Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
Methods
The sample consisted of 29 swimmers, 10 of them were disabled swimmers
of functional classes 1 to 5 (G1), 9 disabled swimmers of functional
classes 6 to 10 (G2) and 10 able swimmers (G3). The descriptive average
values of the swimmers characteristics were (mean±standard error of
the mean) height 163.8±6.17 cm, weight 56.83±2.39 kg and age 27±2.04
years for G1; 170.67±5.39 cm, 62.72±5.67 kg and 27.44±3.5 years for G2;
and 174.72±2.3 cm, 66.87±2.68 kg and 17.5±0.8 years for G3. Table 1
presents information about the disability of the G1 and G2 swimmers.
Table 1. Type of disability, and number of subjects affected by each disability
of the Groups 1 and 2
Disability Group 1 (n=10) Group 2 (n=9)
Focamelia 1 3
Arthrogryposis 1 0
Paraplegia 3 1
Amputee 1 1
Cerebral palsy 4 0
Brachial plexus lesion 0 1
Perthes 0 1
Spinal cord disorder 0 1
Muscular atrophy 0 1
All the swimmers of G1 and G2 belonged to the national swimming team
that competed at the Paralympic Games in Beijing. G3 group subjects
were national level swimmers without disability from different clubs. The
subjects signed an informed consent form before starting the protocol,
this being checked by the Research Commission of the Department of
Physical Education and Sports at the University of Valencia (Spain). All
procedures described in this section comply with the requirements listed
in the 1975 Declaration of Helsinki and its later amendment in 2008.
With the aim of verifying whether the lactate accumulation after a
maximum anaerobic effort (R1) and another aerobic-anaerobic effort (R2)
differ between disabled swimmers (high and low classes) and non disabled
swimmers, each subject performed one set of each test (R1 and R2). The
subjects did the tests using their competition stroke. Table 2 shows the
number of swimmers for each stroke. The subjects did two series. The
objectives of these series were to reach the maximum LA concentration
after an anaerobic effort (R1) and an aerobic-anaerobic effort (R2). After
finishing each test, LA level was registered at five points (i.e. 1, 3, 5, 7 and
9 minutes after the test). Before test R1, resting LA was taken (mean±
SEM) (G1: 1.38±0.09, G2: 1.48±0.10, G3: 1.41±0.11). Although resting
LA value before R2 was not registered, R2 was not started until the LA
value was similar to resting LA before R1. One minute after finishing each
series, a blood sample for LA level, was taken every two minutes till the
highest LA peak was reached (i.e. 1, 3, 5, 7,… minutes). The highest lactate
peak was the one used for later analysis.
Table 2. Number of subjects that used each swimming stroke in the three
groups.
Group 1 (n=10) Group 2 (n=9) Group 3 (n=10)
Freestyle 3 5 8
Butterfly 1 0 0
Backstroke 3 1 0
Breaststroke 3 3 2
All the subjects did the R1 series first at the maximum intensity. After a 30
minute rest, they did R2 series to the maximum intensity. R1 distance for
each subject was the one that allowed (depending on the swimmer’s disability
and or performance level) to complete as many laps (i.e. 25 meters)
each as near 60 seconds as possible. To calculate the swimming distance of
R2, approximately 240 seconds was the length to complete. Average time
360
(mean±standard error of the mean, SEM) for R1 was 73.23±3.15 seconds
and for R2 was 224.48±11.3 seconds, without differences between groups.
Lactate level for each subject was registered after the test. 5 µl of capillary
blood was examined with the lactate examiner Lactate-Pro.
Statistical analysis was carried out using SPSS software version 17
(SPSS inc., Chicago, IL, USA). It was checked that all the variables complied
with the assumption of normality (K-S normality test) before analyzing
the data. Standard statistical methods were used to obtain the mean
as a measurement of the central trend and the standard error of the mean
(SEM) as a measurement of dispersion. A mixed model 3(group) x 2 (test)
ANOVA was performed to discover differences between the exercises and
groups. For those variables where the ANOVA showed significant differences,
post hoc analysis were requested using Bonferroni adjustment to
determine between which exercises these differences appeared. The level
of statistical significance was set at p