Biomechanics and Medicine in Swimming XI

Besides, the methodology of establishing the relationship and/or its
quality between swimming velocity at a given distance and the characteristics
of pulling force realized by tethered swimming requires that the
test lasts at least approximately as long as the distance covered. In that
way it is possible to adjust the observed occurrences, i.e., the characteristics
of pulling force and the velocity of swimming (as criterion and
predictor variables), also taking into consideration the load exerted on
the same energy system (Ring et al., 1996).
According to previous research, the question that occurs is with
which of the two events, 100m freestyle or tethered swimming of equal
duration to 100m, maximum accumulation of lactic acid in blood can
be achieved. Also, if there is a relationship between maximal performance
in 100m freestyle swimming (the level of competitor fitness) and
strength.
The purpose of this study was to examine lactic acid accumulation
in blood after two efforts of maximum intensity and equal duration: a)
100m freestyle swimming and b) tethered swimming, as well as to find
differences between these two measurements concerning lactate production
and heart rate. Moreover, this study attempts to investigate the
relationship between performance in 100m freestyle and the forces produced
in tethered swimming. It was hypothesized that there are no significant
differences in blood lactate accumulation after the two events.
Methods
In this study 12 active swimmers of national level participated
(age = 21.50±0.68 years, Body stature =182.83±7.24 cm and Body
mass=80.75±8.00) in freestyle swimming (Table 1). At the beginning,
they swam 100 meters freestyle with maximum intensity and time performance
and blood lactate accumulation were measured. Samples of
blood were taken at 3 rd , 5 th and 7th minute of recovery time and analysed
immediately using the reflectance photometry - enzymatic reaction
method (Accusport, Boehringer, Germany) in order to determine maximum
accumulation of lactic acid in 100m freestyle swimming.
Two days later the same athletes were tested in tethered swimming, over
an equal time to that achieved in the 100 meters swim. Blood samples
were also taken in 3 rd , 5 th and 7 th minute of recovery time in order to
determine maximum lactate accumulation and strength characteristics
were measured (Keskinen et al., 1989; Sidney et al., 1996), according to
the standardized procedure (Dopsaj, 2000).
Table 1. Swimmers characteristics
Age (years) Body Stature (cm) Body Mass (kg)
Male (N=12) 21.50±0.68 182.83±7.24 80.75±8.00
Before the test, the swimmers warmed up swimming independently up
to 1000 m. After a 10-minute rest the measuring started. On his turn,
each swimmer put on a belted harness adjusting it to his body dimensions
(Figure 1). Then he hooked a 1cm-thick PVC rope to the belt
at the back hip region. The other end of the 5m rope was attached to
a water-resistant high-resolution (100 kHz) tensiometric dynamometer
placed on a metal support fixed on the side of the pool (Figure 2).
The dynamometer was connected to a PC. Having entered the pool,
the swimmer did a 10-second trial of tethered swimming at medium
intensity in order to get familiar with the equipment and the testing
procedure. After a 1minute rest the measuring commenced.
chaPter3.PhysioLogyandBioenergetics
Fig. 1. Swimmer with the belted harness adjusting it to his body dimensions
The swimmers started tethered swimming (full technique – arms and
legs stroke) at medium intensity and after two to three strokes, at the
whistle of the timekeeper, they swam at maximal intensity for the same
time as that achieved in 100m freestyle swimming. At the whistle, the
assistant timekeeper, who operated the PC, started the program for
measuring and acquisition of data. The raw data were processed by software
specially designed by ProIng to analyze the parameters relevant to
pulling force.
Fig. 2. The support with the dynamometer used to measure tethered
pulling force
After the time of 100m freestyle there was a second whistle as the signal
to stop swimming. This procedure yielded the entire recording of
the pulling force during the achieved time of 100m freestyle. Swimmers
were told to follow the breathing pattern they would normally apply
during a race. The test was done in the indoor swimming pool of the
Physical Education Faculty of Athens Kapodistrian University a week
before the summer national senior championships.
All results are expressed as means and standard deviations. For the
comparison of mean values of blood lactate production and of heart rate
in the two tests, t - test with depended samples was applied. In addition,
Pearson’s correlation coefficient was used to calculate the relationships
between time of performance in 100m freestyle and strength produced
in tethered swimming, as well as their relationship with lactic acid accumulation
in both events. Statistical significance was set at p