Effect of Using a Treadmill Workstation on Performance of Simulated Office Work Tasks
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Journal of Physical Activity and Health, 2009, 6. 617-624
©2009 Human Kinetics, Inc.
Effect of Using a Treadmill Workstation on Performance
of Simulated Office Work Tasks
Dinesh John, David Bassett, Dixie Thompson, Jeffrey Fairbrother, and Debora Baldwin
Although using a treadmill workstation may Currently, two-thirds of American adults are either
change the sedentary nature of desk jobs, it is overweight or obese.' Obesity rates are rapidly increas-
unknown if walking while woridng affects per- ing in most modern and industrialized nations.'-^ Tbe
formance on office-work related tasks. .Piir- obesity epidemic has been attributed to the increased
pose: To assess differences between seated and avaiiability of inexpensive energy-dense foods in con-
walkitig conditions on motor skills and cogni- junction with a modem environment that has reduced
tive function tests. Methods: Eleven males opportunities to be physically active.- To combat this
(24.6 ± 3.5 y) and 9 females (27.0 ± 3.9 y) epidemic, tbere has been an empbasis on increasing
completed a test battery to assess selective physical activity through structured exercise regimens.
attention and processing speed, typing speed, More recently, it has been suggested that an increase in
mouse clicking/drag-and-drop speed, and GRE nonexercise activity thermogenesis (NEAT) may help
math and reading comprehension. Testing was control weight.^ In 2003. the U.S. Census bureau esti-
performed under seated and walking condi- mated that approximately 52.4% of employed Ameri-
tions on 2 separate days using a counterbal- cans use a computer at work.^ Because many Americans
anced, within subjects design. Participants did spend time at work sitting in front of a computer,
not have an acclimation period before the researchers have identified the work environment as a
walking condition. Results: Paired t tests (P < place to increase NEAT.'^-''
.05) revealed that in the seated condition, com-
The treadmill workstation was first proposed and
pletion times were shorter for mouse clicking
built twenty years ago by Edelson to reduce inactivity in
(26.6 ± 3.0 vs. 28.2 ± 2.5s) and drag-and-drop
office workers.*^** It was touted to solve the hazards of
(40.3 ± 4.2 vs. 43.9 ± 2.5s) tests, typing speed
continuous sitting (postural fixity). These hazards
was greater (40.2 ± 9.1 vs. 36.9 ± 10.2 adjusted
included aches and pains, stress, and other illnesses.^^
words • min~'). and math scores were better
Treadmill workstations allow users to alternate between
(71.4± 15.2 vs. 64.3 ± 13.4%). There were no
sitting and walking while working during a regular
significant differences between conditions in
workday. Treadmill workstations consist of a conven-
selective attention and processing speed or in
tional motorized treadmill that slides under a height
reading comprehension. Conclusion: Com-
adjustable sit-to-stand table. A regular office cbair
pared with the seated condition, treadmill
allows tbe user to sit, if they choose.
walking caused a 6% to 11% decrease in mea-
sures of fine motor skills and math problem After briefiy disappearing, the treadmill worksta-
solving, but did not affect selective attention tion concept was reintroduced as a potential weight loss
and processing speed or reading comprehen- strategy by Levine and coworkers.-'' They suggested that
sion. if an obese individual walked 2 to 4 hrs/workday at a
treadmill workstation, he/she would increase daily
energy expenditure by about 500 kcal day^'.^ Tbey esti-
Keywords: light-intensity activity, walk-work, mated that this could translate to a yearly weight loss in
NEAT tbe range of 20 to 30 kg.^
Although the treadmill workstation seems to have
tbe potential for weight loss, the effects of this approach
on work performance still need to be assessed. An indi-
vidual using a treadmill workstation may need to divide
attentional resources between treadmill walking and
The authors are with the Dept of Exercise, Sport, and Leisure office work, which might compromise work perfor-
Studies, University of Tennessee. Knoxille. mance. It remains to be seen if slow walking at a tread-
617
618 John et al
mill workstation affects performance in work related approved by the University of Tennessee Institutional
variables. The results of such a study would establish Review Board. As a safety precaution, a I-meter lanyard
the feasibility of the treadmill workstation as an effec- was attached to the participant's clothing that would
tive strategy for weight control. Tiius. the purpose of automatically turn off the treadmill if they moved more
this study was to determine if walking while working at than 1 meter away from the treadmill control panel
a treadmill workstation affects selective attention and during walking, Height and weight of each participant
mental processing speed and the performance of simu- was measured using a stadiometer and physician's scale,
lated office work tasks involving 1) fine motor move- respectively. Participant characteristics are shown in
ments (typing and mouse movements) and 2) mathe- Table 1.
matical and verbal reasoning.
Test Battery
Methods Participants had to complete a test battery comprising of
5 tests to assess selective attention and processing speed,
Workstation cognitive function and fine motor movement. The paper-
and-pencil form of the Stroop Color and Word Test
The treadmill workstation consisted of a sjt-stand table (Stoelting Co., Wood Dale, IL.) was used to measure
(501-11; Conset A/S. Denmark), height adjustable selective attention and processing speed." The Stroop
office chair, treadmill (TI450: Vision Fitness. Lake test activates an automatic verbal interference that
Mills. Wl), and a computer. These components were impedes the task ofcolor naming.'-This test is valid and
purchased separately and assembled in the Applied reliable in identifying individual differences in the allo-
Physiology Laboratory {Dept of Exercise, Sport, and cation of attentionai resources caused by interference.'^
Leisure Studies) at the University of Tennessee. The The test had 3 sections of 100 items each and partici-
table used in the current study could be lowered to a pants had 45 seconds per section to complete as many
minimum height of 76 cm for seated work and raised to items as possible. During testing, participants had to
a maximum height of 113 cm above the treadmill deck verbally identify each item so that the test administrator
during walking. The recommended heights while per- could verify if items were being correctly identified.
forming normal sitting and standing work are 70 to 78 The first section required participants to read the names
cm and 95 to 115 cm, respectively.'" The treadmill of colors printed in black ink. The second section had
workstation was constructed in a way that the user items represented by 4 consecutive X symbols printed
could alternate between treadmill walking and sitting in red, blue, or green and participants had to identify the
by simply stepping off the treadmill, sitting on the color of the print. Items in the third section were names
chair, and adjusting the table to a desired height by of colors (Red, Blue, and Green) printed in a color not
means of an electronic switch. The computer screen represented by the word. Participants had to identify the
was placed on the table surface and could be moved to color of the printed word rather than simply read the
suit treadmill walking or sitting. word. For instance, if an item on the test were the word
Red printed in green ink, the correct answer to this item
Participants would be green. The number of correct items for each
section were recorded and used to determine /-scores.
Eleven male (24.6 + 3.5 y) and 9 female (27.0 ± 3.9 y) The method of obtaining i-scores is described in the
graduate students from the University of Tennessee vol- product manual that accompanies the Stroop Color and
unteered to participate in this study. Ability to participate Word Test."
in the study was assessed using a medicai history ques-
tionnaire. Ail participants provided written, informed Fine motor movement performance was assessed
consent. Although all participants were famihar with with a typing and 2 computer mouse proficiency tests.
treadmili waiking, none were used to continuous, slow These tests were conducted on a Dell OptiPiex GX260
treadmiii waiking at imph or had previously used a desk top computer with an Intei Pentium 4 processor
treadmiii workstation. The experimental protocol was (2.40 GHz) and 256MB RAM. The Mavis Beacon
Teaches Typing 17 (Riverdeep Inc., San Francisco, CA.)
computer program was the standard typing exercise for
Table 1 Physical Characteristics of all participants. In this test, participants had to replicate
Participants (N = 20)" sections of text displayed on the screen. On completion
ofthe assigned paragraphs, typing speed, excluding any
Characteristic errors made, was recorded in adjusted words per minute
Age (y) 26.4 (4.04) (AWPM). This software has previously been used in
research studies to assess typing speed.'"*'* Computer
Height (m) 1.69(0.10)
mouse proficiency was assessed using a visual basic
Weight (kg) 67.05(15.76)
program. In this test, participants were instructed to per-
BMI (kg/m^) 22.98 (3.44) form a mouse clicking and a drag-and-drop task."' In the
' Data expressed as mean (SD). mouse clicking task, the participant had to click on 1 of
Treadmill Workstation Use and Work Performance 619
25 icons that randomly turned red in color until all icons tests (completion time), and GRE math and reading
were clicked. The drag-and-drop task involved dragging comprehension (percentage of correct answers) tests.
and dropping 25 icons 1 at a time (when red) into a Test results are presented as means ± standard devia-
larger black box. An icon stayed red until successfully tions. Paired samples t tests were used to examine dif-
dropped into the box. after which another random icon ferences between test results from treadmill walking
on the screen turned red. The time taken to complete and the sitting conditions. Repeated-measures ANOVAs
each task was recorded. on test versions were performed to determine if GRE
Paper-based graduate record examination (GRE) test versions had a confounding effect on the results
math and verbal (reading comprehension only) sections from the 2 conditions. Statistical significance for all
were used to assess cognitive function of the partici- analyses was set at /* < .05.
pants. These sections were obtained from the official
source for GRE review guide (Educational Testing Ser-
vices) that contain examples of actual GRE tests. The Results
GRE is used to predict academic performance by mea- Paired samples f tests showed significant differences
suring the basic developed abilities related to success in between the 2 conditions on typing, mouse proficiency,
graduate school.'' Mathematical reasoning and reading and GRE math test scores. In the sitting condition, par-
comprehension tests from the GRE have been used in ticipants displayed better scores on the typing (i^ =
previous research studies examining cognitive -3.161, P = .005). recorded lower completion time on
function.'^'^ For the verbal section, each participant the mouse clicking (/¡q = 2.747, P= .013) and drag-and-
was instructed to read a long (600 words) and short drop tests (r|9 = 3.839, P = .001 ). and scored higher on
paragraph (200 words), and to answer 11 related ques- the mathematical reasoning test (r|9 = -2.I69. P= .017).
tions in 18 min. The reading comprehension part of the Eigures 1, 2, and 3 illustrate performances on the Stroop
GRE is designed to measure the ability to analyze, eval- and typing test, mouse proficiency tests, and cognitive
uate, and synthesize information. For the math section tests, respectively. Mouse clicking and drag-and-drop
participants had to answer 30 questions in 30 min. This scores (in seconds) for the walking condition were
section of the GRE measures the participant's ability to lower hy 8% and 6%, respectively. Typing (AWPM) and
reason and solve quantitative problems under a time math scores for the sitting condition were 9% and 11%
constraint. Scores for both GRE tests were calculated as greater than scores for the walking condition, respec-
the total percentage of correct responses from each tively. There were no significant differences (P < .05)
test. between the walking and sitting conditions for the
Stroop and reading comprehension tests. However,
repeated-measures ANOVA showed a significant condi-
Study Design tion X version interaction for reading comprehension {P
Data collection was conducted at the treadmill worksta- < .05). In other words, the group that took version 1
tion during 2 visits separated by 2 days. During their while walking and version 2 while sitting scored better
first visit, the study protocol was explained to the par- in the sitting condition, and the group that took version
ticipants and they completed the test battery for either 2 while walking and version 1 while sitting scored better
the sitting or treadmill walking (with no prior acclima- in the walking condition. However, there was no overall
tion) condition. The test battery for the remaining con- significant difference in reading comprehension between
dition was completed during the second visit. Partici- the sitting and walking conditions.
pants were allowed to adjust the table to a desired height
for both conditions. During the treadmill walking condi-
tion, participants underwent testing while walking at 1 Discussion
mph (27 m-min"'). Participants were allowed to warm
up at this speed for a few minutes before the test began.
The intensity of level walking at 1 mph is less than 2 Test Results
METS.-'' To avoid a testing effect, 2 different versions The results of the current study indicate that walking
of the GRE and typing test paragraphs were used. A while working decreases scores on tests of typing and
counterbalanced, within-subjects design was used to mouse proficiency, and math solving ability by approxi-
avoid confounding due to order effects, mately 6 to 11%. This may be because the added task of
walking puts an increased load on both mental process-
ing and motor control.-^-^ An increased load causes
Statistical Procedures interference in 1 or both tasks, thereby lowering task
Statistical analyses were conducted using SPSS version performance.^"
14 for windows (SPSS, Chicago, IL). The independent Significantly lower (P < .05) peribrmances on fine
variable in this study was the treadmill workstation con- motor movement tests during the walking condition
dition (seated VA. treadmill walking). The dependent may have resulted from the increased complexity of
variables were scores for the Stroop task (t-scores), performing multiple motor tasks (walking and typing/
typing test (AWPM), mouse clicking and drag-and-drop mouse tasks) that require a more complex interaction
620 John et al
70
60
50
Typing 40
Speed
t-score
(AWPM)
30
20
10 -
Typing Stroop
Figure 1 — Mean scores and standard deviations on typing and Stroop tests for walking and sitting conditions (N = 20). * Signifi-
cantly different from each other {P < .05).
Clicking Drag-Drop
Figure 2 — Mean scores and standard deviations on mouse clicking and drag-and-drop tests for walking and sitting conditions (N
= 20). * Significantly different from each other (P < .05).
with cognitive abilities, and iticreased recruitment of and thereby placed a higher than normal demand on
attentional resources.^'•^- Similarly, performing a cogni- attentional resources. This may have resulted in lower
tive function like math problem solving and treadmill scores on the mathematical reasoning tests during the
walking simultaneously may have increased complexity walking condition. Research by Giomo et al^** showed
Treadmill Workstation Use and Work Performance 621
Math Reading comprehension
Figure 3 — Mean scores and standard deviations on GRE math and reading comprehension tests for walking and sitting conditions
(N = 20), * Significantly different from each other {P < .05).
significantly lower performances (P < .05) on a finger in the current study. In addition, Edelson and Danoff
tapping task and a cognitive test during submaximal examined only 5 participants and their study may have
exercise (75% of ventiJatory threshold) as compared lacked the statistical power required to show a signifi-
with performances in a sitting condition.-''* Although the cant difference.
exercise intensity in the study hy Giomo et al was much Unlike fine motor movement and GRE math tests,
higher than the current study, a similar trend of decreased results from the Stroop tests were not significantly dif-
performance during dual task performance was observed ferent between walking and sitting conditions. During
in both studies.^^^ the Stroop test, participants use their working memory
Findings on the typing tests from the current study to resolve a mental conflict between word reading and
were different from those by Edelson and Danoff.^ They color naming.'--^ In the walking condition, participants
found no significant difference in typing performances also had to simultaneously process the task of walking.
between walking and sitting while working at a tread- Findings from the current study were similar to those by
mill workstation."^ In contrast to this finding, the current Grabiner and Troy who did not report a significant dif-
study determined that typing speed decreased slightly ference iP = .052) in Stroop test results between a sta-
(3.3 ± 4.7 AWPM) while walking. This discrepancy tionary condition (standing) and treadmill walking.^"
may have resulted from the fact that participants in However, they reported a significant decrease in step
Edelson and Danoff's study had an average seated width variability during treadmill walking while per-
typing speed of 61 AWPM in comparison with only 40 forming the Stroop test.-" They concluded that volun-
AWPM in participants from the current study.** The tary gait changes occur to compensate for the reduced
average typing speed of the current participants was visual resources allocated to walking while performing
similar to the average speed (40 AWPM) of 3475 par- the Stroop test.-*^ The current study did not assess step
ticipants from Ostrach's study.-^ Results from Ostrach width variability. In general., it can be said that walking
would classify participants tested by Edelson and while performing tasks that invoke a mental load similar
Danoff in the 2nd decile and the current participants in to the Stroop test, does not affect an individual's perfor-
the 5th decile.'^ Therefore, the difference between find- mance on the mental task.
ings from Edelson and Danoff and the current study
Like the Stroop test, reading comprehension scores
may have resulted from the fact that participants in the
in the sitting condition were not significantly different
fomier study were more experienced typists than those
(P < .05) than scores in the walking condition. These
622 John et al
results are in contrast to those of Barnard, Yi, Jacko, and The use of a computer mouse depends mainly on
Sears where reading comprehension scores for sitting tbe type of job being performed. In this study we exam-
were significantly higher (P < .01) than those for walk- ined the effect of walking while working on clicking
ing.^** Unlike Barnard et al who reported a 10% differ- and drag-and- drop tasks only. A previous study exam-
ence between scores, reading comprehension scores ining computer mouse use in office workers showed that
while sitting were only 4% bigher than treadmill walk- an employee moves and clicks tbe mouse approximately
ing in tbe current study. This difference may be attribut- 78 limes per hour.'' In the current study, time taken to
able to the fact that participants from Barnard et al move the mouse and click an item took 1.06 and 1.12s
walked on a narrow course that meandered around a while sitting and walking, respectively. Therefore,
room as compared with the simpler task of treadmill moving the mouse and clicking 78 items in an hour
walking in the current study. In addition, the device used while walking and working would require only 4.68 s
by Barnard et al was a personal digital assistant (PDA) more than sitting, which may not have a substantial
and had a much smaller screen as compared with the effect on overall work productivity. In general, the task
computer monitor in the current study.^** In summary, of dragging-and-dropping items using a mouse at work
reading comprehension may not place as high a demand is less frequent than clicking.
on attentional resources as other tasks, and thus is not The third test tbat showed significantly different
affected by treadmill walking. results between sitting and walking condifions was the
GRE math test. To accommodate errors in the measure-
ment process. Educational Testing Services defines a
Practical implications of Lowered
"meaningful difference between scores" as a value
Performance greater than 2 times the standard error of measurement
Although performance during the walking condition (SEM) of score differences. In the current study, the dif-
was statistically lower for the typing, mouse proficiency, ference between sitting and standing conditions for the
and math tests, this section of the paper attempts to math test wa.s 2.48 times tbe calculated SEM of score
examine how these results could potentially impact real- differences and thus meaningful.^^ However, tbe margin
life work productivity. In this study, average typing tbat renders tbe walking GRE math score to be mean-
speed decreased from 40.2 while sitting to 36.9 AWPM ingfully different from that obtained while sitting is very
while walking. According to Ostrach. the average typing small. In otber words, the score obtained while walking
speed lies between 38 and 43 AWPM.-* It can be specu- (64.3%) would not have been meaningfully different
lated that, because the reduced typing speed during tbe from the score obtained while sitting (71.4%) if it was
walking condition falls out of the average typing speed between 65.6 and 77%.
by just 1 AWPM. tbere may be a marginal impact on The differences between scores for the sitting and
typing while walking and working in an office setting. walking conditions on tbe typing, mouse proficiency,
To substantiate the previous argument, we could con- and the GRE math tests could be reduced tbrough
sider tbe example of emailing, which is a popular form acclimation.^-^ •''' In light of the potential benefits of using
of electronic communication.^^ A study that examined a treadmill workstation, the benefits may outweigh tbe
e-mail communication between physicians and their differences observed.
patients showed that patient emails and physician replies
averaged 139 and 39 words, respectively.-^ If we com- Restoring Energy Balance
pute the time taken to compose an e-mail by these indi-
viduals based on average typing speeds from Ostrach's Current data indicate tbat in the past forty years, there
study (sitting: 40 AWPM) and tbe current study (walk- has been an increase in the average American's caloric
consumption and a concurrent decrease in energy
ing: 36.9 AWPM), patients and physicians using a tread-
expenditure.'^-'^ As a result, tbe average American adult
mill workstation would take only 17.5 and 4.9 s longer
gains 1.8 to 2 pounds/year." Levine and Miller sug-
to compose an e-mail, respectively. In addition, accord-
gested that walking while working at a treadmill work-
ing to the Intemational Organization of Standardization station increases energy expenditure by approximately
(ISO) ergonomie standard for computer visual display 165% in obese individuals as compared with sitting at a
terminals, if a standard keyboard is replaced with a dif- desk.'' They speculate that the treadmill workstation
ferent kind that may cause a decrease in typing speed, may be effective in preventing weight gain or lowering
the speed obtained using the new one must lie within obesity rates in office workers.
0.75 standard deviations of the speed for the standard
keyboard to be acceptable.^" Although we did not com-
pare different keyboards in our study, we can apply ISO Hazards of Sitting
standards to our results because we induced an experi- Occupations involving continuous seated work result in
mental condition that decreased typing speed. Typing increased musculoskeletal discomfort.'^ Individuals
speed during tbe experimental walking condition (36.9 who sit for more tban 95% of time at work experienced
± 10.2AWPM) was within the acceptable range (33.4 to greater musculoskeletal discomfort than those who were
47 AWPM) as per ISO specifications. able to vary tbeir posture.'^ In response to a subjective
Treadmill Workstation Use and Work Performance 623
assessment of musculoskeletal discomfort, users of the energy balance and reduce obesity related
treadmill workstation report that walking while working Using a treadmill workstation could also attenuate mus-
helped reduce back problems associated with continu- culoskeletal discomfort, reduce metabolic risk factors
ous sitting.''^ In addition to musculoskeletal discomfort, associated with continuous sitting, and lower stress
sedentary behaviors like continuous sitting also affect levels.^-"' The current study compared the effects of
the body at a molecular level. Hamilton. Hamilton, and using a treadmill workstation on simulated office work
Zderic proposed that prolonged hours of sitting may tasks. Walking while working was associated with a
upregulate specific molecular, physiologic, and bio- minor 6 to 11% decrease in math problem solving,
chemical responses (also known as inactivity physiol- mousing, and typing performance. It is possible that this
ogy) that could lead to metabolic disorders.'" A specific decrea.se in performance could he eliminated through
example of molecular adaptations to reduced low-inten- acclimation to walking while working. It is imperative
sity activity is the transcription of an inhibitory gene to investigate work performance in a proper office set-
that induces LPL suppression through a posttransla- ting after participants are used to walking and working
tional mechanism.'" Hamilton et al state that inactivity for at least 2 to 3 hrs/day. Future studies should examine
(sitting) and low nonexercise activity may produce seri- if using the treadmill workstation helps lower body
ous health problems that cannot be explained by exer- weight, reduce fat mass, and lower employee health care
cise deficiency alone."' In other words, maintaining costs. If these benefits can be shown, it may be possible
higher levels of low-intensity activity independent of to convince employers that the benefits of treadmill
the recommended moderate-vigorous physical activity workstations justily the costs.
can lower several metabolic risk factors.'^'
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