Patricia Dolan

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We investigated the distribution of compressive 'stress' within cadaver intervertebral discs, using a pressure transducer mounted in a 1.3 mm diameter needle. The needle was pulled along the midsagittal diameter of a lumbar disc with the face of the transducer either vertical or horizontal while the disc was subjected to a constant compressive force. The(More)
STUDY DESIGN This was a cross-sectional study involving 229 healthy, back pain-free individuals. OBJECTIVES To examine the relationship between electromyographic manifestations of fatigue and endurance time during isometric contraction of the back extensors to fatigue. SUMMARY OF BACKGROUND DATA Despite the wide-spread use of electromyography to monitor(More)
STUDY DESIGN The authors investigated fatigue-induced changes in the frequency content of the surface electromyographic (EMG) signal from the erector spinae muscles. OBJECTIVES The objective of the study was to understand the EMG changes in fatiguing muscle and to obtain a reliable index of fatigue. SUMMARY OF BACKGROUND DATA Power spectral analysis has(More)
STUDY DESIGN A prospective study of personal risk factors for first-time low back pain. OBJECTIVES To construct and validate a multivariate model to predict low back pain. SUMMARY OF BACKGROUND DATA Various physical and psychological factors have been reported to increase the risk of low back pain, but conflicting results may be attributable to(More)
STUDY DESIGN Cadaveric motion segment experiment. Measurements on each specimen were compared before and after creep loading. OBJECTIVES To show how sustained "creep" loading affects stress distributions inside intervertebral discs. SUMMARY OF BACKGROUND DATA The central region of an intervertebral disc acts like a hydrostatic "cushion" between adjacent(More)
During manual handling, the back muscles protect the spine from excessive flexion, but in doing so impose a high compressive force on it. Epidemiological links between back pain and repetitive lifting suggest that fatigued muscles may adversely affect the balance between bending and compression. Fifteen volunteers lifted and lowered a 10 kg weight from(More)
We examined the possibility that passive tissues can help the erector spinae to generate large extensor moments during lifting. One hundred and forty-nine healthy men and women participated in the study. Subjects pulled upwards with steadily increasing force on a floor-mounted load cell, while EMG activity was recorded from electrodes overlying the erector(More)
STUDY DESIGN Mechanical testing of cadaveric lumbar motion segments. OBJECTIVES To test the hypothesis that minor damage to a vertebral body can lead to progressive disruption of the adjacent intervertebral disc. SUMMARY OF BACKGROUND DATA Disc degeneration involves gross structural disruption as well as cell-mediated changes in matrix composition, but(More)
In many skeletal muscles the myoelectric power spectrum median frequency (MF) increases with increasing force output, possibly reflecting the greater size and conduction velocity of the later-recruited (fast twitch) fibres. Muscles, such as the erector spinae, in which fast twitch fibres are smaller than slow twitch, may display an atypical relationship(More)