Foot pronation during walking is associated to the mechanical resistance of the midfoot joint complex

BackgroundThe demonstration of the relationship between midfoot passive mechanical resistance and foot pronation during gait may guide the development of assessment and intervention methods to modify foot motion during gait and to alter midfoot passive mechanical resistance.Research questionIs foot pronation during the stance phase of gait related to the midfoot passive mechanical resistance to inversion?MethodsThe resistance torque and stiffness provided by midfoot soft tissues of 33 participants (21 females and 12 males) with average of 26.21 years were measured. In addition, the participants’ forefoot and rearfoot kinematic data during the stance phase of gait were collected with the Qualisys System (Oqus 7+). Correlation Coefficients were calculated to test the association between kinematic variables representing pronation (forefoot-rearfoot inversion, forefoot-rearfoot dorsiflexion and rearfoot-shank eversion) and maximum resistance torque and maximum stiffness of the midfoot with α = 0.05.ResultsReduced maximum midfoot resistance torque was moderately associated with increased forefoot-rearfoot inversion peak (p = 0.029; r = 0.38), with forefoot-rearfoot dorsiflexion peak (p = 0.048; r = −0.35) and with rearfoot-shank eversion peak (p = 0.008; r = −0.45). Maximum midfoot stiffness was not associated to foot pronation.SignificanceThe smaller the midfoot resistance torque, the greater the forefoot-rearfoot inversion and dorsiflexion peaks and the rearfoot-shank eversion peak during gait. The findings suggest the existence of a relationship between foot pronation and midfoot passive mechanical resistance. Thus, changes in midfoot passive mechanical resistance may affect foot pronation during gait.     

Energy expenditure during walking and jogging

BACKGROUND: The aim of this investigation was to compare the physiological and subjective responses during treadmill walking and jogging at several corresponding speeds in physically active young women. METHODS: Experimental design: Maximal oxygen uptake was determined during a continuous treadmill test to exhaustion. The walking protocol consisted of treadmill walking for five min at each of the following speeds: 4.0, 5.6, 7.2, 8.0, 8.8, 9.6 and 10.4 km.hr(-1). The jogging protocol consisted of treadmill walking for five min at 4.0, and 5.6 km.hr(-1) and treadmill jogging for five min at each of the following speeds: 7.2, 8.0, 8.8, 9.6 and 10.4 km.hr(-1). Setting: This research was performed at Washington University School of Medicine. Participants: Fifteen healthy women (mean+/-SE, age; 26.9+/-1.4 yrs, BMI; 22.5+/-0.70, VO2max; 41.9+/-1.9 ml.hr(-1).min(-1)) performed a maximal treadmill exercise test, a walking test and a jogging test. RESULTS: The rate of oxygen consumption, calculated energy expenditure per distance (kJ.hr(-1).mile(-1)) and heart rates were significantly higher during walking compared to jogging at treadmill speeds > or =8.8 km.hr(-1). Plasma lactate concentration and respiratory exchange ratio were significantly higher at treadmill speeds > or =8.0 km.hr(-1) during walking as compared to jogging. Subjects subjectively rated their exertion during walking as being significantly greater when compared to jogging across the range of overlapping treadmill speeds. CONCLUSIONS: These findings demonstrated that walking at speeds > or =8.0 km.hr(-1) resulted in rates of energy expenditure that were as high or higher than jogging at the same speeds. Also, the higher rates of energy expenditure during walking as compared to jogging at speeds greater than 8.0 km.hr(-1) were associated with higher heart rates, RER, RPE and plasma lactate response.     

Calcaneal loading during walking and running

PURPOSE: This study of the foot uses experimentally measured kinematic and kinetic data with a numerical model to evaluate in vivo calcaneal stresses during walking and running. METHODS: External ground reaction forces (GRF) and kinematic data were measured during walking and running using cineradiography and force plate measurements. A contact-coupled finite element model of the foot was developed to assess the forces acting on the calcaneus during gait. RESULTS: We found that the calculated force-time profiles of the joint contact, ligament, and Achilles tendon forces varied with the time-history curve of the moment about the ankle joint. The model predicted peak talocalcaneal and calcaneocuboid joint loads of 5.4 and 4.2 body weights (BW) during walking and 11.1 and 7.9 BW during running. The maximum predicted Achilles tendon forces were 3.9 and 7.7 BW for walking and running. CONCLUSIONS: Large magnitude forces and calcaneal stresses are generated late in the stance phase, with maximum loads occurring at approximately 70% of the stance phase during walking and at approximately 60% of the stance phase during running, for the gait velocities analyzed. The trajectories of the principal stresses, during both walking and running, corresponded to each other and qualitatively to the calcaneal trabecular architecture.     

开放性旋前型踝关节骨折、脱位的治疗策略

回顾分析开放性旋前型踝关节骨折12例,给予彻底清创的同时,采用有效内固定.按Mazur评分标准:优7踝,良3踝,可2踝;优良率达83.3%.     

The influence of foot progression angle on the knee adduction moment during walking and stair climbing in pain free individuals with knee osteoarthritis

The external knee adduction moment during walking and stair climbing has a characteristic double hump pattern. The magnitude of the adduction moment is associated with the development and progression of medial compartment knee osteoarthritis (OA). There is an inverse relationship between the magnitude of the second peak adduction moment and foot progression angle (FPA). Increasing FPA beyond a self-selected degree of toe-out may further reduce the magnitude of this moment for persons with knee OA. In this study, subjects with medial compartment knee OA walked and climbed stairs using their natural (i.e. self-selected) and an increased FPA (i.e. self-selected+15 degrees of additional toe-out). Increasing FPA did not change the magnitude of the first peak adduction moment but it did significantly decrease the second peak during walking. The first peak moment during stair ascent was significantly greater for the increased FPA condition, and a significant reduction was noted for the second peak. No significant differences were noted during stair descent. These results suggest that walking with a toe-out strategy may benefit persons with early stages of medial knee OA.     

Deformation of foot cross-section shapes during walking

To clarify the magnitude of shape change during walking, the shapes of four cross-sections (Forefoot, Instep, Navicular, and Heel) of the right foot during standing and walking were measured using a four-dimensional measurement system we developed (14 Hz) with an accuracy of ±0.5 mm. Images of the sole were measured using a high-speed video camera (120 Hz). Cross-section shapes and derived dimensions were compared between the standing condition, first peak (P1), and midstance valley of two peaks (MSV) of vGRF during walking. Heel and Navicular cross-sections were more laterally inclined during walking than during standing by 6° on average. Compared to at standing, breadth of the cross-section in contact with the ground was wider at the heel and instep at timing P1, and was wider at the forefoot and narrower at heel at timing MSV. Medial length was longer and dorsal arch was higher during walking than during standing. Plantar arch height did not differ between the three conditions. The maximum difference in plantar arch height between standing and P1 was 1.3 mm, much smaller than the inter-individual variation of 7 mm.     

Deformation of foot cross-section shapes during walking

To clarify the magnitude of shape change during walking, the shapes of four cross-sections (Forefoot, Instep, Navicular, and Heel) of the right foot during standing and walking were measured using a four-dimensional measurement system we developed (14 Hz) with an accuracy of ±0.5 mm. Images of the sole were measured using a high-speed video camera (120 Hz). Cross-section shapes and derived dimensions were compared between the standing condition, first peak (P1), and midstance valley of two peaks (MSV) of vGRF during walking. Heel and Navicular cross-sections were more laterally inclined during walking than during standing by 6° on average. Compared to at standing, breadth of the cross-section in contact with the ground was wider at the heel and instep at timing P1, and was wider at the forefoot and narrower at heel at timing MSV. Medial length was longer and dorsal arch was higher during walking than during standing. Plantar arch height did not differ between the three conditions. The maximum difference in plantar arch height between standing and P1 was 1.3 mm, much smaller than the inter-individual variation of 7 mm.     

Synchrony of pelvic and hip joint motion during walking

We report a study into the coordination of the movements of the pelvis and hip joints during walking at two speeds. 108 healthy subjects were filmed using an automated video-based system. Movements of the pelvis and the lower limbs and their contribution to step length were analysed and the coordination of the movements with respect to one another was investigated using cross-correlational analysis. We found strong evidence of consistent temporal relationships within some of the movements with no gender or age effect. Increasing walking speed to a fast comfortable pace tended to produce tighter phase locking of movement patterns. We conclude that expression of the biomechanical determinants of walking ought to include temporal interactions and that axial rotation of the pelvis is probably of little consequence as an essential component of normal gait.     

Comparison of instantaneous knee kinematics during walking and running

BackgroundAccurate measurements of in-vivo knee joint kinematics are essential to elucidate healthy knee motion and the changes that accompany injury and repair. Although numerous experimental measurements have been reported, the accurate non-invasive analysis of in-vivo knee kinematics remains a challenge in biomechanics.Research questionThe study objective was to investigate in-vivo knee kinematics before, at, and after contact during walking and running using a combined high-speed dual fluoroscopic imaging system (DFIS) and magnetic resonance (MR) imaging technique.MethodsThree-dimensional (3D) knee models of ten participants were created using MR images. Knee kinematics during walking and running were determined using high-speed DFIS. The 3D knee models were then related to fluoroscopic images to obtain in-vivo six-degrees-of-freedom knee kinematics.ResultsBefore contact knee flexion, external femoral rotation, and proximal-distal distance were 11.9°, 3.4°, and 1.0 mm greater during running compared to walking, respectively. Similar differences were observed at initial contact (9.9°, 7.9°, and 0.9 mm, respectively) and after contact (6.4°, 2.2°, and 0.8 mm, respectively). Posterior femoral translation at initial contact was also increased during running compared to walking.SignificanceThis study demonstrated accurate instantaneous in-vivo knee kinematic characteristics that may further the understanding of the intrinsic biomechanics of the knee during gait.     

Trunk muscles activation during pole walking vs. walking performed at different speeds and grades

Given their functional role and importance, the activity of several trunk muscles was assessed (via surface electromyography—EMG) during Walking (W) and Pole Walking (PW) in 21 healthy adults. EMG data was collected from the external oblique (EO), the erector spinae longissimus (ES), the multifidus (MU), and the rectus abdominis (RA) while performing W and PW on a motorized treadmill at different speeds (60, 80, and 100% of the highest speed at which the participants still walked naturally; PTS₆₀, PTS₈₀ and PTS₁₀₀, respectively) and grades (0 and 7%; GRADE₀ and GRADE₇, respectively). Stride length, EMG area under the curve (_AUC), muscles activity duration (_ACT), and percentage of coactivation (CO-ACT) of ES, MU and RA, were calculated from the averaged stride for each of the tested combinations.Compared to W, PW significantly increased the stride length, EO_AUC, RA_AUC and the activation time of all the investigated muscles, to different extents depending on treadmill speeds and grades. In addition, MU_AUC was higher in PW than in W at GRADE₀ only (all speeds, p < 0.01), while ES_AUC during W and PW was similar at all the speeds and grades. These changes resulted in longer CO-ACT in PW than W, at GRADE₀-PTS₁₀₀ (p < 0.01) and GRADE₇ (all speeds, p < 0.01). In conclusion, when compared to W, PW requires a greater engagement of the abdominal muscles and, in turn, a higher control of the trunk muscles. These two factors taken together may suggest an elevated spinal stability while walking with poles.     

Human balance and posture control during standing and walking

The common denominator in the assessment of human balance and posture is the inverted pendulum model. If we focus on appropriate versions of the model we can use it to identify the gravitational and acceleration perturbations and pinpoint the motor mechanisms that can defend against any perturbation.

We saw that in quiet standing an ankle strategy applies only in the A/P direction and that a separate hip load/unload strategy by the hip abd/adductors is the totally dominant defence in the M/L direction when standing with feet side by side. In other standing positions (tandem, or intermediate) the two mechanisms still work separately, but their roles reverse. In the tandem position M/L balance is an ankle mechanism (invertors/evertors) while in the A/P direction a hip load/unloading mechanism dominates.

During initiation and termination of gait these two separate mechanisms control the trajectory of the COP to ensure the desired acceleration and deceleration of the COM. During initiation the initial acceleration of the COM forward towards the stance limb is achieved by a posterior and lateral movement of the COP towards the swing limb. After this release phase there is a sudden loading of the stance limb which shifts the COP to the stance limb. The COM is now accelerated forward and laterally towards the future position of the swinging foot. Also M/L shifts of the COP were controlled by the hip abductors/adductors and all A/P shifts were under the control of the ankle plantar/dorsiflexors. During termination the trajectory of both COM and COP reverse. As the final weight-bearing on the stance foot takes place the COM is passing forward along the medial border of that foot. Hyperactivity of that foot's plantarflexors takes the COP forward and when the final foot begins to bear weight the COP moves rapidly across and suddenly stops at a position ahead of the future position of the COM. Then the plantarflexors of both feet release and allow the COP to move posteriorly and approach the COM and meet it as quiet stance is achieved. The inverted pendulum model permitted us to understand the separate roles of the two mechanisms during these critical unbalancing and rebalancing periods.

During walking the inverted pendulum model explained the dynamics of the balance of HAT in both the A/P and M/L directions. Here the model includes the couple due to the acceleration of the weight-bearing hip as well as gravitational perturbations. The exclusive control of A/P balance and posture are the hip extensors and flexors, while in the M/L direction the dominant control is with the hip abductors with very minor adductor involvement. At the ankle the inverted pendulum model sees the COM passing forward along the medial border to the weight-bearing foot. The model predicts that during single support the body is falling forward and being accelerated medially towards the future position of the swing foot. The model predicts an insignificant role of the ankle invertors/evertors in the M/L control. Rather, the future position of the swing foot is the critical variable or more specifically the lateral displacement from the COM at the start of single support. The position is actually under the control of the hip abd/adductors during the previous early swing phase.

The critical importance of the hip abductors/adductors in balance during all phases of standing and walking is now evident. This separate mechanism is important from a neural control perspective and clinically it focuses major attention on therapy and potential problems with some surgical procedures. On the other hand the minuscule role of the ankle invertors/evertors is important to note. Except for the tandem standing position these muscles have negligible involvement in balance control.     

Kinematic and kinetic analysis during forward and backward walking

Backward walking (BW) is a recently emerging exercise. However, limited studies exist regarding the motion analysis of BW compared with that of forward walking (FW). The present study identified the mechanisms of BW through kinetic analysis and focused on BW time-reversed data. A three-dimensional motion capture system was used to acquire the joint movements and to calculate the joint moments and the powers during walking. Ground reaction force curves were acquired from force plates. Each participant performed 10 FW trials and 40 BW trials with bare feet. All data were analyzed using paired t-tests (p < 0.05) to verify the significant differences between FW and BW. In BW, since the progress is in the direction in which the person cannot see, the walker's speed is generally decreased compared to FW. As a result, the stride characteristics for each respective activity showed significant differences. The characteristics of angular displacement in all joints were almost identical in FW and time-reversed BW. However, selected crucial points of joint angles were significantly different. The moment pattern of the ankle joint was very similar in FW and time-reversed BW. In the knee and the hip joint, the joint moment pattern of time-reversed BW was simpler than FW. The joint power patterns of the ankle, the knee and the hip were different in FW and BW. An original finding of this study was that the main propulsion and shock absorption joint during BW is the ankle joint. The knee and hip joint did not generate propulsion power.     

Age- and speed-related differences in harmonic ratios during walking

Harmonic ratios (HRs), derived from trunk accelerations, measure smoothness of trunk motion during gait; higher ratios indicate greater smoothness. Previous research indicates that young adults optimize HRs at preferred pace, exhibiting reduced HRs at speeds faster and slower than preferred. Recent studies examining HRs and other trunk acceleration measures challenge this finding. The purpose of this study was to examine age-related differences in HRs across a range of self-selected overground walking speeds. Anteroposterior (AP), vertical (VT), and mediolateral (ML) HRs were examined in 13 young adults (ages 20-23), 13 healthy older adults (ages 60-69), and 13 healthy old-old adults (ages 80-86) while walking overground at very slow, slow, preferred, fast, and very fast speeds. Young and older adults exhibited similar HRs in all directions of motion across speeds, while old-old adults exhibited lower AP- and VT-HRs. All groups exhibited reduced HRs at speeds slower than preferred. However, there were no differences in HRs between preferred and faster speeds, with the exception of reduced VT-HRs in the very fast condition for the older groups. The ML-HR was not different between groups, and varied less across speeds. Stride time variability exhibited inverse relations with, and independently contributed to, HRs across speeds; lower stride time variability was associated with greater smoothness of trunk motion. Older groups were not disproportionately affected by walking more slowly and smoothness of trunk motion did not show a clear pattern of optimization at preferred pace for any group.     

Triceps surae force, length and velocity during walking

Individuals with neuromuscular conditions may develop muscle contractures that limit joint motion. Decreased muscle length is clinically obvious, but deviations in other functional characteristics of muscle, such as underlying weakness or decreased shortening velocity are more obscure. Therefore, a more comprehensive assessment of muscle characteristics may be required to fully restore function in these individuals. To provide normative comparison data on the force, length and velocity of the triceps surae during walking, 20 adults free from neuromuscular and orthopedic problems were assessed using instrumented gait analysis. Kinematic and kinetic data were used to calculate gastrocnemius and soleus length and velocity, and plantarflexor force during walking. Gastrocnemius length was shortest in early swing and longest in terminal swing and again in midstance. Soleus length was longest throughout the period of single limb stance and was shortest at foot-off. Gastrocnemius shortening velocity was greatest in early swing phase whereas soleus shortening velocity was greatest in pre-swing. Plantarflexor force increased steadily throughout stance phase and peaked in terminal stance at 33.8+/-3.6 N/kg bodyweight. These data provide target levels on the functional parameters of plantarflexor force, length and velocity in order that therapeutic and surgical interventions could be focused on the deviations observed, and the outcomes of these interventions more objectively assessed.     

Medial gastrocnemius muscle behavior during human running and walking

Utilization of elastic energy in the tendinous tissues (TT) of the human skeletal muscle may be task dependent. The present study was designed to investigate this problem by comparing the fascicle-TT interaction of the medial gastrocnemius muscle (MG) during ground contact of running and walking. Seven subjects ran and walked with a natural cadence. Ankle and knee joint angular data were recorded by electrogoniometers for estimating the entire MG muscle-tendon unit (MTU) length, together with the ground reaction forces. The MG fascicle length was measured by using the high-speed ultrasound image scanning during movements. The results showed that in running, after the rapid early fascicle stretching (0-10% of the contact period), the fascicles shortened throughout the ground contact while TT was stretched prior to shortening. In walking, the fascicles shortened initially (0-15% of the contact period) due to sudden plantar-flexion. Thereafter, the fascicles and TT lengthened slowly until the end of single support (15-70% of the contact period.). The fascicles then shorted during the push-off phase (70-100% of the contact period). These results demonstrate that the MG fascicles behaved differently between running and walking and did not follow the length change pattern of the MTU during the ground contact period. The estimated working range of active muscle fibers in force-length relationship could shift more to an ascending limb (shorter length) phase in running than in walking. These results suggest that MG fascicles can work within the optimal working range of the sarcomeres in the force-length relation but are responsible for the effective utilization of the TT elasticity during human running.     

Measures of frontal plane stability during treadmill and overground walking

Given the consequences of falling to the side by older adults, attention has focused on identifying variables associated with changes in lateral stability and fall risk. Step-width (SW) and step-width variability (SWV) have traditionally been associated with such changes. Recently the “margin of stability” (MOS) has been adopted for describing dynamic stability. Although these measures may be influenced by the conditions during which locomotion occurs, only one published within-subject study has compared SW (but not SWV or MOS) during overground and treadmill walking. Therefore, we compared SW, SWV and minimum MOS (MOS_min) in 10 healthy young subjects walking at self-selected speeds, both overground and on a treadmill. We found SW was significantly larger (p = 0.001), and SWV significantly smaller (p = 0.001) during treadmill walking, and that these changes were meaningfully correlated between tasks. In contrast, MOS_min was insensitive to treadmill versus overground walking. This suggested first, that SW and SWV only partially reflect frontal plane stability, and second, that the goal of the central nervous system may be to maintain a constant MOS_min regardless of task.     

The how and why of arm swing during human walking

Humans walk bipedally, and thus, it is unclear why they swing their arms. In this paper, we will review the mechanisms and functions of arm swinging in human gait.First, we discuss the potential advantages of having swinging arms. Second, we go into the detail on the debate whether arm swing is arising actively or passively, where we will conclude that while a large part of arm swinging is mechanically passive, there is an active contribution of muscles (i.e. an activity that is not merely caused by stretch reflexes). Third, we describe the possible function of the active muscular contribution to arm swinging in normal gait, and discuss the possibility that a Central Pattern Generator (CPG) generates this activity. Fourth, we discuss examples from pathological cases, in which arm swinging is affected. Moreover, using the ideas presented, we suggest ways in which arm swing may be used as a therapeutic aid.We conclude that (1) arm swing should be seen as an integral part of human bipedal gait, arising mostly from passive movements, which are stabilized by active muscle control, which mostly originates from locomotor circuits in the central nervous system (2) arm swinging during normal bipedal gait most likely serves to reduce energy expenditure and (3) arm swinging may be of therapeutic value.