Can orthoses and navicular drop affect foot motion patterns during running?

ObjectivesThe purpose of this study was to examine the influence of semi-rigid foot orthoses on forefoot–rearfoot joint coupling patterns in individuals with different navicular drop measures during heel–toe running.DesignTen trials were collected from twenty-three male subjects who ran slowly shod at 170 steps per minute (2.23 m/s) with a semi-rigid orthoses and without.MethodsForefoot–rearfoot coupling motions were assessed using a vector coding technique during four intervals across the first 50% of stance. Subjects were divided into two groups based on navicular drop measures. A three way ANOVA was performed to examine the interaction and main effects of stance interval, orthoses condition and navicular drop (p < 0.05).ResultsThere were no interaction effects among stance interval, orthoses condition, or navicular drop (p = 0.14) whereas an interaction effect of orthoses condition and stance interval was observed (p = 0.01; effect size = 0.74). Forefoot–rearfoot coupling motion in the no-orthoses condition increased from heel-strike to foot-flat phase at a rate faster than the orthoses condition (p = 0.02).ConclusionsFoot orthoses significantly decrease the forefoot–rearfoot joint coupling angle by reducing forefoot frontal plane motion relative to the rearfoot. Navicular drop measures did not influence joint coupling relationships between the forefoot and rearfoot during the first 50% of stance regardless of orthotic condition.     

Dose–response effects of customised foot orthoses on lower limb muscle activity and plantar pressures in pronated foot type

Customised foot orthoses (FOs) featuring extrinsic rearfoot posting are commonly prescribed for individuals with a symptomatic pronated foot type. By altering the angle of the posting it is purported that a controlled dose–response effect during the stance phase of gait can be achieved, however these biomechanical changes have yet to be characterised. Customised FOs were administered to participant groups with symptomatic pronated foot types and asymptomatic normal foot types. The electromyographic (EMG) and plantar pressure effects of varying the dose were measured. Dose was varied by changing the angle of posting from 6° lateral to 10° medial in 2° steps on customised devices produced using computer aided orthoses design software. No effects due to posting level were found for EMG variables. Significant group effects were seen with customised FOs reducing above knee muscle activity in pronated foot types compared to normal foot types (biceps femoris p = 0.022; vastus lateralis p < 0.001; vastus medialis p = 0.001). Interaction effects were seen for gastrocnemius medialis and soleus. Significant linear effects of posting level were seen for plantar pressure at the lateral rearfoot (p = 0.001), midfoot (p < 0.001) and lateral forefoot (p = 0.002). A group effect was also seen for plantar pressure at the medial heel (p = 0.009). This study provides evidence that a customised FOs can provide a dose response effect for selected plantar pressure variables, but no such effect could be identified for muscle activity. Foot type may play an important role in the effect of customised orthoses on activity of muscles above the knee.     

Effect of shoe type on plantar pressure: A gender comparison

Despite the differences in materials, racing flats have begun to be used not only for racing, but also for daily training. As there are data suggesting a gender difference in overuse injuries in runners, shoe choice may affect loading patterns during running. The purpose was to determine differences in plantar pressure between genders when running in training shoes and racing flats. In-shoe plantar pressure data were collected from 34 subjects (17m, 17f) who ran over-ground in both a racing flat and training shoe. Contact area (CA), maximum force (MF), and contact time under the entire foot and beneath eight foot regions were collected. Each variable was analyzed using a shoe by gender repeated measures ANOVA (α = 0.05). In men, MF was increased in the racing flats (p = 0.016) beneath the medial midfoot (MMF), yet was increased beneath the medial forefoot (MFF) in the training shoe (p = 0.018). Independent of gender, CA was decreased in the racing flats beneath the entire foot (p = 0.029), the MMF (p = 0.013), and the MFF (p = 0.030), and increased beneath the lateral forefoot (LFF) (p = 0.023). In the racing flats, MF was increased beneath the entire foot (p < 0.001) and the LFF (p < 0.001). Independent of the shoe, CA was decreased in men beneath the MFF (p = 0.007) and middle forefoot (p < 0.001), while MF was increased in the LFF (p = 0.002). The LFF is an area of increased stress fracture risk in men. Based on the gender differences in loading, running shoe design should be gender specific in an attempt to prevent injuries.     

Landing technique affects knee loading and position during athletic tasks

Anterior cruciate ligament (ACL) injuries have been reported to occur with the ankle in a dorsiflexed position at initial contact. Few studies have attempted to quantify the biomechanical parameters related with such landing patterns during athletic tasks.ObjectivesThe purpose of this study was to evaluate the effects that two landing techniques have in lower extremity biomechanics while performing two tasks.DesignSingle-group repeated measures design.MethodsTwenty female soccer athletes from a Division I institution performed two landing techniques (forefoot and rearfoot) during two unanticipated tasks (sidestep cutting and pivot). Repeated measures analyses of variance were conducted to assess differences in the kinematic and kinetic parameters between landing techniques for each task.ResultsThe forefoot landing technique had significantly higher internal knee adductor moment than the rearfoot for both the pivot and sidestep cutting task (p < 0.001 and p = 0.003, respectively). For the sidestep cutting task, participants had increased knee valgus angle with the rearfoot, whereas for the pivot they had increased knee valgus with the forefoot landing technique (p < 0.05).ConclusionsThe results of this study highlighted that there are inherent differences in biomechanical outcomes between foot-landing techniques. The forefoot landing technique increasingly affects knee adduction moment loading, which can potentially place a higher strain on the ACL. Essentially, the demands of the landing technique on lower extremity biomechanics (e.g., hip and knee) are task dependent.     

Effect of foot orthoses on magnitude and timing of rearfoot and tibial motions,ground reaction force and knee moment during running

Changes in magnitude and timing of rearfoot eversion and tibial internal rotation by foot orthoses and their contributions to vertical ground reaction force and knee joint moments are not well understood. The objectives of this study were to test if orthoses modify the magnitude and time to peak rearfoot eversion, tibial internal rotation, active ground reaction force and knee adduction moment and determine if rearfoot eversion, tibial internal rotation magnitudes are correlated to peak active ground reaction force and knee adduction moment during the first 60% stance phase of running. Eleven healthy men ran at 170 steps per minute in shod and with foot orthoses conditions. Video and force-plate data were collected simultaneously to calculate foot joint angular displacement, ground reaction forces and knee adduction moments. Results showed that wearing semi-rigid foot orthoses significantly reduced rearfoot eversion 40% (4.1°; p = 0.001) and peak active ground reaction force 6% (0.96 N/kg; p = 0.008). No significant time differences occurred among the peak rearfoot eversion, tibial internal rotation and peak active ground reaction force in both conditions. A positive and significant correlation was observed between peak knee adduction moment and the magnitude of rearfoot eversion during shod (r = 0.59; p = 0.04) and shod/orthoses running (r = 0.65; p = 0.02). In conclusion, foot orthoses could reduce rearfoot eversion so that this can be associated with a reduction of knee adduction moment during the first 60% stance phase of running. Finding implies that modifying rearfoot and tibial motions during running could not be related to a reduction of the ground reaction force.     

Tibial rotation in running: Does rearfoot adduction matter?

ObjectiveTo quantify the magnitude of global rearfoot motion, in particular, rearfoot adduction and to investigate its relationship to tibial rotation.DesignOne hundred and four participants ran barefoot on an Ethylene Vinyl Acetate (EVA) foam. Global range of motion values for the shank, rearfoot and medial metatarsal segment as well as foot motion within the transverse plane were determined using an optoelectric motion capture system. Relationships between parameters were assessed using partial correlation analysis.ResultsGlobal rearfoot adduction amounts to 6.1° (±2.7). Furthermore global rearfoot adduction and rearfoot eversion were significantly related to internal tibial rotation (partial correlation: r = 0.37, p < 0.001 and r = −0.24, p = 0.015, respectively). Furthermore, a strong relationship between rearfoot adduction and transverse within foot motion (r = −0.65, p < 0.001) was found.ConclusionNext to rearfoot eversion, rearfoot adduction may be also important to the understanding of ankle joint coupling. Controlling rearfoot adduction and transverse within foot motion may be a mechanism to control excessive tibial rotation.     

Biomechanical strategies implemented to compensate for mild leg length discrepancy during gait

Although mild leg length discrepancy is related to lower limb injuries, there is no consensus regarding its effects on the biomechanics of the lower limbs during gait. Biomechanical data of 19 healthy participants were collected while they walked under different conditions as described: (1) control condition—wearing flat thick sandals; (2) short limb condition—wearing a flat thick sandal on the left and a flat thin sandal on the right foot; (3) long limb condition: wearing flat thin sandal on the left and flat thick sandal on the right foot. The thick and thin sandals had 1.45 cm of mean thickness difference. The right lower limb data were analyzed for all conditions. Ankle, knee, hip and pelvis kinematics and internal moments were measured with a motion capture system and six force platforms. Principal component analysis was used to compare differences between conditions. The scores of the principal components were compared between conditions using one-way repeated measures ANOVA. Twelve gait variables were different between conditions: rearfoot dorsiflexion and inversion (p < 0.001); ankle dorsiflexion and inversion moments (p < 0.001); knee flexion angle and moment (p < 0.001); knee adduction moment (p < 0.001); hip flexion angle and moment (p < 0.001); hip adduction angle (p = 0.001) and moment (p = 0.022); and pelvic ipsilateral drop (p < 0.001). Mild leg length discrepancy caused compensatory changes during gait, apparently to equalize the functional length of the lower limbs. However, these strategies did not fully succeed, since both short and long limb conditions affected pelvic motion in the frontal plane. These results suggest that mild leg length discrepancy should not be overlooked in clinical settings.     

Biomechanical effects following footstrike pattern modification using wearable sensors

ObjectivesThis study sought to examine the biomechanical effects of an in-field sensor-based gait retraining program targeting footstrike pattern modification during level running, uphill running and downhill running.DesignQuasi-experimental design.MethodsSixteen habitual rearfoot strikers were recruited. All participants underwent a baseline evaluation on an instrumented treadmill at their preferred running speeds on three slope settings. Participants were then instructed to modify their footstrike pattern from rearfoot to non-rearfoot strike with real-time audio biofeedback in an 8-session in-field gait retraining program. A reassessment was conducted to evaluate the post-training biomechanical effects. Footstrike pattern, footstrike angle, vertical instantaneous loading rate (VILR), stride length, cadence, and knee flexion angle at initial contact were measured and compared.ResultsNo significant interaction was found between training and slope conditions for all tested variables. Significant main effects were observed for gait retraining (p-values ≤ 0.02) and slopes (p-values ≤ 0.01). After gait retraining, 75% of the participants modified their footstrike pattern during level running, but effects of footstrike pattern modification were inconsistent between slopes. During level running, participants exhibited a smaller footstrike angle (p ≤ 0.01), reduced VILR (p ≤ 0.01) and a larger knee flexion angle (p = 0.01). Similar effects were found during uphill running, together with a shorter stride length (p = 0.01) and an increased cadence (p ≤ 0.01). However, during downhill running, no significant change in VILR was found (p = 0.16), despite differences found in other biomechanical measurements (p-values = 0.02–0.05).ConclusionAn 8-session in-field gait retraining program was effective in modifying footstrike pattern among runners, but discrepancies in VILR, stride length and cadence were found between slope conditions.     

Biomechanics of slow running and walking with a rocker shoe

Evidence suggests a link between the loading of the Achilles tendon and the magnitude of the ankle internal plantar flexion moment during late stance of gait, which is clinically relevant in the management of Achilles tendinopathy. Some studies showed that rocker shoes can reduce the ankle internal plantar flexion moment. However, the existing evidence is not conclusive and focused on walking and scarce in running. Sixteen healthy runners participated in this study. Lower extremity kinetics, kinematics and electromyographic (EMG) signals of triceps surae and tibialis anterior were quantified for two types of shoes during running and walking. The peak ankle plantar flexion moment was reduced significantly in late stance of running (0.27 Nm/kg; p < 0.001) and walking (0.24 Nm/kg; p < 0.001) with the rocker shoe compared to standard shoe. The ankle power generation and plantar flexion moment impulse were also reduced significantly when running and walking with the rocker shoe (p < 0.001). No significant changes in the knee and hip moments were found in running and walking. A significant delay of the EMG peak, approximately 2% (p < 0.001), was present in the triceps surae when walking with rocker shoes. There were no significant changes in the EMG peak amplitude of triceps surae in running and walking. The peak amplitude of tibialis anterior was significantly increased (64.7 μV, p < 0.001) when walking with rocker shoes. The findings show that rocker shoes reduce the ankle plantar flexion moment during the late stance phase of running and walking in healthy people.     

Investigation of treadmill and overground running: Implications for the measurement of oxygen cost in children with developmental coordination disorder

Differences in the kinematics and kinetics of overground running have been reported between boys with and without developmental coordination disorder (DCD). This study compared the kinematics of overground and treadmill running in children with and without DCD to determine whether any differences in technique are maintained, as this may influence the outcome of laboratory treadmill studies of running economy in this population. Nine boys with DCD (10.3 ± 1.1 year) and 10 typically developing (TD) controls (9.7 ± 1 year) ran on a treadmill and overground at a matched velocity (8.8 ± 0.9 km/h). Kinematic data of the trunk and lower limb were obtained for both conditions using a 12-camera Vicon MX system. Both groups displayed an increase in stance time (p < 0.001), shorter stride length (p < 0.001), higher cadence (p < 0.001) and reduced ankle plantar flexion immediately after toe-off (p < 0.05) when running on the treadmill compared with overground. The DCD group had longer stance time (p < 0.009) and decreased knee flexion at mid-swing (p = 0.04) while running overground compared to their peers, but these differences were maintained when running on the treadmill. Treadmill running improved ankle joint symmetry in the DCD group compared with running overground (p = 0.019). Overall, these findings suggest that there are limited differences in joint kinematics and lower limb symmetry between overground and treadmill running in this population. Accordingly, laboratory studies of treadmill running in children with DCD are likely representative of the energy demands of running.     

Forefoot plantar shear stress distribution in hallux valgus patients

BackgroundHallux valgus is a common foot disorder often experienced with secondary callosities and metatarsalgia. Many factors including improper shoes might be responsible in the pathophysiology of the problem. Hallux valgus deformity has been shown to alter the biomechanics of the whole foot rather than affecting only the great toe. Due to changes in the biomechanical functioning of the first ray, other regions of the forefoot area have been shown to bear abnormal loads with increased vertical loading on medial, central and lateral forefoot regions. The purpose of this study was to investigate the pattern of forefoot plantar shear loading in hallux valgus patients and compare these results with those of control subjects.MethodsA total of 28 subjects were recruited for the study of which 14 were clinically diagnosed with hallux valgus. A custom built platform was used to collect peak pressure and shear data. A repeated measures analysis of variance was used to analyze the recorded data.FindingsAntero-posterior shear was significantly lower in the deformity group (p < 0.05). The lateral forefeet of the patients, however, experienced slightly higher shear loads (p > 0.05).InterpretationPropulsive shear force generation mechanism under the medial forefoot was impaired in the disorder group. In general, shear loading of the plantar feet shifted laterally. Previously hypothesized higher medio-lateral shear magnitudes under the hallux were not confirmed.     

Biomechanics and predicted energetics of sprinting on sand: Hints for soccer training

ObjectivesThe purpose of this study was to analyse energetic and biomechanical parameters of sprinting on sand surface, aimed at the evaluation of inherent aspects of soccer training programs, injury prevention and recovery processes.DesignTwenty-nine professional soccer players took part in this study: they performed maximal sprints and maximal shuttle sprints on a 12 m distance on natural grass, artificial turf and soft, dry sand.MethodsSpeed, acceleration, deceleration, stride length, stride frequency, flight and contact time, estimated energy cost, metabolic and mechanical power, efficiency and stiffness values, have been calculated through the instrument SPI-Pro (GPSports, Canberra, Australia) supported by two fixed cameras.ResultsThe comparison between values recorded on sand with those recorded on natural or artificial grass has highlighted significant decreases (p < 0.001) of speed, acceleration, stride length, flight time and mechanical power, efficiency and stiffness. Contact time, energy cost, metabolic power (p < 0.001) and deceleration (p < 0.05) were higher on sand whereas no significant differences were found regarding stride frequency (p > 0.05).ConclusionsThese results show that on sand it is possible to perform maximal intensity sprints with higher energy expenditure and metabolic power values, without reaching maximum speed and with smaller impact shocks. Furthermore, exercises with change of direction carried out on this surface allow to reach higher deceleration values. In addition, sprinting on sand potentially entails a limited stretch of the involved muscles. It can therefore offer a valid alternative to traditional training, injury prevention and rehabilitation programs.     

Effects of flexible and rigid rocker profiles on in-shoe pressure

Rocker profiles are commonly used in the prevention of diabetic foot ulcers. Rockers are mostly stiffened to restrict toe plantarflexion to ensure proper offloading. It is also described that toe dorsiflexion should be restricted. However, the difference in effect on plantar pressure between rigid rockers that restrict this motion and flexible rockers that do not is unknown. In-shoe plantar pressure data were collected for a control shoe and the same shoe with rigid and flexible rockers with the apex positioned at 50% and 60%. For 29 healthy female adults peak plantar pressure (PP), maximum mean pressure (MMP) and force-time integral (FTI) were determined for seven regions of the foot. Generalized estimate equation was used to analyse the effect of the different shoes on the outcome measures for these regions. Compared to the control shoe a significant increase of PP and FTI was found at the first toe for both rigid rockers and the flexible rocker with the apex positioned at 60%, while MMP was significantly increased in rockers with an apex position of 60% (p < 0.001). PP at the first toe was significantly lower in flexible rockers when compared to rigid rockers (p < 0.001). For both central and lateral forefoot PP and MMP were significantly more reduced in rigid rockers (p < 0.001), while for the medial forefoot no differences were found. The use of rigid rockers results in larger reductions of forefoot plantar pressures, but in worse increase of plantar pressures at the first toe compared to rockers that allow toe dorsiflexion.     

Comparison of the correlations between impact loading rates and peak accelerations measured at two different body sites: Intra- and inter-subject analysis

BackgroundHigh average (VALR) and instantaneous vertical loading rates (VILR) during impact have been associated with many running-related injuries. Peak acceleration (PA), measured with an accelerometer, has provided an alternative method to estimate impact loading during outdoor running. This study sought to compare both intra- and inter-subject correlations between vertical loading rates and PA measured at two body sites during running.MethodsGround reaction force data were collected from 10 healthy adults (age = 23.6 ± 3.8 years) during treadmill running at different speeds and inclination surfaces. Concurrently, PAs at the lateral malleoli and the distal tibia were measured using synchronized accelerometers.ResultsWe found significant positive intra-subject correlation between loading rates and PA at the lateral malleoli (r = 0.561–0.950, p < 0.001) and the distal tibia (r = 0.486–0.913, p < 0.001). PA measured at the lateral malleoli showed stronger correlation with loading rates (p = 0.004) than the measurement at the distal tibia. On the other hand, inter-subject variances were observed in the association between PA and vertical loading rates. The inter-subject variances at the distal tibia were 3.88 ± 3.09 BW/s and 5.69 ± 3.05 BW/s in VALR and VLIR respectively. Similarly, the inter-subject variances in the measurement at lateral malleoli were 5.24 ± 2.85 BW/s and 6.67 ± 2.83 BW/s in VALR and VLIR respectively.ConclusionsPA measured at lateral malleoli has stronger correlation with VALR or VILR than the measurement at distal tibia. Caution is advised when using PA to conduct inter-subject comparisons of vertical loading rates during running.     

Foot strike pattern in children during shod-unshod running

The purpose of this study was to determine the foot strike patterns (FSPs) and neutral support (no INV/EVE and no foot rotation) in children, as well as to determine the influence of shod/unshod conditions and sex. A total of 713 children, aged 6 to 16 years, participated in this study (Age = 10.28 ± 2.71 years, body mass index [BMI] = 19.70 ± 3.91 kg/m², 302 girls and 411 boys). A sagittal and frontal-plane video (240 Hz) was recorded using a high-speed camcorder, to record the following variables: rearfoot strike (RFS), midfoot strike (MFS), forefoot strike (FFS), inversion/eversion (INV/EVE) and foot rotation on initial contact. RFS prevalence was similar between boys and girls in both shod and unshod conditions. In the unshod condition there was a significant reduction (p < 0.001) of RFS prevalence both in boys (shod condition = 83.95% vs. 62.65% unshod condition) and in girls (shod condition = 87.85% vs. 62.70% unshod condition). No significant differences were found in INV/EVE and foot rotation between sex groups. In the unshod condition there was a significant increase (p < 0.001) of neutral support (no INV/EVE) both in boys (shod condition = 12.55% vs. 22.22% unshod condition) and in girls (shod condition = 17.9% vs. 28.15% unshod condition). In addition, in the unshod condition there is a significant reduction (p < 0.001) of neutral support (no foot rotation) both in boys (shod condition = 21.55% vs. 11.10% unshod condition) and in girls (shod condition = 21.05% vs. 11.95% unshod condition). In children, RFS prevalence is lower than adult’s population. Additionally, barefoot running reduced the prevalence of RFS and INV/EVE, however increased foot rotation.     

Ageing and physical match performance in English Premier League soccer referees

Soccer referees are required to keep up with play at all times despite occupying an age bracket of on average 10–15 years older than their playing counterparts. Therefore, the aim of the present study was to examine the effect of age upon the physical match performances and match physiological loads of elite-level soccer referees. Match analysis data was collected (Prozone^®, Leeds, UK) from 22 professional soccer referees (age range 31–48 years) on FA Premier League matches over four consecutive seasons (778 observations). Physical match performance categories were total-distance covered (TD); high intensity running distance (speed >5.5 m s^?1, HIR); sprint count (>7.0 m s^?1, SC); top sprinting speed (TS); average distance from the ball (DB) and average distance from fouls (DF). Significant age effects were found for TD (r = ?0.52, p < 0.001), HIR (r = ?0.53, p < 0.001) and SC (r = ?0.53, p < 0.001). No age effect was found for DB and DF (p > 0.05). Despite covering less TD, HIR and performing fewer sprints the older referees (43–48 years) were able to maintain an average distance from fouls that was comparable to that recorded by the young (31–36 years) referees. Therefore, the reduced physical match performances associated with increasing referee age did not appear to impact upon the older referees’ ability to keep up with play. In light of these findings, refereeing governing bodies may wish to review their age-based retirement guidelines.     

Match running performance in elite Australian Rules Football

There is little information describing the match running demands of elite-level Australian Rules Football (AF). The aims of this study were to examine: (1) match running demands; and (2) the influence of periods of increased physical activity on subsequent running performance in the Australian Football League. Time-motion analyses were performed 1–9 times per player from 16 professional AF players from the same club during games in 2005–2007, using portable global positioning systems during 65 matches. Game movements (standing, walking, jogging, running, higher-speed running, and sprinting) and distances (total distance covered [TD]; low-intensity activity [LIA, distance <14.4 km h^?1]; and, high-intensity running distance [HIR, distance > 14.4 km h^?1]) were collected. The influence of the first half physical activities on second half activities, and each quarter on the subsequent quarter were analysed. The mean (±SD) TD and HIR distance covered during the games were 12,939 ± 1145 m and 3880 ± 663 m respectively. There were reductions in TD in the second (?7.3%), third (?5.5%) and fourth (?10.7%) quarters compared to the first quarter (p < 0.01). The HIR was reduced after the first quarter (p < 0.001). Players that covered larger TD or HIR during the first half or quarter decreased distance in the next half and quarter, respectively (p < 0.001). These results show that a reduction in exercise intensity is inevitable during an AF match and that higher intensity activities reduce towards the end of games. High average speed during each half or quarter also affects subsequent running performance in elite-level AF.