Effects of Forefoot Shoe on Knee and Ankle Loading during Running in Male Recreational Runners

Objectives: Although overuse running injury risks for the ankle and knee are high, the effect of different shoe designs on Achilles tendon force (ATF) and Patellofemoral joint contact force (PTF) loading rates are unclear. Therefore, the primary objective of this study was to compare the ATF at the ankle and the PTF and Patellofemoral joint stress force (PP) at the knee using different running shoe designs (forefoot shoes vs. normal shoes). Methods: Fourteen healthy recreational male runners were recruited to run over a force plate under two shoe conditions (forefoot shoes vs. normal shoes). Sagittal plane ankle and knee kinematics and ground reaction forces were simultaneously recorded. Ankle joint mechanics (ankle joint angle, velocity, moment and power) and the ATF were calculated. Knee joint mechanics (knee joint angle velocity, moment and power) and the PTF and PP were also calculated. Results: No significant differences were observed in the PTF, ankle plantarflexion angle, ankle dorsiflexion power, peak vertical active force, contact time and PTF between the two shoe conditions. Compared to wearing normal shoes, wearing the forefoot shoes demonstrated that the ankle dorsiflexion angle, knee flexion velocity, ankle dorsiflexion moment extension, knee extension moment, knee extension power, knee flexion power and the peak patellofemoral contact stress were significantly reduced. However, the ankle dorsiflexion velocity, ankle plantarflexion velocity, ankle plantarflexion moment and Achilles tendons force increased significantly. Conclusions: These findings suggest that wearing forefoot shoes significantly decreases the patellofemoral joint stress by reducing the moment of knee extension, however the shoes increased the ankle plantarflexion moment and ATF force. The forefoot shoes effectively reduced the load on the patellofemoral joint during the stance phase of running. However, it is not recommended for new and novice runners and patients with Achilles tendon injuries to wear forefoot shoes.     

A laboratory captured ‘giving way’ episode during a single-leg landing task in an individual with unilateral chronic ankle instability

An episode of ‘giving way’ at the ankle is described as excessive inversion of the rearfoot that does not result in an acute ankle sprain and is a unique feature associated with chronic ankle instability (CAI). Limited data currently exists describing the preparatory movement patterns and those that occur during an episode of ‘giving way. Therefore, this case report describes the movement patterns and the forces generated during an unintentional ‘giving way’ captured while an individual with unilateral CAI was performing a single-leg landing task in a research laboratory. The participant completed five single-leg landing trials for both limbs. 3D lower extremity kinematics and kinetics for the sagittal and frontal plane were extracted from 200 ms before and after initial contact (IC). Relative to the affected and un-affected single-leg landing trials, the ‘giving way’ episode was characterized by an increase in plantarflexion and hip extension moments before and after IC. The plantarflexion deviation dissipated (50 ms post-IC) and was followed by excessive ankle inversion. The ankle began to plantarflex again (150 ms post-IC) and the knee extended (50 ms post-IC) and adducted (100 ms post-IC). As a result, the ankle inversion angle plateaued at 150 ms post-IC. Furthermore, large sagittal plane internal joint moments were observed. In the frontal plane, the ‘giving way’ trial generated a large inversion joint moment which was counteracted by a large internal eversion joint moment. The observed plantarflexion and knee extension and adduction after initial contact likely contributed to preventing the ankle from continuing to invert and avoid an ankle sprain.     

A mechanical supination sprain simulator for studying ankle supination sprain kinematics

This study presents a free-fall mechanical supination sprain simulator for evaluating the ankle joint kinematics during a simulated ankle supination sprain injury. The device allows the foot to be in an anatomical position before the sudden motion, and also allows different degrees of supination, or a combination of inversion and plantarflexion. Five subjects performed simulated supination sprain trials in five different supination angles. Ankle motion was captured by a motion analysis system, and the ankle kinematics were reported in plantarflexion/dorsiflexion, inversion/eversion and internal/external rotation planes. Results showed that all sprain motions were not pure single-plane motions but were accompanied by motion in other two planes, therefore, different degrees of supination were achieved. The presented sprain simulator allows a more comprehensive study of the kinematics of ankle sprain when compared with some previous laboratory research designs.     

Quantifying plyometric intensity via rate of force development, knee joint, and ground reaction forces

Because the intensity of plyometric exercises usually is based simply upon anecdotal recommendations rather than empirical evidence, this study sought to quantify a variety of these exercises based on forces placed upon the knee. Six National Collegiate Athletic Association Division I athletes who routinely trained with plyometric exercises performed depth jumps from 46 and 61 cm, a pike jump, tuck jump, single-leg jump, countermovement jump, squat jump, and a squat jump holding dumbbells equal to 30% of 1 repetition maximum (RM). Ground reaction forces obtained via an AMTI force plate and video analysis of markers placed on the left hip, knee, lateral malleolus, and fifth metatarsal were used to estimate rate of eccentric force development (E-RFD), peak ground reaction forces (GRF), ground reaction forces relative to body weight (GRF/BW), knee joint reaction forces (K-JRF), and knee joint reaction forces relative to body weight (K-JRF/BW) for each plyometric exercise. One-way repeated measures analysis of variance indicated that E-RFD, K-JRF, and K-JRF/BW were different across the conditions (p < 0.05), but peak GRF and GRF/BW were not (p > 0.05). Results indicate that there are quantitative differences between plyometric exercises in the rate of force development during landing and the forces placed on the knee, though peak GRF forces associated with landing may not differ.     

Effects of inversion perturbation after step down on the latency of the peroneus longus and peroneus brevis

The purpose of this investigation was to determine the effect of different types of ankle sprains on the response latency of the peroneus longus and peroneus brevis to an inversion perturbation, as well as the time to complete the perturbation (time to maximum inversion). To create a forced inversion moment of the ankle, an outer sole with fulcrum was used to cause 25 degrees of inversion at the ankle upon landing from a 27 cm step-down task. Forty participants completed the study: 15 participants had no history of any ankle sprain, 15 participants had a history of a lateral ankle sprain, and 10 participants had a history of a high ankle sprain. There was not a significant difference between the injury groups for the latency measurements or the time to maximum inversion. These findings indicate that a previous lateral ankle sprain or high ankle sprain does not affect the latency of the peroneal muscles or the time to complete the inversion range of motion.     

Correlation between ground reaction force and tibial acceleration in vertical jumping

Modern electronics allow for the unobtrusive measurement of accelerations outside the laboratory using wireless sensor nodes. The ability to accurately measure joint accelerations under unrestricted conditions, and to correlate them with jump height and landing force, could provide important data to better understand joint mechanics subject to real-life conditions. This study investigates the correlation between peak vertical ground reaction forces, as measured by a force plate, and tibial axial accelerations during free vertical jumping. The jump heights calculated from force-plate data and accelerometer measurements are also compared. For six male subjects participating in this study, the average coefficient of determination between peak ground reaction force and peak tibial axial acceleration is found to be 0.81. The coefficient of determination between jump height calculated using force plate and accelerometer data is 0.88. Data show that the landing forces could be as high as 8 body weights of the jumper. The measured peak tibial accelerations ranged up to 42 g. Jump heights calculated from force plate and accelerometer sensors data differed by less than 2.5 cm. It is found that both impact accelerations and landing forces are only weakly correlated with jump height (the average coefficient of determination is 0.12). This study shows that unobtrusive accelerometers can be used to determine the ground reaction forces experienced in a jump landing. Whereas the device also permitted an accurate determination of jump height, there was no correlation between peak ground reaction force and jump height.     

The effects of articulated figure skates on jump landing forces

Lower extremity injuries in figure skating have long been linked to skating boot stiffness, and recent increases in jump practice time may be influencing the frequency and seriousness of these injuries. It is hypothesized that stiff boots compromise skaters' abilities to attenuate jump landing forces. Decreasing boot stiffness by adding an articulation at the ankle may reduce the rate and magnitude of landing forces. Prototype articulated figure skating boots were tested in this study to determine their effectiveness in enabling skaters to land with lower peak impact forces. Nine competitive figure skaters, who trained in standard boots and subsequently in articulated boots, performed off-ice jump simulations and on-ice axels, double toe loops, and double axels. Analysis of the off-ice simulations showed decreases in peak heel force and loading rate with use of the articulated boot, although the exact kinematic mechanisms responsible for these decreases are still unclear. Analysis of the on-ice jumps revealed few kinematic differences between boot types, implying that the skaters did not use the articulation. Greater adaptation and training time is likely needed for the results seen off-ice to transfer to difficult on-ice jumps.     

Mobility of the subtalar joint in the intact ankle complex

A previous study by these authors showed that the calcaneus follows a unique path of unresisted coupled motion relative to the tibia during passive flexion and that most of this motion occurred at the ankle level. Subtalar motion in the intact ankle complex was observed only when perturbations from this path were induced by the application of force to the calcaneus. Relative motion of the bones of the ankle complex was tracked by stereophotogrammetry in seven specimens. Anatomical landmarks, reference frames and joint angles were defined by standard techniques. Sequential moments were applied to the calcaneus about the long axis of the tibia. Measured movements at subtalar level demonstrated plantarflexion coupled to supination and internal rotation (inversion) and dorsiflexion coupled to pronation and external rotation (eversion). These movements were resisted and were fully recovered when the external load was removed. Subtalar motion diminished as the ankle approached maximal dorsi- and plantarflexion. Two clearly distinguished mean axes of rotation were observed for inversion and eversion runs. The axes of inversion and eversion of the subtalar complex changed orientation along a preferred and repeatable path. The subtalar joint complex occupied only a single stable position in the unloaded state and with no range of unresisted motion. It is inferred that mobility was possible only by the stretching and lengthening of the ligaments and the indentation of the articular surfaces, requiring the application of loads. The subtalar joint complex behaves like a flexible structure.     

Influence of landing on the supination and pronation in the foot joint

The purpose of this study was to measure the changes of supination and pronation in the ankle joint at landing to quantify the influence of shock attenuation during landing. The subjects did two different motions, jumping down on the force platform from posterior and lateral views. The rear view of single foot contact in a jump from height of 30 and 60 cm showed a landing on the inside of the rear part of the foot (pronation) followed after about 0.03 sec by a rolling outward of the foot (supination). The variables describing changes in three angles of the ankle joint indicated that the standing position was more sensitive on the pronation and supination during ground contact.     

Foot modeling affects ankle sagittal plane kinematics during jump-landing

The foot-ankle complex is a key-element to mitigate impact forces during jump-landing activities. Biomechanical studies commonly model the foot as a single-segment, which can provide different ankle kinematics compared to a multi-segmented model. Also, it can neglect intersegmental kinematics of the foot-ankle joints, such as the hindfoot-tibia, forefoot-hindfoot, and hallux-forefoot joints, that are used during jump-landing activities. The purpose of this short communication was to compare ankle kinematics between a three- and single-segmented foot models, during forward and lateral single-leg jump-landings. Marker trajectories and synchronized ground reaction forces of 30 participants were collected using motion capture and a force plate, during multidirectional single-leg jump-landings. Ankle kinematics were computed using a three- (hindfoot-tibia) and a single-segmented (ankle) foot models, at initial contact (IC), peak vertical ground reaction force (PvGRF) and peak knee flexion (PKF). Repeated measures ANOVAs were conducted (p < 0.05). The findings of this study showed that during lateral and forward jump-landing directions, the three-segmented foot model exhibited lower hindfoot-tibia dorsiflexion angles (PvGRF and PKF, p < 0.001) and excursions (sagittal: p < 0.001; frontal: p < 0.05) during the weightbearing acceptance phase than the single-segmented model. Overall, the two foot models provided distinctive sagittal ankle kinematics, with lower magnitudes in the hindfoot-tibia of the three-segmented foot. Furthermore, the three-segmented foot model may provide additional and representative kinematic data of the ankle and foot joints, to better comprehend its function, particularly in populations whose foot-ankle complex plays an important role (e.g., dancers).     

Mechanomyogram amplitude vs. isometric ankle plantarflexion torque of human medial gastrocnemius muscle at different ankle joint angles

The purpose of this study was to investigate the influence of changes in ankle joint angle on the mechanomyogram (MMG) amplitude of the human medial gastrocnemius (MG) muscle during voluntary isometric plantarflexion contractions. Ten healthy individuals were asked to perform voluntary isometric contractions at six different contraction intensities (from 10% to 100%) and at three different ankle joint angles (plantarflexion of 26°; plantarflexion of 10°; dorsiflexion of 3°). MMG signals were recorded from the surface over the MG muscle, using a 3-axis accelerometer. The relations between root mean square (RMS) MMG and isometric plantarflexion torque at different ankle joint angles were characterized to evaluate the effects of altered muscle mechanical properties on RMS MMG.We found that the relation between RMS MMG and plantarflexion torque is changed at different ankle joint angles: RMS MMG increases monotonically with increasing the plantarflexion torque but decreases as the ankle joint became dorsiflexed. Moreover, RMS MMG shows a negative correlation with muscle length, with passive torque, and with maximum voluntary torque, which were all changed significantly at different ankle joint angles.Our findings demonstrate the potential effects of changing muscle mechanical properties on muscle vibration amplitude. Future studies are required to explore the major sources of this muscle vibration from the perspective of muscle mechanics and muscle activation level, attributable to changes in the neural command.     

Effects of gender and foot-landing techniques on lower extremity kinematics during drop-jump landings

The purpose of this study was to assess kinematic lower extremity motion patterns (hip flexion, knee flexion, knee valgus, and ankle dorsiflexion) during various foot-landing techniques (self-preferred, forefoot, and rear foot) between genders. 3-D kinematics were collected on 50 (25 male and 25 female) college-age recreational athletes selected from a sample of convenience. Separate repeated-measures ANOVAs were used to analyze each variable at three time instants (initial contact, peak vertical ground reaction force, and maximum knee flexion angle). There were no significant differences found between genders at the three instants for each variable. At initial contact, the forefoot technique (35.79 degrees +/- 11.78 degrees ) resulted in significantly (p = .001) less hip flexion than did the self-preferred (41.25 degrees +/- 12.89 degrees ) and rear foot (43.15 degrees +/- 11.77 degrees ) techniques. At peak vertical ground reaction force, the rear foot technique (26.77 degrees +/- 9.49 degrees ) presented significantly lower (p = .001) knee flexion angles as compared with forefoot (58.77 degrees +/- 20.00 degrees ) and self-preferred (54.21 degrees +/- 23.78 degrees ) techniques. A significant difference for knee valgus angles (p = .001) was also found between landing techniques at peak vertical ground reaction force. The self-preferred (4.12 degrees +/- 7.51 degrees ) and forefoot (4.97 degrees +/- 7.90 degrees ) techniques presented greater knee varus angles as compared with the rear foot technique (0.08 degrees +/- 6.52 degrees ). The rear foot technique created more ankle dorsiflexion and less knee flexion than did the other techniques. The lack of gender differences can mean that lower extremity injuries (e.g., ACL tears) may not be related solely to gender but may instead be associated with the landing technique used and, consequently, the way each individual absorbs jump-landing energy.     

Identification of feigned ankle plantar and dorsiflexors weakness in normal subjects

Based on the limited ability of the human being to voluntarily control submaximal eccentric exertions, previous studies have indicated that isokinetic testing with a combined concentric–eccentric exercise protocol could effectively identify submaximal (feigned) effort in various muscle groups by showing an abnormally high eccentric to concentric ratio (ECR). The objective of this study was to determine the validity and accuracy of an ECR-based isokinetic test in identifying feigned ankle weakness. Thirty-eight normal subjects performed maximal and feigned efforts in an isokinetic concentric and eccentric ankle plantar- and dorsiflexion protocol with two different velocities, 30 and 120° s⁻¹. The isokinetic parameters ECR and the derivatives DEC (difference between ECR at high speed of motion and ECR at low speed of motion) and SEC (sum of ECR at high speed of motion plus the ratio between eccentric peak torque at high speed and concentric peak torque at low speed) were calculated. The ECR, DEC and SEC scores were significantly greater in feigned conditions for ankle plantarflexion, but not for dorsiflexion. Using optimal cutoff scores based on 99% tolerance intervals, it was disclosed that the most efficient parameter was the SEC, identifying 92% of the feigned efforts with 99% confidence, indicating that the ankle plantarflexors are less controllable in fast eccentric conditions than that in concentric conditions. The ECR-based parameters are valid for effectively identifying feigned plantarflexion effort with high accuracy, but do not allow the detection of feigned dorsiflexion weakness.     

The validation of a portable force plate for measuring force-time data during jumping and landing tasks

The purpose of this study was to determine the reliability and validity of a portable force plate when analyzing jumping and landing tasks. Subjects performed 3 drop vertical jumps and 3 drop landings on both a standard strain gauge laboratory force plate and a portable force plate. In contrast to typical laboratory installed force plates, the portable 6-component force plate can be easily transported and used onsite at various training or data collection sites and incorporates Hall effect technology. The measured parameters included maximum force and time to maximum force for initial stance of the both tests, maximum takeoff force, and time to maximum takeoff force for the drop vertical jump. The Pearson correlation coefficients for the drop landing and the drop vertical jump for maximum force (r = 0.942, r = 0.940), time to maximum force (r = 0.891, r = 0.920) and for drop jump maximum jumping force (r = 0.971), and time to maximum takeoff force (r = 0.917) were all high and indicate that the force data collected by a resistor-type portable force plate provide similar measures to a standard strain-gauge laboratory force plate. Additionally, the within session reliability of the drop landing and the drop vertical jump measured by the portable force plate showed high interclass correlation coefficients for examined variables of 0.979 and 9.67 for maximum landing force and 0.917 and 0.920 for time to maximum landing force, respectively. The interclass correlation coefficients for the maximum takeoff force and time to maximum takeoff force during the drop vertical jump were 0.991 and 0.86. The results indicate the force and timing measurements from the portable force plate were both valid and reliable. Use of the portable force plate may facilitate methods of force measurement that can be applied out into the field and therefore a valuable tool for on site landing and jump force measurements in a variety of settings for large numbers of subjects.     

Pre-impact lower extremity posture and brake pedal force predict foot and ankle forces during an automobile collision

BACKGROUND: The purpose of this study was to determine how a driver's foot and ankle forces during a frontal vehicle collision depend on initial lower extremity posture and brake pedal force. METHOD OF APPROACH: A 2D musculoskeletal model with seven segments and six right-side muscle groups was used. A simulation of a three-second braking task found 3647 sets of muscle activation levels that resulted in stable braking postures with realistic pedal force. These activation patterns were then used in impact simulations where vehicle deceleration was applied and driver movements and foot and ankle forces were simulated. Peak rearfoot ground reaction force (F(RF)), peak Achilles tendon force (FAT), peak calcaneal force (F(CF)) and peak ankle joint force (F(AJ)) were calculated. RESULTS: Peak forces during the impact simulation were 476 +/- 687 N (F(RF)), 2934 +/- 944 N (F(CF)) and 2449 +/- 918 N (F(AJ)). Many simulations resulted in force levels that could cause fractures. Multivariate quadratic regression determined that the pre-impact brake pedal force (PF), knee angle (KA) and heel distance (HD) explained 72% of the variance in peak FRF, 62% in peak F(CF) and 73% in peak F(AJ). CONCLUSIONS: Foot and ankle forces during a collision depend on initial posture and pedal force. Braking postures with increased knee flexion, while keeping the seat position fixed, are associated with higher foot and ankle forces during a collision.     

Predictability of in vivo changes in pennation angle of human tibialis anterior muscle from rest to maximum isometric dorsiflexion

The aim of this study was to assess the predictability of in vivo, ultrasound-based changes in human tibialis anterior (TA) pennation angle from rest to maximum isometric dorsiflexion (MVC) using a planimetric model assuming constant thickness between aponeuroses and straight muscle fibres. Sagittal sonographs of TA were taken in six males at ankle angles of -15 degrees (dorsiflexion direction), 0 degrees (neutral position), + 15 (plantarflexion direction) and + 30 degrees both at rest and during dorsiflexor MVC trials performed on an isokinetic dynamometer. At all four ankle angles scans were taken from the TA proximal, central and distal regions. TA architecture did not differ (P > 0.05) neither between its two unipennate parts nor along the scanned regions over its length at a given ankle angle and state of contraction. Comparing MVC with rest at any given ankle angle, pennation angle was larger (62-71%, P < 0.01), fibre length smaller (37-40%, P < 0.01) and muscle thickness unchanged (P > 0.05). The model used estimated accurately (P > 0.05) changes in TA pennation angle occurring in the transition from rest to MVC and therefore its use is encouraged for estimating the isometric TA ankle moment and force generating capacity using musculoskeletal modelling.     

The correlation of segment accelerations and impact forces with knee angle in jump landing

Impact forces and shock deceleration during jumping and running have been associated with various knee injury etiologies. This study investigates the influence of jump height and knee contact angle on peak ground reaction force and segment axial accelerations. Ground reaction force, segment axial acceleration, and knee angles were measured for 6 male subjects during vertical jumping. A simple spring-mass model is used to predict the landing stiffness at impact as a function of (1) jump height, (2) peak impact force, (3) peak tibial axial acceleration, (4) peak thigh axial acceleration, and (5) peak trunk axial acceleration. Using a nonlinear least square fit, a strong (r = 0.86) and significant (p < or = 0.05) correlation was found between knee contact angle and stiffness calculated using the peak impact force and jump height. The same model also showed that the correlation was strong (r = 0.81) and significant (p < or = 0.05) between knee contact angle and stiffness calculated from the peak trunk axial accelerations. The correlation was weaker for the peak thigh (r = 0.71) and tibial (r = 0.45) axial accelerations. Using the peak force but neglecting jump height in the model, produces significantly worse correlation (r = 0.58). It was concluded that knee contact angle significantly influences both peak ground reaction forces and segment accelerations. However, owing to the nonlinear relationship, peak forces and segment accelerations change more rapidly at smaller knee flexion angles (i.e., close to full extension) than at greater knee flexion angles.     

Articular contact at the tibiotalar joint in passive flexion

The knowledge of the contact areas at the tibiotalar articulating surfaces during passive flexion is fundamental for the understanding of ankle joint mobility. Traditional contact area reports are limited by the invasive measuring techniques used and by the complicated loading conditions applied. In the present study, passive flexion tests were performed on three anatomical preparations from lower leg amputation. Roentgen Stereophotogrammetric Analysis was used to accurately reconstruct the position of the tibia and the talus at a number of unconstrained flexion positions. A large number of points was collected on the surface of the tibial mortise and on the trochlea tali by a 3-D digitiser. Articular surfaces were modelled by thin plate splines approximating these points. Relative positions of these surfaces in all the flexion positions were obtained from corresponding bone position data. A distance threshold was chosen to define contact areas. A consistent pattern of contact was found on the articulating surfaces. The area moved anteriorly on both articular surfaces with dorsiflexion. The average position of the contact area centroid along the tibial mortise at maximum plantarflexion and at maximum dorsiflexion was respectively 58% posterior and 40% anterior of the entire antero-posterior length. For increasing dorsiflexion, the contact area moved from medial to lateral in all the specimens.     

A closed-loop cadaveric foot and ankle loading model

Investigations of human foot and ankle biomechanics rely chiefly on cadaver experiments. The application of proper force magnitudes to the cadaver foot and ankle is essential to obtain valid biomechanical data. Data for external ground reaction forces are readily available from human motion analysis. However, determining appropriate forces for extrinsic foot and ankle muscles is more problematic. A common approach is the estimation of forces from muscle physiological cross-sectional areas and electromyographic data. We have developed a novel approach for loading the Achilles and posterior tibialis tendons that does not prescribe predetermined muscle forces. For our loading model, these muscle forces are determined experimentally using independent plantarflexion and inversion angle feedback control. The independent (input) parameters -- calcaneus plantarflexion, calcaneus inversion, ground reaction forces, and peroneus forces -- are specified. The dependent (output) parameters -- Achilles force, posterior tibialis force, joint motion, and spring ligament strain -- are functions of the independent parameters and the kinematics of the foot and ankle. We have investigated the performance of our model for a single, clinically relevant event during the gait cycle. The instantaneous external forces and foot orientation determined from human subjects in a motion analysis laboratory were simulated in vitro using closed-loop feedback control. Compared to muscle force estimates based on physiological cross-sectional area data and EMG activity at 40% of the gait cycle, the posterior tibialis force and Achilles force required when using position feedback control were greater.