title: Changes in muscle activation patterns in response to enhanced sensory input during treadmill stepping in infants born with myelomeningocele.
abstract: Infants with myelomeningocele (MMC) increase step frequency in response to modifications to the treadmill surface. The aim was to investigate how these modifications impacted the electromyographic (EMG) patterns. We analyzed EMG from 19 infants aged 2-10 months, with MMC at the lumbosacral level. We supported infants upright on the treadmill for 12 trials, each 30 seconds long. Modifications included visual flow, unloading, weights, Velcro and lcriction. Surface electrodes recorded EMG from tibialis anterior, lateral gastrocnemius, rectus femoris and biceps femoris. We determined muscle bursts for each stride cycle and from these calculated various parameters. Results indicated that each of the five sensory conditions generated different motor patterns. Visual flow and friction which we previously reported increased step frequency impacted lateral gastrocnemius most. Weights, which significantly decreased step frequency increased burst duration and co-activity of the proximal muscles. We also observed an age effect, with all conditions increasing muscle activity in younger infants whereas in older infants visual flow and unloading stimulated most activity. In conclusion, we have demonstrated that infants with myelomeningocele at levels which impact the myotomes of major locomotor muscles find ways to respond and adapt their motor output to changes in sensory input.
authors.affiliation: Center for Human Movement Studies, School of Applied Physiology, Georgia Institute of Technology, 555, 14th Street, Atlanta, GA 30332-0356, USA. annette.pantall@ap.gatech.edu
authors.forename: Annette
authors.initials: A
authors.lastname: Pantall
authors.forename: Caroline
authors.initials: C
authors.lastname: Teulier
authors.forename: Beverly D
authors.initials: BD
authors.lastname: Ulrich
mesh_terms: D004576:Electromyography; D005080:Exercise Test; D006801:Humans; D007223:Infant; D007699:Kinesthesis / Q000502:physiology; D008591:Meningomyelocele / Q000503:physiopathology* / Q000534:rehabilitation*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D010775:Photic Stimulation; D026741:Physical Therapy Modalities; D012815:Signal Processing, Computer-Assisted; D014110:Touch / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*