A test of the effort equalization hypothesis in children with cerebral palsy who have an asymmetric gait

Healthy people can walk nearly effortlessly thanks to their instinctively adaptive gait patterns that tend to minimize metabolic energy consumption. However, the economy of gait is severely impaired in many neurological disorders such as stroke or cerebral palsy (CP). Moreover, self-selected asymmetry of impaired gait does not seem to unequivocally coincide with the minimal energy cost, suggesting the presence of other adaptive origins. Here, we used hemiparetic CP gait as a model to test the hypothesis that pathological asymmetric gait patterns are chosen to equalize the relative muscle efforts between the affected and unaffected limbs. We determined the relative muscle efforts for the ankle and knee extensors by relating extensor joint moments during gait to maximum moments obtained from all-out hopping reference test. During asymmetric CP gait, the unaffected limb generated greater ankle (1.36 +/- 0.15 vs 1.17 +/- 0.16 Nm/kg, p = 0.002) and knee (0.74 +/- 0.33 vs 0.44 +/- 0.19 Nm/kg, p = 0.007) extensor moments compared with the affected limb. Similarly, the maximum moment generation capacity was greater in the unaffected limb versus the affected limb (ankle extensors: 1.81 +/- 0.39 Nm/kg vs 1.51 +/- 0.34 Nm/kg, p = 0.033; knee extensors: 1.83 +/- 0.37 Nm/kg vs 1.34 +/- 0.38 Nm/kg, p = 0.021) in our force reference test. As a consequence, no differences were found in the relative efforts between unaffected and affected limb ankle extensors (77 +/- 12% vs 80 +/- 16%, p = 0.69) and knee extensors (41 +/- 17% vs 38 +/- 23%, p = 0.54). In conclusion, asymmetric CP gait resulted in similar relative muscle efforts between affected and unaffected limbs. The tendency for effort equalization may thus be an important driver of self-selected gait asymmetry patterns, and consequently advantageous for preventing fatigue of the weaker affected side musculature.Peer reviewe

Noninvasive reactivation of motor descending control after paralysis

© Mary Ann Liebert, Inc. 2015. The present prognosis for the recovery of voluntary control of movement in patients diagnosed as motor complete is generally poor. Herein we introduce a novel and noninvasive stimulation strategy of painless transcutaneous electrical enabling motor control and a pharmacological enabling motor control strategy to neuromodulate the physiological state of the spinal cord. This neuromodulation enabled the spinal locomotor networks of individuals with motor complete paralysis for 2-6 years American Spinal Cord Injury Association Impairment Scale (AIS) to be re-engaged and trained. We showed that locomotor-like stepping could be induced without voluntary effort within a single test session using electrical stimulation and training. We also observed significant facilitation of voluntary influence on the stepping movements in the presence of stimulation over a 4-week period in each subject. Using these strategies we transformed brain-spinal neuronal networks from a dormant to a functional state sufficiently to enable recovery of voluntary movement in five out of five subjects. Pharmacological intervention combined with stimulation and training resulted in further improvement in voluntary motor control of stepping-like movements in all subjects. We also observed on-command selective activation of the gastrocnemius and soleus muscles when attempting to plantarflex. At the end of 18 weeks of weekly interventions the mean changes in the amplitude of voluntarily controlled movement without stimulation was as high as occurred when combined with electrical stimulation. Additionally, spinally evoked motor potentials were readily modulated in the presence of voluntary effort, providing electrophysiological evidence of the re-establishment of functional connectivity among neural networks between the brain and the spinal cord

The paradox from within: research participants doing-being-observed

This article analyses a collection of cases from video recordings of naturally occurring interaction in institutional settings, where members display an orientation to the presence of the recording equipment. Such instances have been treated elsewhere as evidence of contamination of the ecology of the setting. The findings suggest that participants do remain aware of the recording activity, but that they publicly display when they are attending to it. Indeed, it is used as one resource to occasion identity work as competent, knowledgeable members of a particular institutional community, displaying to one another their understanding of the research aims, and their knowledge of how these kinds of data are constituted. Investigating how observational research is oriented to and constituted by the observed allows for a better understanding of what at that moment and in that setting is deemed recording-appropriate or -inappropriate conduct, and offers a more nuanced perspective on how data are co-constituted

Muscle activity and inactivity periods during normal daily life

Recent findings suggest that not only the lack of physical activity, but also prolonged times of sedentary behaviour where major locomotor muscles are inactive, significantly increase the risk of chronic diseases. The purpose of this study was to provide details of quadriceps and hamstring muscle inactivity and activity during normal daily life of ordinary people. Eighty-four volunteers (44 females, 40 males, 44.1±17.3 years, 172.3±6.1 cm, 70.1±10.2 kg) were measured during normal daily life using shorts measuring muscle electromyographic (EMG) activity (recording time 11.3±2.0 hours). EMG was normalized to isometric MVC (EMGMVC) during knee flexion and extension, and inactivity threshold of each muscle group was defined as 90% of EMG activity during standing (2.5±1.7% of EMGMVC). During normal daily life the average EMG amplitude was 4.0±2.6% and average activity burst amplitude was 5.8±3.4% of EMGMVC (mean duration of 1.4±1.4 s) which is below the EMG level required for walking (5 km/h corresponding to EMG level of about 10% of EMGMVC). Using the proposed individual inactivity threshold, thigh muscles were inactive 67.5±11.9% of the total recording time and the longest inactivity periods lasted for 13.9±7.3 min (2.5–38.3 min). Women had more activity bursts and spent more time at intensities above 40% EMGMVC than men (p<0.05). In conclusion, during normal daily life the locomotor muscles are inactive about 7.5 hours, and only a small fraction of muscle\u27s maximal voluntary activation capacity is used averaging only 4% of the maximal recruitment of the thigh muscles. Some daily non-exercise activities such as stair climbing produce much higher muscle activity levels than brisk walking, and replacing sitting by standing can considerably increase cumulative daily muscle activity

Laughter as medical providers' resource : negotiating informed choice in prenatal genetic counseling

This article aims to challenge the perception that in medical encounters laughter is an interactional resource primarily employed by patients. Drawing on 34 video-recorded prenatal genetic counseling (PGC) sessions collected in a Hong Kong hospital, and combining quantitative and qualitative methods, we illustrate that laughter is in fact frequently employed by the medical providers in our data. The particular focus of the article is on the ways in which laughter initiated by the medical providers assists interlocutors in negotiating informed choice, a crucial aspect of PGC sessions. Findings indicate that laughter initiated by the medical providers performs at least two PGC-specific functions: It assists the medical providers in olaughing offo and overcoming patients' resistance, and it helps them in dealing with patients' direct questions. Laughter is thus an important resource for the medical providers in pursuing the institutional goals of the interaction, namely negotiating informed choice with their patients

Using Laugh Responses to Defuse Complaints

This research uses conversation analysis to explore a collection of extracts from telephone calls involving laughter as a response in a sequence characterized by complaining. In these instances, the laugh responses fail to align with the complaint in progress and are somewhat disaffiliative (in that they do not display the same stance as that taken by the complainant). However, they do not strongly disaffiliate; they do not, for example, overtly disagree with complaint-relevant assessments produced in prior turns. In this way, recipients of a complaint work to display a somewhat discordant stance to that of the teller, and to discourage further development of the topic in progress while maintaining social solidarity. Thus, the current research adds to the finding (see also Drew, 1987, and Jefferson, Sacks, & Schegloff, 1987) that laughter can be located somewhere in the middle of a continuum ranging from overt affiliation to disaffiliatio

Increasing the plant species selection in traffic environment

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