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PubMed1981

The variation of hand steadiness with physical stress.

The performance of 12 subjects in a hand steadiness task was compared at different work loads. Hand steadiness expressed in the form of values of hand shakiness was found not to increase linearly with work intensity. On the contrary, the relation between hand shakiness and activation level, induced by physical work, was found to be positively accelerated by an exponent of 1.6. Subjective effort measured by a ratio estimation method grew, likewise, according to a positively accelerating function with an exponent of about 1.6, while subjective effort according to the "RPE" category scale like hear rate grew linearly with work load.

Journal Article↗
PubMedDate not supplied

[Computer psychoses].

Literature review and our observations allow drawing a conclusion that it is harmful for health to work on a computer for a long period of time without making short breaks. Round-the-clock working on a computer may cause some mental disorders. Appropriate individual conditions, regular rest periods with food taking should be in an intensive working day plan of personnel using a computer. All staff, who use intensively computer should be periodically observed by psychiatrists and psychologists to prevent the development of mental disorders.

Adult↗
PubMed1994

Hemodynamic responses to 30-min cycling exercise at 70% VO2 max both in ambiant air and during chest-immersion.

The aim of this study was to examine the influence of water immersion to the chest on cardio-vascular adaptation to exercise. Upright or sitting immersion causes an increase in central blood volume, but it remains controversial whether central blood volume remains elevated during dynamic exercise in water and facilitates cardiac adaptation, depending particularly on the intensity of exercise which can be matched for O2 consumption (metabolic range) or for mechanical intensity (work load). We have compared hemodynamic variables measured during two cycling exercises at the same mechanical intensity, performed both in ambiant air and during immersion up to the chest.

Adult↗
PubMedDate not supplied

The physiological requirements of Soccer refereeing.

The movement patterns and heart rate responses of Soccer referees during matches were examined. A movement analysis was performed using a grid method and subjects wore a PE 3000 heart rate monitor during the match. The mean distance (+/- SD) covered was 9,408 m (+/- 838m) which comprised: walking (18.9%), jogging (46.6%), running/striding (12.1%), sprinting (6.2%) and backwards movement (16.2%). If walking and jogging are pooled as low intensity activity and high intensity work is defined as running/striding and sprinting then the majority of distance was covered by low intensity activity (65.5%). No differences in the total distance covered during the two halves was evident. However, in the second half the subjects walked more than in the first half (p < 0.01), while they ran/strode more in the first when compared to the second half (p < 0.01). The subjects' mean heart rate during the first and second halves was not significantly different and were 163 and 162 beats per minute (b.min-1) respectively. If the theoretical maximum heart rate for each subject (220-age) is used, the major percentage of the time was spent at heart rates above 85% HRmax. Based upon the distance results of this study, the major energy source for Soccer refereeing would appear to be the aerobic system with the anaerobic system contributing to ATP production to a lesser extent. The results of this study suggest that refereeing at a high level places a significant physiological demand upon these athletes; they therefore require specialised assessment and training.

Adult↗
PubMed1988

Physiological responses to the wearing of fire fighter's turnout gear with neoprene and GORE-TEX barrier liners.

This study examined the physiological effects of performing moderate and high intensity work while wearing fire fighter's turnout gear with either a neoprene or GORE-TEX barrier liner. Eight healthy men, experienced with the use of respirators and protective clothing, each performed moderate and high intensity treadmill exercise (44% and 71% of maximum work capacity) in a double-blind study at 27.6 degrees C (50% RH) while wearing complete fire fighter's turnout gear (weighing 23 kg) with either a neoprene or GORE-TEX barrier liner. Physiological measurements obtained included minute ventilation, heart rate, skin temperature, rectal temperature and sweat rate. Subjective evaluations of perceived exertion, comfort, clothing breathability, temperature and perspiration also were obtained. Tests were terminated (tolerance time) when objective or subjective signs of near maximal stress were observed (i.e., 90% of the maximum heart rate, rectal temperature of 39 degrees C, dizziness, etc.). Mean tolerance times for the moderate intensity exercise were 27.4 (+/- 7.3 S.D.) and 30.9 (+/- 7.9) min, respectively, for the neoprene and GORE-TEX barrier liners and at the high intensity were 7.2 (+/- 2.1) and 7.5 (+/- 2.3) min, respectively. Analysis of variance indicated that significant differences caused by liner were observed in skin temperature (0.6 degrees C higher with the neoprene ensemble). No significant differences caused by liner were seen in tolerance time, heart rate, sweat rate or subjective ratings.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Physiological cost of apple-farming activities.

Seventeen agricultural male workers, aged between 21 and 56 years, were investigated in the field during six different job-activities of apple-farming: pruning, weeding, hand and mechanical spraying, mowing and picking. Pulmonary ventilation and oxygen consumption were recorded for short periods by Oxylog, while heart rate was monitored for more than 24 hours by Holter's method. The farmers also rated the work intensity according to Borg's RPE scale. Pulmonary ventilation ranged on average between 13 and 30 1/min and oxygen consumption between 500 and 1300 ml/min, with a relative aerobic cost between 15 and 40%, in the different work activities. Heart rate varied on average between 80 and 94 beats/min with a relative cardiac cost between 20 and 30%. The physiological criteria (oxygen uptake and cardiac response) and the subjective rating of fatigue gave a substantially similar evaluation of the work strain, 'moderate-heavy' for mowing, weeding and picking, 'moderate' for pruning and hand spraying, 'light' for mechanical spraying of pesticides. On the whole, apple-farming can be evaluated as 'moderate' intensity, thanks to the mechanisation implemented in reducing the work-load and the work-time of many job activities.

Journal Article↗
PubMedDate not supplied

Cognitive performance and mood during respirator wear and exercise.

The combined effects of respirator wear and low-intensity work on decision making and mood were assessed in eight subjects during 60 min of low-intensity treadmill walking with and without a respirator to determine whether the stresses of respirator wear negatively impact decision making. Subjects completed walks during no mask wear, wear of a respirator with high inspiratory resistance, and wear of a respirator with low resistance. Cognitive tasks included choice reaction (CHO), serial addition/subtraction (ADD), logical reasoning (LOG), and serial reaction (SER). Mood was measured using a questionnaire with 36 adjectives representing the factors of activity, anger, depression, fear, happiness, and fatigue. Data were obtained preexercise, after 20 and 40 min of walking, and postexercise. Combined respirator wear and low-intensity exercise did not affect accuracy, speed, or throughout in any of the cognitive tasks. Likewise, no significant effects of condition on the six mood factor scores were observed. These results show that the combination of respirator wear and low-level activity does not adversely alter cognitive performance or mood.

Adult↗
PubMedDate not supplied

Part-time work and cigarette use among teenagers. Does age moderate this relationship?

OBJECTIVES: Previous studies on part-time work and substance use suggest that those teenagers working longer hours during the school year use cigarettes more frequently than those working less or not at all. The purpose of this study was to investigate whether age moderates the relationship between part-time work hours and smoking status. METHODS: This 1999 study consisted of a cross-sectional survey of 4,297 junior high and high school students aged 13 to 19 from 111 randomly selected schools in Ontario. RESULTS: Compared to not working at all,moderate (11 to 20 hours/week) to long (21+ hours) work hours was more strongly associated with the probability of being a smoker among young teenagers (13 to 16 years old). Work intensity was only weakly associated with cigarette use in late adolescence (17 to 19 years old). CONCLUSIONS: Working longer hours during school is associated with cigarette use, particularly among young teenagers. Although these cross-sectional data prohibit any firm conclusions regarding causality, the strong association observed among young teenagers increases the plausibility of early work transition being a risk factor for initiating smoking.

Adolescent↗
PubMed2002

Effects of resistance exercise bouts of different intensities but equal work on EPOC.

PURPOSE: To compare the effect of low- and high-intensity resistance exercise of equal work output, on exercise and excess postexercise oxygen consumption (EPOC). METHODS: Fourteen female subjects performed a no-exercise baseline control (CN), and nine exercises for two sets of 15 repetitions at 45% of their 8-RM during one session (LO) and two sets of 8 repetitions at 85% of their 8-RM during another session (HI). Measures for all three sessions included: heart rate (HR) and blood lactate (La) preexercise, immediately postexercise and 20 min, 60 min, and 120 min postexercise; and ventilation volume (VE), oxygen consumption (VO(2)), and respiratory exchange ratio (RER) during exercise and at intervals 0-20 min, 45-60 min, and 105-120 min postexercise. RESULTS: Exercise .VO(2) was not significantly different between HI and LO, but VE, [La], and HR were significantly greater for HI compared with LO. Exercise RER for HI (1.07 +/- 0.03 and LO (1.05 +/- 0.02) were significantly higher than CN (0.86 +/- 0.02), but there were no differences among conditions postexercise. EPOC was greater for HI compared with low at 0-20 min (HI,1.72 +/- 0.70 LO(2); LO, 0.9 +/- 0.65, LO(2)), 45-60 min (HI, 0.35 +/- 0.25 LO(2); LO, 0.14 +/- 0.19 LO2), and 105-120 min (HI, 0.22 +/- 0.22 LO(2); LO, 0.05 +/- 0.11, LO(2)). CONCLUSION: These data indicate that for resistance exercise bouts with an equated work volume, high-intensity exercise (85% 8-RM) will produce similar exercise oxygen consumption, with a greater EPOC magnitude and volume than low-intensity exercise (45% 8-RM).

Adult↗
PubMed1996

A state university's model program to increase the number of its disadvantaged students who matriculate into health professions schools.

Health professions schools often provide support for minority and disadvantaged students in high school or in a single college summer program. However, long-term support for students during their undergraduate years is also crucial. Since 1990, San Diego State University (SDSU), a large urban public university, has implemented the Health Careers Opportunity Program (HCOP) to increase the number of the university's disadvantaged students (most of whom are from minority groups) who matriculate into medical, dental, veterinary, and physician assistant schools. The program's 11 components, each dedicated to some form of educational intervention and support, emphasize developing students' collaborative learning skills, fostering their pride in accomplishment, and helping them achieve positive self-images and self-confidence; these goals are linked with building students' analytical and problem-solving skills. Weekly journals kept by students' mentors serve as an "early warning system" for "bad" feelings, attitudes, and behaviors that reflect students' personal problems and correlate with lower grades, and help the program staff work intensively with students immediately, before problems become severe. The SDSU's HCOP increased the number of disadvantaged (mostly minority) students staying in the prehealth career path (not counting those in the schools of nursing and public health) from 70 in 1989 to 360 in 1995. In 1992 through 1994, the students who had completed the HCOP's Summer Academic Program (to help them bridge into a science curriculum) had pass rates for entry-level math, writing competency, and math placement that were consistently higher than the rates for other SDSU students. The overall grade-point average of HCOP students in the spring of 1995 (3.05) was significantly higher than the overall GPA of all minority students in prehealth training before the HCOP began (2.59 in 1988). The number of SDSU's minority students accepted by health professions schools (primarily medical schools) rose significantly from six in 1990 to 23 in 1995. It is clear that the labor-intensive interventions of the HCOP throughout students' years at SDSU until they matriculate into health professions schools are working.

California↗
PubMed1986

Carbohydrate metabolism in fructose-fed and food-restricted running rats.

In chronically catheterized rats hepatic glycogen was increased by fructose (approximately 10 g/kg) gavage (FF rats) or lowered by overnight food restriction (FR rats). [3-3H]- and [U-14C]glucose were infused before, during, and after treadmill running. During exercise the increase in glucose production (Ra) was always directly related to work intensity and faster than the increase in glucose disappearance, resulting in increased plasma glucose levels. At identical work-loads the increase in Ra and plasma glucose as well as liver glycogen breakdown were higher in FF and control (C) rats than in FR rats. Breakdown of muscle glycogen was less in FF than in C rats. Incorporation of [14C]glucose in glycogen at rest and mobilization of label during exercise partly explained that 14C estimates of carbohydrate metabolism disagreed with chemical measurements. In some muscles glycogen depletion was not accompanied by loss of 14C and 3H, indicating futile cycling of glucose. In FR rats a postexercise increase in liver glycogen was seen with 14C/3H similar to that of plasma glucose, indicating direct synthesis from glucose. In conclusion, in exercising rats the increase in glucose production is subjected to feedforward regulation and depends on the liver glycogen concentration. Endogenous glucose may be incorporated in glycogen in working muscle and may be used directly for liver glycogen synthesis rather than after conversion to trioses. Fructose ingestion may diminish muscular glycogen breakdown. The [14C]glucose infusion technique for determination of muscular glycogenolysis is of doubtful value in rats.

Animals↗
PubMed1991

Linear and nonlinear characteristics of oxygen uptake kinetics during heavy exercise.

We assessed the linearity of oxygen uptake (VO2) kinetics for several work intensities in four trained cyclists. VO2 was measured breath by breath during transitions from 33 W (baseline) to work rates requiring 38, 54, 85, and 100% of maximal aerobic capacity (VO2max). Each subject repeated each work rate four times over 8 test days. In every case, three phases (phases 1, 2, and 3) of the VO2 response could be identified. VO2 during phase 2 was fit by one of two models: model 1, a double exponential where both terms begin together close to the start of phase 2, and model 2, a double exponential where each of the exponential terms begins independently with separate time delays. VO2 rose linearly for the two lower work rates (slope 11 ml.min-1 W-1) but increased to a greater asymptote for the two heavier work rates. In all four subjects, for the two lighter work rates the double-exponential regression reduced to a single value for the time constant (average across subjects 16.1 +/- 7.7 s), indicating a truly monoexponential response. In addition, one of the responses to the heaviest work rate was monoexponential. For the remaining seven biexponential responses to the two heaviest work rates, model 2 produced a significantly better fit to the responses (P less than 0.05), with a mean time delay for the slow component of 105 +/- 46 s.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Impact of posttraumatic stress disorder symptoms and their intensity on patients working ability].

After the war in Croatia, many people are suffering from posttraumatic stress disorder (PTSD). The aim of this research was to analyse the impact of symptoms of PTSD and their intensity on working ability of those patients. Two groups of patients with PTSD hospitalized at Psychiatric Department of osijek Clinical Hospital were interviewed. The first one consisted of 80 patients who were (by psychiatrist) estimated as able to work, and the second of 80 patients who were estimated as unable to work. In this research we used ICD-10 classification for diagnosis of PTSD, self-estimate scale for evaluation of intensity of simptoms of PTSD, Brief psychiatric ratin scale (BPRS) and medical files. Data were statistically arranged by SAS. Working status is correlated to values on Brief psychiatric rating scale (BPRS) and self-estimate scale for evaluation of symptoms intensity of PTSD. Work disability was statistically significantly correlated to: earlier appearance of symptoms of PTSD, more frequent reminding of stressor by live memories, and symptoms intensity. The intensity of symptoms was statistically more significantly correlated to work ability than their form, and the number of stressors lived through the war (through more severe illness) had more influence on work ability than characteristics or durability of a stressor.

Croatia↗
PubMed1982

Dynamic and steady-state metabolic changes in running dogs.

Dynamic and steady-state changes of VO2, VE, VCO2, PaO2 and blood lactate concentration (Lab) were studied in 4 intact (I) and in the same tracheostomized (T) dogs walking or running uphill (+ 10%) on a treadmill at speeds up to 12 km X h-1. A) Non-steady state results: The half times of the VO2 on-response (t1/2 VO2 on-) to rectangular work loads were 18.9 sec +/- 1.2 (SE) in I and 15.6 sec +/- 1.0 in T dogs (P less than 0.05), independent of work intensity and similar to those found for isolated perfused dog gastrocnemii (15-17 sec). Lab during the rest to work transient was almost unchanged. B) Steady-state results: VO2 and VE increased with increasing speed up to 8 km X h-1 (+ 10%) then levelled off both in I and T. Asymptotic VO2, and VE values were higher for I than for T (VO2 = 93 and 83 ml X kg-1 X min-1; VE = 2.6 and 1.75 l X kg-1 X min-1, respectively). Calculated delta VO2/delta VE ratios for equal external work loads indicate that the energy cost of breathing was about 12 ml O2 per liter VE. From (A) it is concluded that the adjustment of oxidative reactions upon work onset is as fast for the whole animal as for isolated gastrocnemius and can be assessed from gas exchange in the upper airways. From (B) it appears that, in the absence of glycolysis, the cost of running per unit distance decreases with increasing speed while the cost of VE becomes a sizeable part of the overall energy expenditure.

Animals↗
PubMed2002

Relationship between maximum acceptable work time and physical workload.

For safe job design, it is necessary to know the maximum acceptable work time (MAWT) for a given workload. The aim was to establish the relationship between MAWT and physical workload. Cycling tests at six different work rates relative to personal maximum working capacity were performed by 12 young adults in the laboratory. The oxygen uptake (VO(2)) in the per cent maximum aerobic capacity (%VO(2max)), relative heart rate (RHR) and relative oxygen uptake (RVO(2)) were collected throughout the test. MAWT was determined by observing the heart rate data during the test. The results showed that MAWT was negatively correlated with %VO(2max), RHR and RVO(2) (p < 0.01). Three exponential regression models were obtained and all their R(2) > 0.80. These models suggest that long-hour shifts (> 10 h) should assign a lower work intensity than for an 8-h workday. It is also logical that the workload limit for a 4-h work shift could be set at about 10% VO(2max) higher than the suggested limit for an 8-h workday.

Adult↗
PubMed2002

Community medicine in action: an integrated, fourth-year urban continuity preceptorship.

OBJECTIVE: To provide an opportunity for fourth-year students at the University of Wisconsin Medical School in Madison to immerse in urban community medicine during a 34-week program. This experience enhances the integrity of the fourth year as well as merges medicine and public health perspectives in medical education as called for by the Medicine and Public Health Initiative. DESCRIPTION: A limited number of fourth-year Wisconsin medical students have the opportunity to select a one-year, continuity-based preceptorship at the Milwaukee clinical campus with a focus in one of three domains: family medicine, internal medicine, or women's health. Students participate in the following clinical activities: a one-year, integrated preceptorship (one to three half days per week in a primary preceptor's office), medicine subinternship, senior surgery clerkship, selectives (16-20 weeks of clerkships relevant to preceptorship focus area), and one month of out-of-city electives. Complementing this community-based clinical experience is the opportunity to develop an increased appreciation for urban community health issues and resources by participating in a required urban community medicine clerkship and a mentored student scholarly project focusing on an aspect of urban community medicine and population health. All students begin the year in July with a four-week urban community medicine clerkship, which is based on the St. Luke's family practice residency's community medicine rotation and arranged by residency faculty. They conduct a "windshield survey" of a Milwaukee neighborhood, observing health hazards and identifying assets, and then present these observations to others in the clerkship. During this first month, students are introduced to the work of a variety of social service agencies, the Milwaukee City Health Department, and the Aurora Health Care/UW community clinics, which serve the state's most diverse zip codes. They meet with providers and researchers who share their expertise in infectious disease, preventive medicine, perinatal epidemiology, domestic violence, sexual assault, and disease management. Students develop increased understanding of barriers to health and personal resilience by listening to focus groups conducted with homeless men and undocumented Latino women. They participate in a resident and faculty development retreat on enhancing community medicine knowledge and skills. By August, students select an advisor and outline a project designed to expand understanding in the areas of urban population health research, community health education, professional education, or health intervention planning and evaluation. Faculty members at the Center for Urban Population Health work closely with the students throughout the year, which includes two weeks in the spring that are dedicated to intensive work on the projects. DISCUSSION: This fourth-year, urban community-based preceptorship is designed to provide students with an alternative fourth year that integrates skill development in clinical and community medicine, offers a continuity primary care experience, and showcases innovative urban health resources and role models. It is hoped that these students will pursue graduate medical education in Milwaukee, incorporate a population perspective in their practice, and choose to work in neighborhoods that are currently underserved.

Community Medicine↗
PubMed1996

Optimal pedaling rate estimated from neuromuscular fatigue for cyclists.

This study was designed to examine the optimal pedaling rate for pedaling exercise at a given work intensity for cyclists. Six college-aged cyclists each performed six sessions of heavy pedaling exercise at individually selected work rates based on their aerobic capacity. The optimal pedaling rate was evaluated on the basis of minimal neuromuscular fatigue as evidenced by the integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time. The means of the iEMG slope demonstrated a quadratic curve versus pedaling rate. The mean values at 80 rpm (0.53 (SD 0.20) microV.min-1) and 90 rpm (0.67 (SD 0.23) microV.min-1) were significantly smaller than those values at any other pedaling rate. On the other hand, the mean value of oxygen uptake (VO2) expressed as a percent of the subject's maximal VO2 (% VO2max) at each pedaling rate also showed a quadratic curve with minimal values at about 60 or 70 rpm. VO2 at 70 rpm (84.0 (SD 5.0) % VO2max) was significantly smaller than those values at 80 rpm (86.3 (SD 3.5) % VO2max), 90 rpm (87.4 (SD 3.8) % VO2max), and 100 rpm (90.1 (SD 3.8) % VO2max). These data strongly suggest that the optimal pedaling rate estimated from neuromuscular fatigue in working muscles is not coincident with the pedaling rate at which the smallest VO2 was obtained, but with the preferred pedaling rate of the subjects. Our findings also suggest that the reason that cyclists prefer a higher pedaling rate is closely related to the development of neuromuscular fatigue in the working muscles.

Adult↗
PubMed1994

The measured intensity of work-related stressors in pediatric oncology nursing.

The purpose of this descriptive study was to measure the rated intensity of work-related stressors experienced by pediatric oncology nurses and to examine the reliability of a new instrument. The Stressor Scale for Pediatric Oncology Nurses (SSPON), a 50-item visual analogue instrument, was used to measure the intensity of those work-related stressors. A national sample (n = 92) of randomly selected members of the Association of Pediatric Oncology Nurses participated. Although most subjects had 2 or more years of pediatric oncology nursing experience (92%), the majority had greater than 5 years of experience (52%). Median scores on the SSPON indicated that the nurses sampled experienced a moderately high level of work stress. Scale items rated most stressful were "watching a patient suffer and not be able to do anything about it," "when a favorite patient dies," and "making mistakes." Scale items rated least stressful were "when patients die at home rather than here at the hospital with us," "not feeling comfortable with my skills," and "when I can't answer a question about my patient." A comparison of total scale scores, using a t-test for independent samples, indicated that nurses with less than 5 years of pediatric oncology experience (n = 44) did not differ significantly from nurses with greater than 5 years of pediatric oncology experience (n = 48; t = 1.30, P = .199), in relation to intensity of work-related stress. Reliability was estimated using coefficient alpha. The total scale SSPON was found to be internally consistent (coefficient alpha = 0.93).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗