The determinants of performance in master swimmers: a cross sectional study on the age related changes in propelling efficiency, hydrodynamic position and energy cost of front crawl

The decrease in swimming performance (vmax) that occurs with age is a not only consequence of the physiological decrease in maximal metabolic power ( _E max) but can also be expected to depend on an increase in the energy cost of swimming (C) mmax ¼ _Emax=C: In turn, for a given speed and stroke C = Wd / (gPgo) where Wd is hydrodynamic resistance, gP is propelling efficiency and go is overall efficiency. The aim of this study was to measure C in 47 male masters (31–85 years old) swimming the front crawl at sub-maximal, aerobic, speeds. During the experiments propelling efficiency and projected frontal area (Aeff, an index of Wd) were also determined by kinematic analysis. ‘‘Elder’’ masters (60–80 years) swam at a significantly slower pace (0.65 vs. 0.91 m s-1), with a lower gP (0.23 vs. 0.31) and a larger Aeff (0.39 vs. 0.23 m2) than ‘‘younger’’ masters (30–60 years). No significant differences in C (1.45 kJ m-1, on the average) were observed as a function of age or speed, but C values were significantly higher than those assessed in young elite swimmers at the very same speeds; the difference increasing with age with a rate of 0.75 % per year. With the due considerations (in this study the observed changes in gP, Aeff and C can be either attributed to changes in speed or age) these data confirm the hypothesis that an increase in C contributes to the decrease in swimming performance that occurs with age.