| cardiovascular load assessment of coal mine shovelers in west bengal, india: a comparison between middle age groups. | cardiovascular load of underground shovelers was assessed in terms of heart rate changes at work in haulage coalmines. twenty underground shovelers of two different age groups (those of age 31-39 and those of age 40-49) served as subjects. working heart rate was significantly higher (p < 0.01) in the older group (138.2 beats/min) than in the younger group (130.4 beats/min). though the net cardiac cost did not differ significantly between the groups (64.8 beats/min and 69.4 beats/min in younger a ... | 2006 | 18516876 |