Sarah Jane Hobbs

The influence of barefoot and barefoot-inspired footwear on the kinetics and kinematics of running in comparison to conventional running shoes

Background: Barefoot running has been the subject of much attention in footwear biomechanics literature, based on the supposition that it serves to reduce the occurrence of overuse injuries in comparison to conventional shoe models. This consensus has led footwear manufacturers to develop shoes that aim to mimic the mechanics of barefoot locomotion. Objectives: This study compared the impact kinetics and three-dimensional (3-D) joint angular kinematics observed while running barefoot, in conventional cushioned running shoes and in shoes designed to integrate the perceived benefits of barefoot locomotion. The aim of the current investigation was therefore to determine whether differences in impact kinetics exist between the footwear conditions and whether shoes that aim to simulate barefoot movement patterns can closely mimic the 3-D kinematics of barefoot running. Method: Twelve participants ran at 4.0 m s−1 (±5%) in each footwear condition. Angular joint kinematics from the hip, knee and ankle in the sagittal, coronal and transverse planes were measured using an eight-camera motion analysis system. In addition, simultaneous tibial acceleration and ground reaction forces were obtained. Impact parameters and joint kinematics were subsequently compared using repeated-measures analyses of variance (ANOVAs). Results: The kinematic analysis indicated that, in comparison to the conventional and barefoot-inspired shoes, running barefoot was associated with significantly greater plantar–flexion at footstrike and range of motion to peak dorsiflexion. Furthermore, the kinetic analysis revealed that, compared to the conventional footwear, impact parameters were significantly greater in the barefoot condition. Conclusions: This study suggests that barefoot running is associated with impact kinetics linked to an increased risk of overuse injury when compared to conventional shod running. Furthermore, the mechanics of the shoes that aim to simulate barefoot movement patterns do not seem to closely mimic the kinematics of barefoot locomotion.

Three-dimensional kinematic comparison of treadmill and overground running

The treadmill is an attractive device for the investigation of human locomotion, yet the extent to which lower limb kinematics differ from overground running remains a controversial topic. This study aimed to provide an extensive three-dimensional kinematic comparison of the lower extremities during overground and treadmill running. Twelve participants ran at 4.0 m/s ( ± 5%) in both treadmill and overground conditions. Angular kinematic parameters of the lower extremities during the stance phase were collected at 250 Hz using an eight-camera motion analysis system. Hip, knee, and ankle joint kinematics were quantified in the sagittal, coronal, and transverse planes, and contrasted using paired t-tests. Of the analysed parameters hip flexion at footstrike and ankle excursion to peak angle were found to be significantly reduced during treadmill running by 12° (p = 0.001) and 6.6° (p = 0.010), respectively. Treadmill running was found to be associated with significantly greater peak ankle eversion (by 6.3°, p = 0.006). It was concluded that the mechanics of treadmill running cannot be generalized to overground running.

The difference in kinematics of horses walking, trotting and cantering on a flat and banked 10 m circle

REASONS FOR PERFORMING STUDY Locomotion adaptation mechanisms have been observed in horses, but little information is available in relation to banked and nonbanked curve locomotion, which might be important to optimise training environments. OBJECTIVES To determine if adaptation mechanisms in horses existed when moving on a banked compared to a flat curve and whether adaptation was similar in different gaits. METHODS Eight infrared cameras were positioned on the outside of a 10 m lungeing circle and calibrated. Retroreflective markers were used to define left and right metacarpus (McIII) and proximal phalanges (P1), metatarsus (MtIII), head and sacrum. Data were recorded at 308 Hz from 6 horses lunged at walk, trot and canter on a flat and 10° banked circle in a crossover design. Measurements extracted were speed, stride length, McIII inclination, MtIII inclination, relative body inclination and duty factor. Data were smoothed with a fourth order Butterworth filter with 30 Hz cut-off. ANOVA was used to determine differences between conditions and limbs. RESULTS Adaptation mechanisms were influenced by gait. At canter inside forelimb duty factor was significantly longer (P<0.05) on a flat curve compared to a banked curve; at walk this was reversed. McIII inclination, MtIII inclination and relative body inclination were significantly greater (P<0.05) at trot and canter on a flat curve, so more inward tilt was found relative to the bearing surface. CONCLUSION Adaptation to curved motion is gait specific. At faster gaits it appears that horses negotiate a banked curve with limb posture closer to body posture and probably with demands on the musculoskeletal system more similar to straight canter.

The Influence of Different Force and Pressure Measuring Transducers on Lower Extremity Kinematics Measured during Running

In running analyses where both kinetic and kinematic information is recorded, participants are required to make foot contact with a force and/or pressure measuring transducer. Problems arise if participants modify their gait patterns to ensure contact with the device. There is currently a paucity of research investigating the influence of different underfoot kinetic measuring devices on 3-dimensional kinematics of running. Fifteen participants ran at 4.0 m/s in four different conditions: over a floor embedded force plate, Footscan, Matscan, and with no device. Three-dimensional angular kinematic parameters were collected using an eight camera motion analysis system. Hip, knee, and ankle joint kinematics were contrasted using repeated-measures ANOVAs. Participants also rated their subjective comfort in striking each of the three force measuring devices. Significant differences from the uninhibited condition were observed using the Footscan and Matscan in all three planes of rotation, whereas participants subjectively rated the force plate significantly more comfortable than either the Footscan/Matscan devices. The findings of the current investigation therefore suggest that the disguised floor embedded force plate offers the most natural running condition. It is recommended that analyses using devices such as the Footscan/Matscan mats overlying the laboratory surface during running should be interpreted with caution.

Influence of the helical and six available Cardan sequences on 3D ankle joint kinematic parameters

Cardan/Euler and helical angles are the popular methods of quantifying angular kinematics. Cardan angles are sequence dependent and crosstalk can influence the kinematic calculations. The International Society of Biomechanics (ISB) recommends a sagittal, coronal, and then transverse (XYZ) sequence of rotations, although it has been proposed that when calculating rotations outside of the sagittal plane, this may not be the most appropriate method. This study investigated the influence of the helical and six available Cardan sequences on three-dimensional (3D) ankle joint kinematics. Kinematic data were obtained using an eight-camera motion analysis system as participants ran at 4.0 m/s ± 5%. Repeated measures ANOVAs were used to compare kinematic parameters, and intra-class correlations were employed to identify evidence of crosstalk across planes. The results indicate that in the transverse and coronal planes, peak angle and range of motion values using the YXZ and ZXY sequences were significantly greater than the other sequences. Furthermore, utilization of YXZ and ZXY sequences was associated with the strongest correlations from the sagittal plane, and the XYZ sequence was found to be associated with the lowest correlations. It appears that for the representation of 3D ankle joint kinematics, the XYZ sequence is associated with minimal planar crosstalk and as such its use is encouraged.

Digital Filtering of Three-Dimensional Lower Extremity Kinematics: an Assessment

Abstract Errors in kinematic data are referred to as noise and are an undesirable portion of any waveform. Noise is typically removed using a low-pass filter which removes the high frequency components of the signal. The selection of an optimal frequency cut-off is very important when processing kinematic information and a number of techniques exists for the determination of an optimal frequency cut-off. Despite the importance of cut-off frequency to the efficacy of kinematic analyses there is currently a paucity of research examining the influence of different cut-off frequencies on the resultant 3-D kinematic waveforms and discrete parameters. Twenty participants ran at 4.0 m•s-1 as lower extremity kinematics in the sagittal, coronal and transverse planes were measured using an eight camera motion analysis system. The data were filtered at a range of cut-off frequencies and the discrete kinematic parameters were examined using repeated measures ANOVA’s. The similarity between the raw and filtered waveforms were examined using intra-class correlations. The results show that the cut-off frequency has a significant influence on the discrete kinematic measure across displacement and derivative information in all three planes of rotation. Furthermore, it was also revealed that as the cut-off frequency decreased the attenuation of the kinematic waveforms became more pronounced, particularly in the coronal and transverse planes at the second derivative. In conclusion, this investigation provides new information regarding the influence of digital filtering on lower extremity kinematics and re-emphasizes the importance of selecting the correct cut-off frequency.

A comparison of several barefoot inspired footwear models in relation to barefoot and conventional running footwear

This study examined differences in kinetics and kinematics between barefoot and shod running, as well as between several barefoot inspired footwear models. Fifteen participants ran at 4.0 m/s ±5% in each footwear condition. Lower extremity kinematics in the sagittal, coronal and transverse planes were measured using an eight camera motion analysis system alongside ground reaction force parameters. Impact parameters and joint kinematics were subsequently compared using repeated measures ANOVAs. The kinetic analysis revealed that, compared to the conventional footwear, impact parameters were significantly greater in the barefoot and more minimal in barefoot inspired footwear. Running barefoot and in the minimal barefoot inspired footwear was associated with increases in flexion parameters of the knee and ankle at footstrike in relation to the conventional footwear. Finally, the results indicated that the barefoot and minimal barefoot inspired footwear were associated with greater peak eversion magnitude whe...

Real-Time Immersive Table Tennis Game for Two Players with Motion Tracking

Presented in this paper is a novel real-time virtual reality game developed to enable two participants to play table tennis immersively with each other’s avatar in a shared virtual environment. It uses a wireless hybrid inertial and ultrasonic tracking system to provide the positions and orientations of both the head (view point) and hand (racket) of each player, as well as two large rear-projection stereoscopic screens to provide a view-dependent 3D display of the game environment. Additionally, a physics-based ball animation model is designed for the game, which includes fast detection of the ball colliding with table, net and quick moving rackets. The system is shown to offer some unique features and form a good platform for development of other immersive games for multiple players.

Sagittal plane ground reaction forces, centre of pressure and centre of mass in trotting horses

The aims of this study were to measure ground reaction forces (GRFs) of concurrently loaded limbs and to evaluate spatial relationships between the centre of pressure (COP) and centre of mass (COM) in trotting horses. Kinematic (120Hz) and GRF data were collected at trot from three trials of eight horses using four force plates (960 Hz). Forelimb and hind limb GRFs were measured, COP was calculated from the resultant vertical GRF vector and COM was calculated by summation of weighted segmental COMs. Peak total vertical force (19.3 ± 1.3N/kg at 45.1 ± 2.3% diagonal stance) coincided with zero total longitudinal force (45.1 ± 2.4% stance). Initially, COP position corresponded with the fore or hind hoof of the diagonal that contacted the ground earlier. During diagonal overlap, COP position reflected forelimb contribution to total vertical GRF; it maintained a fairly constant position relative to the base of support through the middle part of stance, then moved cranially in the last third of stance towards the fore hoof, which was always the last hoof to leave the ground. The COM moved forward continuously; its longitudinal velocity decreased with the net braking force in early stance and increased with the net propulsive force in late stance. The COM was caudal to the COP in early stance, coincident at 35.8 ± 4.4% stance and was maximally ahead of the COP at 67.6 ± 4.8% stance. Changes in the spatial relationship between COP and COM affect the moment arms of the forelimb and hind limb vertical GRFs and their effect in generating a pitching torque around the COM.

Functional Locomotor Consequences of Uneven Forefeet for Trot Symmetry in Individual Riding Horses

Left-right symmetrical distal limb conformation can be an important prerequisite for a successful performance, and it is often hypothesized that asymmetric or uneven feet are important enhancing factors for the development of lameness. On a population level, it has been demonstrated that uneven footed horses are retiring earlier from elite level competition, but the biomechanical consequences are not yet known. The objectives of this study were to compare the functional locomotor asymmetries of horses with uneven to those with even feet. Hoof kinetics and distal limb kinematics were collected from horses (n = 34) at trot. Dorsal hoof wall angle was used to classify horses as even or uneven (<1.5 and >1.5° difference between forefeet respectively) and individual feet as flat (<50°), medium (between 50° and 55°) or upright (>55°). Functional kinetic parameters were compared between even and uneven forefeet using MANOVA followed by ANOVA. The relative influences of differences in hoof angle between the forefeet and of absolute hoof angle on functional parameters were analysed using multiple regression analysis (P<0.05). In horses with uneven feet, the side with the flatter foot showed a significantly larger maximal horizontal braking and vertical ground reaction force, a larger vertical fetlock displacement and a suppler fetlock spring. The foot with a steeper hoof angle was linearly correlated with an earlier braking-propulsion transition. The conformational differences between both forefeet were more important for loading characteristics than the individual foot conformation of each individual horse. The differences in vertical force and braking force between uneven forefeet could imply either an asymmetrical loading pattern without a pathological component or a subclinical lameness as a result of a pathological development in the steeper foot.