Energy cost of gait in children and the effect of speed, age, and body size

Background: Energy cost (EC) of comfortable walking is often used in clinical evaluation of children with altered gait function. EC is presented as energy expenditure per kg bodyweight per meter, either in total (grossEC) or in addition to resting energy expenditure (netEC). GrossEC is considered more reliable and netEC less affected by between-subject variations in speed, age, and body size. However, the effect of the individual child's speed on EC is rarely considered, while altered gait function may affect both speed and EC. Research question: To what extent are grossEC and netEC affected by within-subject variation in speed and between-subject variations in speed, age, and body size? Methods: Forty-two typically developing children (7–15 y) were included in this cross-sectional study. Age, height, and bodyweight were obtained. Breath-to-breath gas-exchange measures of VO2 and VCO2 were conducted during rest and five over-ground gait conditions: walking at slow, comfortable, and fast speed, jogging and running. All conditions lasted 3–5 min. Body surface area, non-dimensional speed, grossEC, and netEC were calculated. Regression analyses and mixed model analyses were conducted to explain the effect of speed, age, and body size on variations in EC. Results: GrossEC showed a non-significant, concave up relation to within-subject variation in speed, with a minimum around comfortable/fast walking speed. NetEC had a strong positive linear relation to within-subject variation in speed. For each gait condition, grossEC was more affected by between-subject variations in speed, age, and body size compared to netEC. However, the effect of age and body size was not eliminated for netEC but was quadratic. Significance: Although normalised to speed and bodyweight, grossEC and netEC are still affected by those factors. However, they are affected differently for within- and between-subject variations. This must be considered when interpreting EC in children in relation to gait function

Lower limb muscle fatigue during walking in children with cerebral palsy

Aim: To investigate whether more prominent signs of muscle fatigue occur during self-paced walking in children with cerebral palsy (CP) compared to typically developing peers. Method: In this case–control study, 13 children with CP (four males, nine females; mean age [SD] 11y 4mo [3y 8mo]; nine in Gross Motor Function Classification System [GMFCS] level I, three in GMFCS level II, and one in GMFCS level III) and 14 typically developing peers (nine males, five females; mean age [SD] 9y 10mo [1y 10mo]) walked 5 minutes overground at a self-selected walking speed. Electromyography (EMG) median frequency and root mean square (RMS) were identified per gait cycle from EMG recordings of the tibialis anterior, gastrocnemius medialis, soleus, rectus femoris, and semitendinosus. Rate of change in those variables was analysed using mixed linear model analyses. Results: The decrease in EMG median frequency of gastrocnemius medialis and soleus and increase in EMG-RMS of tibialis anterior, gastrocnemius medialis, and soleus were significantly larger in the most affected leg of children with CP compared with typically developing peers. Interpretation: Increased selective muscle fatigue of the lower leg muscles was observed during self-paced walking in children with mild-to-moderate severe CP. This could contribute to and account for limited walking capacity. What this paper adds: Children with cerebral palsy (CP) show more signs of lower leg muscle fatigue than typically developing peers. No signs of muscle fatigue were observed in upper leg muscles of children with CP

Lower limb muscle fatigue during walking in children with cerebral palsy

Aim To investigate whether more prominent signs of muscle fatigue occur during self‐paced walking in children with cerebral palsy (CP) compared to typically developing peers. Method In this case–control study, 13 children with CP (four males, nine females; mean age [SD] 11y 4mo [3y 8mo]; nine in Gross Motor Function Classification System [GMFCS] level I, three in GMFCS level II, and one in GMFCS level III) and 14 typically developing peers (nine males, five females; mean age [SD] 9y 10mo [1y 10mo]) walked 5 minutes overground at a self‐selected walking speed. Electromyography (EMG) median frequency and root mean square (RMS) were identified per gait cycle from EMG recordings of the tibialis anterior, gastrocnemius medialis, soleus, rectus femoris, and semitendinosus. Rate of change in those variables was analysed using mixed linear model analyses. Results The decrease in EMG median frequency of gastrocnemius medialis and soleus and increase in EMG‐RMS of tibialis anterior, gastrocnemius medialis, and soleus were significantly larger in the most affected leg of children with CP compared with typically developing peers. Interpretation Increased selective muscle fatigue of the lower leg muscles was observed during self‐paced walking in children with mild‐to‐moderate severe CP. This could contribute to and account for limited walking capacity

Effectiveness of resistance training in combination with botulinum toxin-A on hand and arm use in children with cerebral palsy: a pre-post intervention study

<p>Abstract</p> <p>Background</p> <p>The aim of this pilot study was to examine the effects of additional resistance training after use of Botulinum Toxin-A (BoNT-A) on the upper limbs in children with cerebral palsy (CP).</p> <p>Methods</p> <p>Ten children with CP (9–17 years) with unilaterally affected upper limbs according to Manual Ability Classification System II were assigned to two intervention groups. One group received BoNT-A treatment (group B), the other BoNT-A plus eight weeks resistance training (group BT). Hand and arm use were evaluated by means of the Melbourne assessment of unilateral upper limb function (Melbourne) and Assisting Hand Assessment (AHA). Measures of muscle strength, muscle tone, and active range of motion were used to assess neuromuscular body function. Measurements were performed before and two and five months after intervention start. Change scores and differences between the groups in such scores were subjected to Mann–Whitney U and Wilcoxon Signed Rank tests, respectively.</p> <p>Results</p> <p>Both groups had very small improvements in AHA and Melbourne two months after BoNT-A injections, without differences between groups. There were significant, or close to significant, short-term treatment effects in favour of group BT for muscle strength in injected muscles (elbow flexion strength, <it>p</it> = .08) and non-injected muscles (elbow extension and supination strength, both <it>p</it> = .05), without concomitant increases in muscle tone. Active supination range improved in both groups, but more so in group BT (<it>p</it> = .09). There were no differences between the groups five months after intervention start.</p> <p>Conclusions</p> <p>Resistance training strengthens non-injected muscles temporarily and may reduce short-term strength loss that results from BoNT-A injections without increasing muscle tone. Moreover, additional resistance training may increase active range of motion to a greater extent than BoNT-A alone. None of the improvements in neuromuscular impairments further augmented use of the hand and arm. Larger clinical trials are needed to establish whether resistance training can counteract strength loss caused by BoNT-A, whether the combination of BoNT-A and resistance training is superior to BoNT-A or resistance training alone in improving active range of motion, and whether increased task-related training is a more effective approach to improve hand and arm use in children with CP.</p

European consensus on the concepts and measurement of the pathophysiological neuromuscular responses to passive muscle stretch

Background and purpose To support clinical decision-making in central neurological disorders, a physical examination is used to assess responses to passive muscle stretch. However, what exactly is being assessed is expressed and interpreted in different ways. A clear diagnostic framework is lacking. Therefore, the aim was to arrive at unambiguous terminology about the concepts and measurement around pathophysiological neuromuscular response to passive muscle stretch. Methods During two consensus meetings, 37 experts from 12 European countries filled online questionnaires based on a Delphi approach, followed by plenary discussion after rounds. Consensus was reached for agreement ≥75%. Results The term hyper-resistance should be used to describe the phenomenon of impaired neuromuscular response during passive stretch, instead of for example ‘spasticity’ or ‘hypertonia’. From there, it is essential to distinguish non-neural (tissue-related) from neural (central nervous system related) contributions to hyper-resistance. Tissue contributions are elasticity, viscosity and muscle shortening. Neural contributions are velocity dependent stretch hyperreflexia and non-velocity dependent involuntary background activation. The term ‘spasticity’ should only be used next to stretch hyperreflexia, and ‘stiffness’ next to passive tissue contributions. When joint angle, moment and electromyography are recorded, components of hyper-resistance within the framework can be quantitatively assessed. Conclusions A conceptual framework of pathophysiological responses to passive muscle stretch is defined. This framework can be used in clinical assessment of hyper-resistance and will improve communication between clinicians. Components within the framework are defined by objective parameters from instrumented assessment. These parameters need experimental validation in order to develop treatment algorithms based on the aetiology of the clinical phenomena