Richard Wells 1,2

(1) Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada(2) Centre of Research Expertise for the Prevention of Musculoskeletal Disorders

(CRE-MSD)

1. Understand the characteristics of gloves that increase fatigue and decrease prehensile performance

2. Apply these ideas to evaluate anti-vibration gloves

3. Apply these ideas to evaluate surgical gloves

Glove is stiff Glove reduces tactility Glove changes effective size of hand

BUT how to determine which of these factors is important The approach is to separate out these factors using multiple measures

Independent variable: hand coveringGloves – specific glove used by power line maintainers made of the same material and shape and available in different sizes which only differed in thicknessInterdigital spacers – to mimic the spacing between fingers caused by the glove thickness between the digits

Grip Force – grip dynamometer Tactile Sensitivity – Von Frey hair

test Perceived Exertion – self report

exertion on a 100-point rating scale Surface EMG of seven forearm

muscles. flexor digitorum superficialis(FDS) flexor pollicis longus (FPL) flexor carpi radialis (FCR) flexor carpi ulnaris (FCU) extensor carpi radialis (ECR(B)) extensor carpi ulnaris (ECU) extensor digitorum (ED)

Protocol/Participants10 male and 10 female university students who were free of upper extremity injury or painOrder randomized to control for any fatigue or learning effects

Maximum Effort – ramping effort up to maximum and hold for 3 sec

Form a grip posture – used to estimate effort required to form the hand into power grip posture Grip foam cylinder without causing foam to visibly

compress Maintain a fixed force – maintain 75-N grip force

on the dynamometer for 5 sec using visual feedback via an oscilloscope

Lift an object – grip the vertical arms of the dynamometer in a power grip and elevate without any horizontal movement to an approximate height of 20 mm

Grip size – dynamometer grip span was adjusted such that the thumb and tip of index finger lightly touched each other in a bare-handed relaxed grip

1. Increasing glove thickness and finger spacing reduces maximum grip force

-40

-30

-20

-10

0bare class 0 class 2 class 4 spacer 0 spacer 2 spacer 4

Grip

F

orc

e D

iffe

re

nc

e (

% M

VC

)

Mean Maximum Grip Force = 384.0 � 79.2 N

A a

B

C

D

b

b

b

Thicker gloves increased grip force for a constant lifting task (safety margin?)

0

5

10

15

20

25

30

35

40

0.00 0.39 0.77 1.16 1.55 1.93 2.32 2.71 3.09 3.48 3.87 4.25 4.64

Time (s)

Gri

p F

orc

e (

N)

bare class 0 class 2 class 4 space 0 space 2 space 4

0

0.5

1

1.5

2

2.5

3

3.5

Position Fixed Lift

No

rm

ali

zed

Perceiv

ed

Exerti

on

Bare

Class 0

Class 2

Class 4

Spacer 0

Spacer 2

Spacer 4

AA AAA

B

C

B

AAAAA

C aa

x

a

c

b

a

a

xx

o

xxx

Increases in glove thickness increased perceived exertion during performance of a constant submaximal grip force

Increases in glove thickness increased perceived exertion to create an unloaded grip posture

Increases in glove thickness increased forearm muscle activation during performance of a constant submaximal grip force

Increases in glove thickness increased forearm muscle activation to create an unloaded grip posture

Increases in glove thickness increased forearm muscle activation during performance of a constant submaximal grip force

Increases in glove thickness increased forearm muscle activation to create an unloaded grip posture

Increased glove thickness reduced tactile sensitivity

Increasing glove thickness made it impossible for the fingers to reach around and touch the thumb as in the bare hand condition

Adjusting the grip span to compensate for the effective increase of grip span incurred by wearing thick gloves decreased grip force output

b This load is present in all situations

Tactility on palmar surface

Fit at fingertips

Thickness between fingers

Stiffness/ Resistance to bending

Friction/texture on palmar surface

Friction inside glove

Fit Overall

Style: Finger vs Fingerless

Vibration Dampening: Air Bladder vs Sorbothane + Match glove to tool frequency

Age of glove: Decrement in performance with age

Quality: Adherence to ISO 10819 Glove Testing Standard

Trade-offs

Vibration dampening material thickness

Reduced tactility

Increased grip force

Increased vibration transmission

VIBRATION

Increased efforts to use gloveHAND

Protection Cuts Punctures Bare 0 0 Single Latex + + Double Latex ++ ++ Triple Latex ++┤ ++ Orthopaedic Latex ++ ++

Glove Liners Woven +++ + Non-woven ++ +++

Indicator gloves* ++ ++Overgloves ++ ++*But more cuts/punctures found during surgery

http://en.wikipedia.org/wiki/Medical_glove

DexterityLatex gloves are recommended when manual dexterity and tactility are particularly important.Neoprene and nitrile gloves typically have a lower elasticity and are less comfortable than latex

Latex Allergy OptionsLow-allergen gloves (but amount of latex is not usually stated on packaging), Non-powdered gloves, as the cornstarch power in powdered gloves is an efficient allergen carrier. Non-latex gloves, nitrile, vinyl, polyisoprene, vinyl(PVC) and neoprene. BUT, latex gloves are more flexible and reseal more readily after minor punctures.

Latex

Neoprene

Nitrilehttp://en.wikipedia.org/wiki/Medical_glove

1. Understand characteristics of gloves in general that increase fatigue and decrease prehensile performance

2. Use these ideas to evaluate anti-vibration gloves

3. Use these ideas to evaluate surgical gloves

Heather Carnahan Kirsten Willms Patricia Rosati Kevin Hurley

EUSA Shannon Hunt (nee Maracle) Carrie Boyle

Workplace Safety and Insurance Board

Willms, K*., Wells, R., and Carnahan, H. Determinants of force decrement in gloved power grip, Human Factors, 51:797-812, 2009.

Wells, R., Hunt, S. Hurley, K., Rosati, P. (2010) Laboratory assessment of the effect of heavy rubber glove thickness and sizing on effort, performance and comfort., International Journal of Industrial Ergonomics, 40:386-391.

Wells, R., Hunt, S, Rosati, P., Hurley, K. The effects of heavy electrical gloves on powerline maintainers' effort and performance: Opportunities for improvement, submitted to Applied Ergonomics

Hunt, S, Boyle, C and Wells, R. Comparison of five approaches to keeping power line maintainers’ hands warm during work in the cold, abstract for presentation at IEA2012

http://cre-msd.uwaterloo.ca/Position_Papers.aspx