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.