Determination of lumbar muscular activity in helicopter pilots: a new approach.

BACKGROUND: Discomfort in the lumbar region is a frequent complaint of helicopter pilots. Two factors that helicopter crewmembers relate to back pain are exposure to vibration and poor posture during flight, because during flight the seat and controls force the pilot to adopt an asymmetric posture. Repeated exposure to these adverse flight conditions could cause pathological changes in the spine. The purpose of this study was to compare right and left sided lumbar muscular activity in helicopter pilots under real flight conditions, using surface electromyography (SEMG) to demonstrate the effects of asymmetrical posture on the musculoskeletal system. An attempt was also made to correlate lumbar muscular activity with environmental factors and such variables as type of flight, type of helicopter, duration of flight, age, physical fitness, and height. METHODS: Right- and left-sided lumbar electrical activity were measured using two-channel SEMG during 35 flights in 2 types of helicopter and a cockpit mock-up. RESULTS: There was a statistically significant increase in right-sided lumbar activity when related to the duration of flight. CONCLUSIONS: The data showed that when the pilot used the manual controls during flight, he did not maintain a symmetrical posture and contracted one side more than the other. We think the relationship between the greatest right-sided contraction and flight duration is due to maintaining an asymmetric posture over a long period. We also noted a tendency towards greater right lumbar musculature activity in older pilots.

Evaluation of different drugs in two models of immediate hypersensitivity.

The effect of the calcium antagonists, verapamil, nicardipine and diltiazem, the two cromones, disodium cromoglycate and SM-857 (11-oxo-11H-pyrido[2,1-b]quinazoline-2-carboxylic acid), and the anthelmintic, diethylcarbamazine citrate, have been compared on the ovalbumin (OA)-induced contraction of the isolated trachea and longitudinal muscle-myenteric plexus (LM-MP) from sensitized guinea-pigs. The calcium antagonists prevented the OA-induced contractions in LM-MP and to a lesser degree the OA-induced contractions in trachea. Similar doses of SM-857 protected both tissues but neither cromoglycate (10(-5)M) nor diethylcarbamazine (10(-5)M) affected these contractions. The OA-induced contraction in trachea had a tonic phase that was not present in the LM-MP response. Only the calcium antagonists succeeded in relaxing this OA tonic component, diltiazem being the more potent. These results unmask different mechanisms of drug action on immediate hypersensitivity and specific sensibilities, depending on the kind of tissue.