Perception of Muscular Effort During Dynamic Elbow Extension in Multiple Sclerosis

Abstract

ObjectiveTo investigate the perception of muscular effort in individuals with multiple sclerosis (MS) and healthy controls during dynamic contractions. DesignCase-control study. SettingMS day care center. ParticipantsIndividuals with MS (n=28) and controls (n=28) (N=56). InterventionsNot applicable. Main Outcome MeasuresPerceived muscular effort during dynamic elbow extensions was rated at 9 different weight intensities (10%–90% of 1-repetition maximum) in a single-blind, randomized order using the OMNI-Resistance Exercise Scale. Muscle activity of the triceps brachii muscle (lateral head) was measured via surface electromyography and normalized to maximal voluntary excitation. ResultsAccording to OMNI-level ratings, significant main effects were found for the diagnostic condition (F=27.33, P<.001, η2=.11), indicating 0.7 (95% confidence interval [CI], 0.3–1.1) lower mean OMNI-level ratings for MS, and for the intensity level (F=46.81, P<.001, η2=.46), showing increased OMNI-level ratings for increased intensity levels for both groups. Furthermore, significant main effects were found for the diagnostic condition (F=16.52, P<.001, η2=.07), indicating 7.1% (95% CI, −8.6 to 22.8) higher maximal voluntary excitation values for MS, and for the intensity level (F=33.09, P<.001, η2=.36), showing higher relative muscle activities for increasing intensity levels in both groups. ConclusionsSimilar to controls, individuals with MS were able to differentiate between different intensities of weight during dynamic elbow extensions when provided in a single-blind, randomized order. Therefore, perceived muscular effort might be considered to control resistance training intensities in individuals with MS. However, training intensity for individuals with MS should be chosen at approximately 1 OMNI level lower than recommended, at least for dynamic elbow extension exercises.