The purpose of this study was to analyze the
relationships between energy cost (C), swimming velocity
(v), stroke frequency (SF) and stroke length (SL) in toplevel
swimmers. Eighteen elite swimmers (four freestylers,
five backstrokers, five breaststrokers and four butterflyers)
performed an intermittent set of n 9 200 m swims (n B 8)
with increasing velocity. The oxygen consumption was
measured breath-by-breath by a portable metabolic cart
(K4 b2, Cosmed, Rome, Italy). A respiratory snorkel and
valve system with low hydrodynamic resistance was used
to measure pulmonary ventilation and collect expiratory
gases. Blood samples were taken from the ear lobe before
and after each swim to analyze the blood lactate concentration
(YSI 1500L, Yellow Springs, OH, USA). At
Backstroke, Breaststroke and Butterfly strokes, increases of
SF were associated to increases of C, even when controlling
the v. The increases in SL only promoted significant
decreases in the C in Breaststroke. There was a significant
and polynomial relationship between v and SF for all
competitive swimming techniques. The polynomial relationship
between v and SL was significant only in Freestyle
and Butterfly stroke. Partial correlations between v and SF
controlling the effect of SL and between v and SL controlling
the effect of SF, were positive and significant for
all techniques. It is concluded that manipulation of stroke
mechanics variables (SF and SL) may be one of the factors
through which C in competitive swimming can be altered
for a given v.
