title: Influence of prolonged bed-rest on spectral and temporal electromyographic motor control characteristics of the superficial lumbo-pelvic musculature.
abstract: Little is known about the motor control of the lumbo-pelvic musculature in microgravity and its simulation (bed-rest). Analysis of spectral and temporal electromyographic variables can provide information on motor control relevant for normal function. This study examined the effect of 56-days of bed-rest with 1-year follow-up in 10 male subjects on the median frequency and the activation timing in surface electromyographic recordings from five superficial lumbo-pelvic muscles during a repetitive knee movement task. Trunk fat mass (from whole body-composition measurements) and movement accuracy as possible explanatory factors were included. Increased median frequency was observed in the lumbar erector spinae starting late in bed-rest, but this was not seen in its synergist, the thoracic erector spinae (p<.0001). These changes persisted up to 1-year after bed-rest and were independent of changes in body-composition or movement accuracy. Analysis suggested decreases of median frequency (p<.0001) in the abdominal and gluteal muscles to result from increased (p<.01) trunk fat levels during and after bed-rest. No changes in lumbo-pelvic muscle activation timing were seen. The results suggest that bed-rest particularly affects the shorter lumbar erector spinae and that the temporal sequencing of superficial lumbo-pelvic muscle activation is relatively robust.
authors.affiliation: Zentrum für Muskel- und Knochenforschung, Charité Campus Benjamin Franklin, Berlin, Germany. belavy@gmail.com
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Belavý
authors.forename: Joseph K-F
authors.initials: JK
authors.lastname: Ng
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wilson
authors.forename: Gabriele
authors.initials: G
authors.lastname: Armbrecht
authors.forename: Dick F
authors.initials: DF
authors.lastname: Stegeman
authors.forename: Jörn
authors.initials: J
authors.lastname: Rittweger
authors.forename: Dieter
authors.initials: D
authors.lastname: Felsenberg
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Richardson
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D001510:Bed Rest / Q000379:methods*; D025461:Feedback, Physiological / Q000502:physiology; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010388:Pelvis / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D013997:Time Factors; D018474:Weightlessness Simulation / Q000379:methods*