Effects of Physical Workload on Salivary Cortisol Level / 대한산업의학회지

OBJECTIVE: Workload is known to affect the hypothalamus-pituitary-adrenal axis. Although many studies had revealed that job stress related factors could affect the neuroendocrine system among blue-collar workers, these studies had limitations as they had not evaluated the workload by objective methods which took into consideration individual physiological differences. This study was conducted to evaluate the effects of physical workload adjusted job stress on cortisol regulation by using objective tools for workers having various job tasks. METHODS: Among 110 foundry workers, shipyard workers, and fine machine assemblers for whom saliva samples were obtained, 102 without any past history of conditions that could affect hormonal regulation such as diabetes, and hypertension were included in this study. Among the 102 study participants, 15 workers whose saliva for morning or afternoon or heart rate monitoring data was not attained were excluded from the final analysis. Workload was evaluated by RHR (relative heart rate) using a heart rate monitor, and job stress was evaluated by Karasek's Job Content Questionnaire. Saliva samples were gathered during 8 - 9 am and 5 - 6 pm, and salivary cortisol levels were analysed by radioimmunoassay. RESULTS: After adjusting several variables which could effect cortisol secretion including job stress, among the higher RHR group morning salivary cortisol level was increased (beta=60.32, S.E.=26.35, p=0.0266), afternoon salivary cortisol level was decreased (beta=-7.43, S.E.=29.73, p=0.8044), and salivary cortisol level difference between morning and afternoon was increased (beta=72.10, SE=35.50, p=0.0509). CONCLUSIONS: As physical workload increases morning cortisol level, which is caused by the effect of arousal, and decreases afternoon cortisol level, which is caused by exhaustion, physical workload enlarges the width of diurnal cortisol variance. Therefore, physical exhaustion due to excessive workload could have adverse effects on the neuroendocrine system.

Coffee Consumption and Decreased Serum Gamma-glutamyltransferase Activity in Men of Rural Area / 한국역학회지

PURPOSE: There has been various reports on the inverse association between coffee consumption and serum gamma-glutamyltransferase(GGT) activity in the general population of Western countries. However, this association is uncertain in the communities in which coffee consumption is less popular. So we tried to identify this association in men of rural area in Korea. METHODS: We examined the association between coffee consumption and serum GGT activity in cross-sectional study involving 379 male population health examinees aged 40 years and older from rural areas in Kyungnam prefecture in Korea. Those who perceived their health status as poor were excluded. Possible confounding effects of age, body mass index, alcohol consumption and cigarette smoking were controlled by multiple regression analysis and analysis of covariance. RESULTS: In multiple regression analysis, serum GGT activity was positively associated with alcohol intake, body mass index(P<0.001) and was negatively associated with coffee consumption(P=0.022), whereas no significant association was observed in cigarette smoking(P=0.094). Adjusted serum GGT activity level at the coffee consumption level of 0, one and two or more cups a day was 37.6 U/l, 35.9 U/l and 26.8 U/l respectively(Ptrend=0.008). CONCLUSION: Decreased serum GGT activity appears to be associated with coffee consumption in men of rural area, and further studies on the interrelationships among coffee consumption, alcohol intake and obesity will be necessary.