Muscle fatigue of the lower limbs is considered a main contributor to the perceived fatigue in children with cerebral palsy (CP) and is expected to occur during prolonged walking. In adults without disabilities, muscle fatigue has been proposed to be associated with adaptations in complexity of neuromuscular control. What are the effects of prolonged walking on signs of muscle fatigue and complexity of neuromuscular control in children with CP? Ten children with CP and fifteen typically developing (TD) children performed a standardised protocol on an instrumented treadmill consisting of three stages: six-minutes walking at preferred speed (6 MW), moderate-intensity walking (MIW, with two minutes at heart rate > 70% of predicted maximal heart rate) and four-minutes walking at preferred speed (post-MIW). Electromyography (EMG) data were analysed for eight muscles of one leg during three time periods: 6 MW-start, 6 MW-end and post-MIW. Signs of muscle fatigue were quantified as changes in EMG median frequency and EMG root mean square (RMS). Complexity of neuromuscular control was quantified by total variance accounted for by one synergy (tVAF1). Muscle coactivation was assessed for antagonistic muscle pairs. EMG median frequency was decreased at 6 MW-end and post-MIW compared to 6 MW-start in children with CP (p < 0.05), but not in TD children. In both groups, EMG-RMS (p < 0.01) and muscle coactivation (p < 0.01) were decreased at 6 MW-end and post-MIW compared to 6 MW-start. tVAF1 decreased slightly at 6 MW-end and post-MIW compared to 6 MW-start in both groups (p < 0.05). Changes were most pronounced from 6 MW-start to 6 MW-end. Children with CP presented signs of muscle fatigue after prolonged walking, while no effects were found for TD. Both groups showed minimal changes in tVAF1, suggesting signs of muscle fatigue are not associated with changes in complexity of neuromuscular control.

Background: Impaired postural control is a key feature of cerebral palsy that affects daily living. Measures of trunk movement and acceleration have been used to assess dynamic postural control previously. In many children with cerebral palsy, ankle-foot orthoses are used to provide a stable base of support, but their effect on postural control is not yet understood. Objectives: The objectives of the current study were to investigate the effects of ankle-foot orthoses on postural control and energy cost of walking in children with cerebral palsy. Study design: Clinical study with controls. Methods: Trunk accelerometry (amplitude and structure) and energy cost of walking (J/kg/m) were recorded from five-minute walking trials with and without ankle-foot orthoses for children with cerebral palsy and without orthoses for the reference group. Results: Nineteen children with unilateral spastic cerebral palsy and fourteen typically developed children participated. The use of ankle-foot orthoses increased structure complexity of trunk acceleration in mediolateral and anterior–posterior directions. The use of ankle-foot orthoses changed mediolateral-structure toward values found in typically developed children. This change was not associated with a change in energy cost during walking. Conclusions: The use of ankle-foot orthoses does affect trunk acceleration that may indicate a beneficial effect on postural control. Using measures of trunk acceleration may contribute to clinical understanding on how the use of orthoses affect postural control.

Introduction Difficulty descending stairs is common in persons with knee osteoarthritis (OA). Clinically, it is important to know if and how this is explained by objectively measured difficulty to descend stairs, muscle weakness, pain, fear of movement, or knee joint status. Objective Identify the potential of these factors to explain self-reported difficulty descending stairs Design Cross sectional, case-control Setting Hospital outpatient and physiotherapy clinic Participants 28 men and women with knee OA (age 62.2 SD 5.9 years) and 31 controls (age 50.0 SD 8.5 years). Intervention Not applicable Main outcome measures Using multivariate statistics, group comparisons were made for lower extremity kinematics (incorporating hip-, knee-, and ankle- angles) and stance time in stair-descent and lower extremity muscle-strength. Then, a stepwise linear regression analysis was performed within the OA-group to explain self-reported difficulties in stair descent where pain, kinesiophobia, radiographic signs, and outcomes that differed from controls for stair-descent kinematics and muscle-strength were independent variables. Results Multivariate statistics showed that the OA-group displayed different all-over lower extremity kinematics (F_{8, 42,} = 2.44 p = 0.029, η² = 0.32) and a longer stance time (F_{3, 50,} = 6.46; p = 0.001, η² = 0.28) in stair descent, and lower muscle strength (F_{7, 47,} = 2.39; p = 0.035, η² = 0.26) compared to controls. Regression analysis within the OA-group for explaining self-rated difficulties to descend stairs showed that the strongest association with kinesiophobia (ß = 0.607, p=0.001) that combined with pain last week and radiographic signs explained almost 100 % (ß = 0.972). Stair descent kinematics and strength variables that differed between groups did not explain self-rated difficulties to descend stairs. Conclusion Kinesiophobia and pain rather than stair-descent kinematics and reduced muscle-strength explained self-rated difficulties in stair descent in the OA-group.