Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
The Effects of Rubber Swimsuits on Swimmers
Using a Lactic Acid Curve Test
shiraki, t. 1 , Wakayoshi, K. 1 , hata, h. 1 , Yamamoto, t. 2 , tomikawa,
M. 3
1 Biwako Seikei Sport College, Japan
2 YAMAMOTO CORPORATION CO., LTD., Japan
3 University of Tsukuba, Japan
The rubber swimsuit, made from Neoprene rubber, was one of the causes
of the swimming record rush in 2009. The benefits of wearing a wetsuit
on swimmers were widely reported. This study verified the influence of
wearing the rubber swimsuit on a swimming exercise load. Eight female
university swimmers performed 4 x 200 m crawl swimming at incremental
speeds, set from the best record of each 200 m freestyle race
(80%V 200 , 85% V 200 , 90% V 200 , 95% V 200 ). Four different suits (three
types of rubber suits and a cloth swimsuit) were used and lactic acid
curve tests were conducted. The blood lactate concentration after 90%
V 200 and 95% V 200 trials with rubber swimsuits tended to be lower than
those with a cloth swimsuit. An examination of the trials revealed that
the total number of arm strokes tended to decrease due to the use of the
rubber swimsuits. It is suggested that the rubber swimsuits might improve
propulsion efficiency and decreased the swimmer’s exercise load,
indicating that the rubber swimsuit may improve the race performance
of swimmers.
Key words: rubber swimsuit, lactic acid curve test
IntroductIon
Forty-three new world records were set in 13 th FINA World Championships
in Rome 2009. It was not just a historical coincidence that
the 43 new world records were established in just one meeting. These
records were reached with new swimsuits with high technology. In fact,
the rubber swimsuit was one of the causes of this record rush. Being
similar to wetsuits, the rubber swimsuit was made from Neoprene rubber.
So, rubber swimsuits probably present beneficial characteristics similar
to wetsuits. The effects of using wetsuits on swimmers were widely
reported:(i) triathletes are able to hold their bodies in a more horizontal
position because of the added buoyancy (Chatard et al., 1996, Chatard
et al., 1995, Toussaint et al., 1989) and (ii) drag force is reduced by the
smooth surface provided by a wetsuit (Chatard et al., 1995, Toussaint
et al., 1989).
Additionally, Tomikawa et al. (2008) showed that swimming velocity
at maximal oxygen consumption with a wetsuit was 5.4% higher than
with a swimsuit, and that the swimming energy cost of swimming with
a wetsuit was lower by 14.4% at 60% of the velocity corresponding to
VO 2 max and 7.5% at 80% of the velocity corresponding to VO 2 max.
These results suggest that the benefits of wearing a wetsuit include not
only the improvement in swimming propulsion efficiency, but also the
reduction in energy consumption. While the thickness of a wetsuit is
2-5mm, a rubber swimsuit is only 0.3mm thick, which seems to imply
that the benefits of wearing a rubber swimsuit might be less than those
of using a wetsuit.
A lactic acid curve test is usually used to determine the anaerobic
threshold to monitor training (Maglischo, 2003). The test is an incremental
one, allowing that the values of blood lactate concentration be
plotted on a graph in combination with the swimming velocity. If the
lactate-velocity curve will move to the right when wearing a wetsuit,
the swimming performance is improved. This study aimed to verify the
influence of wearing a rubber swimsuit on the swimming exercise load
by using a lactic-velocity curve test.
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Methods
Eight female university swimmers participated in this study. The average
of their best records for 200 m freestyle swimming was 129.8 ± 4.5 seconds.
They attended the Japanese inter-college swim meet 2009. Their
age, height and weight were 19.8 ± 0.9 years, 160.8 ± 4.2 cm and
58.0 ± 2.8 kg, respectively, and they had a body fat % of 28.4 ± 3.6.
Four types of suits were used in this study. Three rubber suits were
made from Neoprene rubber: (i) rubber suit A was a commercially available
suit: (ii) rubber suit B was made from Neoprene rubber, and metallic
minerals were contained between rubber and back fabric layers: (iii)
rubber suit C was also made from Neoprene rubber, in which titanium
was included in bond part between rubber and back fabric layers. Rubber
suit B and C were not commercially available. The 4 th suit type was a
cloth swimsuit, being a common water-repellent competitive swimsuit
with. All swimsuits were the full-length type, covering from shoulder
to ankle.
Swimmers performed a 4 x 200 m incremental swimming protocol,
the speed of the four stages set from the best record of each 200 m
freestyle race (80%V 200 , 85% V 200 , 90% V 200 , 95% V 200 ). The speed was
controlled by a pace maker set on the bottom of pool. Blood from the
fingertip was taken at 0, 3 and 5 min after each trial. The blood lactate
concentration was determined using Lactate Pro analyzer (ARKRAY,
Inc.). Arm strokes in the trials were counted each 25 m (LAP 1 to 8).
The mean and standard deviation were computed for all variables.
ANOVA with repeated measures was used to compare the data obtained
in the wetsuits and a swimsuit condition. A probability level of 5% was
selected for tests of statistical significance.
results
The mean ± SD values of blood lactate concentrations in each trial are
shown in Table 1. No significant differences were found in blood lactate
concentration between different rubber suit conditions.
Table 1. Means ± SD of Blood lactate concentration in each suit
condition
NS
mmol·L -1
RS-A
mmol·L -1
RS-B
mmol·L -1
RS-C
mmol·L -1
80%V200 1.49 ± 0.45 1.61 ± 0.54 1.54 ± 0.51 1.30 ± 0.47
85%V200 2.11 ± 0.59 1.95 ± 0.88 1.83 ± 0.69 1.78 ± 0.61
90%V200 3.89 ± 1.37 3.20 ± 1.73 2.89 ± 1.21 2.95 ± 1.45
95%V200 10.46 ± 2.37 8.68 ± 2.66 9.35 ± 2.24 8.18 ± 2.98
However, the blood lactate concentration after 90% V 200 and 95% V 200
trials with rubber swimsuits tended to be lower than those with a cloth
swimsuit (Figure 1). Especially, when wearing rubber suit C, the blood
lactate concentration tended to be lower than wearing other suits. The
blood lactate concentrations after 90% V 200 and 95% V 200 trials with the
four suits were at the same level.
Fig 1. The blood lactate concentration-Swimming velocity curve in an
experimental suits conditions