[Measured and predicted oxygen uptake in highly qualified athletes]

Applied methods of maximal oxygen uptake (VO2max) estimation can be generally divided into direct ones, based on oxygen uptake measured at maximal load level, and indirect ones, connected with submaximal load levels. It has been observed that maximal oxygen uptake in adults and people well adapted to physical exercise undergoes only small changes, whereas reaction of the circulatory system at submaximal load is variable and may influence the results achieved by indirect methods of oxygen uptake estimation, based on referring heart rate to the load level. Maximal oxygen uptake values measured directly were compared with foreseen values using two indirect methods: Astrand-Rhyming nomogram and von Döbeln formula. Studies were performed in highly qualified oarsmen, cyclists and swimmers (Tb. 1), representatives of sport disciplines significantly different as far as the type of physical exercise is concerned, which may cause different developing adaptation mechanisms. In groups we carried out spiroergometric test which can provide reports of the patient's heart rates (HR) and direct measurements of oxygen uptake (VO2) in steady state at different load levels. At the maximal exercise load we measured VO2max and HRmax. HR values were used to estimate VO2max by indirect methods. Following questions have been asked: 1. What is the convergence between VO2max values measured directly and those estimated by Astrand-Rhyming and von Döbeln methods? 2. What is the diagnostic usefulness of the indirect VO2max estimation in highly qualified groups of sportsmen? At the end of the test VO2max values were in oarsmen 5.139 +/- 0.06 1/min, in cyclists 5.085 +/- 0.05 l/min, in swimmers 4.689 +/- 0.01 l/min. Average VO2max values in indirect Astrand-Rhyming method (Tab. 2) in all groups estimated using HR values taken at lower exercise loads (100 W, 150 W, 200 W), were statistically lower than those measured directly (P < 0.01, P < 0.001, while values taken at 250 W were situated close to. VO2max estimated directly and indirectly being correlated in oarsmen at 200 W (0.316 < r < 0.411), in cyclists at 150 W and 200 W (0.343 < r < 0.599), and in swimmers at 150 W and 200 W--only for A3-VO2max (r = 0.3 and r = 0.37). Maximal oxygen uptake estimated by using von Döbeln formula (Tab. 3) was in all cases significantly lower (P < 0.001) then measured (values ranged from 72% to 79% VO2max of those measured directly). Significant correlation was observed at all applied exercise loads in oarsmen and cyclists (0.284 < r < 0.597) and in swimmers only at 200 W and 250 W (0.245 < r < 0.370).

1. Indirect VO2max estimation based on load level and heart rate in Astrand-Rhyming method gives results compatible with direct measurements of oxygen uptake only using significant loads, adequate to physical efficiency in investigated people (HR near 160 beats per min., 70-80% Hrmax; oxygen uptake near 80% VO2max. 2. Estimating VO2max by Astrand-Rhyming method one should apply the correction regarding maximal heart rate, in case of unknown maximal heart rate the age-factor should be applied, which is of lower significance. 3. In highly qualified sportsmen one should't estimate VO2max using von Döbeln method; values achieved are significantly lower than those estimated in direct oxygen uptake measurements.