Premium
Neuromuscular control of lumbar instability following static work of various loads
Author(s) -
Le Brook,
Davidson Bradley,
Solomonow Deborah,
Zhou Bing He,
Lu Yun,
Patel Vikas,
Solomonow Moshe
Publication year - 2009
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.21214
Subject(s) - physical medicine and rehabilitation , work (physics) , instability , medicine , lumbar , electromyography , anatomy , engineering , mechanics , physics , mechanical engineering
Neuromuscular control of lumbar stability following exposure to prolonged static work, under low and high loads, was assessed in the in vivo feline model. Six sessions of 10 min work at 20N with 10 min between rest was compared to a group subjected to the same protocol but carrying high loads of 60N. Displacement and tension developed in the spine at the instant the multifidus muscles applied stabilizing contractions, and their amplitudes were obtained from their electromyogram (EMG). Significant ( P < 0.001) laxity developed in the various viscoelastic tissues of the lumbar spine that did not recover during and up to 7 h of rest postwork. Simultaneously, there was a significant ( P < 0.001) decrease in muscular activity in the 3–4 h immediately postwork under low load but only during the first hour in the high load group. After that period the musculature compensated for the laxity of the viscoelastic tissues by a significant ( P < 0.001) increase in activity in the high‐load group and a nonsignificant increase in the low group. It was concluded that during 1–3 h immediately poststatic work a significant decrease in the stabilizing function of viscoelastic tissues together with a significant decrease in muscular activity is present, and they render the spine unstable and exposed to high risk of injury. Performance of prolonged static work under low loads, while not harmful during the work, cannot be designated as a “no‐risk” condition, as it may result in injury postwork. Muscle Nerve 39: 71–82, 2009