Effect of foot orthotics on rearfoot and tibia joint coupling patterns and variability

The purpose of this study was to compare joint coupling patterns and variability of the rearfoot and tibia during running in subjects who were treated with two types of orthotic devices to that of controls. Eleven subjects with various lower extremity injuries were treated unsuccessfully with a standard orthotic, and then successfully with an inverted orthotic. Three-dimensional kinematic data were collected while subjects ran without orthoses and then in standard and inverted orthoses. Eleven healthy subjects ran without orthoses for comparison. The rearfoot inversion/eversion and tibial internal/external rotation joint coupling pattern and variability relationship was assessed using a vector coding technique. It was hypothesized that when the treated runners ran without orthotic devices, they would exhibit lower joint coupling angles and lower joint coupling variability compared to the controls. In addition, it was hypothesized that there would be no difference in the coupling angle or coupling variability between the standard and no orthotic conditions of the treated runners. Finally, it was hypothesized that coupling angle would decrease and variability would increase in the inverted versus the standard and non-orthotic conditions. No significant differences in joint coupling pattern or variability were observed between the treated and control subjects. In addition, no significant differences were noted between the orthotic conditions in the treated group. These results suggest that foot orthotic devices do not produce significant changes in rearfoot-tibial coupling. Therefore, the relief experienced with the inverted orthotic is likely due to factors other than alterations in this coupling.     

Foot joint coupling variability differences between habitual rearfoot and forefoot runners prior to and following an exhaustive run

As joint coupling variability has been associated with running-related lower extremity injury, the purpose of this study was to identify how variability within the foot may be different between forefoot (FFS) and rearfoot strike (RFS) runners. Identifying typical variability in uninjured runners may contribute to understanding of ideal coordination associated with running foot strike patterns.Fifteen FFS and 15 RFS runners performed a maximal-effort 5 km treadmill run. A 7-segment foot model identified 6 functional articulations (rearfoot, medial and lateral midfoot and forefoot, and 1st metatarsophalangeal) for analysis. Beginning and end of the run motion capture data were analyzed. Vector coding was used to calculate 6 joint couples. Standard deviations of the coupling angles were used to identify variability within subphases of stance (loading, mid-stance, terminal, and pre-swing). Mixed between-within subjects ANOVAs compared differences between the foot strikes, pre and post run.Increased variability was identified within medial foot coupling for FFS and within lateral foot coupling for RFS during loading and mid-stance. The exhaustive run increased variability during mid-stance for both groups.Interpretation. Joint coupling variability profiles for FFS and RFS runners suggest different foot regions have varying coordination needs which should be considered when comparing the strike patterns.     

Continuous relative phase variability during an exhaustive run in runners with a history of iliotibial band syndrome

Previous research has proposed that a lack of variability in lower extremity coupling during running is associated with pathology. The purpose of the study was to evaluate lower extremity coupling variability in runners with and without a history of iliotibial band syndrome (ITBS) during an exhaustive run. Sixteen runners ran to voluntary exhaustion on a motorized treadmill while a motion capture system recorded reflective marker locations. Eight runners had a history of ITBS. At the start and end of the run, continuous relative phase (CRP) angles and CRP variability between strides were calculated for key lower extremity kinematic couplings. The ITBS runners demonstrated less CRP variability than controls in several couplings between segments that have been associated with knee pain and ITBS symptoms, including tibia rotation-rearfoot motion and rearfoot motion-thigh ad/abduction, but more variability in knee flexion/extension-foot ad/abduction. The ITBS runners also demonstrated low variability at heel strike in coupling between rearfoot motion-tibia rotation. The results suggest that runners prone to ITBS use abnormal segmental coordination patterns, particular in couplings involving thigh ad/abduction and tibia internal/external rotation. Implications for variability in injury etiology are suggested.     

Effect of prefabricated thermoformable foot orthoses on plantar surface temperature after running: A gender comparison

There is a lack of evidence about the effect of different type of foot orthoses on plantar surface temperature. Moreover, that effect could be different depending on gender due to anatomical and physiological differences between men and women. The aim of the study was to analyze the effect of a prefabricated thermoformable foot orthosis on plantar surface temperature after running and taking gender differences into account. Thirty recreational runners (15 males, mean (standard deviation): 28 (7) years, 69.7 (6.5) kg, 1.74 (0.05) cm and 22.9 (1.7) kg/m²; and 15 females: 35 (7) years, 55.2 (6.9) kg, 1.63 (0.06) cm and 20.6 (1.9) kg/m²) carried out a maximum incremental test as pre-test, and two running tests on a treadmill at the laboratory wearing previously randomized different foot orthoses (thermoformable and prefabricated generic). The plantar surface temperature of the dominant foot sole in ten regions of interest was assessed before and immediately after 30-min running at 75% of VO_2max. The use of thermoformable foot orthoses produced lower temperatures only in men after the run in medial heel (P = 0.033, ES = 0.7), which then disappeared in temperature variation (after – before) (P = 0.910). Regarding gender, women showed lower temperatures before the run in both orthosis conditions (P < 0.039, ES > 0.8), but no differences in temperatures after the run (P = 0.910) in comparison with men. Moreover, absolute temperatures after running were always greater than before the run (P < 0.001, ES > 5.0). In conclusion, the thermoformable foot orthoses do not modify plantar surface temperature after running in healthy runners of either gender, compared to prefabricated generic foot orthoses. Although women present lower baseline plantar temperatures than men, these differences disappear after exercise.     

Triceps surae activation is altered in male runners with Achilles tendinopathy

Achilles tendinopathy is a common injury in running sports however the exact etiology of Achilles injury is still unclear. In recent years, altered neuromotor recruitment patterns of the triceps surae have been hypothesized to create differential intra-tendinous loads leading to pathology; however, this hypothesis has not been investigated. Further, the effect foot orthoses may have on neuromotor recruitment of the triceps surae in Achilles tendinopathy has not been investigated. Methods: The electromyographic activity of the triceps surae was recorded during an over-ground running task. Fifteen Achilles injured participants and 19 asymptomatic controls were assessed in a footwear only condition. The Achilles injured participants were also assessed running in a pre-fabricated foot orthoses. Results: In Achilles injured participants, there was a significant difference between soleus and lateral gastrocnemius offset times during running compared to the asymptomatic controls (p < 0.05). There were no significant differences in triceps surae muscle activity between the footwear only and footwear and orthoses condition in the Achilles injured participants. Conclusions: The finding that triceps surae activity is altered in participants with Achilles tendinopathy may have clinical importance as it suggests that intra-tendinous loads are altered which may contribute to pathological changes. Further, foot orthoses have no immediate effect on the neuromotor control of the triceps surae.     

Contributions of proximal and distal moments to axial tibial rotation during walking and running

The purpose of this study was to determine the cause and effect relationship between tibial internal rotation and pronation of the foot during walking and heel-toe running. This would allow predictions of orthotic effectiveness in reducing knee pain related to excessive internal tibial rotation. Kinematic and force plate data were collected from twenty subjects performing ten running and ten walking trials across a force plate. Using a least-squares algorithm, attitude matrices for each segment in each frame were obtained and the angular velocity vector of the tibia was calculated. The intersegmental moment at the ankle was calculated from ground reaction force and kinematic data, and the power flow from foot to tibia associated with axial tibial rotation was calculated. In walking, all subjects exhibited a clear power flow from tibia to foot during most of the stance phase, indicating that the foot was following the body. This suggests that the use of foot orthoses to reduce knee pain associated with tibial rotation during walking will not be successful. During running, power flow was also mainly proximal to distal, but there were brief periods of opposite power flow. There was more variability between subjects during running, with five subjects having large distal to proximal power flow peaks. These observations may explain and support previous work that has found variable clinical effects of orthoses between patients.     

Kinetic asymmetry in female runners with and without retrospective tibial stress fractures

Gait asymmetry may be linked to the tendency for runners to sustain chronic overuse injuries. This paper compares gait asymmetry in female runners who have never sustained a running-related injury to those who have sustained unilateral tibial stress fractures. The symmetry index was used to characterize asymmetry in the kinetics of both subject groups. There were three aims to this study: (1) to report natural levels of asymmetry for healthy, never-injured female runners, (2) to compare asymmetry levels between never-injured runners and those who have sustained stress fractures, and (3) to examine the kinetics between the involved and uninvolved limbs of runners who have sustained stress fractures. In all three aims, peak medial, lateral, braking, vertical impact, and vertical ground reaction forces, average and peak instantaneous vertical loading rates, and peak shock were examined. In the never-injured runner group, natural levels of asymmetry ranged from 3.1% for peak vertical ground reaction force up to 49.8% for peak lateral ground reaction force. Symmetry indices were not significantly different in the runners who had previously sustained stress fractures. The involved limb of the previously injured runners demonstrated higher values for braking and vertical impact ground reaction force and peak shock. Interestingly, these runners appeared to have bilaterally-elevated lateral ground reaction forces and loading rates as compared to the never-injured group, although this was not statistically tested. This suggests that previously injured runners may be closer to the injury threshold and, thus, more susceptible. Asymmetry may simply influence the side on which they become injured.     

Running related gluteus medius function in health and injury: A systematic review with meta-analysis

Running is a popular sport and recreational physical activity worldwide. Musculoskeletal injuries in runners are common and may be attributed to the inability to control pelvic equilibrium in the coronal plane. This lack of pelvic control in the frontal plane can stem from dysfunction of the gluteus medius. The aim of this systematic review was therefore to: (i) compile evidence of the activity profile of gluteus medius when running; (ii) identify how gluteus medius activity (electromyography) varies with speed, cadence and gender when running; (iii) compare gluteus medius activity in injured runners to matched controls. Seven electronic databases were searched from their earliest date until March 2015. Thirteen studies met our eligibility criteria. The activity profile was mono-phasic with a peak during initial loading (four studies). Gluteus medius amplitude increases with running speed; this is most evident in females. The muscles’ activity has been recorded in injured runners with Achilles tendinopathy (two studies) and patellofemoral pain syndrome (three studies). The strongest evidence indicates a moderate and significant reduction in gluteus medius duration of activity when running in people with patellofemoral pain syndrome. This dysfunction can potentially be mediated with running retraining strategies.     

Free moment as a predictor of tibial stress fracture in distance runners

Stress fractures are a common and serious overuse injury in runners, particularly female runners. They may be related to loading characteristics of the lower extremity during running stance. Some tibial stress fractures (TSFs) are spiral in nature and, therefore, may be related to torque. Free moment (FM) is a measure of torque about a vertical axis at the interface with the shoe and ground. Increases in FM variables may be related to a history of TSF in runners. The purpose of this cross-sectional study was to investigate differences in FM between female distance runners with and without a history of TSF and, additionally, to investigate the relationship between absolute FM and the occurrence of TSF. A group of 25 currently uninjured female distance runners with a history of TSF (28+/-10 years, 46+/-15 km week(-1)) and an age- and mileage-matched control group of 25 healthy runners with no previous lower extremity fractures (26+/-9 years, 46+/-19 km week(-1)) participated in this study. Ground reaction forces and foot placement on the force platform were recorded during running at 3.7 ms(-1) (+/-5%). Peak adduction, braking peak and absolute peak FM and impulse were compared between groups using one-tailed t-tests. The predictive value of absolute peak FM was investigated via a binary logistic regression. All variables, except impulse, were significantly greater in runners with a history of TSF. Absolute peak FM had a significant predictive relationship with history of TSF. There is a significant relationship between higher values for FM variables and a history of TSF.     

An analysis of the mechanisms for reducing the knee adduction moment during walking using a variable stiffness shoe in subjects with knee osteoarthritis

Variable stiffness shoes that have a stiffer lateral than medial sole may reduce the external knee adduction moment (EKAM) and pain during walking in patients with medial compartment knee osteoarthritis (OA). However, the mechanism by which EKAM may be reduced in the OA knee with this intervention remains unclear. Three hypotheses were tested in this study: (1) The reduction in EKAM during walking with the variable stiffness shoe is associated with a reduction in GRF magnitude and/or (2) frontal plane lever arm. (3) A reduction in frontal plane lever arm occurs either by moving the center of pressure laterally under the shoe and/or by dynamically reducing the medial component of GRF. Thirty-two subjects (20 male, 12 female; age: 58.7 ± 9.3 years; height: 1.62 ± 0.08 m; mass: 81.3 ± 14.6 kg) with medial compartment knee osteoarthritis were studied walking in a gait laboratory. The frontal plane lever arm was significantly reduced (1.62%, 0.07%ht, p=0.02) on the affected side while the magnitude of the GRF was not significantly changed. The reduction in the lever arm was weakly correlated with a medial shift in the COP. However, the combined medial shift in the COP and reduction in the medial GRF explained 50% of the change of the frontal plane lever arm. These results suggest that the medial shift in the COP at the foot produced by the intervention shoe stimulates an adaptive dynamic response during gait that reduces the frontal plane lever arm.     

Decreased frontal plane hip joint moments in runners with excessive varus excursion at the knee

Knee varus position and motion have been correlated with increased medial knee loading during gait. The purpose of this study is to determine whether runners with excessive varus excursion (EVE) at the knee demonstrate frontal plane knee and hip kinetics that are different from those of runners with normal varus excursion (NVE). Twelve runners with EVE were compared with 12 NVE subjects using three-dimensional kinematics and kinetics. Frontal plane angles and moments were compared at the knee and hip. Runners with EVE had significantly greater abductor moment of the knee (p = .004) and lower peak abductor moment of the hip (p = .047). Runners with EVE demonstrate knee and hip mechanics thought to be associated with increased medial tibiofemoral loading. Further understanding of how changing hip abductor moments may affect changes in knee abductor moments during running may potentially lead to interventions that augment long-term risk of injury.     

Dynamic plantar loading index: understanding the benefit of custom foot orthoses for painful pes cavus

The purpose of this study was to evaluate a new method showing how custom foot orthoses (CFO) improve dynamics of plantar loading. The method is based on the probability distribution of peak pressure time series and is quantified using the Regression Factor (RF). RF is a least square regression slope between the experimentally observed plantar pressure magnitude probability distribution and a modeled Gaussian shape. Plantar pressure data from a randomized controlled trial of 154 participants with painful Pes Cavus were retrospectively re-analyzed. The participants were randomized to an active treatment group given CFO or a control group given sham orthoses. The location of 2(nd) Peak pressure as a percentage of stance time (P(Loc2)) and its magnitude (P(M2)) was also calculated. In addition, plantar pressure data were collected on 23 healthy volunteers with normal foot alignment and no foot pain. Results demonstrated Pes Cavus had a significantly lower RF than healthy participants (0.30 v. 0.51; p<10(-7)). P(M2) was reduced in both active and control groups. However, RF and the P(Loc2) were only changed in the active group (p<0.005) without any significant change in the control group (p>0.5). This study suggests that painful Pes Cavus alters the shape of probability distribution of plantar loading during walking and CFO are an effective therapeutic solution that can significantly improve it. Further use of the RF index and 2(nd) peak pressure location as an outcome measure for treatment of foot and ankle deformities is suggested.     

Biomechanical analysis of the stance phase during barefoot and shod running

This study investigated spatio-temporal variables, ground reaction forces and sagittal and frontal plane kinematics during the stance phase of nine trained subjects running barefoot and shod at three different velocities (3.5, 4.5, 5.5 m s(-1)). Differences between conditions were detected with the general linear method (factorial model). Barefoot running is characterized by a significantly larger external loading rate than the shod condition. The flatter foot placement at touchdown is prepared in free flight, implying an actively induced adaptation strategy. In the barefoot condition, plantar pressure measurements reveal a flatter foot placement to correlate with lower peak heel pressures. Therefore, it is assumed that runners adopt this different touchdown geometry in barefoot running in an attempt to limit the local pressure underneath the heel. A significantly higher leg stiffness during the stance phase was found for the barefoot condition. The sagittal kinematic adaptations between conditions were found in the same way for all subjects and at the three running velocities. However, large individual variations were observed between the runners for the rearfoot kinematics.     

The influence of iliotibial band syndrome history on running biomechanics examined via principal components analysis

Iliotibial band syndrome (ITBS) is a common knee overuse injury among female runners. Atypical discrete trunk and lower extremity biomechanics during running may be associated with the etiology of ITBS. Examining discrete data points limits the interpretation of a waveform to a single value. Characterizing entire kinematic and kinetic waveforms may provide additional insight into biomechanical factors associated with ITBS. Therefore, the purpose of this cross-sectional investigation was to determine whether female runners with previous ITBS exhibited differences in kinematics and kinetics compared to controls using a principal components analysis (PCA) approach. Forty participants comprised two groups: previous ITBS and controls. Principal component scores were retained for the first three principal components and were analyzed using independent t-tests. The retained principal components accounted for 93–99% of the total variance within each waveform. Runners with previous ITBS exhibited low principal component one scores for frontal plane hip angle. Principal component one accounted for the overall magnitude in hip adduction which indicated that runners with previous ITBS assumed less hip adduction throughout stance. No differences in the remaining retained principal component scores for the waveforms were detected among groups. A smaller hip adduction angle throughout the stance phase of running may be a compensatory strategy to limit iliotibial band strain. This running strategy may have persisted after ITBS symptoms subsided.     

Evaluation of lower limb cross planar kinetic connectivity signatures post-stroke

Following stroke, aberrant three dimensional multijoint gait impairments emerge that present in kinematic asymmetries such as circumduction. A precise pattern of cross-planar coordination may underlie abnormal hemiparetic gait as several studies have underscored distinctive neural couplings between medio-lateral control and sagittal plane progression during walking. Here we investigate potential neuromechanical constraints governing abnormal multijoint coordination post-stroke. 15 chronic monohemispheric stroke patients and 10 healthy subjects were recruited. Coupled torque production patterns were assessed using a volitional isometric torque generation task where subjects matched torque targets for a primary joint in 4 directions while receiving visual feedback of the magnitude and direction of the torque. Secondary torques at other lower limb joints were recorded without subject feedback. We find that common features of cross-planar connectivity in stroke subjects include statistically significant frontal to sagittal plane kinetic coupling that overlay a common sagittal plane coupling in healthy subjects. Such coupling is independent of proximal or distal joint control and limb biomechanics. Principal component analysis of the stroke aggregate kinetic signature reveals unique abnormal frontal plane coupling features that explain a larger percentage of the total torque coupling variance. This study supports the idea that coupled cross-planar kinetic outflow between the lower limb joints uniquely emerges during pathological control of frontal plane degrees of freedom resulting in a generalized extension of the limb. It remains to be seen if a pattern of lower limb motor outflow that is centrally mediated contributes to abnormal hemiparetic gait.     

Effects of treadmill running on plasma beta-endorphin, corticotropin, and cortisol levels in male and female 10K runners

Reports of plasma beta-endorphin (B-EN) levels in response to submaximal exercise have been highly disparate. Variations in experimental design have complicated interpretation of previous research. The present study was designed to determine whether a sequential change in plasma beta-endorphin (B-EN), corticotropin (ACTH), and cortisol levels occurs in response to a 30-min submaximal run. Twenty-three subjects were divided into four groups: male runners, female runners, sedentary males and sedentary females. Subjects ran on a treadmill at 80% of previously determined maximum heart rate. Five plasma samples were obtained through an indwelling catheter before exercise (-30 and 0 min), at 15 and 30 min of exercise, and after 30 minutes of recovery. The run resulted in no rise in B-EN, ACTH, and cortisol despite an elevated rectal temperature. B-EN values were significantly higher in males than in females (p less than 0.01). No sex or training differences were seen with respect to change of hormone concentrations over the course of the run. Three male runners developed symptoms of vasovagal syncope after the catheter placement and had high initial B-EN, ACTH, and cortisol concentrations which decreased throughout the run. These data indicate that gender and training do not affect ACTH and cortisol concentrations before, during, and after 30 min of treadmill running at 80% of maximum heart rate, whereas B-EN concentrations are higher in males under these conditions.     

Sex-Specific associations between hip muscle strength and foot progression angle

The foot progression angle (FPA) influences knee loading during gait, but its determinants are unclear. The purpose of this study was to compare FPA between males and females and also examine the association between lower extremity kinematics during gait, hip strength, and the FPA. 25 males and 25 females completed 5 gait trials while FPA and frontal and transverse plane hip and knee angles were calculated from the dominant limb during the foot flat portion of stance. Hip extensor/flexor, abductor/adductor, and internal/external rotator strength were evaluated using maximum voluntary isometric contractions. One-way MANOVAs compared gait and strength outcomes. Stepwise regression assessed the association between FPA, and MVIC and kinematics after accounting for speed in males and females. There was no difference in FPA between sexes (p > 0.05), but females had greater frontal and transverse plane hip angles compared with males (all p < 0.05). Greater hip abduction (p = 0.02) strength was associated with greater FPA, but only in males. In males, greater hip abductor strength may contribute to a more neutral position of the foot during gait, which could help maintain an equal knee loading distribution. Our results suggest that there are sex specific control strategies to achieve a similar FPA during gait.     

Energy expenditure and influence of physiologic factors during marathon running

This study examined energy expenditure and physiologic determinants for marathon performance in recreational runners. Twenty recreational marathon runners participated (10 males aged 41 +/- 11.3 years, 10 females aged 42.7 +/- 11.7 years). Each subject completed a V(.-)O2max and a 1-hour treadmill run at recent marathon pace, and body composition was indirectly determined via dual energy X-ray absorptiometry. The male runners exhibited higher V(.-)O2max (ml x kg(-1) x min(-1)) values (52.6 +/- 5.5) than their female counterparts (41.9 +/- 6.6), although ventilatory threshold (T-vent) values were similar between groups (males: 76.2 +/- 6.1 % of V(.-)O2max, females: 75.1 +/- 5.1%). The male runners expended more energy (2,792 +/- 235 kcal) for their most recent marathon as calculated from the 1-hour treadmill run at marathon pace than the female runners (2,436 +/- 297 kcal). Body composition parameters correlated moderately to highly (r ranging from 0.50 to 0.87) with marathon run time. Also, V(.-)O2max (r = -0.73) and ventilatory threshold (r = -0.73) moderately correlated with marathon run time. As a group, the participants ran near their ventilatory threshold for their most recent marathon (r = 0.74). These results indicate the influence of body size on marathon run performance. In general, the larger male and female runners ran slower and expended more kilocalories than smaller runners. Regardless of marathon finishing time, the runners maintained a pace near their T-vent, and as T-vent or V(.-)O2max increased, marathon performance time decreased.     

Gender differences in lower extremity coupling variability during an unanticipated cutting maneuver

The purpose of this study was to determine if gender differences exist in the variability of various lower extremity (LE) segment and joint couplings during an unanticipated cutting maneuver. 3-D kinematics were collected on 24 college soccer players (12 M, 12 F) while each performed the cutting maneuver. The following intralimb couplings were studied: thigh rotation (rot)/leg rot; thigh abduction-adduction/leg abd-add; hip abd-add/knee rot; hip rot/knee abd-add; knee flexion-extension/knee rot; knee flx-ext/hip rot. A vector-coding technique applied to angle-angle plots was used to quantify the coordination of each coupling. The average between-trial standard deviation of the coordination pattern during the initial 40 % of stance was used to indicate the coordination variability. One-tailed t-tests were used to determine differences between genders in coordination variability for each coupling. Women had decreased variability in four couplings: 32 % less thigh rot/leg rot variability; 40 % less thigh abd-add/leg abd-add variability; 46 % less knee flx-ext/knee rot variability; and 44 % less knee flx-ext/hip rot variability. These gender differences in LE coordination variability may be associated with the increased incidence of ACL injury in women. If women exhibit less flexible coordination patterns during competition, they may be less able to adapt to the environmental perturbations experienced during sports. These perturbations applied to a less flexible system may result in ligament injury.     

Hip and knee joint kinematics during a diagonal jump landing in anterior cruciate ligament reconstructed females

Anterior cruciate ligament (ACL) injury is a common injury encountered by sport medicine clinicians. Surgical reconstruction is the recommended treatment of choice for those athletes wishing to return to full-contact sports participation and for sports requiring multi-directional movement patterns. The aim of ACL reconstruction is to restore knee joint mechanical stability such that the athlete can return to sporting participation. However, knowledge regarding the extent to which lower limb kinematic profiles are restored following ACL reconstruction is limited. In the present study the hip and knee joint kinematic profiles of 13 ACL reconstructed (ACL-R) and 16 non-injured control subjects were investigated during the performance of a diagonal jump landing task. The ACL-R group exhibited significantly less peak knee joint flexion (P=0.01). Significant between group differences were noted for time averaged hip joint sagittal plane (P<0.05) and transverse plane (P<0.05) kinematic profiles, as well as knee joint frontal plane (P<0.05) and sagittal plane (P<0.05) kinematic profiles. These results suggest that aberrant hip and knee joint kinematic profiles are present following ACL reconstruction, which could influence future injury risk.