10.09.2012 Cortesi et al
EFFECTS OF DISTANCE SPECIALIZATION ON THE BACKSTROKE SWIMMING KINEMATICS
Cortesi, M., F., Fantozzi, S., Gatta,G.
ABSTRACT
The purpose of the present study was to investigate different
biomechanical variables of backstroke technique in swimmers
specialized in different distance events, in order to investigate
the capacity to modify the timing of the arm stroke when changing
the swimming velocity from sub-maximal to maximal. Two
25-m backstroke trials respectively at 70% of maximum velocity
(V70) and at 100% of maximum velocity (Vmax) were performed
by 9 200-m distance swimmers and 9 50-m distance
swimmers. Swimming velocity, stroke length, stroke rate, duration
of different phases of the arm stroke and selected kinematic
variables were assessed in both cases. In the 50-m distance
swimmers, the duration of the propulsive phase at Vmax, expressed
as a percentage of the duration of the total underwater
arm stroke, increased significantly (p = 0.001) with increasing
swimming velocity. Specifically, both the pull and push phases
were fundamental in the increase of duration of the propulsive
phase. When compared to 200-m specialists, 50-m distance
swimmers seem to be more able to modify their arm stroke
phases duration when increasing the swimming velocity in
backstroke.