Faculty Bibliography

We have developed an educational program to train industry-based physicians in a new low back pain assessment procedure based on the recommendation of The Clinical Practice Guidelines on Acute Low Back Pain Problems in Adults published by the Agency for Health Care Policy and Research, U.S. Department of Health and Human Services. The clinical classification system based on the findings from the Quebec Task Force was used to categorize the subjects. The educational program included group and individual sessions with an extensive period of active follow-up. Protocol compliance was measured through a computer-based surveillance system that monitored evaluation form completion. The results showed significant change (p < 0.001) in physician compliance in completing a standardized examination following an administrative mandate to change. Little change in clinical practice was recorded with an educational training program only. Further research into the factors responsible for the results is suggested

This paper describes the application of the ability requirements approach to study the relationship between back injuries and job demands. The procedure used groups of active workers to construct profiles of job demands by rating physical abilities needed to perform various tasks in the job. Environmental demands were similarly rated. Profiles were developed for 25 high injury rate jobs in a mass transit company. Worker ratings of job demands were correlated with back injury rates. The results confirm that back injuries are associated with physical effort or work conditions in some jobs. Several abilities formed a single factor of physical effort while the present inventory of work conditions did not. A multidimensional job description of physical effort, environmental and organizational factors is proposed to explain adequately occupational back injuries in the public transportation, construction and utilities.

To search for evidence of sympathetic dysregulation during cluster headache attacks, microneurographic recordings of muscle nerve sympathetic activity (MSA) were obtained from the peroneal nerve. In three recordings commenced after the onset of spontaneous attacks, MSA was about twice as high during the attack as afterwards. In four nitroglycerin-induced attacks, MSA showed a rise paralleling the pain, preceded by an initial peak. The latter accompanied hypotension, whereas the rise coinciding with cluster headache was associated with rising blood pressure. The normal baroreflex-governed pulse synchrony of MSA was preserved both during spontaneous and provoked attacks. In seven cluster headache patients in whom nitroglycerin did not cause an attack, only an initial peak in MSA occurred. Nor was any late nitroglycerin-induced rise in MSA observed in nine healthy subjects; the initial peak in MSA and heart rate was followed by a rapid return to normal despite a falling blood pressure. It is concluded that cluster headache attacks are associated with an increase in MSA that elevates blood pressure by causing vasoconstriction, and that this increase, rather than indicating sympathetic dysregulation, is a normal pain-evoked secondary phenomenon. The findings in healthy subjects support the notion that nitroglycerin has a central sympatho-inhibitory effect

This study examined the effect of previous contraction condition on subsequent eccentric power production in the elbow flexor muscles in 20 healthy volunteers (10 males, 10 females). Power production was determined during constant velocity eccentric loading at 60degree/s when preceded by: condition 1 passive elbow flexion; condition 2 maximal concentric contraction of the elbow flexor muscles; or condition 3 maximal isometric contraction of the elbow flexors. Comparison of eccentric power production under the different conditions was conducted using a repeated measures ANOVA. Results indicated that a continuum exists between conditions such that eccentric power production when preceded by condition 1 is < power production when preceded by condition 2, is < power production when preceded by condition 3. Implications are that contraction condition previous to eccentric loading allows various levels of tension transfer in the series elastic and the contractile components producing different levels of torque during the ensuing eccentric loading of the muscle. Techniques utilizing combinations of movement to enhancing muscle contraction should be examined critically with regard to order of movement and contraction conditions

Health care providers often prescribe exercises as treatment for nonspecific low back pain. However, the effectiveness of this treatment is poorly documented in the literature. While the evidence suggests that exercise in general is beneficial, there is a lack of knowledge about the types, frequency and duration of exercises that should be prescribed and at what stage of injury they are most helpful. In addition, few studies have dealt with exercise treatment alone rather than in combination with other treatments, making it hard to decipher the unique contribution of exercise. Inadequate study designs also make conclusions difficult. Conversely, the literature clearly shows that inactivity has detrimental effects (i.e. delayed return to normal activity, and negative physiological and psychological effects) for low back pain patients

The vibration sensitivity of feline muscle spindle endings is known to vary as a result of preceding muscle conditioning manoeuvres. If similar after-effects occur in man they should be expected to influence the strength of the tonic vibration reflex (TVR). To study this issue, vibration was applied over the finger extensor tendons of 11 volunteers who actively held their fingers in a semi-extended position. The TVR, measured as electromyographic responses and angular deflections at the metacarpophalangeal joints, was found to be stronger when the extensors prior to the test had been contracted in a shortened position than when they had been contracted in a stretched position. This difference was reduced when the vibration stimulus was preceded by a strong extensor contraction in the test position. The antigravity extensor EMG activity required to keep the fingers in the test position was weaker when the conditioning contraction was performed at a short muscle length than when it was performed at a long muscle length. The variations in magnitude of the TVR can be attributed to 'thixotropic' properties of intrafusal muscle fibres, resulting in a slack following conditioning at a long muscle length. The different EMG levels required for position holding can be explained by similar properties of extrafusal muscle fibres. In conclusion, the results demonstrate the importance of taking the 'history of movement' into account in the design of all TVR studies