Eliezer Kamon

Dynamic and static lifting capacity and muscular strength of steelmill workers

Dynamic and static strength measurements were compared respectively to maximal actual lifting and to a static lifting strength of 228 male steelmill workers. The strength tests were reasonably correlated with the lifting measurements. The dynamic strength test was the simplest, the least time consuming, revealing one to one ratio with the maximal actual lift and was not perceived as an exerting maneuver. Therefore, when matching between the job and a worker is desirable, it is suggested to use the dynamic strength test as a predictor for lifting capacity.

In-plant evaluation of the muscle strength of workers

The static muscular strength of the back extensors, arm flexors and hand grip were measured on industrial workers (463 men and 139 women) involved in physically demanding jobs. No significant differences in strength were found among workers on different jobs. However, strength differences were evident with respect to age and sex; women were about 60 percent as strong as men, and men below 31 years of age were stronger than men above this age.

Readdressing Personal Cooling With Ice

An ice-based system of personal, non-restrictive cooling of workers exposed to high temperature work environments in nuclear power plants was evaluated. The garments were designed to be worn under the protective clothing donned for penetration into radiation areas. The cooling system consisted of direct body contact with small packets of frozen water enclosed in the pockets of a shirt in high ambient temperatures (55 degrees C) and moderate metabolic heat production (200-300 kcal/hr). Mean exposure time without cooling (control) was 52 min for workloads demanding 200 kcal/hr energy expenditure. A long garment with 7.2 kg of frozen water (LFWG) increased mean exposure time over the control by 242% (163% for the same garment with 6.2 kg of frozen water). A short version garment with 3.8 kg of frozen water (SFWG) increased the stay time by 115%. In field observations, the LFWG with 6.2 kg of frozen water improved stay time by 125%. The leveling off of the body temperatures and heart rates during the work both in the laboratory and in the field confirmed a reduction of heat strain associated with the use of these garments. Calculated heat balance equations of heat uptake by the ice predicted these results very closely. It was concluded that direct body contact with frozen water provided predictable adequate body cooling for the work and ambient conditions investigated in this study.

Effects of Carbon Dioxide Inhalation on Psychomotor and Mental Performance during Exercise and Recovery

Psychomotor and mental tests involving reaction time, rotor pursuit, short-term memory for digits and letters, and reasoning ability were administered to subjects inhaling up to 5% CO2 in air and in gas mixtures containing 50% O2, The psychomotor and mental tests were given during the 6 min of recovery following 10 min of treadmill running at 80% of aerobic capacity. Although the subjects inhaled the CO2 during the entire exercise and recovery period there was no difference in performance between the CO2 inhalation condition and the control condition for any of the performance measures.

Posture and Subjective Evaluation at Flat and Slanted Desks

Back posture was photographed and back, neck, and upper arm electromyograms(EMGs) were recorded for six subjects during reading and writing at flat and slanted (12°, 24°) desk surfaces. In addition, the subjects rated fatigue and back discomfort. Sitting with a backpack, while leaning 45° forward, was used as a preliminary procedure to standardize the back discomfort ratings. Results indicated more erect posture and less back movement (reduced EMG) at the slanted surfaces, while slanting the desks also reduced fatigue and discomfort. The pattern in which the slanted surfaces were significantly better than the flat surface varied with each measurement technique.

Effective heat strain index using pocket computer

An effective heat strain index (EHSI) using a hand calculator with memory is suggested for on-site evaluation of prevailing hot ambient conditions. The inputs to the programmed calculator include dry-bulb, wet-bulb and globe temperatures, and estimates of metabolism and air movements. The index is based on a program for calculation of the total heat balance and on the efficiency of sweating. The display of information on the ambient conditions EHSI display is one of following: no strain; low strain; high strain; or time limits of exposure.

Scheduling Cycles of Work for Hot Ambient Conditions

Abstract Schedules of working and resting periods were designed separately for work at 40% [Vdot] O2maxand for work at 60% [Vdot] O2max each under the two following ambient conditions: (a) warm-humid, T db 36°C, T wb31°C and; (b) hot-dry, T db50°C, T wb25°C. Two conditions were provided for the resting period: (1) under the same ambient conditions as for the working conditions: (2) under neutral ambient conditions of T db 23°C, T wb 16°C. The working periods were determined by the total sum of the expected work specific heart rate (HR) and the expected heat induced increments in HR. The total sum of the HR was treated in terms of its equivalence to the fraction of [Vdot] O2max, based on the linear relationship between the two parameters. The limiting factor was taken to be the lower end of the 95th percentile maximal HR for the population of the 20–30 yr old participants. Six heat acclimatized male subjects participated in testing the adequacy of the design of the work and rest periods. The schedule of wo...

Estimation of oxygen consumption from pulmonary ventilation during exercise.

Pulmonary ventilation ( E) and oxygen uptake ( O2) were measured and regressions between them were found for men and for women exercising from light levels (1.3 kcal/min) to maximal levels (20 kcal/min) of work. Increases in pulmonary ventilation were proportionately greater than increases in oxygen consumption, and, therefore, nonlinear regressions were determined for a range of E which was wider than the linear regressions previously suggested by other investigators. Because the data for men and women diverged, two separate curves were computed. In addition to the sex differences, each equation had an adjustment for age. The standard error of estimate for O2 was 0.21/min.

Scheduling rest for consecutive light and heavy work loads under hot ambient conditions.

Three male and three female heat-acclimated subjects participated in a series of five testing sessions aimed at validating a resting period which was assigned to follow work under warm-humid (Tdb 36°C, Twb 31°C) and hot-dry (Tdb 50°C, Twb 25°C) ambient conditions. Each working period consisted of 25 min of walking at 30% [Vdot]o2max followed by five minutes of carrying a load uphill at 75% [Vdot]o2max. The working period was based on the expected HR as it could be derived from: (1) the work-specific HR as determined from the linear relationship between % [Vdot]o2max and HR; (2) the heat-induced increments in HR; and (3) the endurance limits imposed by the age-dependent HRmax. Each 30 min of work was followed by 30 min of rest either under the same ambient conditions as for the working period, or under neutral ambient conditions. Judged by the levelling off of HR and by setting the limits of the Tre rise to 38°C during the consecutive walking periods, only the resting under the neutral conditions proved ad...

Long-term mortality experience of steelworkers. VIII. Mortality patterns of open hearth steelworkers (a preliminary report).

The findings in this report of a deficit in mortality from cardiovascular diseases and an excess in diseases of the digestive system among open hearth workers indicate the need for further study of men working in hot environments. In future reports we hope to refine the comparisons by obtaining data which will enable classification of workers more precisely by intensity and duration of exposure within the open hearth. Of particular importance in future work are the evaluation of possible relationships between the actual levels of heat exposure and subsequent morbidity and mortality, as well as possible interactions between heat stress and physical exertion in terms of the incidence of heart disease and other select diseases.