The risk of heat exhaustion at a deep underground metalliferous mine in relation to surface temperatures

The risk of heat exhaustion at a deep underground metalliferous mine was assessed in relation to thermal conditions prevailing on the surface. For each day of a 1-year prospective case series of heat exhaustion, surface 24-h mean wet and dry bulb temperatures were recorded. From this data, 24-h mean wet bulb globe temperatures were derived using certain assumptions. The three surface temperature variables were significantly higher on those days on which heat exhaustion occurred, compared to those days on which it did not occur (P < 0.001). The relative risk of heat exhaustion on days when the 24-h mean wet bulb globe temperature was in the range 26.0-28.0 degrees C was 4.82 (95% confidence interval 2.12-10.96). Surface temperature data could be used at this mine to warn miners about the risk of heat exhaustion.     

Miliaria rubra of the lower limbs in underground miners

This report documents a case series of miliaria rubra of the lower limbs in miners at a deep underground metalliferous mine in tropical arid Australia. During the summer months of February and March 1999, all cases of miliaria rubra of the lower limbs in underground miners seen at the mine's medical centre were clinically examined and administered a questionnaire. Twenty-five patients were seen, an incidence of 56.4 cases per million man-hours. Miliaria rubra was most often located between the ankle and knee (88% of cases). Twenty-four percent had concurrent folliculitis and 20% had concurrent tinea. Thirty-two percent had a personal history of asthma. Walking through ground-water and splashing of the legs was common. Three to 4 weeks of sedentary duties in air conditioning was generally required to achieve resolution of miliaria rubra. The incidence of miliaria rubra of the lower limbs is 38% of the incidence of heat exhaustion at the same mine. The length of disablement is greater, however. Atopics may be at increased risk of miliaria rubra. Control measures are discussed.     

Evaluation of a treadmill test for predicting the aerobic capacity of firefighters

BACKGROUND: As part of a comprehensive occupational medical program for fire departments in the USA, the National Fire Protection Association and The Fire Service Joint Labor Management Wellness/Fitness Initiative endorse a standardized submaximal test that uses the Gerkin treadmill protocol for predicting the maximal oxygen uptake (VO(2max)) of firefighters. AIMS: To test the validity of the Gerkin treadmill protocol in healthy men and women. METHODS: Fifty-four healthy men and women (age range 19-58 years) performed the Gerkin test and a treadmill run test to maximal exhaustion. Their heart rates were monitored continuously with an electrocardiogram during each test. During the VO(2max) test, the subjects' VO(2) was measured continuously using indirect calorimetry. RESULTS: Although the predicted and observed VO(2max) values correlated (r = 0.70, P < 0.001 and standard error of estimate = 5.98 ml/kg/min), the mean values differed (49.8 +/- 8.3 and 41.8 +/- 5.8 ml/kg/min, respectively) (P < 0.001). The VO(2max) value was overestimated in 50 (93%) participants. The overestimation was >25% in 18 (33%) participants. Gender, age and VO(2max) did not affect the Gerkin protocol's predictability of VO(2max). CONCLUSIONS: The Gerkin treadmill protocol overpredicts VO(2max) in healthy men and women and, therefore, should not be used for predicting VO(2max) in individual firefighters, particularly if VO(2max) is a criterion for inclusion or exclusion from duty. At this time, a valid treadmill running test is needed for predicting the VO(2max) value of individual firefighters.     

Heat exhaustion in a deep underground metalliferous mine

OBJECTIVES—To examine the incidence, clinical state, personal risk factors, haematology, and biochemistry of heat exhaustion occurring at a deep underground metalliferous mine. To describe the underground thermal conditions associated with the occurrence of heat exhaustion.
METHODS—A 1 year prospective case series of acute heat exhaustion was undertaken. A history was obtained with a structured questionnaire. Pulse rate, blood pressure, tympanic temperature, and specific gravity of urine were measured before treatment. Venous blood was analysed for haematological and biochemical variables, during the acute presentation and after recovery. Body mass index (BMI) and maximum O₂ consumption (O₂ max) were measured after recovery. Psychrometric wet bulb temperature, dry bulb temperature, and air velocity were measured at the underground sites where heat exhaustion had occurred. Air cooling power and psychrometric wet bulb globe temperature were derived from these data.
RESULTS—106 Cases were studied. The incidence of heat exhaustion during the year was 43.0 cases / million man-hours. In February it was 147 cases / million man-hours. The incidence rate ratio for mines operating below 1200 m compared with those operating above 1200 m was 3.17. Mean estimated fluid intake was 0.64 l/h (SD 0.29, range 0.08-1.50). The following data were increased in acute presentation compared with recovery (p value, % of acute cases above the normal clinical range): neutrophils (p<0.001, 36%), anion gap (p<0.001, 63%), urea (p<0.001, 21%), creatinine (p<0.001, 30%), glucose (p<0.001, 15%), serum osmolality (p=0.030, 71%), creatine kinase (p=0.002, 45%), aspartate transaminase (p<0.001, 14%), lactate dehydrogenase (p<0.001, 9.5%), and ferritin (p<0.001, 26%). The following data were depressed in acute presentation compared with recovery (p value, % of acute cases below the normal clinical range): eosinophils (p=0.003, 38%) and bicarbonate (p=0.011, 32%). Urea and creatinine were significantly increased in miners with heat cramps compared with miners without this symptom (p<0.001), but there was no significant difference in sodium concentration (p=0.384). Mean psychrometric wet bulb temperature was 29.0°C (SD 2.2, range 21.0-34.0). Mean dry bulb temperature was 37.4°C (SD 2.4, range 31.0-43.0). Mean air velocity was 0.54 m/s (SD 0.57, range 0.00-4.00). Mean air cooling power was 148 W/m² (SD 49, range 33-290) Mean psychrometric wet bulb globe temperature was 31.5°C (SD 2.0, range 25.2-35.3). Few cases (<5%) occurred at psychrometric wet bulb temperature <25.0°C, dry bulb temperature <33.8°C, air velocity >1.56 m/s, air cooling power >248 W/m², or psychrometric wet bulb globe temperature <28.5°C.
CONCLUSION—Heat exhaustion in underground miners is associated with dehydration, neutrophil leukocytosis, eosinopenia, metabolic acidosis, increased glucose and ferritin, and a mild rise in creatine kinase, aspartate transaminase, and lactate dehydrogenase. Heat cramps are associated with dehydration but not hyponatraemia. The incidence of heat exhaustion increases during summer and at depth. An increased fluid intake is required. Heat exhaustion would be unlikely to occur if ventilation and refrigeration achieved air cooling power >250 W/m² at all underground work sites.


Keywords: heat; mining; ventilation     

Lung cancer among Dutch coal miners: a case-control study

A case-control study was conducted in the southern part of The Netherlands to investigate the risk of lung cancer in coal miners; 381 age-matched pairs of primary lung cancer cases and controls, diagnosed between 1972 and 1988, were selected from the pathology department of the University Hospital in the region. Information about past employment in coal mines was obtained through the registers of the collaborative pension fund for Dutch miners. 20% of the cases were (at some time) employed in coal mining, compared with 21% of the controls (odds ratio 0.95; 95% confidence interval: 0.65-1.38). 9% of both cases and controls had an underground work history (odds ratio 0.96; 95% confidence interval: 0.56-1.65). The duration of underground coal mining did not differ substantially between cases and referents (average duration: respectively 117 and 108 months). No relation between specific histologic tumor cell types and coal mining could be demonstrated. The study gives no indication that workers in Dutch coal mines have an increased risk of developing lung malignancies.     

Physical activity, cardiorespiratory fitness and body mass index as predictors of substantial weight gain and obesity: the Canadian physical activity longitudinal study

BACKGROUND: Obesity is a growing health issue in Canada and the identification of the determinants of obesity is important for the development of prevention strategies. The purpose of this investigation was to determine the relationships between physical activity, cardiorespiratory fitness, body mass index (BMI), and the development of future obesity. METHODS: The sample included 459 adults (18+ y; 223 men, 236 women) from the Canadian Physical Activity Longitudinal Study (PALS; 2002-04). Data on physical activity, smoking, alcohol consumption, BMI, and cardiorespiratory fitness (VO2max) were collected in 1981 and 1988. The mean BMI, physical activity, and VO2max were calculated across the 1981 and 1988 measures. Self-reported height and weight were collected in the 2002-04 survey, and participants were classified as overweight (BMI 25 to 29.9 kg/m2) or obese (BMI 230 kg/m2). Logistic regression was used to predict overweight, obesity or substantial weight gain (10 kg or more) in 2002-04, controlling for age, sex, smoking and alcohol use. RESULTS: Higher VO2max in 1981-88 was associated with lower odds of obesity in 2002-04 (OR = 0.87; 95% Cl: 0.76-0.99, p < 0.05), and higher BMI in 1981-88 was associated with higher odds of obesity in 2002-04 (1.84; 1.52-2.20, p < 0.0001). In women, higher VO2max (0.82; 0.72-0.93) resulted in lower odds of a 10 kg weight gain. CONCLUSIONS: The results indicate that cardiorespiratory fitness and previous BMI are important predictors of future weight gain and obesity, and should be incorporated in strategies to identify individuals at increased risk of obesity.     

Type A lactic acidosis in occupational heat exhaustion

BACKGROUND: This paper presents a further analysis of biochemical data collected during a 1 year prospective study of 106 cases of heat exhaustion at a deep underground metalliferous mine. RESULTS: Multiple regression analysis results indicate that the haemoglobin, serum creatinine and plasma lactate concentrations are statistically significant predictors of the anion gap. Together, they explain 65% of the variance in the anion gap (R(2) = 0.650). Spearman's rho correlation results also confirm that haemoglobin, creatinine and lactate are each statistically significantly correlated with the anion gap (P < 0.001). CONCLUSIONS: These results indicate that dehydration and lactate are important determinants of the metabolic acidosis previously observed in occupational heat exhaustion. It is likely that dehydration in these workers has resulted in poor muscle perfusion, anaerobic conditions and elevated lactate. This constitutes Type A lactic acidosis. Creatine kinase is not a statistically significant predictor of the anion gap in multiple regression (P = 0.956). Furthermore, the Spearman's rho correlation coefficient for creatine kinase versus the anion gap is weak (r(s) = 0.175) and is not statistically significant (P = 0.073). These results suggest that there was no rhabdomyolysis contributing to the metabolic acidosis.     

Possible beneficial effects of health counseling, given less frequently than ordinary, on blood pressure

This study was initiated to investigate the effects of health counseling under Total Health Promotion Plan (THP). The study populations consisted of 1,655 working men who had an initial THP-based counseling and a follow-up 3 yr later (the THP group; the counseling was given on a once-three year basis), and 1,655 age- and body mass index (BMI)-matched controls (working men who had no health counseling; the control group). In the THP group, systolic blood pressure (SBP) and the prevalence of excessive alcohol drinking were decreased, and nutritional score was improved, although BMI was increased. In contrast, SBP, BMI and the ratio of excessive drinkers were all increased in the controls. Multiple regression analysis of the THP group showed that the reduction in SBP was positively associated with the increase in maximal oxygen consumption (VO(2max)) and physical activity scores, as well as the decrease in BMI. In sub-group analyses of the THP group, VO(2max) and physical activity scores were increased, and BMI did not change in the sub-group with marked BP decrease. In the sub-group with marked BP increase, however, BMI was increased, and VO(2max) was decreased. The ratio of excessive drinkers was reduced only in the sub-group with marked BP decrease. The obese-hypertensive subjects in the THP group showed decreases in BMI and BP, and increases in VO(2max). Thus, these results appeared to suggest that health counseling given even at a low frequency of once in three years prevented the age-associated increase in BP through improvement of physical endurance, decrease in alcohol intake and reduction in body weight.     

Case-control study of multiple chemical sensitivity, comparing haematology, biochemistry, vitamins and serum volatile organic compound measures

BACKGROUND: Multiple chemical sensitivity (MCS), although poorly understood, is associated with considerable morbidity. AIM: To investigate potential biological mechanisms underlying MCS in a case-control study. METHODS: Two hundred and twenty-three MCS cases and 194 controls (urban females, aged 30-64 years) fulfilled reproducible eligibility criteria with discriminant validity. Routine laboratory results and serum levels of volatile organic compounds (VOCs) were compared. Dose-response relationships, a criterion for causality, were examined linking exposures to likelihood of case status. RESULTS: Routine laboratory investigations revealed clinically unimportant case-control differences in means. Confounder-adjusted odds ratios (OR) showed MCS was negatively associated with lymphocyte count and total plasma homocysteine, positively associated with mean cell haemoglobin concentration, alanine aminotransferase and serum vitamin B6, and not associated with thyroid stimulating hormone, folate or serum vitamin B12. More cases than controls had detectable serum chloroform (P = 0.001) with the OR for detectability 2.78 (95% confidence interval = 1.73-4.48, P < 0.001). Chloroform levels were higher in cases. However, cases had significantly lower means of detectable serum levels of ethylbenzene, m&p-xylene, 3-methylpentane and hexane, and means of all serum levels of 1,3,5- and 1,2,3-trimethylbenzene, 2- and 3-methylpentane, and m&p-xylene. CONCLUSIONS: Our findings are inconsistent with proposals that MCS is associated with vitamin deficiency or thyroid dysfunction, but the association of lower lymphocyte counts with an increased likelihood of MCS is consistent with theories of immune dysfunction in MCS. Whether avoidance of exposures or different metabolic pathways in cases explain the observed lower VOC levels or the higher chloroform levels should be investigated.     

Short-term (-)-hydroxycitrate ingestion increases fat oxidation during exercise in athletes

(-)-Hydroxycitrate (HCA) is known to inhibit increasing malonyl CoA concentration during endurance exercise. Furthermore, a short-term administration of HCA enhances endurance exercise performance in mice. Therefore we investigated the short-term administration of HCA on the exercise performance of athletes. Subjects were administered 250 mg of HCA or placebo as a control (CON) for 5 d, after each time performing cycle ergometer exercise at 60% VO2max for 60 min followed by 80% VO2max until exhaustion. Blood was collected and expired gas samples analyzed at rest and every 15 min. The respiratory exchange ratio was significantly lower in the HCA trial than in the CON trial (p < 0.05). Fat oxidation was significantly increased by short-term administration of HCA, and carbohydrate oxidation was significantly decreased (p < 0.05) during exercise, presumably resulting in increasing the cycle ergometer exercise time to exhaustion after 1 h of 60% VO2max exercise (p < 0.05). These results suggest that a short-term administration of HCA enhances endurance performance with increasing fat oxidation, which spares glycogen utilization during moderate intensity exercise in athletes.     

The effects of creatine supplementation on cardiovascular, metabolic, and thermoregulatory responses during exercise in the heat in endurance-trained humans

The effects of creatine (Cr) supplementation on cardiovascular, metabolic, and thermoregulatory responses, and on the capacity of trained humans to perform prolonged exercise in the heat was examined. Endurance-trained males (n = 21) performed 2 constant-load exercise tests to exhaustion at 63 +/- 5 % VO(2max) in the heat (ambient temperature: 30.3 +/- 0.5 C) before and after 7 d of Cr (20 g x d (-1 ) Cr + 140 g x d (-1 ) glucose polymer) or placebo. Cr increased intracellular water and reduced thermoregulatory and cardiovascular responses (e.g., heart rate, rectal temperature, sweat rate) but did not significantly increase time to exhaustion (47.0 +/-4.7 min vs. 49.7 +/- 7.5 min, P =0.095). Time to exhaustion was increased significantly in subjects whose estimated intramuscular Cr levels were substantially increased ("responders" : 47.3 +/- 4.9 min vs. 51.7 +/- 7.4 min, P = 0.031). Cr-induced hyperhydration can result in a more efficient thermoregulatory response during prolonged exercise in the heat.     

Lifestyle and the development of hypertension: a 3-year follow-up study of middle-aged Japanese male office workers.

The association of lifestyle factors with the development of hypertension (blood pressure > or = 140/90 mmHg) over a 3-year follow-up period was studied in 949 hypertension-free Japanese male office workers aged 35 to 54 years. From the Cox proportional hazards model, age, alcohol intake, body mass index (BMI) and hours of work were independent factors associated with the development of hypertension. Adjusted hazard ratios for 5-year increases in age, daily consumption of alcohol, 5-kg/m2 increases in BMI and working 10 hours per day or more were 1.18 [95% confidence interval (CI) = 1.02-1.35]; 1.53 (CI = 1.14-2.05); 1.79 (CI = 1.38-2.33) and 0.58 (CI = 0.41-0.82), respectively. In the analysis using logistic regression, BMI was independently related to working 10 hours per day or more, controlling for other lifestyle factors. Adjusted odds ratio for 5-kg/m2 increase in BMI was 0.66 (CI = 0.49-0.88). These results suggest that the influences of long working hours on blood pressure are likely to be indirectly mediated through less overall obesity.     

Working hours and mental and physical fatigue in Japanese workers

BACKGROUND: Establishing a threshold number of working hours is very important when making recommendations to protect people from the potentially harmful health effects caused by long working hours. AIM: To clarify the influence of working hours on both mental and physical symptoms of fatigue and use the data obtained to determine permissible working hours. METHODS: Cross-sectional survey of male day-shift workers using the Self-Rating Depression Scale (SDS) and the Cumulative Fatigue Symptoms Index (CFSI). Working hours were subdivided into six groups and odds ratios were calculated for positive outcomes on the SDS and CFSI using logistic regression analysis. RESULTS: A total of 715 workers participated. In the group working 260-279 h/month, the odds ratios for SDS and 'irritability', 'anxiety' and 'chronic tiredness' of the CFSI were significantly increased. In the group working >or=280 h/month, the odds ratios on CFSI for 'general fatigue', 'physical disorders', 'anxiety' and 'chronic tiredness' were likewise significantly increased. CONCLUSIONS: The present results clarified that working hours should be <260 h/month in order to minimize fatigue symptoms in male day workers.     

Effect of iron injections on aerobic-exercise performance of iron-depleted female athletes

This investigation examined the effect of intramuscular iron injections on aerobic-exercise performance in iron-deficient women. Sixteen athletes performed a 10-min steady-state submaximal economy test, a VO2max test, and a timed test to exhaustion at VO2max workload. Subjects were randomly assigned to an iron-supplemented group (IG) receiving intramuscular iron injections or to a placebo group (PG). Twenty days after the first injection, exercise and blood testing were repeated. A final blood test occurred on Day 28. Post supplementation, no differences were found between the groups' submaximal or maximal VO2, heart rate, or blood lactate (P > 0.05). Time to exhaustion was increased in the IG (P < 0.05) but was not greater than that of the PG (P > 0.05). The IG's serum ferritin (SF) was significantly increased on Days 20 and 28 (mean +/- standard error: 19 +/- 3 to 65 +/- 11 to 57 +/- 12 microg/L; P < 0.01), with a percentage change from baseline significantly greater than in the PG (P < 0.01). It was concluded that intramuscular iron injections can effectively increase SF without enhancing submaximal or maximal aerobic-exercise performance in iron-depleted female athletes.     

Occupational fitness standards for beach lifeguards. Phase 2: the development of an easily administered fitness test

BACKGROUND: No task-based fitness standard currently exists for beach lifeguards (BLGs). AIM: To formulate an easily administered fitness test for BLGs based on the physical demands identified in Phase 1 of the project (previous paper). METHODS: A range of anthropometric and land- and water-based (swimming pool and flume) fitness assessments were administered to 25 male and female volunteer subjects (13 BLGs from the UK). RESULTS: The mean (SD) VO(2max) (l/min) were 3.04 (0.61) for towing a casualty, 2.08 (0.53) for board paddling with a casualty and 2.97 (0.67) for freestyle swimming. A significant correlation (r = -0.82, P < 0.001) was identified between distance paddled in the sea in 3.5 min (established in Phase 1) and pool 400-m front crawl swim time and between towing VO(2max) and deltoid circumference/log(10) 400-m front crawl swim time (r = -0.83, P < 0.001). CONCLUSIONS: The regression identified allows the conclusion that if a BLG can swim 400-m front crawl in a pool in <7.5 min, he/she should be able to paddle 310 m in the sea in <3.5 min. Final recommendations for a fitness test for potential BLGs are presented.     

Urothelial cancer of the bladder in an area of former coal, iron, and steel industries in Germany: a case-control study

In a case-control study performed in an area of former coal, iron, and steel industries, the professional and lifestyle histories of 412 male urothelial bladder cancer inpatients (cases) and 414 inpatients with benign prostatic hyperplasia (controls) were investigated. Smoking habits were identified as the main confounder for occupational bladder cancer risk. Two hundred and forty (58.3%) of the bladder cancer inpatients and 146 (35.3%) of the inpatients with benign prostatic hyperplasia were smokers. The percentage of ex-smokers in the bladder cancer cases was 10.2%; the percentage of ex-smokers in the controls was 9.7%. Smoking-adjusted Mantel-Haenszel estimates of the odds ratios (OR&infMH;) for bladder cancer were elevated in underground hard-coal miners (OR&infMH; =2. 54, 95% CI =[1.64; 3.93]), chemical workers (OR&infMH; =2.16, 95% CI =[0.87; 5.38]), painters/varnishers (OR&infMH; = 2.42, 95% CI =[1. 05; 5.57]), technicians (OR&infMH; = 1.99, 95% CI =[0.95; 4.16]), and foundry workers (OR&infMH; = 2.22, 95% CI = [0.53; 9.08]). Administrative officers had significantly lower smoking-adjusted odds ratios (OR&infMH; = 0.61, 95% CI = [0.42; 0.88]). Although statistically not significant, the results of the Breslow-Day test of homogeneity of the odds ratios over the strata are compatible with interactions between tobacco smoking and the occupations of underground hard-coal miners (chi(2)&infBD; = 4.91, p=0.07) and chemical workers (chi(2)&infBR; = 3.32, p=0.06).     

Regular dark chocolate consumption's reduction of oxidative stress and increase of free-fatty-acid mobilization in response to prolonged cycling

This study investigated the effects of regular consumption of dark chocolate (DC), rich in cocoa polyphenols, on plasma metabolites, hormones, and markers of oxidative stress after prolonged exhaustive exercise. Twenty active men cycled at 60% maximal oxygen uptake (VO2max) for 1.5 hr, with the intensity increased to 90% VO2max for a 30-s period every 10 min, followed by a ride to exhaustion at 90% VO2max. In the 2 wk before exercise participants consumed 40 g of DC or an isocarbohydrate-fat control cocoa liquor-free chocolate (CON) twice daily and once 2 hr before exercise in a randomized, counterbalanced, crossover design. Venous blood samples were taken immediately before exercise, postexercise (fixed duration), postexhaustion, and after 1 hr of recovery. F2-isoprostanes were significantly lower (post hoc tests: p < .001) at exhaustion and after 1 hr of recovery with DC. Oxidized low-density lipoproteins were significantly lower with DC (p < .001) both before and after exercise and at exhaustion. DC was also associated with ~21% greater rises in free fatty acids during exercise (main effect: p < .05). Changes in circulating glucose, insulin, glucagon, cortisol, and interleukin (IL)-6, IL-10, and IL-1ra were unaffected by treatment. Time to exhaustion at 90% VO2max was not significantly different between trials (398 ± 204 and 374 ± 194 s for DC and CON, respectively). These results suggest that regular DC intake is associated with reduced oxidative-stress markers and increased mobilization of free fatty acids after exercise but has no observed effect on exercise performance.     

Colorectal cancer among Chinese restaurant waiters

To investigate whether Chinese restaurant waiters in Hong Kong had an increased risk of dying from colorectal cancer, we linked the records of deceased union members to the mortality information for the general population between 1986 and 1995. A case-control analysis among the deceased was performed with 346 deceased waiters and 306 deceased male kitchen workers. Waiters were found to have a significantly higher mortality odds ratio [(MOR) 2.29; 95% confidence interval (CI) = 1.47-3.56] of colorectal cancer when compared with the general population. The MOR (1.45; 95% CI = 0.71-2.93) was increased, but not significantly, when compared with the kitchen workers. The study suggested that waiters in Hong Kong Chinese restaurants are at a higher risk of dying from colorectal cancer. An unhealthy diet associated with their job is a possible explanation, and interventions should be initiated.     

Effects of coenzyme athletic performance system as an ergogenic aid on endurance performance to exhaustion.

This study examined the effects of the Coenzyme Athletic Performance System (CAPS) on endurance performance to exhaustion. CAPS contains 100 mg coenzyme Q10, 500 mg cytochrome C, 100 mg inosine, and 200 IU vitamin E. Eleven highly trained male triathletes were given three daily doses of either CAPS or placebo (dicalcium phosphate) for two 4-week periods using a double-blind crossover design. A 4-week washout period separated the two treatment periods. An exhaustive performance test, consisting of 90 minutes of running on a treadmill (70% VO2max) followed by cycling (70% VO2max) until exhaustion, was conducted after each treatment period. The mean (+/- SEM) time to exhaustion for the subjects using CAPS (223 +/- 17 min) was not significantly different (p = 0.57) from the placebo trial (215 +/- 9 min). Blood glucose, lactate, and free fatty acid concentrations at exhaustion did not differ between treatments (p < 0.05). CAPS had no apparent benefit on exercise to exhaustion.     

Vibration exposure and myocardial infarction incidence: the VHEEP case-control study

OBJECTIVES: The main objectives of this study were to assess the risk of contracting first episode of myocardial infarction (MI) subsequent to vibration exposure and to assess a possible exposure-response relationship. METHODS: The V?sternorrland heart epidemiology programme (VHEEP, a part of the Stockholm heart epidemiology programme study) was the source of the data. VHEEP is a population-based case-control study of risk factors for acute MI. Exposure information was collected by questionnaire and vibration exposure was assessed in 218 cases and 257 controls. Relative risks were estimated using odds ratios (ORs) from binary logistic regression. RESULTS: The results show that the OR of acute MI when exposed to vibration was 1.6 (95% CI: 1.1-2.4). It was not possible, however, to determine whether an exposure-response relationship was present. CONCLUSIONS: Working entailing vibrating machines is associated with an increased risk for acute MI.