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COBA Floor Matting Study 2007 page 1 of 39

The effect of COBA floor matting on worker comfort during standing work

Prof. George Havenith and Lucy Dorman Loughborough University Department of Human Sciences


EXECUTIVE SUMMARY

By request of COBA Plastics Ltd of Fleckney, Leicestershire an experiment was

performed to test the effect of 8 different types of floor matting on objective and subjective

measures related to thermal comfort and fatigue in comparison to standing directly on

concrete slabs. As a compromise between precision, duration and cost it was decided to

perform a study in the laboratory ensuring identical conditions in all tests. Participants in

the study performed diverse light tasks while standing for 90 minutes either directly on the

concrete slabs or with a mat on the concrete. Objective data (temperatures of the foot, leg

and body) were obtained as well as participants’ perceptions of their (dis)comfort and

fatigue.

None of the temperature measurements showed significant differences between the

conditions which was attributed to the limited test duration of 90 minutes and the large day

to day variability of these measurements on the same participants.

However a number of the subjective (dis)comfort sensations did show statistically

significant improvements related to mat use. Firstly the thermal comfort vote for the whole

body showed less discomfort when standing on the mats. Votes moved from slightly

uncomfortable towards neutral in that case. This improved whole body thermal comfort

was accompanied by a reduced postural discomfort in a number of body parts. The

discomfort vote for the lower legs, the upper legs and the lower back all improved (i.e.

discomfort reduced) statistically significantly, when using a mat. The lower back and lower

legs showed the largest improvement.

No clear differentiation in the effects could be made for the individual mat types tested.

From the test results it can be concluded that the use of the mats has a beneficial effect

on the experienced thermal and postural comfort of the workers. Given the relative short

duration of the present 90 minutes test compared to a full working day, a larger benefit

can be expected for full working day exposures.


1 INTRODUCTION

By request of COBA Plastics Ltd of Fleckney, Leicestershire an experiment was

performed to test the effect of different types of floor matting on objective and subjective

measures related to thermal comfort and fatigue.

In many industrial situations, workers stand on hard floors, usually concrete. These floors

are highly thermally conductive and thus may lead to excessive cooling of the foot.

Placing an insulative mat on the concrete floor is expected to alleviate this problem. In

addition, several research studies have indicated that standing on, usually rubber, mats

may also reduce fatigue and general discomfort (relevant literature is listed at the end of

this report).

A problem when studying effects like these is that often these effects are subtle, and

difficult to demonstrate in small scale scientific studies. Hence, several of the studies listed

show seemingly conflicting results. One of the main reasons for this is that people’s

responses show a certain amount of variability day to day, even when doing exactly the

same thing, which may mask the effect of the matting. In addition, due to the cost of such

studies, it is not feasible to study a large number of people in long term exposures in the

laboratory. Such large studies are usually performed in the field, where conditions

(temperature etc) may not be constant, and thus also influence the results. The

advantage of laboratory studies is that conditions are reproduced exactly the same, day

by day, leaving only the variability within the people tested as a problem.

For the present project the goal was to study 8 different mats and to determine which

effect these have on the users in comparison to standing on concrete slabs. As a

compromise between precision, duration and cost it was decided to perform a study in the

laboratory ensuring identical conditions in all tests. Participants in the study performed

diverse light tasks while standing for 90 minutes either directly on the concrete slabs or

with a mat on the concrete. Objective data (temperatures of the foot, leg and body) were

obtained as well as participants perceptions of their (dis)comfort and fatigue. As part of

the work participants performed a number of reaction time tests. Partly this was added to

keep them occupied and avoid boredom, but these test also provided an additional

evaluation criterion.

2 METHODOLOGY 2.1 Experimental design

The aim of the study was to compare a number of thermal and subjective responses

whilst participants stood on different anti-fatigue mats for 90 minutes. The mats were split


into 2 groups (1-4 and 5-8, see tables 1 and 2 for labels). 14 participants took part in the

study (average age 20.4+3.8 years, height 170.6+9 cm, weight 64.9+14 kg, UK shoe size

7+2), visiting the lab for 5 sessions each at the same time of day. 7 participants stood on

mats 1-4 plus a control (concrete) with the other 7 participants standing on mats 5-8 plus

a control (concrete). The order in which participants stood on the different mats was

balanced to avoid order effects (e.g. if a certain mat would always be tested last,

differences observed may be caused by increasing boredom or other such factors

developing during the testing). The study took place in the environmental chamber at

Loughborough University, with average conditions during the testing periods of, room

temperature 15.8+0.2oC, floor temperature underneath the concrete slabs of 10.2+0.3oC

and relative humidity 43+1%.

2.2 Equipment

2.2.1 Mats

8 mats were tested; the details are included in Table 1 with photographs provided in Fig. 2.

Mats were placed on concrete slabs which in turn were placed on a temperature

controlled floor.

2.2.2 Clothing

Participants were all provided with the same test clothing (participants own underwear

worn under test clothing) to ensure equal conditions in all tests. The clothing is shown in

Fig. 1. • Cotton sweatshirt • Cotton overall • Cotton socks • Army boots


Fig. 1 Test clothing; Army boot and cotton socks, cotton overall and sweatshirt (worn under overall).

Table 1. Details of mats tested including labels used and product name.

Label Product Name Size Material Thickness Description

1 COBA Elite 0.6m x 0.9m polyurethane 15mm black bubble surface

2 Solid Fatigue

Step 0.9m x 0.9m natural rubber and nitrile compound 16mm large black rubber tile

3 Orthomat® 0.9m x 1.5m closed cell vinyl foam 9mm foam mat with ramped edges

4 Deckplate 0.9m x 1.5m pvc surface, foam base 14mm deckplate pattern pvc topped

foam mat

5 Cobamat 0.9m x 1m pvc 12mm interwoven strips of pvc

6 Rampmat 0.9m x 1.5m SBR Rubber 14mm raised circular surface

7 Bubble Mat 0.6m x 0.9m rubber 14mm black bubble surface

8 Fatigue Fighter

II® 0.6m x 0.9m pvc 12.5mm fused dual layer with pvc top


1 COBA elite

2. Solid fatigue step 3. Orthomat ®

4. Deckplate 5. Cobamat

6. Rampmat

7. Bubble mat

8. Fatigue fighter II ®

Fig. 2, Photographs of mats tested including labels used and product name.


2.3 Procedure

At the beginning of each session, before participants arrived, the chamber conditions

were checked and the data logger recording environmental data switched on. The correct

mats were laid out for each participant according to the order planned.

On arrival at the lab, participants entered a thermoneutral preparation room, their current

health status was checked and core temperature taken. Participants then removed all

their clothes except underwear. The 7 skin temperature sensors were attached and

connected to a data logger. The circumference of the calf was measured and four infrared

photos of the foot taken. Participants then dressed in the sweatshirt, overall, socks and

boots provided. Participants filled in the subjective (dis)comfort scales before entering the

chamber. On entering the chamber and taking their position on the concrete slab data

logging was started. Participants first completed two cognitive tests. They completed the

cognitive tests again after 75 minutes. Participants completed the subjective scales again

at 45 and 90 minutes. At the end of 90 minutes participants left the chamber and returned

to the prep room where after removing the test clothing infrared photographs were taken

and calf circumference and oral temperature noted.

For their subjective (dis)comfort assessment participants were asked to rate:

• Thermal Sensation (whole body and feet) • Thermal Comfort (whole body) • Fatigue / Tiredness (whole body) • Body Part Discomfort (in 13 body segments) • The sensation scales looked as follows: Table 2, thermal sensation scales

Thermal Sensation Scale 13 Hot 12 11 Warm 10 9 Slightly warm 8 7 Neutral 6 5 Slightly cool 4 3 Cool 2 1 Cold


Table 3, thermal comfort scale

Thermal Comfort 3 very comfortable 2 comfortable 1 slightly comfortable 0 neutral -1 slightly uncomfortable -2 uncomfortable -3 very uncomfortable

Table 4, fatigue and tiredness scale

Fatigue / Tiredness scale 5 extreme fatigue / tiredness 4 3 moderate fatigue / tiredness 2 slight fatigue / tiredness 1 0 no fatigue / tiredness

Table 5, body part discomfort scale

Body Part Discomfort 5 extreme discomfort 4 3 moderate discomfort 2 slight discomfort 1 0 no discomfort


This discomfort scale was scored for different body parts: Table 6, Body areas for which discomfort was scored.

feet ankles lower legs knees upper legs hips / bottom lower back mid back upper back shoulders neck arms hands Table 7, thermal sensation of feet.

Thermal Sensation OF YOUR FEET

13 Hot 12 11 Warm 10 9 Slightly warm 8 7 Neutral 6 5 Slightly cool 4 3 Cool 2 1 Cold

Full details on the methodology, including description of detailed data analysis and

statistical testing is provided in the appendix. Photographs of the experimental setup are

given in

Fig. 3


3 stations set up in chamber

Participants standing at stations


Station 3

Station 3

Station 3

Fig. 3 Photographs of experimental area and station set up.


3 RESULTS AND DISCUSSION

Detailed results for all measured variables and all mats are shown in the appendix in Table 8 and

Table 9. Statistically significant results (mat compared to no-mat) are highlighted.

As an illustration of the foot cooling observed, below two sets of infra red pictures of the sole and

upper part of the foot, showing the cooling of the toes and the sole area during the test.

Fig. 4, Infra-Red pictures of the sole of the foot before the test (top) and after the test (bottom), showing the

cooling of the toes and sole. The pictures are of a male participant’s foot.


Fig. 5, Infra-Red pictures of the foot before the test (top) and after the test (bottom), showing the cooling of the

foot. The pictures are of a female participant’s foot.

Do the mats have a beneficial effect?

The main question tested was whether the mats in general show a beneficial effect to the user.

For this purpose all individual data were analysed in relation to their individual control value (i.e.

standing directly on the concrete tiles), and the differences analysed to see whether the results of

the mats overall was different from those for the concrete slab only. None of the cognitive tests or

the body and skin temperatures showed a statistically significant difference, most likely due to the

high variation present within the results for each person (i.e. the day to day variability typical


observed in people). However when the subjective perceptions (‘what the person experiences’)

were analysed, a number of effects were visible:

Firstly the thermal comfort vote for the whole body (Fig. 6) as expected became lower in the

duration of the test. Also it showed significantly less discomfort at the end of the period when

standing on the mats compared to the concrete. Votes moved from slightly uncomfortable towards

neutral; in that case for the no-mat to the mat condition.

Thermal Comfort

-1.5-1.0-0.50.00.51.01.5

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 6, comparison of the thermal comfort vote for the whole body at the end of the test between the condition

without and with the mat. More negative values indicate more discomfort. The difference at the end of the test is statistically significant.

.

This improved whole body thermal comfort was accompanied by a reduced postural discomfort in

a number of body parts when using the mats compared to the no-mat condition. Discomfort

always increased during the test. Comparing the final values, the discomfort vote for the lower

legs (Fig. 7), the upper legs (Fig. 8) and the lower back (Fig. 9) all improved (i.e. discomfort

reduced) significantly, when using a mat. The lower back and lower legs showed the largest

improvement.


Lower Leg Discomfort

0.00.10.20.30.40.50.60.7

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 7, comparison of the discomfort vote for the lower legs at the end of the test between the condition without

and with the mat. Higher values indicate more discomfort. The difference at the end of the test is statistically significant.

Upper Leg Discomfort

0.000.050.100.150.200.250.300.350.40

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 8, comparison of the discomfort vote for the upper legs at the end of the test between the condition without

and with the mat. Higher values indicate more discomfort. The difference at the end of the test is statistically significant.


Lower Back Discomfort

0.0

0.5

1.0

1.5

2.0

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 9, comparison of the discomfort vote for the lower back during the test between the condition without and

with the mat. Higher values indicate more discomfort. The difference at the end of the test is statistically significant.

From the subjective results it can be concluded that the use of the mats has a beneficial effect on

the experienced thermal and postural comfort of the workers. Given the relative short duration of

the present test compared to a full working day, and the increasing difference between the mat

and no-mat condition over time, a larger benefit can be expected for full working day exposures.

This is visible in the graphs by the widening difference between the mat and no-mat condition over

time.

Though the other data did not show a significant difference between mat and no-mat, some

figures are presented below to show the different development of these data over time, illustrating

the cooling response. Thermal sensation (overall and for the feet) reduced over time in both

conditions showing the cooling effect. Also fatigue increased over the test duration, as may be

expected. Trends are visible towards an improvement caused by the mat; however these

differences were not statistically significant.


Thermal Sensation

0.0

2.0

4.0

6.0

8.0

10.0

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 10, comparison of the thermal sensation vote for the whole body during the test between the condition

without and with the mat. Lower values indicate cooling.

Fatigue

0.0

0.5

1.0

1.5

2.0

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 11, comparison of the fatigue vote for the whole body during the test between the condition without and

with the mat. Higher values indicate more fatigue.


Feet temperature sensation

0.01.02.03.04.05.06.07.08.0

0.0 45.0 90.0Time (min)

Rat

ing

concretemat

Fig. 12, comparison of the thermal sensation vote for the foot during the test between the condition without and

with the mat. Lower values indicate colder feet.

A discussion of the individual mat results is provided in the appendix. The overall summary of

these individual results is that due to the small number of test participants and the variability within

the participants, the differences between mats (as opposed to the difference between mat and no

mat presented earlier) was not statistically different.

4. CONCLUSION

The overall conclusion that can be drawn from the present study of 8 COBA floor mats is that

improvements in whole body thermal comfort and in the postural comfort of the lower, and upper

legs, and of the lower back are observed with statistical significance after a 90 minute exposure.

Due to large variability in skin temperatures, no significant differences are observed there for this

exposure duration. For the same reason it is difficult to discriminate between the different mat

types studied.

It is reasonable to expect differences between the mat and no-mat condition to become larger

when the workers are exposed longer than the 90 minutes studied here, as increases in the

differences are observed over time.

Appendix 1– Overview of all data

Table 8, Results summary for individual mats, and for the overall mat-effect. All values expressed as differences from control value (mat – control). Positive values imply higher values for the mats than for the control, negative values imply lower values for the mats than for the control.

mat 1 2 3 4 5 6 7 8 mean

all mats

SD all

mats

start values

Stroop % correct 1.8 ± 2.0 0.2 ± 2.4 1.4 ± 2.6 1.2 ± 3.0 1.2 ± 3.8 0.6 ± 3.1 0.2 ± 3.7 0.7 ± 3.9 0.9 ± 0.6

Stroop reaction

time 44.5 ± 114.5 51.4 ± 100.7 60.7 ± 164.4 37.7 ± 99.8 -150.6 ± 223.9 -184.9 ± 256.7 -185.2 ± 287.5 -89.8 ± 319.5 -52.0 ± 111.7

Stroop SD RT 11.9 ± 123.4 -2.1 ± 118.3 1.5 ± 114.8 -31.7 ± 92.6 -305.6 ± 701.5 -342.3 ± 695.9 -314.7 ± 726.5 -276.4 ± 721.2 -157.4 ± 164.3

mental rotation %

correct -2.6 ± 11.1 1.7 ± 5.7 0.6 ± 5.5 -1.1 ± 6.0 0.9 ± 6.0 1.7 ± 6.9 -1.7 ± 13.6 0.9 ± 6.8 0.0 ± 1.6

Mental rotation reaction

time

-45.2 ± 1154.8 -64.4 ± 1110.0 89.0 ± 1257.1 28.5 ± 761.1 -474.2 ± 1577.2 -434.0 ± 1918.5 -819.6 ± 2080.9 -193.4 ± 1977.1 -239.2 ± 311.6

mental rotation SD

RT 12.2 ± 1047.1 -146.5 ± 842.4 101.5 ± 1192.0 54.2 ± 802.6 -466.8 ± 1457.0 -200.3 ± 1991.8 -447.3 ± 2206.5 -151.9 ± 2150.3 -155.6 ± 214.6

final values

Stroop % correct 0.0 ± 7.2 2.7 ± 4.5 -0.2 ± 7.8 0.0 ± 7.5 -1.9 ± 2.9 0.0 ± 1.2 -1.6 ± 3.0 -1.3 ± 3.8 -0.3 ± 1.4

Stroop reaction

time

-30.4 ± 169.5 -28.5 ± 79.6 10.6 ± 200.7 -11.2 ± 183.4 5.2 ± 126.1 14.9 ± 80.3 -6.9 ± 73.1 -2.2 ± 98.4 -6.1 ± 16.8

Stroop SD RT 12.8 ± 95.9 30.9 ± 161.9 111.7 ± 134.6 50.1 ± 96.3 51.8 ± 149.0 -1.8 ± 67.7 -23.0 ± 45.6 -25.9 ± 61.6 25.8 ± 45.8

mental rotation %

correct 0.0 ± 13.3 0.0 ± 8.3 -1.1 ± 11.2 4.0 ± 8.7 1.1 ± 7.2 3.7 ± 11.5 0.9 ± 7.2 -2.9 ± 9.6 0.7 ± 2.3


mat 1 2 3 4 5 6 7 8 mean

all mats

SD all

mats

Mental rotation reaction

time

50.7 ± 938.8 -56.2 ± 624.1 50.9 ± 529.3 130.9 ± 448.5 -253.8 ± 1548.2 -155.0 ± 1695.6 -439.6 ± 1991.4 -234.0 ± 1902.3 -113.3 ± 192.4

mental rotation SD

RT 14.9 ± 1076.2 -180.6 ± 557.6 -25.9 ± 361.9 40.2 ± 325.3 -554.0 ± 1810.9 -285.8 ± 1969.1 -501.5 ± 2384.7 -282.7 ± 2405.5 -221.9 ± 227.1

Tsk toe -0.9 ± 2.9 -1.6 ± 3.1 -1.1 ± 3.9 0.5 ± 2.4 -0.5 ± 1.9 -0.2 ± 4.9 0.4 ± 3.7 0.7 ± 4.2 -0.3 ± 0.8 Tsk foot -0.2 ± 1.1 -0.6 ± 2.1 -0.5 ± 1.8 0.0 ± 1.9 -0.1 ± 1.4 0.0 ± 1.9 0.5 ± 1.4 0.8 ± 1.5 0.0 ± 0.5 Tsk shin 0.1 ± 1.1 -0.2 ± 1.2 0.0 ± 0.7 0.2 ± 1.1 0.4 ± 1.7 0.0 ± 1.3 -3.6 ± 11.4 -0.3 ± 1.5 -0.4 ± 1.3 Tsk thigh 0.0 ± 0.3 -0.4 ± 0.5 -0.3 ± 0.5 0.1 ± 0.4 0.0 ± 1.6 0.2 ± 1.5 -0.6 ± 1.6 -0.2 ± 1.5 -0.2 ± 0.3 Tsk chest 0.0 ± 0.7 -0.1 ± 1.3 -0.3 ± 0.7 -0.1 ± 0.7 0.6 ± 0.4 -0.7 ± 3.1 0.4 ± 0.7 -0.1 ± 0.9 0.0 ± 0.4 Tsk hand 0.3 ± 2.5 -0.4 ± 1.9 -1.0 ± 1.1 0.1 ± 1.2 0.5 ± 2.1 -0.7 ± 2.0 0.3 ± 1.0 0.0 ± 1.1 -0.1 ± 0.5 Tsk arm -0.3 ± 1.2 0.3 ± 0.9 -0.2 ± 1.0 0.4 ± 1.3 0.4 ± 1.0 0.2 ± 1.2 0.3 ± 0.9 0.9 ± 0.7 0.3 ± 0.4

start values

IR temperature

foot1 -1.7 ± 3.0 -1.7 ± 3.1 -2.3 ± 3.8 -0.9 ± 3.4 0.6 ± 5.1 0.0 ± 3.3 2.0 ± 4.1 0.7 ± 2.7 -0.4 ± 1.5

IR temperature

foot2 -0.4 ± 1.4 -0.7 ± 1.3 -0.6 ± 1.8 -0.1 ± 1.3 0.1 ± 1.8 0.1 ± 2.0 0.0 ± 2.3 0.3 ± 1.4 -0.2 ± 0.4

IR temperature

sole 1 -0.7 ± 1.7 -0.6 ± 2.0 -0.4 ± 1.5 0.3 ± 1.2 -0.5 ± 2.6 -0.9 ± 2.9 1.0 ± 2.6 1.6 ± 1.8 0.0 ± 0.9

IR temperature

sole 2 -2.1 ± 1.7 -0.9 ± 1.7 -0.9 ± 1.2 -1.0 ± 0.8 -1.1 ± 1.1 -0.9 ± 3.2 1.1 ± 3.3 0.2 ± 3.0 -0.7 ± 0.9

final values


mat 1 2 3 4 5 6 7 8 mean

all mats

SD all

mats

IR temperature

foot1 -0.3 ± 2.1 -0.4 ± 2.9 -0.4 ± 3.7 0.6 ± 3.1 -0.7 ± 1.9 -0.5 ± 3.5 0.6 ± 2.0 -0.5 ± 1.8 -0.2 ± 0.5

IR temperature

foot2 -0.4 ± 1.9 -0.7 ± 2.4 -0.8 ± 3.0 0.2 ± 1.8 -0.5 ± 1.2 -0.1 ± 1.8 0.0 ± 1.0 -0.3 ± 0.8 -0.3 ± 0.3

IR temperature

sole 1 -0.7 ± 1.8 -0.7 ± 2.6 -0.8 ± 2.6 -0.1 ± 1.7 0.2 ± 1.5 -0.2 ± 2.6 0.0 ± 1.5 0.3 ± 1.3 -0.2 ± 0.4

IR temperature

sole 2 -0.6 ± 1.8 0.3 ± 1.6 -0.5 ± 1.4 0.1 ± 1.1 -0.3 ± 0.8 0.9 ± 2.3 0.8 ± 0.9 0.6 ± 2.0 0.1 ± 0.6


Table 9, Results summary for individual mats, and for the overall mat-effect. All values expressed as differences from control value (mat – control). Positive values imply higher values for the mats than for the control, negative values imply lower values for the mats than for the control.

Mat 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Average all

Mats mean ± SD mean ± SD mean ± SD mean ± SD mean ± SD mean ± SD mean ± SD mean ± SD mean ± SD oral temperature -0.10 ± 0.40 -0.20 ± 0.31 -0.11 ± 0.26 -0.01 ± 0.51 -0.04 ± 0.53 -0.04 ± 0.53 -0.14 ± 0.43 0.04 ± 0.33 -0.08 ± 0.08

calf circumference -0.1 ± 0.8 0.3 ± 0.4 0.1 ± 0.4 -0.2 ± 0.5 0.5 ± 0.4 0.4 ± 0.4 0.6 ± 0.4 0.3 ± 0.3 0.2 ± 0.3

thermal sensation whole body

-0.1 ± 2.1 0.0 ± 1.3 -0.4 ± 1.3 -0.6 ± 1.0 1.1 ± 1.6 2.1 ± 3.0 2.7 ± 3.3 0.9 ± 1.3 0.7 ± 1.2

thermal comfort whole body

0.4 ± 1.3 0.3 ± 1.6 -0.1 ± 1.1 0.0 ± 1.3 1.4 ± 1.6 1.1 ± 1.5 1.3 ± 1.6 0.6 ± 1.0 0.6 ± 0.6

fatigue -0.9 ± 1.1 -0.7 ± 0.8 -0.6 ± 1.3 -0.3 ± 0.8 0.0 ± 1.7 0.1 ± 1.6 -0.1 ± 1.2 0.6 ± 1.7 -0.2 ± 0.5 Discomfort sensation: feet 0.1 ± 0.4 0.4 ± 1.1 0.4 ± 0.8 -0.1 ± 0.4 -1.3 ± 1.1 -0.4 ± 1.1 -0.7 ± 1.1 -0.4 ± 1.6 -0.3 ± 0.6 ankles -0.1 ± 0.7 -0.3 ± 0.5 -0.1 ± 0.4 -0.3 ± 0.5 -0.6 ± 1.0 -0.4 ± 1.1 -0.1 ± 0.9 -0.4 ± 1.1 -0.3 ± 0.2 lower legs -0.6 ± 0.5 -0.7 ± 0.8 -0.4 ± 0.5 -0.6 ± 0.5 -0.6 ± 1.0 -0.6 ± 1.0 -0.3 ± 1.4 -0.4 ± 1.1 -0.5 ± 0.1 knees -0.3 ± 0.8 -0.3 ± 0.8 -0.1 ± 0.4 -0.1 ± 0.4 -0.4 ± 0.8 -0.1 ± 0.9 -0.1 ± 0.9 -0.1 ± 0.9 -0.2 ± 0.1 upper legs -0.6 ± 0.5 -0.6 ± 0.5 -0.4 ± 0.5 -0.6 ± 0.5 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 -0.3 ± 0.3 hips -0.3 ± 0.8 -0.4 ± 1.1 -0.1 ± 0.4 -0.3 ± 0.8 -0.3 ± 0.8 -0.3 ± 0.8 -0.3 ± 0.8 -0.3 ± 0.8 -0.3 ± 0.1 lower back 0.0 ± 1.3 -0.3 ± 1.3 -0.3 ± 0.8 -0.4 ± 1.0 -0.7 ± 1.6 -0.9 ± 1.2 -1.4 ± 1.1 -1.1 ± 1.9 -0.6 ± 0.5 mid back -0.1 ± 1.2 0.0 ± 1.0 0.0 ± 0.8 0.1 ± 1.1 0.1 ± 0.4 -0.1 ± 0.4 -0.3 ± 0.8 0.0 ± 0.0 0.0 ± 0.1 upper back -0.6 ± 1.0 -0.4 ± 1.1 -0.4 ± 0.8 0.0 ± 0.8 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.1 ± 0.4 -0.2 ± 0.3 shoulders -0.6 ± 1.0 -0.3 ± 1.4 -0.1 ± 1.1 -0.4 ± 0.8 -0.3 ± 0.8 0.1 ± 0.4 -0.3 ± 0.8 -0.1 ± 0.9 -0.3 ± 0.2 neck -0.6 ± 1.1 -0.6 ± 1.0 -0.4 ± 1.0 -0.4 ± 0.5 -0.3 ± 0.8 0.1 ± 0.4 -0.1 ± 0.9 0.1 ± 1.2 -0.3 ± 0.3 arm -0.1 ± 0.4 -0.1 ± 0.4 -0.1 ± 0.4 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 -0.1 ± 0.1 hands -0.6 ± 1.1 -0.3 ± 1.0 0.0 ± 0.6 0.0 ± 0.6 -0.4 ± 1.1 -0.7 ± 1.6 -0.9 ± 1.5 -0.9 ± 1.5 -0.5 ± 0.3 feet thermal sensation -0.1 ± 2.1 -0.1 ± 0.7 -0.7 ± 0.8 -0.9 ± 2.0 2.4 ± 2.6 2.1 ± 3.8 2.1 ± 5.3 1.4 ± 4.1 0.8 ± 1.4

Appendix 3 Literature 22 of 39

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Hansen, L., Winkel, J. & Jorgensen, K., 1998, Significance of mat and shoe softness during

prolonged work in upright position: based on measurements of low back muscle EMG,

foot volume changes and ground force reactions. Applied Ergonomics 29 (3), 217-224.

Hinnen, P. & Konz, S., 1994, Fatigue mats. Advances in Industrial Ergonomics & Safety VI, Taylor

& Francis, London, pp 323-327.

Kendrick J., 1997, "The pains of standing", Occupational Health and Safety, April 1997, pages 54

to 76.

Kim, J.Y., 1999, Industrial mats. In: The Occupational Ergonomics Handbook, (eds). Karwowski,

W. & Marras, W.S., CRC Press, pp877-882.

Kim, J.Y., Stuart-Buttle, C. & Marras, W.S., 1994, The effects of mats on back and leg fatigue.

applied Ergonomics, 25 (1), 29-34.

King, P.M., 2002, A comparison of the effects of floor mats and shoe in-soles on standing, Applied

Ergonomics, 33, 477-484.

Konz, S., Bandla, V., Rys, M. & Sambasivan, J., 1990, Standing on concrete vs. floor mats.

Advances in Industrial Ergonomics & Safety II, Taylor & Francis, London, pp 991-998.

Kuorinka, I., Hakkanen, S., Nieminen, K. & Saari, J., 1978, Comparison of floor surfaces for

standing work. Biomechanics VI-B, 207-211.

Orlando, N. & King, P.M., 2004, Relationship of demographic variables on perception of fatigue

and discomfort following prolonged standing under various flooring conditions. Journal of

Occupational Rehabilitation, 22:13, 63-76.

Redfern, M.S. & Chaffin, D.B., 1988, The effect of floor types on standing tolerance in industry.

Trends in Ergonomics/Human Factors V, (ed). Aghazadeh, F., Elsevier Science Pub.

Appendix 2 Literature 23 of 39

Ryan, G.A.,1989, The prevalence of musculoskeletal symptoms in supermarket workers.

Ergonomics 32, 359-371.

Rys, M.J. & Konz, S., 1989, Standing with one foot forward. Advances in Industrial Ergonomics

and Safety, ed. Mital, A., Taylor & Francis, London.

Winkel, J.,1981, Swelling of the lower leg in sedentary work - pilot study. journal of Human

Ergology, 10, 139-149.

Zander, J. & King, P. M., 2004, Influences of flooring conditions on lower leg volume following

prolonged standing. International Journal of Industrial Ergonomics , 34, 279-288.

Zhang, L., Drury, C.G. & Woollet, S.M., 1991, Constrained standing: evaluation of the foot/floor

interface. Ergonomics, 34, 175-192.

Appendix 3 Methodology 24 of 39

FULL METHODOLOGY 1 Experimental design

The aim of the study was to compare a number of thermal and subjective responses whilst

participants stood on different anti-fatigue mats for 90 minutes. The mats were split into 2 groups

(1-4 and 5-8, see tables 1 and 2 for labels). 14 participants took part in the study (average age

20.4+3.8 years, height 170.6+9 cm, weight 64.9+14 kg, UK shoe size 7+2), visiting the lab for 5

sessions each at the same time of day. 7 participants stood on mats 1-4 plus a control (concrete)

with the other 7 participants standing on mats 5-8 plus a control (concrete). The order in which

participants stood on the different mats was balanced to avoid order effects (e.g. if a certain mat

would always be tested last, differences observed may be caused by increasing boredom or other

such factors developing during the testing). A Latin square design (a scientific method to

determine the order of the different tests) was used to balance the order of the mats. The study

took place in the environmental chamber at Loughborough University, with average conditions

during the testing periods of, room temperature 15.8+0.2oC, floor temperature underneath the

concrete slabs of 10.2+0.3oC and relative humidity 43+1%.

2 Equipment

2.1 Mats

8 mats were tested, the details are included in Table 1 with photographs provided in Table 2. Mats

were placed on concrete slabs which in turn were placed on a temperature controlled floor.

2.2 Clothing

Participants were all provided with the same test clothing (participants own underwear worn under

test clothing) to ensure equal conditions in all tests. The clothing is shown in Fig. 1.

• Cotton sweatshirt • Cotton overall • Cotton socks • Army boots


Fig. 13 Test clothing; Army boot and cotton socks, cotton overall and sweatshirt (worn under overall).

Table 10. Details of mats tested including labels used and product name.

Label Product Name Size Material Thickness Description

1 COBA Elite 0.6m x 0.9m polyurethane 15mm black bubble surface

2 Solid Fatigue

Step 0.9m x 0.9m natural rubber and nitrile compound 16mm large black rubber tile

3 Orthomat® 0.9m x 1.5m closed cell vinyl foam 9mm foam mat with ramped edges

4 Deckplate 0.9m x 1.5m pvc surface, foam base 14mm deckplate pattern pvc topped

foam mat

5 Cobamat 0.9m x 1m pvc 12mm interwoven strips of pvc

6 Rampmat 0.9m x 1.5m SBR Rubber 14mm raised circular surface

7 Bubble Mat 0.6m x 0.9m rubber 14mm black bubble surface

8 Fatigue Fighter

II® 0.6m x 0.9m pvc 12.5mm fused dual layer with pvc top


Table 11. Photographs of mats tested including labels used and product name.

1 COBA elite

2. Solid fatigue step

3. Orthomat ®

4. Deckplate

5. Cobamat

6. Rampmat


7. Bubble mat

8. Fatigue fighter II ®

3 Objective measures and data acquisition

3.1 Environmental conditions

Room temperature and relative humidity were recorded with a temperature and humidity probe,

as shown in Fig. 14, which was placed in the chamber, floor temperature (below the concrete

slabs) was measured with a thermistor taped to the floor. All sensors were connected to a Grant

data logger, recording at 5 minute intervals. After each session the data stored on the ‘squirrel’

data logger was downloaded into an Excel file.

Fig. 14 Photograph of temperature and humidity probe connected to data logger.

3.2 Calf circumference

This was measured with a standard tape measure before and after exposure in the chamber. A

note of the measurement was made on the data sheet.


3.3 Cognitive tests

Two cognitive tests were completed on a laptop computer in the chamber when participants first

entered the chamber and after 75 minutes of the 90 minute exposure. Tests were part of the

Hogervorst-Bandelow Cognitive Test Battery (HBC test). Tests chosen were:

The Stroop test

The Mental Rotation test

Both tests provided measures of accuracy and reaction times, as well as variations in reaction

times.

The results of the tests were logged on the laptops and downloaded at the end of each session to

a PC.

The test battery used was produced by Dr. S Bandelow and Prof. E. Hogervorst, Loughborough

University.

Computerized Stroop test: The computer screen shows the following instructions:

For test 1: "Quickly choose the word that matches the word on centre screen, like in the example

below. Use the arrow keys to select between the two choices on either side of the large word in

the centre. We will begin with 5 practice runs. Press any key to begin."

For test 2: "Quickly choose the colour in which the word on centre screen is written, rather than

the colour that the word names. Most people find this level the hardest. You probably will take

more time for each word, and may frequently make the mistake of saying the word itself, rather

than naming the colour in which the word appears. Use the arrow keys to select between the two

choices on either side of the large word in the centre. We will begin with 5 practice runs. Press any

key to begin."

This test measures the sensitivity to interference (median RT interference — median RT reading

colours) and the ability to suppress an automated response (time needed to read the words rather

than the time it takes to name the colour of the letters). The capacity to inhibit or suppress an

automated response requires intact executive (frontal lobe) functions. Errors are also recorded for

speed-accuracy trade-offs (often occur in younger participants).

The first test has 15 stimuli (reading colours), the second (with interference) has 40 stimuli. The

Stroop Colour- Word Test is very sensitive to the effects of aging and AD and to a wide variety of

interventions such as exercise, caffeine, HRT etc. (Hogervorst, 1998, see pubmed for many

references).

References:

Stroop JR. The Stroop Test J Exp Psychol; 1935, 18:643-662


Mental rotations test: The computerized mental rotation test is based on the paper and pencil version (Shepherd &

Melzer, 1971). Participants are shown three stimuli consisting of blocks which form complicated

three-dimensional figures. The instruction is to look at the centre top figure and match this to the

correct stimulus on the right or left side below it by using the arrow keys. The rotation angle for

stimuli (target and distractor) varies at random. This test measures the ability to perform mental

rotations and, in general, men tend to outperform women on this task. The test is very sensitive to

fluctuations in hormone levels (see below).

Response times, percentage correct and angle of the stimulus (to be entered as a covariate) are

automatically recorded. Stimuli are completely counterbalanced using 5 angles (0, 20, 40, 60 and

80 degrees) and the correct target is presented alternating on the left or right side of the computer

screen below the stimulus (with 5 targets either side). There are thus 50 stimuli in total and

stimulus presentation is indefinite (no time-limit for response but parameters can be altered). The

order of the stimuli is randomized but a tap is put on a maximum of 4 targets appearing in order on

a given side to avoid response bias. There are 5 learning trials with feed-back.

Parameters collected are response time (in msec), correct/incorrect

Test references: Shepherd RN & Melzer J (1971) Mental Rotation Test of three dimensional

objec6ts. Science 1717: 701-703. Vandenberg SG & Kuse A (1978) Mental rotations, a group test

of three-dimensional spatial visualization. Perceptual and Motor Skills, 47, 599-604.

3.4 Body temperature

Body temperature was measured with a sublingual thermometer before and after exposure in the

chamber. The core temperature was recorded on the data sheet.

3.5 Skin temperature

Skin temperature was measured at 7 sites; toe, foot, shin, thigh, chest, lower arm, hand with

thermistors taped to the skin as shown in Fig. 15. All sensors were connected to a Grant data

logger recording at 1 minute intervals. After each session the data was downloaded into an Excel

file.

3.6 Infrared images

Four photos were taken before and after exposure in the chamber, of the front of the lower legs,

back of the lower legs, top of the feet, sole of the right foot, as shown in Fig. 16. A note was made

of the photograph numbers on the data sheet. At the end of each session the infrared

photographs were downloaded from the camera and identified and labelled.


front of the lower legs

back of the lower legs

top of the feet

sole of the right foot Fig. 16 Illustration of 4 infrared photos taken before and after exposure in the chamber.

Fig. 15 Illustration of 7 skin thermistor sites. Lower body; toe, foot, shin, thigh and upper body; chest, lower arm

and hand.


4 Subjective measures and data acquisition

Participants were asked to rate a number of subjective measures using scales provided, they did

this before exposure, after 45 minutes exposure and after 90 minutes (just before leaving the

chamber). A copy of the rating scales is provided in, Table 13, Table 14, Table 15, Table 16, and

Table 17

They were asked to rate:

• Thermal Sensation (whole body and feet) • Thermal Comfort (whole body) • Fatigue / Tiredness (whole body) • Body Part Discomfort (in 13 body segments)

All scales used are shown below: Table 12, thermal sensation scales

Thermal Sensation Scale


Table 13, thermal comfort scale

Thermal Comfort

3 very comfortable 2 comfortable 1 slightly comfortable 0 neutral -1 slightly uncomfortable -2 uncomfortable -3 very uncomfortable


Table 14, fatigue and tiredness scale

Fatigue / Tiredness scale 5 extreme fatigue / tiredness 4 3 moderate fatigue / tiredness 2 slight fatigue / tiredness 1 0 no fatigue / tiredness

Table 15, body part discomfort scale

Body Part Discomfort 5 extreme discomfort 4 3 moderate discomfort 2 slight discomfort 1 0 no discomfort

This discomfort scale was scored for different body parts: Table 16, Body areas for which discomfort was scored.

feet ankles lower legs knees upper legs hips / bottom lower back mid back upper back shoulders neck arms hands


Table 17, thermal sensation of feet.

Thermal Sensation OF YOUR FEET


5 Experimental area

The chamber was set up to accommodate 3 participants at a time, concrete slabs were laid on the

floor of the chamber where participants would be standing, with the mats placed on top. Each

station had a table, laptop on which to do the cognitive tests and a box on which to rest. During

their time in the chamber participants were allowed to play computer games, work on the laptops

or read whilst remaining at their station. The stations were labelled 1, 2 and 3. Participants always

stood at the same platform, on the same section of concrete with the same laptop for all of their 5

sessions. Photographs of the experimental area and station set up are provided in Fig. 17.


3 stations set up in chamber



Station 3

Station 3

Station 3

Fig. 17 Photographs of experimental area and station set up. 6 Safety

When participants attended the laboratory on the first occasion, the details of the study were fully

explained to them and they were shown the chamber, questionnaires, thermistors etc. They were

given a chance to ask questions before completing an informed consent form and generic Health

Screen questionnaire, which included additional questions regarding previous history of fainting,

circulatory problems and cold injuries. Participants were informed of their right to withdraw at any

time without having to provide a reason.


7 Procedure

At the beginning of each session, before participants arrived, the chamber conditions were

checked and the ‘squirrel’ recording environmental data switched on. The correct mats were laid

out for each participant according to the order planned.

On arrival at the lab, participants entered a thermoneutral preparation room, their current health

status was checked and core temperature taken. Participants then removed all their clothes

except underwear. The 7 skin thermistors were attached with medical tape and connected to a

‘squirrel’ data logger. The circumference of the calf was measured and the four infrared photos of

the foot taken. Participants then dressed in the sweatshirt, overall, socks and boots provided.

Participants filled in the subjective scales before entering the chamber. On entering the chamber

the squirrel was set to start logging, a timer was started for the participant and they took their

place at their designated station. Participants first completed the cognitive tests on the laptop,

always completing the Stroop test first followed by the Mental Rotation task. They completed the

cognitive tests again after 75 minutes. Participants completed the subjective scales again at 45

and 90 minutes. At the end of 90 minutes participants left the chamber and returned to the prep

room where after removing the test clothing infrared photographs were taken and calf

circumference and oral temperature noted.

Three participants were completed per session with their start and end times staggered as shown

in Table 18.

8 Data analysis Core temperature, calf circumference and thermal sensation, thermal comfort, fatigue / tiredness,

body discomfort votes were entered into an excel spreadsheet.

Percentage correct and average reaction times were calculated for each of the cognitive tests

excel files.

5 minute averages of the skin temperatures at all sites were calculated for the last 5 minutes of

exposure (in chamber). The infrared photographs were analysed individually using Flir software

for 2 sites on the top of the foot (on the inside of the big toe and middle of foot) and 2 sites on the

sole of the foot (ball of foot behind big toe and at the heel).

Data were analysed statistically using analysis of variance with post-hoc tests, paired t-tests and

for non-parametric data Wilcoxon tests; significance levels of p<0.05 were accepted (this means


that where an effect is identified as statistically significant, the probability that this effect could have

been found by chance is less than 1 in 20).

Overall matt effects were determined on the differences between matt and concrete data for each

individual person. This was analysed by a single sample t-test to see whether there was a

difference present. Degrees of freedom in the test were corrected to represent to actual number of

independent data points (14), thus providing a conservative estimate. Table 18. Timings and order of events for one session for 3 participants.

Clock time

Chamber time Participant 1



0900 arrives / core temp / calf

circumference

0915 thermistors / photos /

questionnaires /

0930 0 enters chamber / cognitive tests arrives / core temp /

calf circumference

0945 15 thermistors / photos /

questionnaires /

1000 30 0 enters chamber /

cognitive tests arrives / core temp / calf circumference

1015 45 questionnaires 15 thermistors / photos /

questionnaires /

1030 60 30 0 enters chamber /

cognitive tests

1045 75 cognitive tests 45 questionnaires 15

1100 90 questionnaires / leaves

chamber 60 30

1115

core temp / calf circumference / photos

/ remove sensors 75 cognitive tests 45 questionnaires

1130 90 questionnaires /

leaves chamber 60

1145

core temp / calf circumference / photos / remove

sensors 75 cognitive tests

1200 90 questionnaires / leaves

chamber

core temp / calf circumference / photos

/ remove sensors

Appendix 3 Analysis of Individual Mats 37 of 39

Can individual mats be discriminated in terms of the benefit they provide?

From the start of this project it was clear that it may be difficult to show the benefit of individual

mats compared to each other, due to the day to day variability in the participants’ responses, the

limited duration of the test (90 minutes rather than a full working day) and the subtle differences

between some of the mats.

The results indeed show no statistically significance in the differences between the mats. Though

it can be said that the tested mats have a beneficial effect in general, no conclusion can be drawn

which of the mats is better than the other. Analysing the results indicates that this would have

required an experiment with at least the double number of participants to achieve sufficient

statistical power, or one may expect differences to be shown more clearly with testing longer, as

e.g. a full working day. As the latter would have extended the duration and cost of the testing at

least fourfold, this was deemed unrealistic from the start.

For those subjective votes given by the participants where there was a mat effect, the results per

mat are presented below in Fig. 18, Fig. 19, Fig. 20, and Fig. 21. In some of these figures one can

see a clear difference between mats 1-4 and 5-9. It should be noted that mats 1-4 were tested

with 7 different participants from the 7 participants using mats 5-8. This difference illustrates the

problems of getting statistical significance with limited test group sizes. Nevertheless do these

figures illustrate the benefits of the mats.

Change in Thermal Comfort Vote Relative to Control

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1 2 3 4 5 6 7 8

Mat Code

Vote

Fig. 18 comparison of the thermal comfort vote for the whole body at the end of the test between the condition

without and with the individual mats. The error bar show the standard deviation in the results, which is an indication of the variation in the data observed. Higher values indicate less discomfort with the mat. Zero indicates no difference observed.


Change in Discomfort Vote Lower Legs Relative to Control

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

1 2 3 4 5 6 7 8

Mat Code

Vote

Cha

nge

Fig. 19, comparison of the discomfort vote for the lower legs at the end of the test between the condition without

and with the mat. The error bar show the standard deviation in the results, which is an indication of the variation in the data observed. More negative values indicate less discomfort with the mat.

Change in Discomfort Vote Upper Legs Relative to Control

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

1 2 3 4 5 6 7 8

Mat Code

Vot

e Ch

ange

Fig. 20, comparison of the discomfort vote for the upper legs at the end of the test between the condition

without and with the mat. The error bar show the standard deviation in the results, which is an indication of the variation in the data observed. More negative values indicate less discomfort with the mat. For mat 5, 6, 7, and 8 no differences were observed.


Change in Discomfort Vote Lower Back Relative to Control

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

1 2 3 4 5 6 7 8

Mat Code

Vote

Cha

nge

Fig. 21 comparison of the discomfort vote for the lower back at the end of the test between the condition without

and with the mat. The error bar show the standard deviation in the results, which is an indication of the variation in the data observed. More negative values indicate less discomfort with the mat.

When individual mats are tested statistically in relation to the ‘no-mat’ condition, the following

differences are significant:

For the fatigue score, mat 2 is significantly better than no-mat. (this effect was not significant

when tested over all mats due to the variation in responses).

For postural discomfort: mat 5 reduces feet discomfort; mat 1, 2 and 4 lower leg discomfort

and upper leg discomfort; mat 7 reduces lower back discomfort, all compared to the no-mat

condition.

This should not be interpreted that these mats are better than the others, as the mats did not differ

significantly amongst themselves. It only indicates that tested on its own, these mats differed from

the no-mat condition.

__________

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