Limb Stride Research Articles

INFLUENCE OF FEMUR LENGTH ON ASYMMETRY OF PROSTHETIC GAIT BIOMECHANICS IN TRANSFEMORAL AMPUTATION

This study compares the prosthetic gait asymmetry in transfemoral amputees with varied femoral lengths to able-bodied participants in terms of temporal-spatial parameters and joint kinematics. Sixteen young and active transfemoral amputees with short and long residual limbs were divided into two groups and subjected to three-dimensional quantitative motion analysis through high definition optoelectronic cameras and force platform. The prosthetic gait of amputees was compared with those of 15 participants with normal gait to analyze the asymmetry. There was a significant difference in temporal-spatial gait parameters between the amputee groups in terms of intact limb stride length and swing time ([Formula: see text]). The gait of amputees with long femoral lengths was with comparatively higher mean step length (0.31 versus 0.35[Formula: see text]m), velocity (0.48 versus 0.44[Formula: see text]m/s), and cadence (73.58 versus 66.62 steps/min) compared to short residual limbs, however these results are nonsignificant ([Formula: see text]). Amputees and able-bodied participants differed significantly for all measured parameters ([Formula: see text]). The amputees with short residual limbs had more variation in sagittal plane hip flexion at initial contact than long amputees and able-bodied subjects. Amputees with longer residual limbs demonstrated peak swing prosthetic hip flexion closer to able-bodied individuals. The frontal pelvic obliquity and sagittal pelvic tilt revealed more variance among amputees with shorter residual limbs than longer ones. This study will aid in identifying the underlying mechanism of gait asymmetry in transfemoral amputees in relation to residual femoral length and hence will pave a path for improving the knee and foot prosthetic components.

Effect of treadmill training on fibrocartilage complex repair in tendon-bone insertion healing in the postinflammatory stage.

Mechanical stimulation is a key factor in the development and healing of tendon-bone insertion. Treadmill training is an important rehabilitation treatment. This study aims to investigate the benefits of treadmill training initiated on postoperative day 7 for tendon-bone insertion healing. A tendon-bone insertion injury healing model was established in 92 C57BL/6 male mice. All mice were divided into control and training groups by random digital table method. The control group mice had full free activity in the cage, and the training group mice started the treadmill training on postoperative day 7. The quality of tendon-bone insertion healing was evaluated by histology, immunohistochemistry, reverse transcription quantitative polymerase chain reaction, Western blotting, micro-CT, micro-MRI, open field tests, and CatWalk gait and biomechanical assessments. Our results showed a significantly higher tendon-bone insertion histomorphological score in the training group, and the messenger RNA and protein expression levels of type II collagen (COL2A1), SOX9, and type X collagen (COL10A1) were significantly elevated. Additionally, tendon-bone insertion resulted in less scar hyperplasia after treadmill training, the bone mineral density (BMD) and bone volume/tissue volume (BV/TV) were significantly improved, and the force required to induce failure became stronger in the training group. Functionally, the motor ability, limb stride length, and stride frequency of mice with tendon-bone insertion injuries were significantly improved in the training group compared with the control group. Treadmill training initiated on postoperative day 7 is beneficial to tendon-bone insertion healing, promoting biomechanical strength and motor function. Our findings are expected to guide clinical rehabilitation training programmes.

Spatiotemporal Parameters of Gait in Filipino Adults Using the 3-D Motion Capture System

Background and Purpose: Gait is one of the outcome measures used in evaluation in the field of rehabilitation and there is a need for reference data of gait parameters primarily to understand the physiological significance of these parameters, describe their changes in pathologic gait for better understanding of pathophysiology and be able to provide the appropriate therapeutic approach. The purpose of this study was: 1) To derive a reference data of spatiotemporal parameters of gait among Filipinos, which include step time, stride time, stance time, swing time, single limb support time, double limb support time, cadence, speed, step length, stride length, and step width; 2) To determine correlation of age, gender, and anthropometric measures with spatiotemporal parameters, and 3) To determine gait symmetry. Materials and Methods: In this cross-sectional study, 374 participants aged 20-69 years (males = 181, females = 193) were included. They were asked to walk in their comfortable speed. Spatiotemporal parameters were obtained using the Vicon motion capture system. Results: The walking speed, step length, stride length, and step width declined with age. Filipino men demonstrated higher values in all parameters except cadence which is higher in Filipino women. Height and leg length both have positive correlation with all parameters except for cadence. Weight has a positive correlation with all spatiotemporal parameters except for cadence, swing time, single limb support time, and speed. Cadence and stride length were symmetrical between right and left lower extremities. Conclusion: Spatiotemporal parameters among healthy Filipinos 20-69 years old were presented including their correlations with age, gender, and anthropometric measures. This can serve as a reference for future studies in gait where Filipinos are the participants.

Tail Base Deflection but not Tail Curvature Varies with Speed in Lizards: Results from an Automated Tracking Analysis Pipeline.

Tail movement is an important component of vertebrate locomotion and likely contributes to dynamic stability during steady-state locomotion. Previous results suggest that the tail plays a significant role in lizard locomotion, but little data are available on tail motion during locomotion and how it differs with morphological, ecological, and phylogenetic parameters. We collected high-speed vertical climbing and horizontal locomotion video data from 43 lizard species from four taxonomic groups (Agamidae, Gekkota, Scincidae, and Varanidae) across four habitats. We introduce a new semi-automated and generalizable analysis pipeline for tail and spine motion analysis including markerless pose-estimation, semi-automated kinematic recognition, and muti-species data analysis. We found that step length relative to snout-vent length (SVL) increased with tail length relative to SVL. Examining spine cycles agnostic to limb stride phase, we found that ranges of inter-tail bending compared with inter-spine bending increased with relative tail length, while ranges of tail deflection relative to spine deflection increased with relative speed. Considering stepwise strides, we found the angular velocity and acceleration of the tail center of mass increased with relative speed. These results will provide general insights into the biomechanics of tails in sprawling locomotion enabling biomimetic applications in robotics, and a better understanding of vertebrate form and function. We look forward to adding more species, behaviors, and locomotor speeds to our analysis pipeline through collaboration with other research groups.

Patterns of Limb and Epaxial Muscle Activity During Walking in the Fire Salamander, Salamandra salamandra.

SynopsisSalamanders and newts (urodeles) are often used as a model system to elucidate the evolution of tetrapod locomotion. Studies range from detailed descriptions of musculoskeletal anatomy and segment kinematics, to bone loading mechanics and inferring central pattern generators. A further area of interest has been in vivo muscle activity patterns, measured through electromyography (EMG). However, most prior EMG work has primarily focused on muscles of the forelimb or hindlimb in specific species or the axial system in others. Here we present data on forelimb, hindlimb, and epaxial muscle activity patterns in one species, Salamandra salamandra, during steady state walking. The data are calibrated to limb stride cycle events (stance phase, swing phase), allowing direct comparisons to homologous muscle activation patterns recorded for other walking tetrapods (e.g., lizards, alligators, turtles, mammals). Results demonstrate that Salamandra has similar walking kinematics and muscle activity patterns to other urodele species, but that interspecies variation does exist. In the forelimb, both the m. dorsalis scapulae and m. latissimus dorsi are active for 80% of the forelimb swing phase, while the m. anconaeus humeralis lateralis is active at the swing–stance phase transition and continues through 86% of the stance phase. In the hindlimb, both the m. puboischiofemoralis internus and m. extensor iliotibialis anterior are active for 30% of the hindlimb swing phase, while the m. caudofemoralis is active 65% through the swing phase and remains active for most of the stance phase. With respect to the axial system, both the anterior and posterior m. dorsalis trunci display two activation bursts, a pattern consistent with stabilization and rotation of the pectoral and pelvic girdles. In support of previous assertions, comparison of Salamandra muscle activity timings to other walking tetrapods revealed broad-scale similarities, potentially indicating conservation of some aspects of neuromuscular function across tetrapods. Our data provide the foundation for building and testing dynamic simulations of fire salamander locomotor biomechanics to better understand musculoskeletal function. They could also be applied to future musculoskeletal simulations of extinct species to explore the evolution of tetrapod locomotion across deep-time.

Kinetic and kinematic follow-up gait analysis in Doberman Pinschers with cervical spondylomyelopathy treated medically and surgically.

BackgroundThe efficacy of treatment of dogs with cervical spondylomyelopathy (CSM) is commonly based on the owner's and clinician's perception of the gait, which is highly subjective and suffers from observer bias.Hypothesis/ObjectivesTo compare selected kinetic and kinematic parameters before and after treatments and to correlate the findings of gait analysis to clinical outcome.AnimalsEight Doberman Pinschers with CSM confirmed by magnetic resonsance imaging.MethodsPatients were prospectively studied and treated with either medical management (n = 5) or surgery (n = 3). Force plate analysis and 3‐D kinematic motion capture were performed at initial presentation and approximately 8 weeks later. Force plate parameters evaluated included peak vertical force (PVF). Kinematic parameters measured included number of pelvic limb strides, stifle flexion and extension, maximum and minimum thoracic limb distance, truncal sway, and thoracic limb stride duration.ResultsKinematic analysis showed that deviation of the spine to the right (truncal sway) was significantly smaller (P < .001) and the degree of right stifle flexion was significantly larger (P = .029) after treatment. Force plate analysis indicated that PVF was significantly different after treatment (P = .049) and the difference of the PVF also was significantly larger (P = .027). However, no correlation was found with either method of gait analysis and clinical recovery.Conclusions and Clinical ImportanceKinetic and kinematic gait analysis were able to detect differences in dogs with CSM before and after treatment. A correlation of gait analysis to clinical improvement could not be determined.

Body-foot geometries as revealed by perturbed obstacle position with different time constraints.

This study examined the geometrical relationships between the feet, pelvis and an environmental obstruction when crossing an obstacle with unexpected changes to its position. Nine healthy young adults stepped over an obstacle 19cm high with their right leg leading. The obstacle could be static or advanced at either lead (early detection) or trail (late detection) foot contact prior to clearance to force an adaptive reorganization of body-foot geometry and foot proximity to the obstacle. Stride length, minimum foot clearance over the obstacle, and foot-obstacle horizontal proximity before and after clearance were measured along with the relative position of the pelvis to each foot at eight points (four for each foot) during approach and clearance: heel contacts before and after crossing the obstacle, maximum foot heights and foot clearances. With early obstacle movement, trail limb stride length before crossing was lengthened, but foot proximity was still far from the final obstacle position. Clearance was less affected for the trail foot as compared to the lead foot. Proximity of the lead limb following clearance was the same for both early and late perturbations and closer than for the static obstacle condition. For relative body-foot positioning, significant differences were found only in the anterior-posterior direction. Following obstacle displacement, body-foot geometry was initially adapted, but then re-established to static obstacle values with an apparent focus on a balance geometry with the forward placed foot establishing new contact. These findings support an overall balance geometry that can be temporarily adjusted and coordinated with foot proximity to the obstruction to maintain continual gait and safe clearance.

An investigation into the limb phasing characteristics and stride duration of fully shod, partially shod and unshod horses on a twenty metre circle in walk and trot

An investigation into the limb phasing characteristics and stride duration of fully shod, partially shod and unshod horses on a twenty metre circle in walk and trot

P178. The effect of cognitively challenging tasks on walking in Parkinson’s Patients

Background The interaction between motor and cognitive functions has an important impact on daily activities, is altered during ageing, and particularly affected in age-associated chronic diseases such as Parkinson’s disease (PD). Therefore, this motor-cognitive interaction has been extensively studied e.g. with dual task paradigms. It has become clear that particularly simultaneously performed cognitive secondary tasks with (an additional) motor aspect (such as carrying a glass of water or checking boxes) lead to impaired walking performance, and increase the risk of falls and injuries in PD patients. Yet, a detailed understanding of the changes which occur in PD when performing dual tasks is still lacking. Methods Fourty-four PD patients in off medication and 44 age- and gender-matched healthy controls were included. Dual tasking effects on gait velocity, number of steps, step duration, gait variability, double limb support and stride asymmetry of the primary task as well as velocity of the secondary tasks (subtracting serial sevens and checking boxes) during a 1 min “as fast as possible” walking condition were investigated. Participants wore a portable quantitative gait assessment system with six sensors (Mobility Lab®, APDM, Oregon, USA). Single as well as dual tasking performances were calculated for each group, and compared among groups. Results During the checking boxes task, all six above-mentioned gait parameters deteriorated in both PD patients and controls. Velocity of checking boxes decreased significantly under the dual tasking condition compared to single task also in both groups. During the subtraction task, four gait parameters deteriorated in PD patients but only two in controls. Velocity of serial subtraction decreased significantly only in PD patients but not in controls. Conclusion Dual tasking affects the quality of the performed tasks differently in PD patients and controls, depending on the kind of the secondary task. To study differences of dual tasking performance between PD patients and controls, a more “cognitive” task such as serial subtraction seems more promising than a secondary task that includes substantial motor aspects.

Alterations in Balance and Gait Characteristics in Community-Dwelling Elderly Subjects Following Hemi Hip-Arthroplasty Compared to Healthy Control Subjects

The objective of this study was to identify changes in balance and deviations in gait following hemi hip arthroplasty in 52 community-dwelling elderly individuals (n = 21) compared to healthy elderly subjects (n = 31). We assessed the outcome measures of balance (Berg balance scale) and gait parameters (temporal, spatial, and walking velocity). Those who received a hemi hip arthroplasty demonstrated poor balance (37.857 ± 8.673) compared to healthy elderly (52.484 ± 2.096). During gait, right and left single-limb stance time did not show differences, but double limb support time and cadence had significant differences (P < 0.001) between the groups. Hemi hip arthroplasty elderly had shorter step length (25.055 ± 4.045 cm) and shorter stride length (49.583 ± 8.054 cm) compared to healthy elderly (36.212 ± 9.620 and 72.722 ± 21.036 cm, respectively). Step height was less in those who received a hemi hip arthroplasty thank in healthy elderly. Walking velocity for the hemi hip arthroplasty group (28.690 ± 7.406 cm/sec) was 48.99% less (P < 0.001) than that in the healthy elderly group (58.557 ± 19.210). Effects of exercise on balance and gait parameters for subjects with hemi hip arthroplasty were not significant. Body mass index did not influence the balance and gait parameters. Progressive aging does influence walking velocity between hemi hip arthroplasty and healthy elderly. In conclusion, community-dwelling elderly with hemi hip arthroplasty had poor balance and reduced gait parameters (i.e., double limb support time, cadence, step length, stride length, step height, and walking velocity) compared to age-matched healthy control subjects.

Three‐Dimensional Kinematic Gait Analysis of Doberman Pinschers with and without Cervical Spondylomyelopathy

The optimal treatment of cervical spondylomyelopathy (CSM) is controversial, with the owner's and clinician's perception of gait improvement often being used as outcome measures. These methods are subjective and suffer from observer bias. To establish kinematic gait parameters utilizing digital motion capture in normal Doberman Pinschers and compare them with CSM-affected Dobermans. Nineteen Doberman Pinschers; 10 clinically normal and 9 with CSM. All dogs were enrolled prospectively and fitted with a Lycra(®) body suit, and motion capture was performed and used to reconstruct a 3-D stick diagram representation of each dog based on 32 reflective markers, from which several parameters were measured. These included stride duration, length, and height; maximal and minimal spinal angles; elbow and stifle flexion and extension; and maximum and minimum distances between the thoracic and pelvic limbs. A random-effects linear regression model was used to compare parameters between groups. Significant differences between groups included smaller minimum (mean = 116 mm; P = .024) and maximum (mean = 184 mm; P = .001) distance between the thoracic limbs in CSM-affected dogs. Additionally, thoracic limb stride duration was also smaller (P = .009) in CSM-affected dogs (mean = 0.7 seconds) when compared with normal dogs (mean = 0.8 seconds). In the pelvic limbs, the average stifle flexion (mean = 100°; P = .048) and extension (mean = 136°; P = .009), as well as number of strides (mean = 2.7 strides; P = .033) were different between groups. Our findings suggest that computerized gait analysis reveals more consistent kinematic differences in the thoracic limbs, which can be used as future objective outcome measures.

Clinical and Spatiotemporal Gait Effects of Canes in Hip Osteoarthritis

To investigate the effects of cane use on spatiotemporal gait parameters, pain, and function in adults with hip osteoarthritis (OA). Prospective observational study. An academic tertiary Veterans Affairs Healthcare Center. Thirteen adults with symptomatic hip OA and 13 healthy adults. We undertook gait analysis in all subjects with an optoelectronic camera system. Pain, stiffness, and physical function in subjects with hip OA were assessed with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Baseline spatiotemporal measures of unaided gait were obtained for healthy subjects. Baseline and 4-week spatiotemporal gait parameters were assessed for hip OA subjects while they walked with and without a cane. Participants with hip OA completed the WOMAC at baseline and after 4 weeks of cane use. At baseline when walking unaided, the subjects with hip OA (age range 60-75 years) had a significantly slower gait velocity, shorter affected limb stride length, and longer double-stance time compared with healthy control subjects. When walking with a cane, they had a reduction in gait velocity (P < .05) caused by a decrease in cadence (P < .05) compared with walking unaided. After 4 weeks of cane use, the participants with hip OA demonstrated significant improvements in gait velocity (P < .05) and double-stance time (P < .05) when walking with a cane in comparison with baseline data. There was no improvement in pain and function after 4 weeks of cane use, a period in which only approximately 60% of the hip OA subjects used the cane 6 or more times per week. Initial use of a cane led to decreased gait velocity and cadence in people with hip OA compared with walking unaided. This difference in gait velocity diminished after they practiced walking with the cane. Inconsistent use of the cane may have contributed to the lack of improvement in the subjects' hip OA pain and function.

Comparison of transtibial amputee and non-amputee biomechanics during a common turning task

The biomechanics of amputee turning gait has been minimally studied, in spite of its integral relationship with the more complex gait required for household or community ambulation. This study compares the biomechanics of unilateral transtibial amputees and non-amputees completing a common turning task. Full body gait analysis was completed for subjects walking at comparable self-selected speeds around a 1m radius circular path. Peak internal and external rotation moments of the hip, knee and ankle, mediolateral ground reaction impulse (ML GRI), peak effective limb length, and stride length were compared across conditions (non-amputee, amputee prosthetic limb, amputee sound limb). Amputees showed decreased internal rotation moments at the prosthetic limb hip and knee compared to non-amputees, perhaps as a protective mechanism to minimize stress on the residual limb. There was also an increase in amputee sound limb hip external rotation moment in early stance compared to non-amputees, which may be a compensation for the decrease in prosthetic limb internal rotation moment during late stance of the prior step. ML GRI was decreased for the amputee inside limb compared to non-amputee, possibly to minimize the body's acceleration in the direction of the turn. Amputees also exhibited a shorter inside limb stride length compared to non-amputees. Both decreased ML GRI and stride length indicate a COM that is more centered over the base of support, which may minimize the risk of falling. Finally, a longer effective limb length was found for the amputee inside limb turning, possibly due to excessive trunk shift.

Locomotor imagery training improves gait performance in people with chronic hemiparetic stroke: a controlled clinical trial

Objective: The purpose of this study was to evaluate whether locomotor imagery training leads to clinical improvements in gait after stroke. Design: Pretest—posttest matched control design. Participants: A total of 24 people with chronic hemiparetic stroke (13 for experimental and 11 for control) were recruited in this study. Interventions: The subjects in the experimental group participated in videotape-based locomotor imagery training five days a week for four weeks. They also conducted regular physical therapy. Outcome measures: Kinematic gait parameters were collected using a three-dimensional motion analysis system. Functional gait performance was assessed using clinical measures: Activities-specific Balance Confidence Scale, Berg Balance Test, Dynamic Gait Index and modified Emory Functional Ambulation Profile. Results: After training, walking velocity increased 0.07 ± 0.06 m/s in the experimental group and 0.01 ± 0.07 m/s in the control group. In the experimental group, the affected and less affected limb stride lengths increased by 0.09 ± 0.12 m and 0.10 ± 0.07 m respectively, whereas in the control group they decreased by 0.00 ± 0.04 m and increased by 0.02 ± 0.06 m, respectively. Kinematic parameters in the lower extremity joints during walking were more improved after the training in the experimental group. Confidence in balance, postural control, dynamic balance and performance time for different environmental walking situations were also improved more in the experimental group. Conclusion: Locomotor imagery training can be considered as a useful option for restoration of ambulation for individuals with chronic hemiparetic stroke who are unable to participate in physical gait training.

Automated gait analysis in the open-field test for laboratory mice

In this article, an automated and accurate mouse observation method, based on a conventional test for motor function evaluation, is outlined. The proposed measurement technique was integrated in a regular open-field test, where the trajectory and locomotion of a free-moving mouse were measured simultaneously. The system setup consisted of a transparent cage and a camera placed below it with its lens pointing upward, allowing for images to be captured from underneath the cage while the mouse was walking on the transparent cage floor. Thus, additional information was obtained about the position of the limbs of the mice for gait reconstruction. In a first step, the camera was calibrated as soon as it was fixed in place. A linear calibration factor, relating distances in image coordinates to real-world dimensions, was determined. In a second step, the mouse was located and its body contour segmented from the image by subtracting a previously taken "background" image of the empty cage from the camera image. In a third step, the movement of the mouse was analyzed and its speed estimated from its location in the past few images. If the speed was above a 1-sec threshold, the mouse was recognized to be running, and the image was further processed for footprint recognition. In a fourth step, color filtering was applied within the recovered mouse region to measure the position of the mouse's paws, which were visible in the image as small pink spots. Paws that were detected at the same location in a number of subsequent images were kept as footprints-that is, paws in contact with the cage floor. The footprints were classified by their position relative to the mouse's outline as corresponding to the front left or right paw or the hind left or right paw. Finally, eight parameters were calculated from the footprint pattern to describe the locomotion of the mouse: right/left overlap, front/hind base, right/left front limb stride, and right/left hind limb stride. As an application, the system was tested using normal mice and mice displaying pentobarbital-induced ataxia. The footprint parameters measured using the proposed system showed differences of 10% to 20% between normal and ataxic mice.

Nerve biomechanics and features of gait are altered in rats after mild crush injury to the sciatic nerve

Purpose To investigate biomechanical properties of the rat sciatic nerve and characteristics of gait in the early healing period after a mild crush injury to the nerve. Methods Mild crush injury was achieved through a weight drop onto the left sciatic nerve of Sprague Dawley rats. In uninjured controls, sham-injured and injured rats, gait kinematics and timing variables were measured using a novel pressure mapping system and nerve stiffness under tensile loading was measured periodically for 21 days after injury. Nerve sections were evaluated on post injury days 7 and 21. Results The hind limb force (L:R ratio) was significantly less in the injured and sham-injured groups (injured, day 1, p=0.009, day 3, p=0.003; sham-injured, day 1, p<0.001) compared to controls. The L:R hind limb pressure ratio was also less in the injured and sham-injured groups (injured, day 3, p<0.001; sham-injured, day 1, p=0.019). Although the hind limb stride length and stance time ratios were not different from controls, the force and pressure data indicate that weight was shifted to the non-injured hind limb. Under tensile load, the slope of the stress-strain curve was significantly lower for injured nerves (day 3, p=0.044; day 7, p=0.046), indicating less stiffness compared to sham-injured and control nerves. Macrophage infiltration and edema were apparent by post injury day 7. Conclusions This is the first study to document both mechanical changes in gait and biomechanical changes in nerve stiffness in the early period after a mild nerve crush injury. BB is supported by a Kean Fellowship in the UCSF/SFSU Graduate Program in Physical Therapy.

A new hip-knee-ankle-foot sling: Kinematic comparison with a traditional ankle-foot orthosis

In this study, we performed a kinematic analysis of a new, low-cost sling for the lower limb, compared to a common ankle-foot orthosis (AFO). Gait with no orthosis, with the AFO, and with the new sling was analyzed in one hemiplegic subject. Both the AFO and the sling reduced the mean angle and ROM (range of movement) of the ankle and the vertical displacement of the center of mass. The sling, but not the AFO, restored the normal sequence heel-strike, forefoot contact of the affected side. The sling, but not the AFO, reduced the affected limb stance and stride duration, increased stride length, and improved walking speed. In conclusion, the proposed sling for the lower limb equally improved the affected ankle kinematics in contrast to the traditional AFO, and it also improved some gait variables in this hemiplegic subject.

Kinematic detection of superior gait quality in young trotting warmbloods.

This study was conducted to identify objective criteria to select young horses with a good gait, which is a prerequisite for good performance in adult horses. The trot of 24 26-month-old Dutch Warmbloods, led on a loose shank, was subjectively scored by a judge and objectively assessed on a treadmill by using kinematic analysis equipment. It appeared that forelimb and hind limb stride and swing duration, scapula rotation, forelimb maximal fetlock extension, forelimb maximal retraction, hind limb maximal protraction, maximal stifle flexion, and maximal tarsal flexion significantly correlated with a generally accepted gait score in which length, suppleness, and strength are judged. Moreover, the ranking of the individual horses on the basis of gait quality according to their objectively measured kinematic variables was similar to the subjective ranking given by the judge. Thus, a complete picture was obtained of the variables in equine locomotion that determine the quality of the trot in warmbloods.

Oxygen delivery does not limit peak running speed during incremental downhill running to exhaustion.

Oxygen consumption (VO2), ventilation (VI), respiratory exchange ratio (R), stride frequency and blood lactate concentrations were measured continuously in nine trained athletes during two continuous incremental treadmill runs to exhaustion on gradients of either 0 degree or -3 degrees. Compared to the run at 0 degree gradient, the athletes reached significantly higher maximal treadmill velocities but significantly lower VO2, VI, R and peak blood lactate concentrations (P less than 0.001) during downhill running. These lower VO2 and blood lactate concentrations at exhaustion indicated that factors other than oxygen delivery limited maximal performance during the downhill run. In contrast, stride frequencies were similar at each treadmill velocity; the higher maximal speed during the downhill run was achieved with a significantly longer stride length (P less than 0.001); maximal stride frequency was the same between tests. Equivalent maximal stride frequencies suggested that factors determining the rate of lower limb stride recovery may have limited maximal running speed during downhill running and, possibly, also during horizontal running.

Speed correlated changes in limb orientation, stride frequency and movement components in a generalized lizard

Speed correlated changes in limb orientation, stride frequency and movement components in a generalized lizard