Example: Turkey boning

Turkey Boning: Use of surface EMG to determine force patterns and Application of the ACGIH TLV® for Localized Fatigue

Adapted from: Armstrong, T, Foulke J, Joseph B, & Goldstein S (1982). Investigation of cumulative trauma disorders in a poultry processing plant. Am Indus Hyg Assoc J, 43(2), 103-116.

Job description:

Line Speed:

Workstation:

Turkeys suspended from overhead conveyor
(thighs are 44" above floor)

Tools:

Boning knife (right hand)
stainless steel mesh glove (left hand)

Method (1 thigh of every second turkey):

With one hand grab & hold thigh of moving turkey
With knife hand perform 2-3 cuts along long axis to separate meat from bone
With knife hand perform 1 cut to separate remaining tendinous attachments from end of bone.

Fig 1: Thigh boning workstation (left); boning knife. (Right)

Use of EMG to study worker hand force patterns (see Figure 2)

Fig 2: Equipment used to record surface EMG from forearms as workers boning turkey thighs (Left)); The relationship between EMG_RMS was determined for each subject and work posture in advance of each test(Right). (Right). Armstrong T, Chaffin D, Foulke J (1979) A methodology for documenting hand positions and forces during manual work. *J Biomechanics* Vol 12 pp. 131-133.

Hand Force Profiles

Fig 3a: Force profile based on Surface EMG recording from right forearm while boning two thighs (left); hand strength based on power grip data from Matiowetz et al.(1985). (Right)

Fig 3b: Force profile based on Surface EMG recording from left forearm while boning two thighs (a); hand strength based on lateral pinch data from Matiowetz et al.(1985). (b) hand force data

Applying the ACGIH TLV® for localized fatigue

Fig 4: The observed %MVC and DC exceed the the ACGIH TLV® for localized fatigue both the right and left hands. For the left hand, either the DC must be reduced to 6%% or the %MVC_Avg must be reduced to 17% to not exceed ACGIH® recommenced limits (a). For the right hand, either the DC must be reduced to 48% or the %MVC_Avg must be reduced to 13% to not exceed ACGIH® recommenced limits (b).

Possible job improvements

Slow down the line to provide more recovery time -- good luck!
Knife handle design to reduce hand force
Knife blade sharpness -- maintenance
Select gloves that fit well, with minimize interference with grip, and with enhance traction.
Worker skill training -- slice/not chop
Marel "Automated thigh fillet system"

Fig 5: Modified knife (prototype) reduces force to hold & use knife