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Biomedical subjects

B M Nigg

Publications and source records attributed to B M Nigg.

At least 37 records · Page 2Linked to original sources
PubMed2000

Energy aspects associated with sport shoes.

Sport shoes can have an influence on the energetics of human movement. The two main aspects where sport shoes can play a role are in maximizing the energy which is returned to the athlete and minimizing the energy which is lost by the athlete. Maximum values of energy storage in a shoe sole are on the order of 10 J. However, not all of this energy is returned to the athlete as shoe midsoles lose approximately 30% of the energy input. Depending on the movement, energy return sometimes occurs at the wrong time, frequency, location and in the wrong direction which compromises the ultimate influence on improving performance. As a result, the actual influence that energy return has on performance is probably minimal. Examples of the strategy to minimize energy loss include (1) reducing the mass of the shoe, (2) using appropriate midsole materials which dissipate unwanted vibrations, (3) implementing constructions which improve the stability of the ankle joint and (4) increasing the bending stiffness of shoe midsoles which reduces the energy lost at the metatarso-phalangeal joint. Energy that has not been lost for tasks not directly related to the actual performance may be applied to the movement and may result in an increase of athletic performance. We propose that athletic footwear can have a much larger influence on performance by minimizing the energy which is lost as opposed to maximizing the energy which is returned.

Ankle Joint↗
PubMed2000

The effects of ankle compliance and flexibility on ankle sprains.

PURPOSE: The goal of this study was to examine the influence of changes in subtalar joint flexibility and compliance on ankle sprain occurrence. METHODS: Muscle model driven simulations of 10 subjects performing the landing phase of a side-shuffle movement were performed. The passive flexibility or compliance of the subtalar joint was varied, and each subject-specific simulation was exposed to a set of perturbed floor conditions. RESULTS: Increases in flexibility and compliance both led to an increase in the occurrence of excessive supination, while changes in flexibility had a greater influence. Changes in flexibility or compliance caused only small changes in the occurrence of excessive supination torques. CONCLUSION: These results suggest that increased mechanical laxity does not directly cause an increase in sprain occurrence during side-shuffle movements.

Ankle Injuries↗
PubMed2000

Influence of midsole bending stiffness on joint energy and jump height performance.

PURPOSE: A substantial amount of rotational energy is lost at the metatarsophalangeal joint during running and jumping. We hypothesized that the lost energy could be decreased by increasing the bending stiffness of shoe midsoles. The purposes of this investigation were to determine the influence of stiff shoe midsoles on changes in lower extremity joint power during running and jumping and to determine the influence of stiff shoe midsoles on vertical jump performance. METHODS: Carbon fiber plates were inserted into shoe midsoles and data were collected on five subjects during running and vertical jumping. RESULTS: The data showed that energy generation and absorption at each of the ankle, knee, and hip joints was not influenced by the stiffness of the shoe midsole. The stiff shoes with the carbon fiber plates did not increase the amount of energy stored and reused at the metatarsophalangeal joint; however, they reduced the amount of energy lost at this joint during both running and jumping. Vertical jump height was significantly higher (average, 1.7 cm for a group of 25 subjects) while wearing the stiff shoes. CONCLUSIONS: Increasing the bending stiffness of the metatarsophalangeal joint reduced the amount of energy lost at that joint and resulted in a corresponding improvement of performance.

Adult↗
PubMed2000

Movement coupling at the ankle during the stance phase of running.

The purpose of this study was to quantify movement coupling at the ankle during the stance phase of running using bone-mounted markers. Intracortical bone pins with reflective marker triads were inserted under standard local anaesthesia into the calcaneus and the tibia of five healthy male subjects. The three-dimensional rotations were determined using a joint coordinate system approach. Movement coupling was observed in all test subjects and occurred in phases with considerable individual differences. Between the shoe and the calcaneus coupling increased after midstance which suggested that the test shoes provided more coupling for inversion than for eversion. Movement coupling between calcaneus and tibia was higher in the first phase (from heel strike to midstance) compared with the second phase (from midstance to take-off). This finding is in contrast to previous in-vitro studies but may be explained by the higher vertical loads of the present in-vivo study. Thus, movement coupling measured at the bone level changed throughout the stance phase of running and was found to be far more complex than a simple mitered joint or universal joint model.

Adult↗
PubMed2000

The effect of axial load on the in vivo anterior drawer test of the ankle joint complex.

The anterior drawer test is commonly used in the diagnosis of ankle joint mechanical instability. However, the effect of axial load on the anterior drawer test has not been examined in vivo. The purpose of the study was to assess the effect of axial load on passive anterior instability, and on the diagnostic measurement of the anterior drawer instability of the ankle joint complex. A total of 21 subjects with various degrees of ankle sprains were tested on a device that could continuously record applied anterior force and the resultant displacement of the rear-foot. Anterior drawer flexibility of the ankle joint complex in a neutral dorsi/plantar flexion position was quantified on both feet for all subjects without and with an axial load (385 N). Flexibility of the ankle joint complex in anterior drawer was defined as the slope of a linear load-displacement curve (which fitted test data with high correlation coefficients (r>0.991)). With axial load, anterior drawer flexibility was significantly reduced by 28.8% compared to that without axial load. The difference in anterior drawer flexibility between injured and intact ankles significantly decreased with axial load. An axial load increased the stability of ankle joint complex. However, axial load reduced the sensitivity of anterior drawer test to mechanical instability of the ankle joint complex.

Adult↗
PubMed2000

Influence of foot, leg and shoe characteristics on subjective comfort.

The purpose of this study was to determine the relationships between foot and leg characteristics, shoe characteristics, and the short-term subjective comfort of three different pairs of athletic shoes. Static measurements of foot dimension and leg angles were taken from eighteen subjects. Subjects rated the comfort of three different athletic shoes for standing, walking and running. The shoes were quantified by internal dimensions, hardness, flexibility and torsional stiffness. Average comfort ratings decreased from standing to walking to running. One shoe seemed suited for only a small group of subjects. In contrast, another shoe was generally comfortable for a large group. Skeletal alignment, specifically eversion angle, was related to comfort for one shoe. Therefore, fit of the shoe is not sufficient for comfort. Skeletal alignment, shoe torsional stiffness and cushioning seem to be mechanical variables which may be important for comfort.

Anthropometry↗
PubMed1999

The effect of muscle stiffness and damping on simulated impact force peaks during running.

It has been frequently reported that vertical impact force peaks during running change only minimally when changing the midsole hardness of running shoes. However, the underlying mechanism for these experimental observations is not well understood. An athlete has various possibilities to influence external and internal forces during ground contact (e.g. landing velocity, geometrical alignment, muscle tuning, etc.). The purpose of this study was to discuss one possible strategy to influence external impact forces acting on the athlete's body during running, the strategy to change muscle activity (muscle tuning). The human body was modeled as a simplified mass-spring-damper system. The model included masses of the upper and the lower bodies with each part of the body represented by a rigid and a non-rigid wobbling mass. The influence of mechanical properties of the human body on the vertical impact force peak was examined by varying the spring constants and damping coefficients of the spring-damper units that connected the various masses. Two types of shoe soles were modeled using a non-linear force deformation model with two sets of parameters based on the force-deformation curves of pendulum impact experiments. The simulated results showed that the regulation of the mechanical coupling of rigid and wobbling masses of the human body had an influence on the magnitude of the vertical impact force, but not on its loading rate. It was possible to produce the same impact force peaks altering specific mechanical properties of the system for a soft and a hard shoe sole. This regulation can be achieved through changes of joint angles, changes in joint angular velocities and/or changes in muscle activation levels in the lower extremity. Therefore, it has been concluded that changes in muscle activity (muscle tuning) can be used as a possible strategy to affect vertical impact force peaks during running.

Elasticity↗
PubMed1999

Quantifying a relationship between tactile and vibration sensitivity of the human foot with plantar pressure distributions during gait.

OBJECTIVE: To quantify the relationship between the tactile and vibration sensitivity thresholds of the sole of the human foot with plantar pressure distribution while walking and running. DESIGN: Cross-sectional study performed in a laboratory setting. BACKGROUND: Results of previous studies of human locomotion have identified potentially dangerous variations in locomotion patterns. A common approach to manage these variations is with the use of orthotics. Individual responses to differences in the construction and shape of orthotics cannot be fully explained with a mechanical model. It has been suggested that sensory feedback from the receptors in the feet may play an important role in regulating gait patterns. METHODS: Fifteen subjects were recruited for this study. Pressure (tactile) and vibration thresholds were determined from each subject. Plantar pressure distributions were obtained while walking at 1.5 m s(-1) and running at 3.5 m s(-1). Sensitivity measurements were correlated to pressure measurements under the foot. RESULTS: Significant negative correlation exists between the vibration threshold of the hallux at 125 Hz and peak pressures under the hallux while walking (P=0.02) and running (P=0.01). A significant negative relationship was shown between the foot mean vibration threshold at 125 Hz with peak force during running (P=0.038). A similar trend was seen at the heel, lateral arch and first metatarsal head. CONCLUSIONS: The results from this study support recent hypotheses that suggest that the body can detect and respond to external stimuli. The relationship between plantar sensitivity and peak pressures at the hallux, and the relationship between sensitivity to higher frequency vibrations and peak force during running suggests that neurological feedback should be incorporated in to any model that attempts to explain gait patterns. RELEVANCE: It is suggested that the body is able to detect small biomechanical changes in the external environment and alter gait patterns as a defensive mechanism. Understanding the relationship between neural feedback and gait patterns will help in the development of criteria for the proper application of inserts, and the prevention of lower extremity injuries.

Adult↗
PubMed1999

Relative forefoot abduction and its relationship to foot length in vitro.

BACKGROUND: The human foot is often modelled as a rigid body in gait analysis. A more realistic model separates this segment into a forefoot and rearfoot. However, no three-dimensional data has been published on dynamic relative ab-adduction between these segments, and how this impacts changes in foot shape. OBJECTIVE: The purpose was to quantify three-dimensionally forefoot ab-adduction relative to the rearfoot in vitro, and to determine how forefoot ab-adduction affects foot length. METHODS: Video data were collected from reflective marker triads affixed to the ends of Steinmann pins drilled into the tibia, calcaneus, cuboid, and the first and fifth metatarsal bones. Medial and lateral foot length and forefoot ab-adduction relative to the rearfoot were calculated under two axial tibial loads (200 N, 600 N) and two input motions (dorsi-plantarflexion, internal-external tibial rotation). RESULTS: It was found that patterns of change for each variable were dependent on the degree of rigidity of the foot. Relative forefoot ab-adduction values ranged from 4.4 degrees of adduction to 1.7 degrees of abduction. Medial foot length values changed +/- 0.8 mm (+/- 0.5%) and lateral foot length values changed +/- 0.5 mm (+/- 0.3%). Medial foot length was correlated positively with relative forefoot abduction, and external tibial rotation was correlated positively with relative forefoot adduction.

Anthropometry↗
PubMed1999

An analysis of hip joint loading during walking, running, and skiing.

PURPOSE: It was the purpose of this study to investigate loading of the hip joint during various skiing activities and to compare the results with walking and running. The results are relevant to determine which skiing activities can be recommended for patients after total hip replacement. METHODS: Nine male subjects were instrumented with a 12-channel accelerometer system mounted on the upper body. Data were collected during walking, running, and six skiing activities and used as input for an inverse dynamic analysis that resulted in the time histories of the intersegmental force and moment at the supporting hip joint. Joint contact force was computed using a simple muscle model. Peak values were determined, averaged over all loading cycles, and compared between activities. RESULTS: Intersegmental force, indicating the influence of upper body weight and accelerations, was highest during running. Intersegmental moments were highest during the alpine skiing activities and indicated large extensor muscle forces at the hip joint. The peak joint contact force during walking at 1.5 m x s(-1) was 2.5+/-0.3 times body weight (BW). Running at 3.5 m x s(-1) produced a joint contact force of 5.2+/-0.4 BW during the push-off phase. Joint contact forces during four different alpine skiing conditions ranged from 4.1+/-0.6 BW (long turns, flat slope) to 7.8+/-1.5 BW (short turns, steep slope). Cross-country skiing had lower hip joint loading than running but higher than walking: 4.0+/-1.1 BW for classical technique and 4.6+/-0.6 BW for skating technique. CONCLUSIONS: Assuming that walking is a "safe" activity for a hip prosthetic patient, controlled alpine skiing and cross-country skiing appear relatively safe with respect to the magnitude of loading. However, the skiing activities showed considerably higher mediolateral and anterior-posterior forces than walking. Mechanical testing of prosthetic devices with loading conditions specific to these activities is needed to assess the effect of these force components on hip prostheses and to allow interpretation with respect to potential effects of skiing for a hip prosthetic patient.

Adult↗
PubMed1999

Shoe inserts and orthotics for sport and physical activities.

The purposes of this paper were to discuss the perceived benefits of inserts and orthotics for sport activities and to propose a new concept for inserts and orthotics. There is evidence that inserts or orthotics reduce or prevent movement-related injuries. However, there is limited knowledge about the specific functioning an orthotic or insert provides. The same orthotic or insert is often proposed for different problems. Changes in skeletal movement due to inserts or orthotics seem to be small and not systematic. Based on the results of a study using bone pins, one may question the idea that a major function of orthotics or inserts consists in aligning the skeleton. Impact cushioning with shoe inserts or orthotics is typically below 10%. Such small reductions might not be important for injury reduction. It has been suggested that changes in material properties might produce adjustments in the muscular response of the locomotor system. The foot has various sensors to detect input signals with subject specific thresholds. Subjects with similar sensitivity threshold levels seem to respond in their movement pattern in a similar way. Comfort is an important variable. From a biomechanical point of view, comfort may be related to fit, additional stabilizing muscle work, fatigue, and damping of soft tissue vibrations. Based on the presented evidence, the concept of minimizing muscle work is proposed when using orthotics or inserts. A force signal acts as an input variable on the shoe. The shoe sole acts as a first filter, the insert or orthotic as a second filter, the plantar surface of the foot as a third filter for the force input signal. The filtered information is transferred to the central nervous system that provides a subject specific dynamic response. The subject performs the movement for the task at hand. For a given movement task, the skeleton has a preferred path. If an intervention supports/counteracts the preferred movement path, muscle activity can/must be reduced/increased. Based on this concept, an optimal insert or orthotic would reduce muscle activity, feel comfortable, and should increase performance.

Athletic Injuries↗
PubMed1999

Tibiotalar motion--effect of fibular displacement and deltoid ligament transection: in vitro study.

The purpose of this study was to quantify tibiotalar translation and rotation under various stages of fibular displacement and injury to the syndesmotic and deltoid ligaments. Ten unpaired specimens amputated below the knee were studied using an unconstrained testing apparatus. The specimens were moved through a dorsiflexing and plantarflexing arc of 55 degrees (20 degrees dorsiflexion and 35 degrees plantarflexion). Dorsiflexion of the intact lower leg was associated with an average of 4.2 degrees of external talar rotation, and plantarflexion was associated with an average of 1.4 degrees of internal talar rotation. Fibular osteotomy and displacement of the distal fibular fragment did not change the talar rotation significantly. Additional transection of the deltoid ligament, however, decreased external talar rotation significantly, to 1.4 degrees, and decreased talar internal rotation to 0.6 degrees. Talar shift was not affected in dorsiflexion or plantarflexion by fibular fracture, displacement of the distal fibular fragment, or transection of the deltoid ligament. These data may suggest that in dorsiflexion or plantarflexion, an intact lateral malleolus is not necessary for physiological talar tracking. They further suggest that in a fibular fracture with a significant injury to the deltoid ligament, healing of the ligament at its resting length is crucial to restoring physiological talar rotation.

Ankle Injuries↗
PubMed1998

Contribution of the lower extremity joints to mechanical energy in running vertical jumps and running long jumps.

The energy contribution of the lower extremity joints to vertical jumping and long jumping from a standing position has previously been investigated. However, the resultant joint moment contributions to vertical and long jumps performed with a running approach are unknown. Also, the contribution of the metatarsophalangeal joint to these activities has not been investigated. The objective of this study was to determine the mechanical energy contributions of the hip, knee, ankle and metatarsophalangeal joints to running long jumps and running vertical jumps. A sagittal plane analysis was performed on five male university basketball players while performing running vertical jumps and four male long jumpers while performing running long jumps. The resultant joint moment and power patterns at the ankle, knee and hip were similar to those reported in the literature for standing jumps. It appears that the movement pattern of the jumps is not influenced by an increase in horizontal velocity before take-off. The metatarsophalangeal joint was a large energy absorber and generated only a minimal amount of energy at take-off. The ankle joint was the largest energy generator and absorber for both jumps; however, it played a smaller relative role during long jumping as the energy contribution of the hip increased.

Adult↗
PubMed1998

Effect of shoe insert construction on foot and leg movement.

PURPOSE: The purpose of this study was to quantify changes in foot eversion and tibial rotation during running resulting from systematic changes of material composition of five shoe inserts of the same shape. METHODS: Tests were performed with 12 subjects. The inserts had a bilayer design using two different materials at the top and bottom of the insert. The functional kinematic variables examined in this study were the foot-leg in-eversion angle, beta, and the leg-foot tibial rotation, rho. Additionally, the subject characteristics of arch height, relative arch deformation, and active range of motion were quantified. The statistical analysis used was a two way repeated measures MANOVA (within trials and inserts). RESULTS: The average group changes resulting from the studied inserts in total shoe eversion, total foot eversion, and total internal tibial rotation were typically smaller than 1 degree when compared with the no-insert condition and were statistically not significant. The measured ranges of total foot eversion for all subjects were smallest for the softest and about twice as large for the hardest insert construction. Thus, the soft insert construction was more restrictive, forcing all feet into a similar movement pattern, whereas the harder combinations allowed for more individual variation of foot and leg movement and did not force the foot into a preset movement pattern. The individual results showed substantial differences between subjects and a trend: Subjects who generally showed a reduction of tibial rotation with all tested inserts typically had a flexible foot. However, subjects who generally showed an increase of tibial rotation typically had a stiff foot. CONCLUSIONS: The results of this study suggest that subject specific factors such as static, dynamic, and neuro-physiological characteristics of foot and leg are important to match specific feet and shoe inserts optimally.

Adult↗
PubMed1998

Pronation in runners. Implications for injuries.

In spite of some significant progress in the understanding of the biomechanics of the ankle joint complex, especially the coupling mechanism between foot and leg, various mechanisms causing overuse injuries in the lower extremities are still poorly understood. Some increased pronation of the foot is often physiological, but excessive pronation is potentially harmful. Compensatory overpronation may occur for anatomical reasons. However, not only the amount of foot eversion, but also the way this eversion is transferred into tibial rotation may be crucial to the overloading stress on the knee. In other words, the individual transfer mechanism of foot eversion into internal tibial rotation may be of some predictable value for lower extremity overloading and related injuries. Further research is necessary to improve the functional understanding of anatomical and biomechanical abnormalities and their pathological value in predicting overuse injuries.

Ankle Injuries↗
PubMed1997

A method to determine bone movement in the ankle joint complex in vitro.

An experimental set-up has been developed to quantify motion of bone structures in the ankle joint complex of human cadaver specimens under conditions approximating physiological joint loading. The device allows to load the foot/leg specimen along the axis of the tibia, and muscle forces can be simulated by clamping the extrinsic tendons of the foot. Additionally, an axial moment can be applied to the tibia. A variety of foot movements can be induced by rotating a foot plate around an arbitrary axis in the horizontal plane. The input force which produces the movement at the foot is applied to the entire sole of the foot. A forefoot fixation allows for the natural adaptation of the midfoot and hindfoot which occurs during loading of the specimen. Bone pins were placed in the tibia, talus, calcaneus and navicular, and three reflective markers were attached to each pin in order to record the bone movements with a video system. Intersegmental rotations in the talo-crural, talo-calcaneal, and talo-navicular joints were calculated in three dimensions, compared for different loading and ligament integrity conditions, and related to a functionally/anatomically described foot position. Repeated measurements of relative bone orientations indicated a reproducibility better than 2 degrees; the slope of the curves, representing the kinematic coupling, was virtually identical between repetitions. It is proposed that this method simulates multidirectional AJC compression similar to loading situations during locomotion.

Aged↗
PubMed1997

Effect of skin movement on the analysis of skeletal knee joint motion during running.

It is not known how well skin markers represent the skeletal knee joint motion during running. Hence the purpose of this investigation was to compare the skin marker derived tibiofemoral motion with the skeletal tibiofemoral motion during running. In addition to skin markers attached to the shank and thigh, triads of reflective markers were attached to bone pins inserted into the tibia and femur. Three-dimensional kinematics of the stance phase of five running trials were recorded for three subjects using high-speed cine cameras (200 Hz). The knee motion was expressed in terms of Cardan angles calculated from both the external and skeletal markers. Good agreement was present between the skin and bone marker based knee flexion/extension. For abduction/adduction and internal/external knee rotation, the difference between skeletal and external motion was large compared to the amplitude of these motions. Average errors relative to the range of motion during running stance were 21% for flexion/extension, 63% for internal/external rotation, and 70% for abduction/adduction. The errors were highly subject dependent preventing the realization of a successful correction algorithm. It was concluded that knee rotations other than flexion/extension may be affected with substantial errors when using skin markers.

Adult↗