Biomechanics and Medicine in Swimming XI

a group of young New Zealand adults, 2) Compare these assessed skills
with preconceived estimates of these abilities, and 3) To ascertain selfestimated
perceptions of the risk of drowning.
Method
University students newly enrolled in a four-year professional degree
in physical education were invited to voluntarily participate in a study
entitled the Can you swim project The study consisted of two phases of
data gathering, an initial self-complete questionnaire survey followed by
practical swimming assessment prior to the commencement of study in
2008. The study received ethics clearance from the University of Auckland
Human Participants Ethics Committee (case no.2007/447).
The self-complete questionnaire contained 20 questions, and was
designed to take 10-15 minutes to complete. The written survey sought
information on swimming-related competencies, and perceptions of
drowning risk. Student estimates of their swimming competency were
included in two questions, the first of which provided 5 categories which
best described their capacity from non-swimmer to excellent swimmer,
the second of which asked students to estimate the distance they
thought they could swim non-stop, using distance categories from 300 metres.
Practical aquatic competency was tested in a 25 metre outdoor
heated pool with a 2 metre deep end, using seven tests of aquatic skills
including:
◊ Distance swum non-stop in a 25-metre outdoor heated swimming
pool
◊ Stationary floating in deep-water with minimal swimming motion
◊ Swim 100m non-stop on back
◊ Dive headfirst entry into deep water
◊ Surface dive to deep end of the pool
◊ Swim underwater a maximum of 25 metres
◊ Contact rescue tow 25 metres
Perceptions of risk of drowning was assessed via five water-related scenarios
depicting differing levels of danger using four response categories
ranging from no risk to extreme risk (for example, How would you rate
the risk to your life in the following situation: tipped upside down in a canoe
100m from the shore of a lake,).
Data from the completed questionnaires were statistically analysed using
SPSS Version 16.0 in Windows. Descriptive statistics were used to
report differences in student estimates of swimming competency, and
risk perceptions. Mann-Whitney U tests were used to determine significant
differences between dependent (such as swimming competency)
and independent variables (such as gender).
results
The study included 68 first year students from an intake of 72 enrolments
(four were excluded because they were older than 29 years) prior
to their commencement of a 4-year undergraduate degree. Of these students,
53% were male (n = 36), and two thirds were aged 17-19 years
(69%; n = 47), 22% were aged 20-24 years (n = 15), and 9% were aged
20-29 years (n = 6).
i) Self-estimates of aquatic competency:Students were asked how they
would categorise their aquatic competency and to estimate their swimming
competency in five distance categories (See Table 1). One half
considered they were good/very good (n = 28; 41%) or excellent swimmers
(n = 6; 9%), one third considered themselves to be average swimmers (n
= 25; 37%). One third of the students estimated that they could swim
less than 100 m (n = 21; 32%).
chaPter6.medicineandwatersafety
Table 1. Student Self-estimated Aquatic Competency by Gender
Total Male Female Mann-
Swimming competency
n % n % n %
Whitney
U
p
how would you describe your swimming competency?
Non swimmer 2 2.9 0 0.0 2 6.3
Weak/very weak swimmer 7 7.4 2 5.6 5 15.7
Average swimmer 25 36.8 16 44.4 9 28.1 574.000 .980
Good/very good swimmer 28 41.2 15 41.7 13 40.7
Excellent swimmer
how far do you think you could swim?
6 8.8 3 8.3 3 9.4
300m
could you do this in open deep water?
28 41.2 13 36.1 15 46.9
Complete with difficulty
Complete easily
Can you swim 100 m on your back?
16
52
23.5
76.5
8
28
22.2
77.8
8
24
25.0
75.0
554.000 .758
Yes, can swim 100m on back
No, can’t swim 100m on back
58
10
85.3
14.7
33
3
91.7
8.3
25
7
78.1
21.9
498.000 .118
If Yes, could you do this in open deep water?
Complete with difficulty
Complete easily
can you swim 25 m underwater?
11
48
16.1
86.7
3
30
8.3
90.9
8
18
30.8
69.2
339.000 .133
Yes, can swim underwater
No, can’t swim underwater
If Yes, how do you feel about this task?
45
23
66.2
33.8
25
11
69.4
30.6
20
12
62.5
37.5
536.000 .549
Complete with difficulty
Complete easily
27
19
39.7
27.9
5
21
19.2
80.8
14
6
60.0
40.0
120.000 ≤.001*
Total 68 100.0 36 100.0 32 100.0
*Significant at the 1% level (2-tailed)
More than one quarter of students estimated that they could swim between
100-300 m (n = 19; 28%) and 41% thought that they could swim
> 300 m (n = 28). Most students (n = 52; 76%) reported that they could
achieve their estimate easily in open, deep water. No significant differences
were evident when estimates of aquatic competency were analysed
by gender, the exception being able to swim 25m underwater, where significantly
more males than females thought they could easily complete
the task (U = 120.000, p = ≤ .001).
ii) Practical swimming assessment: Students completed seven swimmingrelated
tasks comparable to the items they had been asked to provide
estimates of their perceived competencies in the written questionnaire
that was completed before the pool tests.
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