Constitutional differences between men recruited for driving and non-driving occupations.

289-293. Earlier studies of busmen have shown that driver recruits differ physically from conductor recruits and these differences are probably constitutional in origin. This was important in relation to the differing ischaemic heart disease experience of drivers and conductors. The present study attempts to confirm that those recruited for driving as opposed to comparable non-driving jobs in the Post Office differ from each other physically in a similar way to the busmen recruits. By a study of old records of certain measurements made on Post Office recruits in two age groups (21-26 years and 40-45 years) it was shown that mail van drivers were on average nearly 0·5 in. (1·27 cm.) taller than postal delivery workers. The difference was less in the older age group. In both age groups the mail drivers were heavier (approx. 5 and 7 lb. (2·3 and 3·2 kg.) respectively) and slightly bigger round the chest than the delivery postmen. Some of the additional weight of drivers can be explained by their greater mean height, but all of it cannot be so explained. For any given height, mail drivers tended to be heavier than delivery postmen. This study supports the view that men who choose mainly sedentary driving jobs are constitutionally different from those who choose more active but otherwise comparable nondriving jobs. It is suggested that this may be an important consideration in any investigations into the morbidity affecting men in driving and possibly other physically inactive jobs.