Leg Asymmetries and Coordination Dynamics in Walking

Models of interlimb coordination (H. Haken, J. A. S. Kelso, &; H. Bunz, 1985 Haken, H., Kelso, J. A. S. and Bunz, H. 1985. A theoretical model of phase transitions in human hand movements. Biological Cybernetics, 51: 347–356. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; P. N. Kugler &; M. T. Turvey, 1987 Kugler, P. N. and Turvey, M. T. 1987. Information, natural law, and the self-assembly of rhythmic movement, Hillsdale, NJ: Erlbaum.  [Google Scholar]) were tested in walking by examining the role of asymmetries between limbs. Participants walked on a treadmill with and without a metronome. Five asymmetry conditions were created via ankle loads of 0, 3, or 6 kg on either leg. With the metronome, participants matched the target period. Without the metronome, stride rate slowed as the mass was increased on either leg. The loads led to an increase in stride period that was predicted by Huygens’ law and the hybrid pendulum-spring model. In agreement with extended Haken–Kelso–Bunz model predictions, leg asymmetries led to deviations from antiphase coordination. Also, perception–action coordination was influenced by the asymmetry between the legs and metronome. In contrast, no predicted stability effects were observed. These findings reveal that some properties of interlimb coordination, apparent in laboratory-based tasks, can also be observed in human walking.     

Coordination Between Arm and Leg Movements During Locomotion

To evaluate the contrasting dynamical and biomechanical interpretations of the 2:1 frequency coordination between arm and leg movements that occurs at low walking velocities and the 1:1 frequency coordination that occurs at higher walking velocities, the authors conducted an experiment in which they quantified the effect of walking velocity on the stability of the frequency and phase coordination between the individual limb movements. Spectral analyses revealed the presence of 2:1 frequency coordination as a consistent feature of the data in only 3 out of 8 participants at walking velocities ranging from 1.0 to 2.0 km/h, in spite of the fact that the eigenfrequencies of the arms were rather similar across participants. The degree of interlimb coupling, as indexed by weighted coherence and variability of relative phase, was lower for the arm movements and for ipsilateral and diagonal combinations of arm and leg movements than for the leg movements. Furthermore, the coupling between all pairs of limb movements was found to increase with walking velocity, whereas no clear signs were observed that the switches from 2:1 to 1:1 frequency coordination and vice versa were preceded by loss of stability. Therefore, neither a purely biomechanical nor a purely dynamical model is optimally suited to explain these results. Instead, an integrative model involving elements of both approaches seems to be required.     

Behavioral Effects of Chronic Melatonin and Pregnenolone Injections in a Myelin Mutant Rat (taiep)

The taiep (tremor, ataxia, immobility, epilepsy, and paralysis) myelin mutant displays a number of locomotor deficits. Taiep rat gait is characterized by shorter stride and step lengths as well as by larger stride widths. Thirty-day-old taiep mutants were placed under a regimen of daily hormone injections for 60 days. Animals in Condition 1 received melatonin, those in Condition 2 received pregnenolone sulfate, and those in a third control condition received injections of saline. Following the injections, each taiep mutant's gait was analyzed. The animals that received melatonin and pregnenolone displayed significantly larger stride and step lengths than did the controls. In addition, the animals that received hormones displayed shorter stride widths than did the controls. These experimental effects are consistent with a normalization of gait. Possible cellular mechanisms of this behavioral effect are discussed.     

Effect of Nonspecific Chronic Low Back Pain on Walking Economy: An Observational Study

The authors investigated the effects of chronic low back pain (LBP) and walking speed (WS) on metabolic power and cost of transport (CT). Subjects with chronic nonspecific LBP (LBP group [LG]; n = 9) and healthy (control group [CG]; n = 9) were included. The test battery was divided into 3 blocks according to WS as follows: preferred self-selected speed (PS), and lower and higher than the PS. In each block, the volunteers walked 5 min, during which oxygen consumption was measured. Although without differences between groups, the LG had CT lower in slower speeds than in faster speeds. Walking speed affected CT only in the LG, which the group had the greatest walking economy at slower speeds.     

Postural and Locomotor Contributions to Affordance Perception

The authors sought to evaluate the relative importance of locomotor control and postural control in the perception of affordances. While seated in a stationary wheelchair, participants made a series of judgments about the minimum lintel height under which they could roll in the wheelchair. Prior to making judgments, participants were given brief (～2 min) experience with wheelchair locomotion. They expected that this practice would influence the accuracy of subsequent affordance judgments. During practice, participants moved under their own power (using their hands on the wheels) or with an experimenter pushing the wheelchair. Also during wheelchair locomotion the participant's head was restrained, or was not. Results revealed that head restraint during the practice session had no effect on the accuracy of subsequent judgments. By contrast, the judgments of participants who controlled locomotion during practice were significantly more accurate than the judgments of participants who had not controlled their locomotion during practice.     

Facilitation of Psychomotor Learning by Classically Differentiated Supplementary Feedback Cues

2 experiments on the control of psychomotor performance by classically differentiated supplementary feedback cues are reported. The first, conducted with 30 Ss as a replication of an earlier study, demonstrated again that otherwise ineffective supplementary cues can be transformed into highly effective regulators of psychomotor performance by differential conditioning procedures. The second, conducted with 78 Ss, showed that the effects of classically differentiated supplementary cues on tracking skill increased as a negatively accelerated function of the number of differentiation trials. Results were interpreted as exemplifying the operation of secondary drive and reinforcement principles, although the nonspecific transfer of arousal and/or warm-up effects were acknowledged as worthy alternatives.     

Shoulder Muscle Activity Dampens Arm Swing Motion When Altering Upper Limb Mass Characteristics During Locomotion

Weighting the arms during locomotion results in decreased swing motion and increased shoulder muscle activity. To determine the functional relevance of this activity, participants walked on a treadmill with the arms unweighted, or weighted unilaterally or bilaterally. Similar to past work, the weighted arms decreased in swing amplitude and increased their shoulder muscle activity. A close examination of shoulder muscle activities in specific regions of the arm swing cycle suggested these muscles primarily acted eccentrically for all weighting conditions. These findings suggest that the increased shoulder muscle activities when weighting the arms act to dampen the arms when the inertial characteristics of the arms are altered, as opposed to assisting in driving swing of the heavier arms.     

调节模式理论：自我调节领域的新进展

作为Higgins自我调节理论体系的重要组成部分,调节模式理论认为自我调节包括运动和评估两种模式,两者分别关注状态的改变和最佳方案的获得。本文分析了两种调节模式的特点并介绍了其测量及诱导方法,概括了调节模式对基本心理现象的影响以及调节匹配效应有关的研究,并对新近进展进行了介绍。未来研究尚可针对调节模式的形成、多元化测量工具及诱发范式的开发、及其对反事实思维等特定心理现象的影响等问题作更深入探讨。     

Investigating mechanisms of social support effectiveness: The case of locomotion motivation

Although social support can entail costs, individuals with a higher locomotion orientation, who are motivated to move and take action, benefit from support. Two dyadic studies tested whether perceived movement toward important goals would mediate the effect of recipients' locomotion motivation on positive outcomes in support contexts. In Study 1, couples completed a 10‐day diary and then recalled support interactions with their partner after the diary period. In Study 2, couples engaged in laboratory support interactions for important goals. Perceived goal movement mediated the effect of higher (vs. lower) locomotion on self‐reported ratings and coder ratings of support outcomes. Higher locomotion recipients may benefit in support contexts because they perceive they can move smoothly toward their goals.     

Effect of Transient Perturbations of Short-Term Memory on Target-Directed Blind Locomotion

It is difficult to walk without vision to a nearby destination if there is a time delay between watching the destination and walking toward it. Indeed, path deviation occurred when delays were introduced before initiating straight ahead blindfolded walking (R. A. Tyrrell, K. K., Rudolph, B. G., Eggers, &; H. W. Leibowitz, 1993 Tyrrell, R. A., Rudolph, K. K., Eggers, B. G., &; Leibowitz, H. W. (1993). Evidence for the persistence of visual guidance information. Perception &; Psychophysics, 54, 431–438.[Crossref], [PubMed] , [Google Scholar]). The questions are whether the location of a 60-s delay in the walking path and whether performing a cognitive task during the delay influence the accuracy in reaching a previously seen target while walking without vision. Thirty young adults walked blindfolded and stopped when they believed they had reached a target at 8 m. Delays were 60 s in duration, were located at 0, 4, and 7 m, and involved waiting or backward counting. Significant differences were found between 0-m and 4-m delay locations for distance to target, distance travelled and path deviation (p < .05). Significant effect of backward counting during the 60-s delay was found at the 0-m delay for distance travelled (p < .05). The interaction between retaining visual guidance information during 60 s and performing a cognitive task likely influenced target-directed blind navigation.