Effects of Standard Labor-Wear on Swimming and Treading Water

Scientific Disciplines
Health & Human Development
Swift water Rescue
treading water
Whitewater Rescue Institute
standard swimwear
Volume 18, No. 1-4

Effects of standard labor-wear on swimming 
And treading water
John A. Amtmann, Whitewater Rescue Institute; Lolo, Montana, Montana Tech, Safety Health, 
Industrial Hygiene Department, Butte, Montana
Cody Harris, Whitewater Rescue Institute, Lolo, Montana
William Spath, Montana Tech, Safety, Health and Industrial Hygiene Department, Butte, Montana
Chip Todd, Montana Tech, Department of Mathematical Sciences, Butte, Montana
We tested the hypothesis that occupational clothing would impair performance during swimming. 
The sub questions included: (1) Will the standard work wear of a railway worker or laborer 
impede swimming ability? (2) Will this clothing impact the individual’s ability to tread water?  We 
addressed the research questions with three hypotheses. Analysis showed statistically significant 
p-values and all three null hypotheses were rejected in favor of the three research hypotheses, 
showing strong evidence that standard labor wear had adverse effects on 11.43 meter/12.5 yard 
swim time, water treading time and rate of perceived exertion  (RPE) during water treading.  The 
mean swim time more than doubled when the subjects wore standard labor-wear and their average 
rate of perceived exertion increased from 11.6 in standard swim wear to 17.1 in standard labor-
wear.  It may be beneficial for those workers who work near water to be exposed to educational 
programs that allow in-water experiences so they develop an understanding of their abilities in, 
and respect for, the water.  
Key Words: Labor-Wear, Swimming, Treading, Effects, Swift water Rescue
Rescue Technician (SRT) as well as the 
In this paper we examine the effect of 
licensed boat pilot.  
standard work clothing on people’s ability 
In July 2011, an oil pipeline on the 
to maneuver in water and rescue themselves 
Yellowstone River ruptured.  The ensuing 
from dangerous situations.  Several 
clean-up effort lasted four months and 
examples demonstrate why understanding 
involved over one thousand people.  Many 
clothing effects is important. On  May 2nd, 
of the laborers were transported on jet-boats 
2003, a laborer was working near a pond 
to islands, and worked in close proximity to 
in Oregon.  The pond was surrounded by 
the flooding river. 
an angled embankment where the laborer 
The SRT personnel, who were involved 
was placing rocks at strategic locations on 
in the jet-boat transportation and safety 
the inclined bank to prevent erosion. The 
support of the laborers, conducted rescue 
laborer fell down the embankment and into 
training on a daily basis.  By predicting how, 
the pond.  By the time that he was rescued 
when and where the workers would enter the 
from the water, first responders were unable 
water, they could focus training efforts to the 
to resuscitate him. It took them 47 minutes 
most likely situations: a worker falling into 
to locate and remove the body before 
the river during transport or during work on 
resuscitation efforts began (NIOSH, 2003).  
the steep embankment along the river.  The 
In March 2011, a train derailment along 
training was successful.  Each and every 
the Kootenai River in Northwest Montana 
simulated victim was rescued during the 
required railway workers to be transported 
training.  But each simulated victim was 
to the derailment site via jet boat and to 
wearing special equipment designed for the 
work on an inclined embankment along 
conditions: During the third week in March 
the river.  Each day the workers were 
on the Kootenai River, for example, the air 
transported seven miles down the river. The 
temperature fluctuated between about 30 and 
crew of each boat included a Swift Water 
54 degrees Fahrenheit, the Kootenai River 

was flowing at about 20,000 cubic feet per 
average 12.5 yard swim time in standard 
second, and the temperature of the water 
was about 39 degrees Fahrenheit (USGS, 
Null Hypothesis 2: 
The average time to failure when 
A common question of the laborers 
treading water in standard labor-wear is ≥ 
during transport was, “If we fall into the 
the average time to failure when treading 
drink [while working], how long would we 
water in standard swim-wear.
be able to stay up before you guys are able 
Research Hypothesis 2: 
to rescue us?” The average worker being 
The average time to failure when 
transported to the worksite was wearing 
treading water in standard labor-wear is < 
standard work-wear: a hard hat with a 
the average time to failure when treading 
liner, a heavy Carharrt canvas jacket with 
water in standard swim-wear.
insulation under the jacket, Carharrt canvas 
bib coveralls, and heavy leather work-boots 
Null Hypothesis 3: 
with steel toe protection.  
The average rate of perceived exertion 
The Occupational Safety and Health 
(RPE) when treading water in standard 
Administration requires the use of personal 
labor-wear is ≤ the average RPE when 
protective equipment and personal flotation 
treading water in standard swim-wear.
devices (PFD) when individuals are working 
Research Hypothesis 3: 
on, over or near water when a drowning 
The average RPE when treading water 
hazard exists (U.S. Department of Labor; 
in standard labor-wear is > the average RPE 
1926.106(a)). However, workers don’t 
when treading water in standard swim-wear.
always comply with this requirement    The 
purpose of this research was to determine 
how swimming performance, water treading 
We tested the hypotheses in a controlled 
time and perceived exertion are influenced 
indoor pool environment.  The subjects 
when workers are wearing typical labor-
participated in four trials:
wear compared to swim-wear.  All study 
procedures were reviewed and approved 
•  Trial 1: Timed freestyle swim of 
by an independent investigational review 
11.43 meter/12.5 yards in standard 
board.  The main research question was, 
what effects would standard labor-wear have 
•  Trial 2: Timed freestyle swim of 
on swimming ability and ability to self-
11.43 meter/12.5 yards in standard 
rescue?  The sub questions that guided the 
development of our hypotheses were:
•  Trial 3: Timed water tread in 
Will the standard labor-wear impede 
standard swimwear.
swimming ability?
  Trial 4: Timed water tread in 
Will this clothing impact the 
standard labor-wear.
individual’s ability to tread water?
Nine volunteer subjects were 
chosen based on current or previous 
experience and credentials.  The inclusion 
Null Hypothesis 1: 
criteria was set so only those who have 
The average 11.43 meter/12.5 yard 
swiftwater rescue technician (SRT) 
swim time in standard labor-wear is ≤ the 
certification, lifeguard certification,  and/
average 12.5 yard swim time in standard 
or competitive swimming experience 
were considered.  The SRT has 
demonstrated swimming abilities that 
Research Hypothesis 1:
The average 11.43 meter/12.5 yard 
meet the Whitewater Rescue Institute’s 
swim time in standard labor-wear is > the 
(WRI) minimum standards to self-rescue 
and to rescue victims of swiftwater 
50          Amtmann et al.

accidents, and certified lifeguards 
required to verbally communicate their 
are required to pass a swim test to 
exertion level on a scale of 6 to 20.  When 
demonstrate proficiency.  
the subject neared the extreme end of the 
The exclusion criteria included any 
scale and their efforts could no longer 
current student of the researcher’s and 
continue, they were instructed to reach for 
was guided by the American College 
the gutter to self-rescue.  If they were unable 
of Sports Medicine risk stratification 
to self-rescue the rescuers planned to use 
process.  American College of Sports 
the rescue/flotation equipment to assist the 
Medicine (ACSM) guidelines suggest a 
pre-participation screening that identifies 
Prior to the trials, each subject was 
current medical conditions that would 
given the following instructions regarding 
exclude those who are at risk for adverse 
the use of the RPE Scale to ensure safety:  
cardiovascular, pulmonary, metabolic, 
“While performing the treading, we 
as well as other conditions, that would 
want you to rate your perception of exertion. 
cause adverse responses to exercise 
This feeling should reflect how heavy 
(ACSM, 2009).  The list of conditions 
and strenuous the treading feels to you, 
that excluded a subject included:
combining all sensations and feelings of 
physical stress, effort, and fatigue. Do not 
•  Pregnancy
concern yourself with any one factor such 
•  Diabetes
as leg pain or shortness of breath, but try 
•  Hypertension or are taking blood 
to focus on your total feeling of exertion. 
pressure medication
Look at the rating scale below while you 
•  Asthma 
are treading; it ranges from 6 to 20, where 
•  Concerns about safety of exercise 
6 means ‘no exertion at all’ and 20 means 
or swimming ability
‘maximal exertion’. Choose the number 
•  Heart surgery 
from below that best describes your level 
•  Chest discomfort with exercise
of exertion. This will give us a good idea of 
•  Unreasonable breathlessness with 
your intensity level and how much longer 
the treading will continue.”  The RPE scale 
•  Unexplained dizziness or fainting
with related descriptions includes (Borg, 
•  Musculoskeletal problems that 
1998, pg. 47):
limit functional capacity
•  Current smoker
  6  ....... No exertion at all  
All subjects completed the pre-
  ....... Extremely light  
participation screening to identify anyone 
who should be eliminated.  Additionally, all 
subjects were under the age of 50 years.
 9  ....... Very light - (easy, comfortable pace)  
Safety of the subjects for the 11.43 
meter/12.5 yard swim was ensured in two 
 11 ....... Light  
ways.  First, the 11.43 meter/12.5 yard swim 
was conducted in water that is 4 feet deep, in 
 13 ....... Somewhat hard (It is quite an ef ort;  
which all of the subjects were able to stand.  
you feel tired but can continue)  
The subjects were instructed to simply stand 
up if they were in distress.  The subjects 
 15 ....... Hard (heavy)  
were also surrounded by lifeguards in the 
water and on the deck with appropriate 
 17 ....... Very hard (very strenuous, and you  
rescue equipment as back-up measures. 
are very fatigued)  
Safety for the subjects during the 
treading consisted of three lifeguards/SRTs 
 19 ....... Extremely hard (you cannot continue  
monitoring the subject with rescue flotation 
for long at this pace)  
devices.  Using Borg’s Rate of Perceived 
  20 ....... Maximal exertion
Exertion (RPE) Scale, the subjects were 
Effects of Standard Labor-Wear on Swimming and Treading Water       51

The subjects were all read an informed 
in standard labor-wear (Tr L) was 8.41 
consent form that emphasized the voluntary 
minutes. The Wilcoxon Signed Rank test 
nature of this study, and that if they were 
showed a p-value of .0156.  Based on this 
uncomfortable doing anything in the study 
result we reject null hypothesis 2 in favor of 
assessment they had the option to not 
research hypothesis 2 at a significance level 
participate.  The decision to take part in this 
of 0.05. Table 3 shows the statistical results 
research study was entirely voluntary, and 
for the water treading tests.  
subject withdrawal from the study could 
The mean RPE for subjects treading 
have occurred at any time.
in standard-swim wear (RPE Tr) was 11.67 
seconds, and the mean RPE for subjects 
treading in standard labor-wear was 17.11 
The subjects were read the informed 
seconds.  The Wilcoxon Signed Rank test 
consent form, and were instructed on the 
showed a p-value of 0.0156  .  Based on this 
proper use of Borg’s (RPE) scale.  Resting 
result we reject null hypothesis 3 in favor of 
heart rate and blood pressure were measured 
research hypothesis 3 at a significance level 
at this time.  The subjects were informed 
of 0.05. Table 4 shows the statistical results 
that the RPE scale were to help the rescuers 
for the subjects’ RPE for the water treading.  
by providing them information that will 
The limitations to the study include 
prepare them to assist the subject.  The order 
the non-randomized order of trials which 
of the timed trials included:
could have caused an order effect.  We did 
this because we felt it would be the safest 
•  First all subjects swam the 11.43 
way to conduct the trials but acknowledge 
meter/12.5 yard swim in standard swim-
that it could have an effect either way on 
the results.  Additionally, a small sample 
•  15-minute rest
size and the lack of objective fitness data, 
•  All subjects swam the 11.43 meter/12.5 
body composition in particular, for each 
yard swim in standard labor-wear
subject, would have allowed us to discuss 
•  15 minute rest
the possible effects of differences in body 
composition on the treading results.  The 
•  Water treading test in standard swim-wear
subjects were very fit and may not be the 
•  One week rest
best representatives of the average work-
•  Water treading test in standard labor-wear
force representative; again pre-test fitness 
measurements may have allowed us to 
compare the subjects with average fitness 
levels in the American work-force.  We 
Table 1 shows the complete results 
established and adhered to the subject 
of the trials.  The mean 11.43 meter/12.5 
guidelines for safety purposes because 
yard swim time for subjects in standard 
we did not want any of the subjects to be 
swim-wear (Sw) was 10.05 seconds and the 
traumatized by the experience. That is, we 
mean swim time for subjects in standard 
had all subjects begin each trial with swim-
labor-wear (Sw L) was 23.37 seconds.  The 
wear to prepare them for the more difficult 
Wilcoxon Signed Rank test is appropriate 
labor-wear trial.  Each subject was allowed 
for relatively small sample sizes, and 
to rest for at least 15 minutes, and heart 
showed a p-value of 0.0039.  Based on this 
rates were monitored prior to the labor-wear 
result we reject null hypothesis 1 in favor of 
trials to ensure the subject was in a resting 
research hypothesis 1 at a significance level 
state.  We acknowledge, however, that the 
of 0.05. Table 2 shows the statistical results 
non-randomized order in which this was 
for the 12.5 yard swim.  
conducted may have had an order-effect.
The mean treading time for subjects in 
Also, the labor-wear only consisted 
standard swim-wear (Tr) was 12.99 minutes 
of boots and the coveralls; no inner layers 
while the mean treading time for subjects 
were worn.  Insulation layers may have 
52          Amtmann et al.

Table 1.
  subject  age 

Sw L 
Tr L 
Rpe L
1  46  60  8.29  18.5  15:00 10:54  15  20
2  21  66  8.61 23.9 10:50  1:06 20  20
3  21  60  10.34  15.3  5:25 55.07  20  20
4  22  78  11.68  33.03 10:40  56  20  20
5  23  78  10.24 30.3  15:00  8:35  6  20
6  21  72 
9.46  20.9  15:00 15:00  6 
7  20  78  8.54 17  15:00  8:18  6  20
8  22  84  11  23  15:00 15:00  6  14
9  21 
95  12.33  28.44 15:00  15:00  6  12
Table 2.
 means 11.43 Meter/12.5 yard Swim

St. Dev. 
9  10.05  1.44  8.29 12.33 4.04 
  Sw L  9  23.37  6.15  15.3  33.03  17.73 0.0039
Table 3.
 means Treading

St. Dev. 
9  12.99  3.38  5.42 15  9.58 
  tr l 
9  8.41 
6.14  0.92  15 
14.08 0.0156
Table 4.
 means Rpe

St. Dev. 
  rpe tr  9 11.67 6.89 6  20  14 
Trpe Tr L 9  17.11  4.59  8 
12  0.0156
had a further impact on the measurements.  
in the labor-wear.  All nine subjects showed 
The environment was controlled; the water 
slower swim times with labor-wear.  One 
was warm, clear and non-moving when, in 
subject only required an extra 5 seconds, but 
reality, many water incidents occur in cold, 
the other 8 subjects all required double or 
dark moving water.  
triple their swim-wear times.  
All of the subjects were current or 
former athletes.  Two were college football 
Based on the results described above, 
players, two were college basketball 
we can say with confidence that it is more 
players, and one was a college volleyball 
difficult to tread water and swim 12.5 
player.  Though standard fitness assessments 
yards in coveralls and heavy work boots 
were not part of the protocol, the subjects 
when compared to wearing a swim-suit.  
were given an initial swim test as part of 
An individual who ends up in the water 
the institutional review board procedure 
with standard labor-wear should expect the 
agreement, and they all appeared to have a 
physical requirements needed for self-rescue 
high level of physical fitness.  We believe 
to be much more difficult than if they had 
the effects on swimming and treading 
simply fallen into a swimming pool with 
efficiency would be much more pronounced 
their swim suit on.  Three of the subjects 
on physically unfit individuals.
who were able to tread water for more than 
All of the subjects reported higher 
5-10 minutes in their swim trunks were only 
levels of difficulty when swimming or 
able to tread water for around one minute 
treading in the labor-wear, but there was 
Effects of Standard Labor-Wear on Swimming and Treading Water       53

disagreement on whether the treading with 
reflect a laborer’s physiological response 
the labor-wear or swimming with the labor-
in the water.  Though it may be difficult to 
wear was harder.  Out of the nine subjects, 
receive institutional review board approval, 
all four of the men believed that the treading 
conducting this research in moving water, 
was more difficult than the swimming, and 
such as an actual river would be more 
all five women believed that the swimming 
realistic. The addition of a PFD would also 
was more difficult than the treading.  
have an effect on self-rescue; treading would 
not be as difficult if a PFD is worn.  Self-
The distance of 11.43 meters/12.5 yards 
rescue swimming with a PFD should be 
is a short swim; five of the nine subjects 
addressed as well; wearing a PFD doesn’t 
stated that the swim was much more difficult 
always mean self-rescue is guaranteed.  
than the treading.  For them, self-rescue 
Monitoring heart rates and comparing 
of distances greater than this may not 
different strokes would provide information 
be possible. Additionally, the controlled 
about which strokes would be more efficient 
environment and relatively warm water is 
in standard labor-wear.
not universally applicable.  Self-rescue in 
cold, dark, moving water is different, and 
probably more difficult, than self-rescue in a 
warm pool with non-moving, clear water.  
American College of Sports Medicine.  
The original question can now be 
(2009).  ACSM’s Guidelines for Exercise 
answered:  In some cases complete 
Testing and Prescription 8th Edition.  
exhaustion occurs in less than one minute.  
Baltimore, MD: Lippincott, Williams & 
This is one reason the Occupational Safety 
and Health Administration requires a life-
Borg, G.  1998.  Borg’s Perceived Exertion 
vest when workers are near a drowning 
and Pain Scales.  Champaign, IL: 
hazard.  Simply wearing a life-vest, a 
Human Kinetics.
personal flotation device (PFD), will prolong 
NIOSH FACE Program (2003).  Hispanic 
this time; however this rule is not always 
Laborer Drowns After Falling Into 
followed and wearing a PFD will not always 
Landscape Pond.  Internet Available: 
prevent the loss of a life.  
Based on the results of this study we 
or/03or008.html. Date of Download:  
believe it may be beneficial for those who 
October 10th, 2011.
work near water to participate in educational 
USGS.  Water Information System.  
programs that allow in-water experiences 
Kootenai River at Bonner’s 
so they develop an understanding of their 
Ferry, ID. March 2011.  Internet 
abilities in, and respect for, the water.  We 
also recommend that any company requiring 
Date of Download: October 8, 2011.
their employees to be working on or near 
water to consider implementing water safety 
United States Department of Labor.  
plans that may include swift water rescue 
Occupational Safety and Health 
professionals to conduct training and to 
Administration website.Internet 
be on-site to help prevent water injury and 
available: http://www.osha.gov/pls/
Date of Download: October 5, 2011.
Recommendations for 
Future research
To gather more information, conducting 
fitness assessments on each subject would be 
beneficial.  Also, adding the insulation layers 
Received July 24, 2012
that are normally worn may more accurately 
Accepted September 5, 2012
54          Amtmann et al.