Job strain and heart rate variability in resident physicians within a general hospital

OBJECTIVE

To evaluate the association of heart rate variability with job strain in first year resident physicians.

METHODS

We performed the study at the "Manuel Gea González" General Hospital in Mexico City. 54 resident doctors were studied over a period of 24 hr in their first year of specialization. Two questionnaires were administered: the first on general demographics, and the second, the Job Content Questionnaire. Heart rate variability was evaluated through the frequency domain (low-frequency power, high-frequency power, and low-frequency power/high-frequency power ratio) and time domain (SDNN). The doctors wore a Holter monitor over a 24-hr period, which included a workday plus their on-call time. They recorded their activities in a log.

RESULTS

Compared to physicians in the "low strain" category, physicians working in the "passive" category had lower overall peak-to-peak cardiac variability (standard deviation of N-N intervals, SDNN), -9.08% (95% CI -17.97, 0.74), a -25% (95% CI -45.00, 0.22) lower high-frequency power, and -26.95% (95% CI -39.00, -12.53) lower low-frequency power. Physicians working in the "high strain" category had lower low-frequency power, -17.85% (95%CI -32.34, -0.25), and lower low-frequency/high-frequency ratio -24.29% (95% CI 38.08, 7.42) compared to those in the "low strain" category.

CONCLUSIONS

High job strain and low job control among medical residents were associated with several indicators of lowered heart rate variability. Thus, analysis of heart rate variability may be an informative marker for evaluating the physiological impacts of workplace stressors.

Gender, aging, and work: aging workers' strategies to confront the demands of production in maquiladora plants in nogales, Mexico

This work is part of a qualitative socio-cultural investigation with a group of men and women 40 years and older in the maquila export industry in Nogales, Sonora, Mexico. In 1994, as a result of the North American Free Trade Agreement, maquila plants combined traditional intensive work methods with new "just in time" production norms that impacted work and health conditions, particularly in older, or aging, workers. The workers that were interviewed for this study show a reduction in their functional ability to work starting at 40 years of age. Work organization demands, general health conditions, and a decrease in physical abilities brings these 40-year-old workers to prematurely construct an image of themselves as aging workers and to develop coping strategies that vary by gender.