VARIATION IN THE AMBULATORY BLOOD-PRESSURE RESPONSE TO DAILY WORK LOAD - THE MODERATING ROLE OF JOB CONTROL

Objectives This quasi-experimental study tested the ambulatory blood p ressure responsivity to daily variation in the work load of the same w orkers and examined whether this responsivity is moderated by perceive d job control. Methods The subjects were 79 nonshift, normotensive men who reported nearly almost equal occurrences of low and high work loa d in a typical workday. Job control was assessed by questionnaire. The workers recorded their situational work load and other parameters at each recording of ambulatory blood pressure. Results An analysis of co variance showed the main effects of both situational work load and job control on systolic ambulatory blood pressure, as well as a significa nt work load by job control interaction, even after control for clinic blood pressure, age, and body mass index. A blood pressure response t o increased work load was observed only for workers with low job contr ol. These workers also had a higher average systolic ambulatory blood pressure than workers reporting high control. The difference was 6.2 m m Hg (0.82 kPa) during the low workload periods and 10.2 mm Hg (1.36 k Pa) during the high workload periods. A further multiple regression an alysis confirmed the interaction and the main effect of job control bu t not that of work load, after control for work-related activities, bo dy position, and hour of examination. Conclusions This study showed th at ambulatory blood pressure at work can fluctuate with variations in work load but only for workers with low job control. Low job control i s independently associated with higher systolic ambulatory blood press ure.