comparison between cardiac strain of normal weight and overweight workers in hot and humid weather of the south of iran

background : in the hot weather overweight and obesity are considered as significant risk factors for incidence of cardiac strain in workers. this study is aimed to compare cardiac strain among overweight and normal-weighted workers in hot and humid conditions of the south of iran. methods : this cross-sectional study was conducted on 71 workers in the south of iran in the summer of 2010. the heart rate was measured at rest and during work. cardiac strain based on working heart rate (whr), relative cardiac cost (rcc), net cardiac cost (ncc), load relative cardiovascular (cvl) and heart rate reduction were analyzed in 35 normal weight people (bmi < 25) and 36 overweight people (bmi > 25) using descriptive statistics and student’s t-test. findings : in 42% of workers body mass index was higher than 25. the average temperature in the two groups was not significantly different. the mean whr in these two groups was 101 ± 20.3 and 112 ± 18.9 respectively (p = 0.026). the acceptable limits in ncc, rcc, whr, and cvl parameters and brouha index were significantly higher in overweight people than in people with normal weight. conclusion: based on the study results, the severity of cardiac strain was higher in overweight workers compared with normal weight workers. hence, in order to decrease cardiac strain, selecting overweight individuals for these jobs should be avoided. moreover, some vital interventions for losing weight, such as nutritional education, should be implemented, and they should be encouraged to increase their physical activity.   keyword: body mass index, cardiac strain, heart rate, hot and humid climate, persian gulf