The aim of this study was: ( 1) to assess the energy cost of swimming ( C-s, kJ km(-1)) in a group of male ( n= 5) and female ( n= 5) elite swimmers specialised in long-distance competitions; ( 2) to evaluate the possible effect of a 2-km trial on the absolute value of C-s. C-s was assessed during three consecutive 400-m trials covered in a 50-m pool at increasing speeds ( v(1), v(2), v(3)). After these experiments the subjects swam a 2-km trial at the 10-km race speed ( v(2km)) after which the three 400-m trials were repeated at the same speed as before ( v(5)= v(1), v(6)= v(2), v(7)= v(3)). C-s was calculated by dividing the net oxygen uptake at steady state (VO2ss) by the corresponding average speed ( v, m s(-1)). VO2ss was estimated by using back extrapolation technique from breath-to-breath VO2 recorded during the first 30 s of recovery after each test. C-s increased ( from 0.69 kJ m(-1) to 1.27 kJ m(-1)) as a function of v ( from 1.29 m s(-1) to 1.50 m s(-1)), its values being comparable to those measured in elite short distance swimmers at similar speeds. In both groups of subjects the speed maintained during the 2-km trial ( v(2km)) was on the average only 1.2% faster than of v(2) and v(6) ( P > 0.05), whereas C-s assessed at the end of the 2-km trial ( v(2km)) turned out to be 21 +/- 26% larger than that assessed at v(2) and v(6) ( P < 0.05); the average stroke frequency ( SF, cycles min(-1)) during the 2-km trial turned to be about 6% ( P < 0.05) faster than that assessed at v(2) and v6. At v(5), Cs turned out to be 19 +/- 9% ( P < 0.05) and 22 +/- 27% ( 0.1 < P= 0.05) larger than at v1 in male and female subjects ( respectively). SF was significantly faster ( P < 0.05, in male subjects) and the distance per stroke ( D-s= v/SF) significantly shorter ( P < 0.05) in female subjects at v(5) and v(6) than at v(1) and v(2). These data suggest that the increase of C-s found after the 2-km trial was likely related to a decrease in propelling efficiency, since the latter is related to the distance per stroke.
Energy cost of swimming of elite long-distance swimmers
Zamparo P.;Schena F.;Capelli C.
2005-01-01
Abstract
The aim of this study was: ( 1) to assess the energy cost of swimming ( C-s, kJ km(-1)) in a group of male ( n= 5) and female ( n= 5) elite swimmers specialised in long-distance competitions; ( 2) to evaluate the possible effect of a 2-km trial on the absolute value of C-s. C-s was assessed during three consecutive 400-m trials covered in a 50-m pool at increasing speeds ( v(1), v(2), v(3)). After these experiments the subjects swam a 2-km trial at the 10-km race speed ( v(2km)) after which the three 400-m trials were repeated at the same speed as before ( v(5)= v(1), v(6)= v(2), v(7)= v(3)). C-s was calculated by dividing the net oxygen uptake at steady state (VO2ss) by the corresponding average speed ( v, m s(-1)). VO2ss was estimated by using back extrapolation technique from breath-to-breath VO2 recorded during the first 30 s of recovery after each test. C-s increased ( from 0.69 kJ m(-1) to 1.27 kJ m(-1)) as a function of v ( from 1.29 m s(-1) to 1.50 m s(-1)), its values being comparable to those measured in elite short distance swimmers at similar speeds. In both groups of subjects the speed maintained during the 2-km trial ( v(2km)) was on the average only 1.2% faster than of v(2) and v(6) ( P > 0.05), whereas C-s assessed at the end of the 2-km trial ( v(2km)) turned out to be 21 +/- 26% larger than that assessed at v(2) and v(6) ( P < 0.05); the average stroke frequency ( SF, cycles min(-1)) during the 2-km trial turned to be about 6% ( P < 0.05) faster than that assessed at v(2) and v6. At v(5), Cs turned out to be 19 +/- 9% ( P < 0.05) and 22 +/- 27% ( 0.1 < P= 0.05) larger than at v1 in male and female subjects ( respectively). SF was significantly faster ( P < 0.05, in male subjects) and the distance per stroke ( D-s= v/SF) significantly shorter ( P < 0.05) in female subjects at v(5) and v(6) than at v(1) and v(2). These data suggest that the increase of C-s found after the 2-km trial was likely related to a decrease in propelling efficiency, since the latter is related to the distance per stroke.
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