The Relationship Among Neuromuscular Impairments, Chronic Back Pain, and Mobility in Older Adults

BackgroundFor older adults with mobility problems, one focus of rehabilitation is treating the underlying neuromuscular impairment(s) that lead to functional decline and disability. Knowing which neuromuscular impairments contribute to basic mobility tasks among older adults with back pain will fill an important knowledge gap and is a critical step towards developing mechanistically based rehabilitative interventions.ObjectiveTo evaluate the relationship of neuromuscular impairments with performance of mobility tasks among older adults with and without back pain.DesignCross-sectional analysis of baseline data from the Boston Rehabilitative Impairment Study of the Elderly.SettingPrimary care−based population.PatientsParticipants (N = 430) were older primary care patients who completed assessments of neuromuscular impairments and mobility tasks.MethodsBack pain was assessed by the use of an established comorbidity questionnaire. Neuromuscular impairments included trunk extensor muscle endurance, kyphosis, leg strength, leg strength asymmetry, leg speed, mean reaction time, leg coordination, and knee and ankle range of motion.Main Outcome MeasurementsMobility tasks included gait speed, standing balance, chair stand, and patient-reported functional status. Analysis of covariance was used to generate adjusted means for neuromuscular impairments that differed significantly by back pain status. Separate multivariable regression models evaluated the association between neuromuscular impairments and mobility based on back pain status after we adjusted for sociodemographic factors and physiologic impairments.ResultsParticipants had an average age of 77 years, 68% were female, and 31% reported back pain. Trunk extensor muscle endurance, leg strength, and rapid leg coordination were significantly lower among those with back pain compared to those without (P < .01, P = .01, P = .04, respectively). Patterns of neuromuscular impairments that were associated with mobility tasks differed according to back pain status.ConclusionsThe neuromuscular impairment profiles associated with mobility function among older adults with back pain vary compared with older adults without back pain.