Influences of Daily Physical Labor on Left Ventricular Dimensions in Normotensives

Abstract

To evaluate the influences of daily physical labor on left ventricular (LV) dimensions, echocardiographic examinations were performed in 471 normotensives (men ages 30-59 years) consisting of geographically, occupationally different four populations: farmers in Akita; clerical workers in Akita; manual workers in Osaka; and clerical workers in Osaka.
In both age group 30-44 and 45-59 years, LV end-diastolic diameter (LVDd) and thickness of the interventricular septum (IVST) and of the LV posterior wall (LVPWT) were the greatest in Akita farmers among four populations, and these were greater in manual workers than in clerical workers in Osaka. These show that the more physically active populations have the greater LV dimensions. IVST and LVPWT were greater in age group 45-59 years than in age group 30-44 years in Akita farmers. This is considered to be the influences of long-term strenuous physical labor.
It is possible that the differences of LV dimensions by district and occupation are related to the differences of genetic predisposition of hypertension. To evaluate the influence of genetic predisposition on LV dimensions, we interviewed the family history of hypertension by questionnaire and compared LV dimensions between two groups, one with hypertensive parents and the other witout. LVPWT was greater in the group with hypertensive parents than in the group without in Akita farmers ages 45-59 years and in Osaka clerical workers age 30-44 years, but there were no significant differences in other populations and age groups. Furthermore, in Akita, we investigated whether parents were hypertensive or not based on their past examination records. LVDd, IVST and LVPWT did not differ significantly between the group with hypertensive parents and the other without in farmers and clerical workers.
These results indicate that LV dimensions are more strongly influenced by daily physical labor than by genetic predisposition of hypertension.