Intraventricular conduction defect (IVCD), real or fancied, QRS duration in 1,254 normal adult white males by a multilead automated algorithm.

The QRS duration (QRSD) on a digital 12 simultaneous lead ECG was measured by a commercially available recording cart (Marquette MACII 12SL) in 1,254 white male safety workers (ages 19-65, mean 34). All had a negative history (including drugs known to affect the cardiovascular or pulmonary systems), a negative family history (in immediate family members before age 55), no physical findings suggestive of heart disease, a normal blood chemistry profile, pulmonary function tests, and symptom limited bicycle exercise test. The frontal QRS axis was between -30 and -65 in 22 of 1,254 (1.8%). Twenty-seven of 1,254 (2.1%) had QRSD greater than or equal to 120 ms-14 of these had normal morphology; 2 had RBB; 3 had atypical RBB; 5 had R' in V1, V2; 2 had WPW; and 1 had Superior Fascicular Block. Sixty-three (5%) had a QRSD greater than or equal to 112 and less than or equal to 116 ms-36 of this group had normal morphology; 1 had typical RBBB; and 26 had R' V1, V2 (considered a normal variant as it occurred in 360 of 1,164 remaining with QRSD less than or equal to 108). In 1,224 white men with normal QRS morphologies and frontal axis (-25 to 100), the 98% upper and lower bounds of QRSD with the 12SL algorithm, like that seen in BSMs, was 80-116 ms, peak 96 ms.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy costs of simulated stair climbing as a job-related task in fire fighting.

The purpose of this investigation was to determine the energy requirement of simulated stair climbing. Metabolic costs of climbing stairs in getting to the scene of a fire can be very demanding for fire personnel. Heart rate and oxygen consumption were measured on 17 fire fighters during each of three conditions: (1) stair climbing without fire-fighting uniform or equipment, (2) stair climbing with fire-fighting uniform and equipment, and (3) pedaling a bicycle ergometer in a graded maximal exercise test. These three conditions were designed to determine (1) baseline reference values, (2) actual work task measures, and (3) maximum reference values. Results showed that climbing stairs with an 8-inch rise at 60 steps per minute with fire fighter's uniform and equipment (86.5 pounds) for five minutes required heart rates to reach 95% (84 to 100) of maximum effort, and oxygen consumption measures were found to be 80% (63 to 97) of maximum. It was concluded for the personnel studied that the rate of energy cost of climbing a simulated staircase with uniform and equipment required an ability to consume at least 2.7 L of oxygen per minute and 39 mL/kg/min.

Program for increasing health and physical fitness of fire fighters.

In 1970 the Los Angeles County Occupational Health Service began a program to monitor the health status and to increase the physical fitness of its 1,800 fire fighters. By 1973 physical examinations including resting ECG and blood laboratory studies had been completed for all fire fighters. In addition, the oldest 998 fire fighters were tested for physical work capacity (PWC), job-related strength performance, and spine flexibility. Exercise prescriptions and health enhancement counseling were given by exercise physiologists at the time of testing, and one hour per shift was assigned for the exercise. Data were not kept to determine compliance with the exercise program but physical activity was evaluated by interview and the same physiological measurements were made at each examination. By 1982 departmental averages for PWC had increased 16%, with the oldest age group (older than 50 years) showing the most marked improvement. The percentage of habitual smokers decreased from 44% to 25%. High levels of PWC, strength, and flexibility were found to be inversely related to workers' compensation costs. Fire fighters with below-average PWCs subsequently experienced 2.6 times more myocardial infarctions than their above-average counterparts. While it is difficult to determine the influence of any one factor on the collective wellbeing of the fire fighters, it is logical to assume that this program has had an important beneficial effect on the maintenance of a healthy work force.

Physical fitness and subsequent myocardial infarction in healthy workers.

Physical work capacity (PWC), a measure of physical fitness, was assessed by bicycle ergometry on 2,779 healthy men younger than 55 years who were subsequently followed up for an average of 4.8 years for symptomatic myocardial infarction (MI). There were 36 MIs. The relative risk (RR) of MI for below median PWC, adjusted for conventional risk factors for heart disease, was 2.2 (95% confidence limits, 1.1 and 4.7). This increased risk appeared to be limited to men with certain other risk factors present simultaneously: above-median cholesterol level, smoking, above-median systolic BP, or a combination of these. Among men with at least two of these factors, the adjusted RR for below-median PWC was 6.6 (95% confidence limits, 2.3 and 27.8). Poor physical fitness may be an important risk factor for heart disease, especially when conventional risk factors are also present.

Heart disease risk factors in Los Angeles County safety personnel.

Eight generally accepted heart disease risk factors (age, sex, family history, blood pressure, cholesterol, weight, smoking and exercise) were used in the computation of a cardiac index (RISKO) for 4,066 safety personnel of the County of Los Angeles. Seventy-one individuals subsequently developed coronary disease. The index had significant value in identifying the individuals who were to develop symptomatic coronary disease, and its discriminative power was comparable to the power of the Framingham index.

Strength and fitness and subsequent back injuries in firefighters.

This prospective investigation was done to evaluate five strength and fitness measurements and the subsequent occurrence of back injuries in 1652 firefighters for the years 1971 to 1974. The prospective measurements included flexibility, isometric lifting strength, bicycle ergometer exercise measurements of two-minute recovery heart rate, diastolic blood pressure at a heart rate of 160 beats per minute and watts of effort required to sustain heart rate at 160. Three fitness and conditioning groups were established by multivariate ranking and regression techniques (259 high, 266 low, and 1127 middle) and the subsequent back injuries were tabulated for the three groups. The results showed a graded and statistically significant protective effect for added levels of fitness and conditioning (least fit, 7.1% injured; middle fit, 3.2% jured; and most fit, 0.8% injured). It was concluded that physical fitness and conditioning of firefighters are preventive of back injuries and that further investigations are warranted to study other injuries and physical fitness in this physically active occupational group.