot. These were modelled by means of a four rigid body system. The maximal eversion at the ankle joint was not influenced by the different mats (hard: 4.6 degrees +/-1.9 to 9.3 degrees +/-3.4, medium: 3.1 degrees +/-2.7 to 7.4 degrees +/-3.5, soft: 4.8 degrees +/-2.1 to 8.4 degrees +/-3.5). The soft mat without the stabilised surface showed higher eversion values (p<0.05) between forefoot and rearfoot (medial joint: hard: 5.1 degrees +/-3.2 to 7.3 degrees +/-3.3, medium: 6.9 degrees +/-3.1 to 7.5 degrees +/-2.9, soft: 12.7 degrees +/-4.1 to 13.4 degrees +/-3.3; lateral joint: hard: 8.5 degrees +/-3.1 to 9.7 degrees +/-1.1, medium: 9.5 degrees +/-2.6 to 11.2 degrees +/-3.3, soft: 12.1 degrees +/-2.3 to 15.7 degrees +/-3.3). For the mats with the surface stabilising interface, the different hardness did not cause any significant differences in maximal eversion values at the medial (hard: 1.5 degrees +/-3.3 to 5.5 degrees +/-4.5, medium: 1.3 degrees +/-3.5 to 5.1 degrees +/-3.6, soft: 0.7 degrees +/-4.9 to 5.4 degrees +/-4.2) nor at the lateral (hard: 11.3 degrees +/-4.2 to 17.3 degrees +/-4.2, medium: 12.3 degrees +/-4.8 to 17.1 degrees +/-3.7, soft: 11.5 degrees +/-4.6 to 17.1 degrees +/-4.3) forefoot joints. The structure of the mat and the consequent deformation hollow did not influence the kinematics of the ankle joint during landings, but it influenced the motion at the medial and the lateral forefoot joints. By means of a stabilised surface, it is possible to reduce the influence of mat deformation on the maximal eversion between forefoot and rearfoot.

Adult↗

PubMed2005

Joint stabilising response to lateral and medial tilts.

BACKGROUND: Joint stabilisation processes have been mainly studied comparing groups or joints with different stabilities and mainly focusing on one single parameter. The inherent limitations are discussed and a study, where kinematic, kinetic and electromyografic parameters gained from sudden tilt tests were measured, is presented. METHODS: The response of 24 subjects to sudden lateral and medial tilts of the foot during one legged stance were compared. A three-dimensional foot model was utilised to describe ankle and foot motion. Electromyografic signals of six muscles of the lower limb as well as the horizontal ground reaction forces were analysed. FINDINGS: Forefoot to rearfoot motion was faster and greater than ankle motion. In general medial tilts showed lower motion amplitudes and angular velocities than lateral tilts but higher horizontal ground reaction force integrals. The electromyography patterns where similar for both conditions. However, a specificity of the muscular response could be identified in the electromyography amplitudes. INTERPRETATION: The higher mediolateral ground reaction forces, together with the reduced kinematic and no general increase in muscular activation in medial tilts suggest, that passive structures seem to be able to counteract destabilising forces and thus reduce the otherwise needed muscular activation.

Adaptation, Physiological↗

PubMed2005

Differences between measured and resultant joint moments during isometric contractions at the ankle joint.

The purpose of this study was to examine two hypotheses: (a) during voluntary and electrically induced isometric contractions the moments measured at the dynamometer are different from the resultant moments in the same plane around the ankle joint and (b) at a given resultant moment during electrically induced isometric contractions the ankle angle while loading is different from the ankle angle while unloading. Twenty-seven long distance runners participated in the study. All subjects performed isometric maximal voluntary contractions (MVC) and contractions induced by electrostimulation at four different ankle-knee angle combinations on a Biodex-dynamometer. The kinematics of the leg were recorded using the vicon 624 system with eight cameras operating at 120 Hz. The main findings were: (a) the resultant moment at the ankle joint and the moment measured by the Biodex-dynamometer during isometric contractions are different, (b) during a plantar flexion effort the ankle angle changes significantly, whereas the knee angle shows only small and in most cases not significant changes, and (c) at identical resultant ankle joint moments the ankle angles are different between the loading and the unloading phases. The observed differences may lead to erroneous conclusions concerning the following: (a) diagnostic of muscle architecture, (b) estimation of the moment-ankle angle relationship and (c) estimation of the strain and hysteresis of tendons and aponeuroses.

Ankle Joint↗

PubMed2005

Joint stabilizing response to expected and unexpected tilts.

BACKGROUND: The results found in the literature regarding functional ankle joint stabilization are controversial possibly because of the testing methods used. METHODS: The responses of 22 subjects to unexpected and expected sudden inversions of the foot were compared for all subjects together, as well as grouped by their self-perceived stability. A three-dimensional foot model was used to describe ankle and foot motion. Electromyographic signals of six muscles of the lower limb as well as the horizontal ground reaction forces were recorded. RESULTS: Whereas unexpected and expected trials did not show significant differences (p > 0.05) in kinematics, higher activation and horizontal force integrals were found for the unexpected trials. In addition, no differences in electromyographic or ground reaction force parameters were found between stable and unstable ankles; however, the kinematics revealed higher amplitudes and velocities for the stable group. CONCLUSIONS: The awareness of the instant of tilt enhances stabilization in that the same motion is achieved with a lower muscle activation. Evidence suggests that this is triggered at supraspinal levels. We found that timing of the EMG signal is not as relevant to stabilization as the amplitude (which has often been disregarded in the literature).

Adult↗

PubMed2004

Choosing EMG parameters: comparison of different onset determination algorithms and EMG integrals in a joint stability study.

OBJECTIVE: The aim was to test various algorithms for onset determination and compare onset repeatability to that from integrals of the EMG signal. The information contained in both parameters is discussed. DESIGN: Onset times were calculated using six different algorithms. The integral of the EMG signal was calculated for seven intervals: from tilt start and from each of the resulting onsets to 200 ms after tilt start. BACKGROUND: EMG onset times are often utilised, especially regarding co-ordination patterns or joint stability. There are almost as many different procedures for onset determination as authors dealing with it. Results in the literature are contradictory. The determination and usage of onset times remains controversial. METHODS: EMG signals from six muscles of the lower leg of 23 subjects were recorded during three consecutive, expected and unexpected sudden inversion and eversion trials while standing on a tilting platform. RESULTS: In most cases the repeatability of the onset times was considerably lower than that of the integrals of the EMG for all studied algorithms. In some cases earlier onset times corresponded to lower integral values and constant onsets to variable integrals. CONCLUSIONS: In many cases onset times alone are not sufficient for describing onset phenomena. The additional calculation of the integrated EMG might provide relevant information regarding the quality of early activation.

Adult↗

PubMed2004

Differences between measured and resultant joint moments during voluntary and artificially elicited isometric knee extension contractions.

OBJECTIVE: Examine two hypotheses: (a) during isometric knee extension contractions the moment measured at the dynamometer is different from the resultant moment in the same plane around the knee joint and (b) during isometric contractions, at the same given resultant moment the knee angle while loading is different from the knee angle while unloading. DESIGN: Comparative study in which the geometrical and the kinetic differences between joint and dynamometer were determined. BACKGROUND: It is usually assumed that the moment measured by the dynamometer is equivalent to the resultant joint moment. The non-rigidity of the dynamometer-leg system can influence the equivalence of these two moments. METHOD: Twenty seven subjects performed isometric maximal knee extension contractions and contractions induced by electrostimulation on a dynamometer. The kinematics of the leg were recorded using 8 cameras (120 Hz). RESULTS: The resultant moment at the knee joint and the moment measured by the dynamometer are different. During a knee extension effort the knee angle changes significantly. At identical resultant knee joint moments the knee angles are different when comparing the loading and the unloading phases. CONCLUSIONS: The differences between the measured and the resultant joint moments might influence the estimation of parameters as: muscle forces, moment-angle relationship and strain and hysteresis of tendons and aponeuroses. RELEVANCE: Torque dynamometers have been often used to estimate muscle forces, to examine neuromuscular processes and to determine the mechanical properties of tendons and aponeuroses.

Biomechanical Phenomena↗

PubMed2004

Effect of ankle joint position and electrode placement on the estimation of the antagonistic moment during maximal plantarflexion.

During maximal efforts, antagonistic activity can significantly influence the joint moment. During maximal voluntary "isometric" contractions, certain joint rotation can not be avoided. This can influence the estimation of the antagonistic moment from the EMG activity. Our study aimed to quantify the influence on the calculated agonistic moment produced during maximal voluntary isometric plantarflexions (a) when estimating antagonistic moments at different ankle angles and (b) when placing the EMG electrodes at different portions over the m. tibialis anterior. Ten subjects performed maximal voluntary isometric plantarflexions at 90 degrees ankle angle. In order to estimate the antagonistic moment, submaximal isometric dorsiflexions were performed at various ankle angles. Moment and EMG signals from mm. triceps surae and tibialis anterior were measured. The RMS differences between plantarflexors moment calculated considering the antagonistic cocontraction estimated at the same ankle angle at which the maximal plantarflexion moment was achieved and at different ankle angles ranged from 0.10 to 2.94 Nm. The location of the electrodes led to greater RMS differences (2.35-5.18 Nm). In conclusion, an angle 10 degrees greater than the initial plantarflexion angle is enough to minimize the effect of the change in length of the m. tibialis anterior during the plantarflexion on the estimation of the plantarflexors moment. The localisation of the electrodes over the m. tibialis anterior can influence the estimation of its cocontraction during maximal plantarflexion efforts.

Adult↗

PubMed2004

Interaction of the human body and surfaces of different stiffness during drop jumps.

PURPOSE: The purpose of this study was to examine two hypotheses: (a) the stiffness of the surface influences the leg stiffness of the subjects during drop jumps, and (b) drop jumping performance (jumping height and energy rates of the subject's center of mass during the contact phase) increases when decreasing surface stiffness due to a greater energy storage capacity of the surface for a given acting force. METHODS: Ten female subjects performed a series of drop jumps from 40-cm height onto two sprung surfaces with different stiffness. Those trials of each subject displaying the maximal mechanical power during the upward phase were analyzed. The ground reaction forces were measured using a force plate. Sagittal kinematics of the subject's body positions and the deformation of the surface were recorded using two high-speed video cameras. RESULTS: On the soft surface, the jumping height and the energy rates of the subjects during the contact phase were greater than on the hard one. The energy delivered by the subjects during the upward phase, the leg and joint stiffness, as well as the range of motion of the subjects remained unchanged for both surfaces. CONCLUSIONS: The absolute energy loss is lower for the hard surface, but the jumping performance is greater for the soft one. The reason is a higher ratio of positive to negative mechanical work done by the subjects during the contact phase. The adjustment of the subjects to different surfaces is not only dependent on the stiffness of the surface but also on the intensity of the movement.

Algorithms↗

PubMed2003

The effect of falling height on muscle activity and foot motion during landings.

The aims of this study were: (a) to examine the effect of falling height on the kinematics of the tibiotalar, talonavicular and calcaneocuboid joints and (b) to study the influence of falling height on the muscle activity of the leg during landings. Six female gymnasts (height: 1.63 +/- 0.04 m, weight: 58.21 +/- 3.46 kg) participated in this study. All six gymnasts carried out barefoot landings, falling from 1.0, 1.5 and 2.0 m height onto a mat. Three genlocked digital high speed video cameras (250 Hz) captured the motion of the left shank and foot. Surface electromyography (EMG) was used to measure muscle activity (1000 Hz) from five muscles (gastrocnemius medialis, tibialis anterior, peroneus longus, vastus lateralis and hamstrings) of the left leg. The kinematics of the tibiotalar, talonavicular and calcaneocuboid joints were studied. The lower-leg and the foot were modelled by means of a multi-body system, comprising seven rigid bodies. The falling height does not show any influence on the kinematics neither of the tibiotalar nor of the talonavicular joints during landing. The eversion at the calcaneocuboid joint increases with increasing falling height. When augmenting falling height, the myoelectric activity of the muscles of the lower limb increases as well during the pre-activation phase as during the landing itself. The muscles of the lower extremities are capable of stabilizing the tibiotalar and the talonavicular joints actively, restricting their maximal motion by means of a higher activation before and after touchdown. Maximal eversion at the calcaneocuboid joint increases about 52% when landing from 2.0 m.

Biomechanical Phenomena↗