Biomedical subjects

R H Rozendal

Publications and source records attributed to R H Rozendal.

At least 19 recordsLinked to original sources

PubMed1997

Parameters for modeling the upper extremity.

The purpose of this paper was to provide parameters for the development of a musculoskeletal model of the upper extremity. Five upper extremity specimens were obtained from four fresh cadavers. Anthropometric measures were obtained for each cadaver. Segment inertial parameters were estimated for each specimen from anthropometric measures of the cadaver from which the specimen was obtained. The three-dimensional kinematics of the humerus, ulna, and radius in different movements of the glenohumeral, humeroulnar and ulnoradial joints were measured for each specimen using of the 3Space tracking system (Isotrack, Polhemus). The instantaneous rotation center of the glenohumeral joint and the instantaneous rotation axes of elbow flexion and forearm pronation were determined for each specimen from the kinematic data. The specimens were dissected and the muscle origins and insertions and bony structures needed in upper extremity modeling were digitized using the 3Space system. The shapes of muscle origins and insertions were estimated. Muscle length, volume and pennation angle were measured for the estimation of physiological cross-sectional areas of each muscle. The results, which are given for one specimen, showed that the rotation center of the glenohumeral joint was very close to the geometric center of the joint with a mean distance of 4 mm. The mean angle between the flexion-extension and pro-supination axes of the elbow joint was 94 degrees. The minimum distance between these two axes was about 4 mm.

Aged↗

PubMed1994

Relationship between physical strain during standardised ADL tasks and physical capacity in men with spinal cord injuries.

To describe physical strain during activities of daily living (ADL), 44 men with spinal cord injuries (C4-L5) performed a set of standardised tasks. The physical strain was defined as the highest heart rate response expressed as a percentage of the individual heart rate reserve (%HRR). The physical strain averaged over the subjects who performed all tasks (n = 24) was (mean +/- SD): 20.2 +/- 7.2 %HRR (washing hands), 20.4 +/- 7.3 %HRR (passing a side-hung door), 28.8 +/- 10.8 %HRR (transfer to a toilet), 31.2 +/- 13.1 %HRR (ascending an 8 cm curb). 33.9 +/- 12.0 %HRR (transfer to a shower seat), 35.1 +/- 10.5 %HRR (transfer to bed), 36.4 +/- 13.3 %HRR (preparing lunch), 37.1 +/- 12.0 %HRR (washing up), 38.7 +/- 14.9 %HRR (ascending a ramp), 39.8 +/- 15.6 %HRR (transfer to a shower wheelchair), 41.4 +/- 12.1 %HRR (changing sheets), and 45.9 +/- 10.4 %HRR (entering a car). Physical strain could be notably high, but large variations among subjects were present. During all tasks, subjects with tetraplegia had significantly higher levels of strain than subjects with low (T6-L5) lesions. Physical strain was inversely related to parameters of physical capacity: isometric strength (r: -0.34 to -0.72), sprint power (r: -0.34 to -0.69), peak oxygen uptake (r: -0.41 to -0.81) and maximal power output (r: -0.52 to -0.82). Parameters of physical capacity were better predictors of physical strain than was the lesion level, and explained 37-71% of the variance in strain during ADL. It was also concluded that the method used in this study provides a quantitative and objective estimation of physical strain and may therefore be a useful tool to identify task difficulty during rehabilitation and to evaluate the results of task and physical training on the physical strain during ADL.

Activities of Daily Living↗

PubMed1992

Geometry parameters for musculoskeletal modelling of the shoulder system.

A dynamical finite-element model of the shoulder mechanism consisting of thorax, clavicula, scapula and humerus is outlined. The parameters needed for the model are obtained in a cadaver experiment consisting of both shoulders of seven cadavers. In this paper, in particular, the derivation of geometry parameters from the measurement data is described. The results for one cadaver are presented as a typical example. Morphological structures are modelled as geometrical forms. Parameters describing this form are estimated from 3-D position coordinates of a large number of datapoints on the morphological structure, using a least-squares criterion. Muscle and ligament attachments are represented as a plane or as a (curved) line. Muscle paths are determined by a geometrical form of the bony contour around which the muscle is wrapped. Muscle architecture is determined by the distribution of muscle bundles over the attachment area, mapping the distribution of the origin to the insertion. Joint rotation centers are derived from articular surfaces. Hence, muscle moment arms can be calculated. The result of this study is a set of parameters for each cadaver, describing very precisely the geometry of the shoulder mechanism. This set allows positioning of muscle force vectors a posteriori, and recalculation of position coordinates and moment arms for any position of the shoulder.

Acceleration↗

PubMed1992

Unilateral immobilization affects contralateral rat gastrocnemius muscle architecture.

In order to study the effects of unilateral short length immobilization on the contralateral gastrocnemius muscle (GM), length measurements were conducted on photographs taken in the active condition (tetanic plateau). Comparison of geometry of experimental and control muscles was made at optimum muscle length. The results show that a process occurred in the muscle which can be ascribed predominantly in terms of atrophy. This atrophy did not reach a maximum after 4 weeks but gradually increased in time. The altered conditions imposed on the muscle changed its architecture. It was shown that variables of the contralateral GM muscle are not representative of those of normally used muscles and should therefore not be used as control muscles for the determination of immobilization effects.

Adaptation, Physiological↗

PubMed1992

Effect of handrim velocity on mechanical efficiency in wheelchair propulsion.

To study the effect of tangential speed of the handrims independent of external power output on gross mechanical efficiency (ME), nine able-bodied subjects performed wheelchair exercise tests on a stationary ergometer. The ergometer allowed for measurement of torque and three-dimensional forces on the rims and tangential velocity of the rear wheels. The experiment comprised two series of submaximal tests against constant external power outputs (0.25 and 0.50 W.kg-1) and four wheelchair speeds (0.83, 1.11, 1.39, and 1.67 m.s-1), which simulated a wheelchair speed of 1.67 m.s-1 and mechanical advantages of 0.43-0.87. ME stayed below 10.5% and changed inversely with speed of movement of the handrims. Peak torques on the right handrim stayed even with speed, leading to a significant increase in peak power output. Energy losses owing to braking torques at the beginning and end of the push phase increased with handrim speed but hardly exceeded 5 W. The effective force component applied to the handrims was below 71% of the magnitude of the total force vector and dropped up to 13% with increasing handrim speed. It is suggested that an ineffective direction of forces on the rims might (partly) be responsible for the low ME and for a decrease in ME in relation to tangential handrim velocity. This suggestion is discussed from a number of theoretical perspectives. It is concluded that the use of handrims with a lower mechanical advantage will increase wheelchair propulsion efficiency.

Adult↗

PubMed1992

A computerized wheelchair ergometer. Results of a comparison study.

To determine the validity of propulsion simulation on a stationary wheelchair ergometer, nine male able-bodied subjects performed submaximal exercise tests on the ergometer and on a motor driven treadmill (MDT). Oxygen uptake, ventilation and stroke parameters were equal for both devices, but heart rate was lower and trunk movement was less for the ergometer test. Analysis of forces and power output on the ergometer indicated that power output was equal for both wheels. The ratio between applied forces and the effectively directed force component was approximately 80%. Also a small torque was applied by the hand onto the handrim surface which contributed to the total propulsion torque around the axle. It is concluded that the ergometer is capable of simulation of wheelchair propulsion, although the different trunk motion may necessitate sufficient wheelchair propulsion experience. Force analysis results are discussed.

Biomechanical Phenomena↗

PubMed1991

Inertia and muscle contraction parameters for musculoskeletal modelling of the shoulder mechanism.

To develop a musculoskeletal model of the shoulder mechanism, both shoulders of seven cadavers were measured to obtain a complete set of parameters. Using antropometric measurements, the mass and rotational inertia of segments were estimated, followed by three-dimensional measurements of all morphological structures relevant for modelling, i.e. muscle origins and insertions, muscle bundle directions, ligament attachments and articular surfaces; all in relation to selected bony landmarks. Subsequently, muscle contraction parameters as muscle mass and physiological cross-sectional area were measured. The method of data collection and the results for inertia and muscle contraction parameters as prerequisities for modelling are described.

Aged↗

PubMed1991

Within-cycle characteristics of the wheelchair push in sprinting on a wheelchair ergometer.

To investigate power output and torque production in wheelchair sprinting, six able-bodied subjects performed nine 20-s sprint tests on a stationary wheelchair ergometer (load 0-8 kg). Ergometer data were analyzed and combined with kinematic data and surface electromyography. Of all power and torque parameters investigated, only maximal power output was independent of load (mean peak value 375 W, one-sided). Mean power output is suggested to be a useful indicator for anaerobic power production, but test conditions concerned speed in relation to handrim diameter should be specified. The relevance of the "mechanical constraint principle" for handrim propulsion is discussed. Within one cycle, power and torque curves showed a negative deflection at the beginning and a valley approximately halfway through the push phase. The relation of these phenomena to kinematic parameters and muscle activity is discussed.

Acceleration↗

PubMed1989

Optimum cycle frequencies in hand-rim wheelchair propulsion. Wheelchair propulsion technique.

To study the effect of different cycle frequencies on cardio-respiratory responses and propulsion technique in hand-rim wheelchair propulsion, experienced wheelchair sportsmen (WS group; n = 6) and non-wheelchair users (NW group; n = 6) performed wheelchair exercise tests on a motor-driven treadmill. The WS group wheeled at velocities of 0.55, 0.83, 1.11 and 1.39 m.s-1 and a slope of 2 degrees. The NW group wheeled at 0.83, 1.11 and 1.39 m.s-1 and a 1 degree slope. In each test, a 3-min period at a freely chosen cycle frequency (FCF: 100%) was followed by four 3-min blocks of paced cycle frequencies at 60%, 80%, 120% and 140% FCF. Effects of both cycle frequency and velocity on physiological and propulsion technique parameters were studied. Analysis of variance showed a significant effect (p less than 0.05) of cycle frequency on oxygen cost and gross mechanical efficiency in both the WS and NW group. This indicated the existence of an optimum cycle frequency which is close to the FCF at any given velocity. The optimum cycle frequency increased with velocity from 0.67 to 1.03 cps over the range studied (p less than 0.05). Oxygen cost was approximately 10% less at 100% FCF than at 60% or 140% FCF. Gross mechanical efficiency for the WS group at 100% FCF was 8.5%, 9.7%, 10.4% and 10.1%, respectively, at the four velocities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Seat height in handrim wheelchair propulsion.

To study the effect of seat height on the cardiorespiratory system and kinematics in handrim wheelchair ambulation, nine non-wheelchair users participated in a wheelchair exercise experiment on a motor-driven treadmill. The subjects conducted five progressive exercise tests. After an initial try-out test, four tests were performed at different standardized seat heights of 100, 120, 140, and 160 degrees elbow extension (subject sitting erect, hands on the rim in top-dead-center = 12.00 hrs; full extension = 180 degrees). Each test consisted of four 3-minute exercise blocks at speeds of respectively 0.55, 0.83, 1.11, and 1.39 m.s-1 (2-5 km.hr-1). Analysis of variance revealed significant effects of seat height (P less than 0.05) on gross mechanical efficiency (ME), oxygen cost, push range, and push duration, and on the ranges of motion in the different arm segments and trunk. Mean ME appeared higher at the lower seat heights of 100 and 120 degrees elbow extension. This is reflected in an enhanced oxygen consumption at seat heights of 140 and 160 degrees elbow extension. Simultaneously, the push range showed a 15 to 20 degree decrease with increasing seat height, which is reflected in a decreased push duration. In the push phase, decreases in retroflexion and abduction/adduction of the upper arm were seen. The trunk shifted further forward, and the motion range in the elbow joint shifted to extension with increasing seat height. No shifts in minimum and maximum angular velocities were seen with increasing seat height. The results showed an interrelationship between wheelchair seat height and both cardiorespiratory and kinematic parameters. With respect to the cardiorespiratory system, the optimization of the wheelchair geometry, based on functional characteristics of the user, appears beneficial.

Adult↗

PubMed1989

Wheelchair propulsion technique at different speeds.

To study wheelchair propulsion technique at different speeds, five well-trained subjects propelled a wheelchair on a treadmill. Measurements were made at four belt speeds of 0.56-1.39 m/s and against slopes of 2 and 3 degrees. Cardiorespiratory data were collected. Three consecutive strokes were filmed. Using markers on subject, wheelchair and treadmill frame a kinematic analysis was performed. Considerable inter-individual differences in propulsion style were found, but also general changes relative to speed occurred in the group as a whole. Cycle time decreased with speed, predominantly as the result of a shorter push time while push angle remained constant and the movement ranges of trunk and arms shifted with speed. It is concluded that despite different propulsion styles, general and continuous adaptations to speed changes occurred, mainly by flexion of the trunk and arms.

Acceleration↗

PubMed1989

The effect of rear wheel camber in manual wheelchair propulsion.

Eight nonimpaired subjects participated in a wheelchair exercise test using a motor-driven treadmill in order to study the effect of rear wheel camber on wheelchair ambulation. The test consisted of four runs with rear wheels in 0, 3, 6, and 9 degrees camber at four speed steps of 2, 3, 4, and 5 km/hr. There were no significant effects upon oxygen cost, heart rate, and mechanical efficiency. The kinematic parameters of push time, push angle, and abduction showed differences between 3 and 6 degrees camber. The relationship between the findings, using surface EMG results for six shoulder muscles, is discussed. For one subject, data were extended to study the angular velocities of shoulder and elbow.

Adult↗

PubMed1989

Growth of medial gastrocnemius muscle and Achilles tendon in Wistar rats.

Dimensions, architecture, material properties and functional characteristics of medial gastrocnemius muscles and Achilles tendons of young and old Wistar rats were compared. Dimensions associated with length of the leg segment grow isometric with it. Muscle belly transsectional dimensions, volume of muscle tissue and associated functional indices increase out of proportion either with the dimensions of the limb segment or the weight of the animal. As the properties of the contractile tissue remain the same and relative proportions of tissue components alter, changes in architecture result. These are not reflected in transsection of the tendon. Functional characteristics of the muscle tendon complex can be explained by architectural or dimensional-peculiarities emerging in the complex by growth processes of which the main is that the muscle belly of this pennated muscle grows in length mainly by increments in girth of the muscle fibers proper.

Achilles Tendon↗

PubMed1988

Manual wheelchair propulsion: effects of power output on physiology and technique.

Eight wheelchair sportsmen conducted eight wheelchair exercise tests on a treadmill. Two workload strategies were followed: strategy 1--increments in speed at a constant slope and strategy 2--increments in slope at constant velocity. Thus, data on cardio-respiratory and propulsion technique parameters were obtained on two identical series of 16 speed and slope combinations. Between each two identical speed and slope combinations of strategies 1 and 2, a different workload history is apparent. A four-factor analysis of variance with repeated measures on the factors "strategy" (workload history), "speed," and "slope" was applied (P less than 0.05). No "strategy" effect was seen in the cardio-respiratory parameters (gross mechanical efficiency, ventilation, oxygen consumption, and heart rate), work/cycle, and cycle time. Thus, within the experimental set-up, workload history did not affect the parameters studied and 3-min workload periods appeared sufficiently long for experienced wheelchair users to adapt to the requirements of a given speed and slope combination. Significant effects were found on "speed," "slope," and their interaction in all parameters tested. Moreover, a comparison of two equal levels of power output, but different speed and slope, led to a significantly higher efficiency, cycle time, and work per cycle for the "low speed and high slope" combination. Push time and recovery time appeared highly dependent on speed and slope, respectively. The findings indicate that propulsion technique and cardio-respiratory parameters should not merely be studied in relation to power output, but also with respect to its constituents, speed, and slope/resistance.

Adult↗

PubMed1988

Wheelchair racing: effects of rim diameter and speed on physiology and technique.

Effects of different hand rim diameters in wheelchair racing were studied with respect to physiological and technique parameters at five speed levels (N = 8 wheelchair sportsmen). In each of five subsequent 15-min exercise tests on a treadmill, a different sized hand rim was mounted to the rear wheels (0.3, 0.35, 0.38, 0.47, 0.56 m). In each test, speed increased with 0.83 m.s-1 every 3 min, starting at 0.83 m.s-1 and ranging up to 4.17 m.s-1 (slope: 0.5 degrees). Cardiorespiratory responses (ventilation, oxygen cost, heart rate, respiratory exchange ratio, mechanical efficiency) and timing data (cycle time, push time, recovery time, push angle, and work per cycle) were obtained every 3rd min, together with the movement pattern of trunk and arm segments. Clear effects of rim diameter and speed were seen for the physiological parameters (P less than 0.05). In physiological terms, D5 appeared the least beneficial, followed by D4. Moreover, increasing rim diameter had a significant effect on movement pattern of the upper arm in the sagittal as well the frontal plane of motion. However, no timing effects were seen with changing rim diameter. On the other hand, timing parameters varied markedly with speed, whereas the segmental excursions of the upper limb did not show a "speed-effect". In general, small hand rims show lower cardiorespiratory responses. This may be related to the decreased segmental excursions of the upper limb and the lower linear hand velocity. Together with a low rolling and air drag, heart rate, and oxygen cost, these are important prerequisites in racing events.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Mechanical properties of passive rat muscle during sinusoidal stretching.

The dynamic passive response of the left gastrocnemius medialis muscle of thirty male Wistar rats was studied as a function of muscle dimensions and absolute and relative amount of connective tissue. Values of the absolute active and passive length-force curves (active force, passive force, active working range) correlated well (coefficients of correlation in a range of 0.62-0.92) with morphological variables (such as muscle optimum length, mean muscle fibre optimum length, physiological cross section, muscle weight and amount of intramuscular connective tissue). To eliminate dimensional effects the active and passive length-force curves were normalized taking maximal active twitch force and muscle optimum length as reference values (100%). The width of the normalized active length-force curve (relative active working range) was correlated negatively with muscle weight, muscle optimum length and physiological cross section. Relative amount of connective tissue and passive tension at optimum length (both independent of muscle dimensions) were positively correlated, indicating that passive muscles are stiffer when relative amount of intramuscular connective tissue is higher. Sinusoidal movements with several amplitudes and frequencies of movement were imposed on the passive gastrocnemius medialis muscle over a range of muscle lengths. In accordance with the approximately exponential increase of static passive muscle force with length, muscle length has a large influence on the shape and magnitude of the hysteresis diagrams resulting from sinusoidal movements: the value of all variables selected increases approximately exponentially with muscle length with the exception of the value of loss tangent, a factor indicating the amount of energy dissipated during each cycle relative to the amount of energy stored and released elastically. Velocity of movement has only minor influence on variables of the hysteresis diagrams as is shown by changing the frequency of movement. As loss tangent and relative amount of connective tissue did not vary with muscle dimensions in the muscles studied, it is likely that material properties of the components causing passive resistance were similar in these muscles.

Animals↗

PubMed1987

Passive resistance of the human knee: the effect of remobilization.

Changes of circumferential dimensions and passive resistance of the human knee caused by immobilization, were studied during remobilization. Patients immobilized with a long leg cast after tibial fractures or ligamentous injuries were studied immediately after removal of the cast and after mean periods of 18, 36 and 81 days of remobilization. Immobilization resulted in a decrease of circumferential dimensions. The difference in mid-thigh circumference between the immobilized and the unaffected leg was still present after 81 days of remobilization both for the patients with tibial fractures and for the remobilization both for the patients with tibial fractures and for the patients with ligamentous lesions. An increase of midpatellar circumference was present exclusively in the patients with ligamentous lesions at all four testing dates, indicating that this is an effect of the ligamentous lesion and not of immobilization per se. Variables of the hysteresis diagrams, resulting from sinusoidal movement of the knee at a range of knee angles, were used to quantify passive resistance of the knee in the flexion-extension plane (the muscles crossing the knee are inactive). Variables related to the elastic storage and release of energy, and variables related to energy dissipation were discerned. During remobilization the increased resistance to flexion (shown by the variables related to the elastic storage of energy), as found immediately after removal of the cast, disappears and the resistance becomes identical to the resistance of the unaffected leg. This may indicate a rapid readaptation of the length of ventral structures (shortened due to immobilization in a shortened position) to almost normal values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1987

The unique action of bi-articular muscles in complex movements.

Actions of muscles that pass over more than one joint are mainly described with respect to movements in the joints that are crossed. In a previous study of push-off without plantar flexion it was shown that the transformation of knee angular velocity into translation of the body is constrained by the fact that velocity difference between hip and ankle has to reach its peak value a long time before the knee is extended. The present study was meant to test the hypothesis that the action of the gastrocnemius can be understood in the light of this constraint. Vertical jumps of ten subjects were analysed cinematographically. Electromyographic signals were derived from knee extensors and plantar flexors simultaneously. The results show that the peak velocity difference between hip and ankle is reached at a mean knee angle of 132 degrees. At that instant a rapid plantar flexion starts, reinforced by a strong increase of activation of gastrocnemius. It is suggested that the bi-articular character of the gastrocnemius muscle enables the knee extensors to continue to deliver work which is transported to the ankle where it is used for plantar flexion. This optimal use of the capabilities of proximally located muscles would not be possible if man had mono-articular muscles only.

Electromyography↗