Selection of gait parameters during constrained walking

Journal of Theoretical Biology, 2001

A person constrained to walk at a given speed v on a treadmill, chooses a particular step frequency f and step length d"v/f. Testing over a range of speeds generates a speed}frequency (v}f) relationship. This relationship is commonly posited as a basic feature of human gait. It is often further posited that this curve follows from minimum energy cost strategy. We observed that individuals walking under di!erent constraint circumstances*walking to a range of "xed metronome frequencies ("xed f) or over a range of spaced markers ("xed d)*produce speed}frequency relations distinct from the constrained v relation. We show here that three distinct speed}frequency curves, similar to those observed, are predicted by the assumption that a walking person optimizes an underlying objective function F (v, f) that has a minimum at the preferred gait. Further, the metabolic cost of transport is a reasonable approximate candidate for the function F.

Journal of Orthopaedic & Sports Physical Therapy, 1997

esearchers studying human movement have attempted to define skilled motor performance by employing a range of kinematic variables, such as movement speed, movement time, timing accuracy, etc. In recent research, temporal and spatial intrasubject variability in kinematic variables is regarded as an important measure of motor skill and practice effects. Intrasubject variability of kinematic variables is an index of movement consistency or stability and thereby provides us with a measure to evaluate motor skill for a given task (8). The variability was examined in human gait, in particular, for its temporal and spatial parameters. It was expected that stability of gait could be assessed using the variability measure, especially for older persons (3-5) and physically disabled subjects (1). In fact, there was a negative correlation between variability in step width and balance performance for women 60 years of age and over (5) and also an increased variability in step length for hospitalized fallers compared with nonfallers (4). The results suggest that the variability measure can be an index of stability of gait performance. These studies, however, measured variability in the gait parameters at the preferred speed of each subject. Maruyama and Nagasaki (8) reported The optimal condition in speed, step rate, and step length of human walking has been reported in terms of temporal consistency, energy cost, and attentional demand. No study, however, has been conducted on the optimal condition in terms of spatial variability of walking. This study examined whether there is an optimal walking speed with minimum intrasubject variability in step length and step width during free walk (experiment 1) and whether there is an optimal step rate with minimum step length variability during walking with imposed step rates (experiment 2). Wearing shoes with ink-applied felt squares attached to the heels, healthy students walked on a flat walkway (0.6 x 16 m) at five different speeds with a freely chosen step rate in experiment 1 and walked at three different speeds with five different step rates in experiment 2. Free walk was found to have the fewest variable errors (VEs) in step length approximately at preferred walking speed. Variable error in step width increased linearly with an increase in walking speed. Under imposed step rates, VEs in step length were the fewest when walking with step rates close to those in free walk. Our everyday walking is performed most frequently at preferred speed and/or with freely chosen step rate, thereby optimizing the consistency of gait performance. Intrasubject variability in step length may be a useful measure for evaluation of walking.

Journal of Applied Physiology, 2012

Journal of Bioanalysis & Biomedicine, 2018

This paper presents the results of studying human gait transition outside the laboratory setting on a treadmill by means of wearable sensor technology. Combined inertial measurement and pressure sensor units embedded in footwear were employed to analyze the movement of the lower limbs during walk-run and run-walk transitions. Experimental data from 20 subjects was used to study three parameters-stride velocity, stride length and stride frequency. We focused on seven strides centered around the transition stride, that is, the stride in-between walking and running that has only a single floating phase. Three subjects underwent additional testing on a treadmill to capture the differences in kinematics between the two environments. The stride frequency varied least with both a subject's individual transition behavior and the environment. The former can be concluded from the standard deviations evaluated for each stride, which were lower for stride frequency than for velocity and length. The latter was derived by comparing the results from within and outside the laboratory: Stride frequency shifted similarly in both cases, mainly within 2-4 strides, to the attractor of the new gait. Velocity profiles differed, with acceleration being more uniform and much lower on the treadmill. Stride lengths were inversely proportional: In the walk-run transition, when the belt of the treadmill was sped up, stride lengths decreased. In the run-walk transition, when the belt was slowed down, stride lengths increased. This phenomenon is attributable mainly to the dominant nature of the stride frequency, which forces changes in stride length in order to fulfill the velocity constraint. A non-laboratory environment lacks such a constraint, thus giving rise to free transition behavior. Stride frequency, being easy to measure, is well suited to analyzing and defining gait in a practical context.

Journal of Experimental Biology - J EXP BIOL, 2005

As walking speed increases, consistent relationships emerge between the three determinant parameters of walking, speed, step frequency and step length. However, when step length or step frequency are predetermined rather than speed, different relationships are spontaneously selected. This result is expected if walking parameters are selected to optimize to an underlying objective function, known as the constrained optimization hypothesis. The most likely candidate for the objective function is metabolic cost per distance traveled, where the hypothesis predicts that the subject will minimize the cost of travel under a given gait constraint even if this requires an unusual step length and frequency combination. In the current study this is tested directly by measuring the walking behavior of subjects constrained systematically to determined speeds, step frequencies or step lengths and comparing behavior to predictions derived directly from minimization of measured metabolic cost. A metabolic cost surface in speed-frequency space is derived from metabolic rate for 10 subjects walking at 49 speed-frequency conditions. Optimization is predicted from the iso-energetic cost contours derived from this surface. Substantial congruence is found between the predicted and observed behavior using the cost of walking per unit distance. Although minimization of cost per distance appears to dominate walking control, certain notable differences from predicted behavior suggest that other factors must also be considered. The results of these studies provide a new perspective on the integration of walking cost with neuromuscular control, and provide a novel approach to the investigation of the control features involved in gait parameter selection.

Neuroscience Letters, 2011

In the absence of visual information, humans cannot maintain a straight walking path. We examined the hypothesis that step frequency during walking affects the magnitude of veering in healthy adults. Subject walked at a preferred (1.77 ± 0.18 Hz), low (0.8 × preferred, 1.41 ± 0.15 Hz), and high (1.2× preferred, 2.13 ± 0.20 Hz) step frequency with and without a blindfold. We compared the absolute differences between estimated and measured points of crossing a target line after 16 m of forward walking at the three step frequencies. There was no significant difference in veering when subjects walked at the different frequencies without a blindfold. However, the magnitude of veering was the smallest at the preferred (mean ± SE = 91.6 ± 33.6 cm) compared with the low (204.3 ± 43.0 cm) and high (112.7 ± 34.0 cm) frequency gaits with a blindfold. Thus, walking at a preferred step frequency minimizes veering, which occurs in the absence of visual information. This phenomenon may be associated with the previously reported minimization of movement variability, energy cost, and attentional demand while walking at a preferred step frequency.

The Journal of Experimental Biology

Minimizing metabolic cost of transport is a strong determinant of the preferred walking speed. While many factors can affect metabolic cost of transport during human walking, its interaction with step-to-step variability is unclear. Here, we aimed to determine the interaction between metabolic cost of transport and step length variability during human walking at different speeds. In particular, two aspects of step length variability were analyzed: the amount of variations (Variations) and the organization of the step-to-step fluctuations (Fluctuations). Ten healthy, young participants walked on a treadmill at five speeds, ranging from 0.75 to 1.75 m s−1. Metabolic cost of transport, step length Variations (coefficient of variation), and step length Fluctuations (quantified via Detrended Fluctuation Analysis) were calculated. A mixed-model ANOVA revealed that Variations and walking speed were strong predictors of metabolic cost of transport (R2=0.917, p<0.001), whereas Fluctuation...

Gait & Posture, 2006

Current definitions of the spatial and temporal parameters of gait have been based on the premise that walking occurs in a straight line. When the direction of progression (DoP) is not consistent and walking is non-linear, these definitions do not provide meaningful information. An alternative method based on the changing direction of each stride is presented. This method is easy to understand and use, and requires no expensive technology. A comparison of the spatial parameters of the footstep pattern during linear trials and trials incorporating a 608 turn was performed, using output derived from the old and the new definitions. The two methods produced very different results. Spatial output from the old definitions was merely dictated by the change of direction. Output calculated relative to the changing stride direction however, provided useful information about the footstep adjustments made for turning and how these would act to improve stability. This method of establishing spatial parameters during non-linear walking should form a useful tool for further investigation of functional locomotion. #

Gait & posture, 2003

This study focused on spatial and temporal variability of the stride in human gait. We determined the role of stride frequency (F) and stride length (L) on those parameters. Eight healthy subjects walked on a treadmill using 25 different FL combinations (0.95<L<1.5 m, and 0.8<F<1.26 Hz). The results showed that spatial and temporal variabilities tend to increase in concert with respect to change in stride parameters. In addition, stride variability was found (1) to be minimal at F=1 Hz; and (2) to increase with smaller L. During additional trials, subjects walked freely at various speeds. Although it is generally hypothesized that freely chosen behaviors are optimal in terms of variability, our data show that this is not always the case in human gait.

Journal of Biomechanics, 2013

Besides a stable gait pattern, gait in daily life requires the capability to adapt this pattern in response to environmental conditions. The purpose of this study was to elucidate the anticipatory strategies used by able-bodied people to attain an adaptive gait pattern, and how these strategies interact with strategies used to maintain gait stability.