Fatigability of elbow muscles in children and adolescents with spina bifida

Due to paralysis in the lower limbs, individuals with spina bifida (SB) rely heavily on upper limb muscles for daily tasks and assisted locomotion. Therefore, reduced upper limb muscle performance may be a key limiting factor. The aim was to investigate differences in elbow muscles strength and fatigability between children and adolescents with SB and their healthy peers. Cross-sectional study. Ribeirão Preto Medical School, University of São Paulo, Brazil. Twenty-three youth with SB (SB, mean age 10.83 years) and 84 age-matched children and adolescents (Controls, mean age 12.17 years), of both sexes. Participants performed five maximum concentric elbow flexion and extension contractions (120°.s-1) in an isokinetic dynamometer, to obtain maximal voluntary elbow flexor and extensor torque (MVT), which after was normalized to body weight (MVT-bw). After 10-min of rest, the participants performed a fatigue test with maximum concentric elbow flexion and extension contractions (120°.s-1) until peak muscle torque (PT) dropped below 50% MVT. PT was recorded in each repetition and normalized to body weight (PT-bw) or maximum voluntary torque (PT-MVT). Simultaneously, surface-EMG was obtained in the biceps and triceps brachii muscles to evaluate changes in neuromuscular activation. SB showed lower MVT-bw for elbow flexors and extensors than Controls. The decline in PT-bw differed between groups for elbow flexors, where SB showed lower absolute decline rates (PT-bw) than Controls. No statistically significant differences were observed for any EMG variables. SB did not exhibit increased fatigability in elbow flexors and extensors compared to Controls.