The Effect of Swim Cap Material on the Speed of Swimmers
Abstract
The purpose of this experiment was to determine the effects of swim cap material
on the speed of swimmers. Latex, silicone, and lycra swim caps have been used in the
world of competitive swimming to decrease drag and increase speed. Participants were
given one of each type of cap and swam four 25-yard freestyle sprints. The control for
this experiment was the use of no swim cap. It was hypothesized that silicone swim caps
would increase speed more than any other cap. The results showed that silicone swim
caps increased speed by an average of 0.29 seconds when compared to the use of no
swim cap; latex swim caps increased speed by an average of 0.16 seconds, and lycra
swim caps increased speed by an average of 0.09 seconds. Three t-tests were performed
on the data, and all three showed that there was no significant difference between the use
of swim caps and the use of no swim cap. This showed that the research hypothesis was
not statistically significant; however, the findings did support the research hypothesis in
the sense that silicone swim caps increased speed more than any other cap. It is believed
that the results are due to the fact that silicone swim caps are thicker than other caps used,
thus decreasing drag and increasing speed. This research could lead to studies
investigating the effect of swim cap usage on longer races and the decrease of drag.
Introduction
For a very long time, competitive swimmers have been wearing swim caps to
increase their speed. But do swim caps really affect how fast a person swims? Previous
studies have shown that drag can be reduced by streamlining the body and appendages
(Fish, 1996). Swim caps help to do that by streamlining the ears and hair. The study of
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swim caps on the speed of swimmers greatly affects the real world. Most swimmers and
coaches alike have come to accept that swim caps make people swim faster, but there
have been no studies that have proven that to be true. Another uncertainty is whether the
type of swim cap makes a difference in how fast a person swims. There are many
different types of swim caps swimmers can choose from; however, the most used are
latex, lycra, or silicone. Latex caps are the cheapest by far, but can cause allergic
reactions in some people, mainly those with a diagnosed latex allergy. Silicone caps are
most often used when there is an allergy to latex caps, but they are more expensive.
Lycra caps are the most expensive of all, and are not used much because of that. If one
type of swim cap proved more effective than another, swimmers would have more
information when they chose the swim cap they wanted to use.
The independent variable in this experiment is the material a swim cap is made
out of. The three materials used in this experiment are latex, lycra, and silicone. Latex in
its natural form has the molecular formula of CH2 : C(CH3)CH : CH2 (Rase, 2000).
Latex swim caps are thin and stretchy, but can cause allergies in some people. They are
the cheapest of all swim caps, and also wear out and rip the fastest. Silicone rubber is a
linear condensation polymer, a dense compound formed by bonding smaller compounds
together (Leucken and Partridge, 2002). The synthesis of silicone rubber can be seen in
diagram one. Silicone caps are less likely to cause allergic reactions than other types of
caps (Gandolfo, 2005). In addition, humidity, oxygen, heat, and sunlight have few
effects on silicone caps, making them excellent choices for outdoor swim meets where
they will be exposed to the elements (Chojnowski, 2002). Lycra caps are made out of a
fabric-like material. It can stretch to up to 600% of its original size, and is resistant to
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oils, lotions, and detergents (Parsons, 2005). Other types of caps react adversely to oils
and the like, which is why they wear out faster than lycra caps. However, lycra caps are
the most expensive, and the price may not be worth the benefits. Other fabrics, such as
cotton and wool, are not used in swimming because they do not repel water; they simply
absorb it. This would do nothing to increase the speed of swimmers or decrease drag,
which is why most swimmers wear caps in the first place.
The dependent variable in this experiment is the speed of swimmers. Many
factors, including drag, arm coordination, and arm movements, can influence a
swimmer’s time. Drag plays a major factor in the speed of swimmers. Swimming at the
surface of the water can increase drag by five times or more. This is due to the waves
created at the surface of the water by the swimmer, which in turn limits how fast the
person can go. It has been shown that alternating arms, legs, or both works better while
swimming at the surface of the water, while swimming underneath the water is best (Fish,
1996). For this reason, freestyle will be used in all trials, as it involves alternating arms
and legs.
There are three types of arm coordination in freestyle swimming: catch-up, where
there is a time lag between the propelling motions of each arm; opposition, where the
propelling motion of one arm begins when the propelling motion of the other arm is
ending; and superposition, where the propelling motions of each arm overlap with each
other. Arm movements in freestyle are divided into four phases. In phase A, the hand
enters the water; in phase B, the arm moves backwards and becomes vertical to the
shoulder; in phase C, the arm continues to move backwards and leaves the water; in
phase D, the arm moves over the surface of the water in order to re-enter. Phases A and
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B must be effective in freestyle swimming; if not, the swimmer will not be propelled
forward, and therefore have a low velocity (Seifert et al, 2004). In competitive swim
meets, race time is the sum of the start time, turning time, and pulling time (Watkins et al,
2005); this “race time” is what is being measured to determine the speed of swimmers.
The purpose of this experiment is to determine if the material a swim cap is made
out of affects the speed of competitive swimmers. There will be four levels of the
independent variable: latex swim caps, lycra swim caps, silicone swim caps, and no swim
caps. The swimmers wearing no swim caps will act as the control for this experiment.
Latex, lycra, and silicone swim caps were decided upon because they are the most
commonly used swim caps among competitive swimmers. It is believed that the use of
silicone swim caps will increase speed more than any other cap.
Procedure
Twenty-five volunteer members of the Senior Development Silver level at NOVA
of Virginia Aquatics were divided into four groups, labeled A, B, C, and D. Group A
contained seven swimmers, group B contained six swimmers, group C contained five
swimmers, and group D contained seven swimmers. The participants were between the
ages of thirteen and sixteen, mixed genders, and all had substantial knowledge of the four
strokes. All participants were asked beforehand if they had any known allergies to latex,
silicone, or lycra. All groups swam a 1400 yard warm-up. Following the warm-up and a
five minute rest period, each member of group A placed a latex swim cap on their head
and swam a twenty-five yard freestyle sprint. Each group swam the same distance, but
with the following swim caps: group B wore silicone, group C wore lycra, and group D
wore no cap. All trials were started from the diving blocks, and the participants’ swims
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were timed in seconds (s). There was a five minute rest period in which the participants
could cool down, drink water, and/or stretch. The sprints were repeated three more times
with the following caps in the order they are written: group A wore silicone, lycra, and no
cap; group B wore lycra, no cap, and latex; group C wore no cap, latex, and silicone;
group D wore latex, lycra, and silicone. The participants were aware that they could
withdraw from the experiment if they ever felt uncomfortable and that no names would
be used in the final paper.
Analysis of Data
The effects of swim cap material on the speed of swimmers were studied. The
results of the statistical analysis are shown in table two and graph one. The research
hypothesis stated that if a silicone swim cap was used, then the swimmer’s speed would
increase. The mean was determined for each of the levels of the independent variable.
The mean of latex caps was 13.50 seconds (s); the mean for silicone caps was 13.37 s; the
mean for lycra caps was 13.57 s; and the mean for no caps was 13.66 s. The silicone caps
increased speed more than any other cap, which supports the research hypothesis. The
variance and standard deviation were calculated for each level of the independent
variable. The standard deviations for each of the four levels were very low. This implies
that the data sets were precise.
A t-test was performed on the data at a level of significance of 0.01. A null
hypothesis was formed and stated that there would be no significant difference between
the different swim caps and the control. The calculated t value for latex caps versus the
control was 0.555; the calculated t value for silicone caps versus the control was 0.978;
and the calculated t value for lycra caps versus the control was 0.298. These are all less
5
than the table t value of 2.689 at a degree of freedom of 48. This implies that the null
hypothesis should not be rejected, and there is no significant difference between the
different swim caps and the control. The probability of the results being due to chance is
greater than 0.01, and implies that the results have a greater probability of 1 in 100 of
being due to chance and error.
The research hypothesis of swim caps having an effect on swimming speed is not
statistically significant. The data for all three swim caps versus the control implies that
the research hypothesis is not statistically significant. The results that were obtained for
latex, silicone, and lycra caps were most likely due to chance and error, rather than the
independent variable. Although the results and the research hypothesis were not
statistically significant, it was found that the mean for wearing a silicone swim cap was
0.29 seconds faster than not wearing a cap at all. Every hundredth of a second counts in
swimming, and swimmers should consider this when choosing what type of swim cap to
wear – or whether to wear one at all.
Conclusion
The purpose of this experiment was to determine the effects of the material a
swim cap is made out of on the speed of swimmers. Swimmers swam four twenty-five
yard sprints of freestyle, wearing a different cap each time: latex, silicone, lycra, or no
cap. The times of the sprints were measured in seconds. The research hypothesis stated
that if a silicone swim cap was used, then the swimmer’s speed would increase. It was
discovered that silicone swim caps did increase the speed of swimmers more than any
other cap. These results supported the research hypothesis.
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A t-test was performed on the data to determine if the data was significant. The
data was deemed not significant. The results obtained for all trials were most likely due
to chance and error, rather than the independent variable. However, silicone swim caps
did increase speed by an average of 0.29 seconds when compared to the use of no swim
cap, which makes a big difference in the world of swimming. This should be considered
by swimmers when they are deciding what type of swim cap to buy.
There is not much available research on the effects swim caps have on speed;
however, many other studies have been conducted that discuss the effects that other
factors have on swimming. One such study conducted by Watkins, Brown, and Nicholas
tested the effects the type of start has on start time. Start time is the time from the
starting signal to the first pull. They determined that the type of start used – grab (both
feet at the front of the diving block) or track (one foot at the front of the diving block, the
other at the back) – has no significant effect on start time (Watkins, J. et al, 2005).
Another study investigated the effects distance has on arm coordination. Seifert, Chollet,
and Bardy determined that swimmers preferred catch-up in longer events and opposition
or superposition in sprints (Seifert et al, 2004). This study was more similar to that
conducted by Watkins, Brown, and Nicholas, since both were investigating the effects of
a variable on speed.
There are several possible explanations for the results of this experiment. Even
though the data was not considered significant, there was a difference in speed that is
significant in the world of competitive swimming. A study conducted by Fish
determined that drag could be reduced by streamlining the body and appendages (Fish,
1996). Swim caps help to streamline the head and ears, thus causing a smoother surface
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with which to swim through the water. Smoother surfaces decrease drag; if the amount
of drag decreases, speed almost always increases. Silicone swim caps were the thickest
of all caps tested, which could explain why they increased speed more than any other cap.
This experiment could have been improved in a number of ways. The swimmers
did not receive the same amount of rest in between each trial, which could have subjected
them to more or less fatigue. The differing fatigue levels could easily have affected the
results. The methods of timing the swimmers could also have been improved. There
were two people, each equipped with a manual stopwatch, timing five lanes of swimmers
at a time. Human error was most likely a factor in obtaining the results, and could have
been reduced or eliminated. An electronic timing system (also known as a touchpad) or a
greater number of timers would have improved the data collection. For further study, the
different swim caps should be tested and evaluated at various distances. In addition, the
swim caps should be tested on the other strokes.
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Works Cited
Chojnowski, Julian. "Silicone Resins." McGraw-Hill Encyclopedia of Science and
Technology. 9th ed. 20 vols. New York: McGraw-Hill, 2002.
Fish, Frank E. “Transitions from Drag-based to Lift-based Propulsion in Mammalian
Swimming.” American Zoologist. 36 (1996): 628-641.
Gandolfo, Christina. The Woman Triathlete. Human Kinetics, 2005. Page 154.
Leucken, John J., and Edward G. Partridge. "Rubber." McGraw-Hill Encyclopedia of
Science and Technology. 9th ed. 20 vols. New York: McGraw-Hill, 2002.
Parsons, Geoff. “Chemistry has the Right Fibre for Sporting Glory.” Chemistry Review.
15.2 (Nov 2005): 10-12.
Rase, Howard F. Handbook of Commercial Catalysts: Heterogeneous Catalysts. CRC
Press, 2000. Page 80.
Seifert, L. et al. “Effect of Swimming Velocity on Arm Coordination in the Front Crawl:
A Dynamic Analysis.” Journal of Sports Sciences. 22.7 (2004): 651-664.
Watkins, J. et al. “The Effect of Grab and Track Start Techniques on Start Time and
Components of Start Time in Freestyle Sprint Swimming.” Journal of Sports
Sciences. 23.11 (2005): 1163-1164.
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Appendix
Experimental Design Diagram
Title: The Effect of Swim Cap Material on the Speed of Swimmers
Hypothesis: If swimmers wear silicone swim caps, then their speed will increase more
than if they used a different type of cap.
Independent Variable: Swim Cap Material
No Cap (Control)
Latex
25
25
Silicone
25
Lycra
25
Dependent Variable: Swimmers’ speed (s)
Constants: ability level of swimmers, age range (13-16), amount of rest allotted between
trials, brand of caps (all latex caps were exactly the same, etc.), pool length (25 yards),
stroke used (freestyle), water temperature, air temperature, test date
Diagram 1. Synthesis of Silicone Rubber (Leucken and Partridge, 2002)
10
Table 1. Raw Data Table for the Effect of Swim Cap Material on the Speed of
Swimmers
Trial Number Latex Cap Silicone Cap Lycra Cap No Cap (Control)
1
12.38 s
12.61 s
12.80 s
13.10 s
2
12.70 s
13.90 s
13.65 s
13.22 s
3
11.79 s
12.03 s
12.17 s
12.21 s
4
13.20 s
13.20 s
14.19 s
14.28 s
5
13.20 s
13.20 s
14.19 s
14.28 s
6
12.56 s
13.13 s
13.41 s
13.22 s
7
15.23 s
14.92 s
15.11 s
15.45 s
8
12.46 s
12.22 s
12.19 s
12.80 s
9
14.00 s
13.67 s
14.39 s
14.73 s
10
13.12 s
14.39 s
13.67 s
14.00 s
11
13.09 s
12.51 s
12.71 s
12.93 s
12
14.26 s
13.71 s
14.43 s
15.29 s
13
13.22 s
13.08 s
12.71 s
13.47 s
14
14.04 s
13.81 s
13.71 s
14.43 s
15
13.08 s
12.71 s
13.08 s
13.22 s
16
13.08 s
12.74 s
12.42 s
13.32 s
17
14.52 s
14.75 s
13.94 s
15.33 s
18
12.59 s
12.08 s
11.83 s
11.74 s
19
14.94 s
14.92 s
14.75 s
14.86 s
20
13.33 s
12.79 s
13.03 s
12.84 s
21
14.11 s
13.36 s
13.80 s
11.04 s
22
13.43 s
13.42 s
13.66 s
13.43 s
23
13.99 s
12.84 s
13.04 s
12.99 s
24
14.36 s
13.85 s
14.38 s
14.25 s
25
14.78 s
15.34 s
15.95 s
15.03 s
Mean
13.50 s
13.37 s
13.57 s
13.66 s
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Table 2. Descriptive and Inferential Statistics Data Table for the Effect of Swim Cap
Material on the Speed of Swimmers
Descriptive
Independent Variable: Material of Swim Cap
Information
Latex
Silicone
Lycra
No Cap
Mean
13.50 s
13.37 s
13.57 s
13.66 s
Range
Maximum
Minimum
3.44 s
15.23 s
11.79 s
3.31 s
15.34 s
12.03 s
4.12 s
15.95 s
11.83 s
4.41 s
15.45 s
11.04 s
Variance
0.783
0.901
0.984
1.295
Standard Deviation
SD 1
SD 2
SD 3
0.885
12.717-14.283
11.934-15.066
11.151-15.849
0.949
12.421-14.319
11.472-15.268
10.594-16.546
0.992
12.578-14.567
11.586-15.554
10.594-16.546
1.138
12.522-14.798
11.384-15.936
10.246-17.074
Number
Results of t-test
25
25
25
25
Latex vs. Control
Silicone vs. Control
Lycra vs. Control
At df = 48 α = 0.01
t = 0.555
p > 0.01
t = 0.978
p > 0.01
t = 0.298
p > 0.01
t = 2.689 for significance
Graph 1. The Effect of Swim Cap Material on the Speed of Swimmers
Average Time (s)
The Effect of Swim Cap Material on the Speed of
Swimmers
13.7
13.65
13.6
13.55
13.5
13.45
13.4
13.35
13.3
13.25
13.2
Latex Cap
Silicone Cap
Lycra Cap
Type of Cap
12
No Cap
(Control)