[Conversion of load intensity from a pedalling ergometer to a walking treadmill in patients with ischemic heart disease].

BACKGROUND

For requirements of physical rehabilitation it is important to know the "safe" load intensity: this can be assessed reliably among others on a pedalling ergometer. The purpose of the present work was to reveal conversion relations between laboratory loads on a pedalling ergometer and the load of walking which is the most natural physical activity recommended for keeping fit and for rehabilitation, incl. rehabilitation of patients with ischaemic heart disease, after cardiosurgery etc.

METHODS AND RESULTS

In order to obtain conversion relations between the load intensity on a pedalling ergometer and walking on a treadmill, on the same day a group of 40 men (mean age 51.0 +/- 5.0 years, body weight 83.7 +/- 9.9 kg, height 175.3 +/- 5.8 cm and mean body fat 18.6 +/- 4.0%) were subjected to both types of exercise. All patients were for varying periods after a myocardial infarction or revascularization surgery (aortocoronary bypass type) and had different load tolerances. From the functional aspect they belonged into group NYHA I: On a single day thy were subjected to examination on a pedalling ergometer with a load of 0.75, 1.25, 1.75 W.kg-1 and on a treadmill, 0 gradient, at a rate of 3.5 and 7 km.h-1. Assuming a linear relationship between load intensity and oxygen consumption a simple relationship is found between the rate of walking in km.hour-1 and the pedalling intensity P/W.kg-1, i.e. v = 3.051 x P + 1.361. This relationship can be used for conversion of load intensities from the bicycle to walking on a treadmill or on even ground up to intensities of a pedalling load 1.75 W.kg-1 and walking at a rate of 7 km.h-1 with an error less than 10%.

CONCLUSIONS

The authors elaborated a mathematically expressed general relation for conversion of the load intensity on a pedalling ergometer to walking on even ground.