Prediction of Harvard Pack Index from the result of an 11 min progressive exercise test and anthropometric measurements in coalminers

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Abstract
The Harvard pack test and an 11 min progressive treadmll test (belt speed 80m min−1 incline increasing by l·4%min−1 for 10min) have been applied to 378 healthy male mine rescue workers aged 20-45 yr. During the treadmill test measurements were made of ventilation, cardiac frequency and stroke volume. Measurements were also made of ventilatory capacity, body dimensions, fat free mass and heart volume The results show that the Harvard pack index (HPI) may be predicted from the last minute cardiac frequency (LMfC) during the progressive treadmill test according' to the following relationship: HPI = 147−0·22 age−0·39 LMfC, the coefficient of variation about this relationship is 10·4% The inclusion in the prediction relationship of fat free mass, cardiac frequency at an oxygen uptake of 67mmol min−1 and stroke volume which in combination are significantly correlated with the HPI, also of leg length, ambient temperature and smoking history, which are not so related, do not materially improve the accuracy of the prediction. Current smoking is associated with a relatively low quantity of body fat and high ventilation minute volume during exercise but is not correlated with the exercise cardiac frequency. Evidence is presented why the submaximal cardiac frequency reflects the physical condition of the subjects.