Caught in the Grip of Repetitive Trauma Injuries

[fa icon="calendar'] Oct 26, 2015 8:00:00 AM / by Deborah Lechner

Many employers struggle with repetitive trauma injuries to the hand, wrist, and elbow – along with their close cousins, carpal tunnel syndrome and tendonitis. Although the causes of these conditions are often multifactorial, occurring on – as well off – the job, some work-related activities are thought to contribute.

Gauging Applicants’ Grip Strength

High on the list of likely culprits is repetitive, forceful gripping. Traditional ergonomic intervention to reduce grip forces have limited effectiveness; there is, after all, only so much that can be done to engineer forceful gripping out of a job that requires it.

As providers of pre-employment Physical Abilities Testing (also known as POET testing, Functional Capacity Evaluation, or Post-Offer Screening), we are often asked to test applicants’ grip strength as part of our protocol. In theory, this makes perfect sense: hire only those who have the demonstrated physical ability to perform the forceful gripping required for the job.

In real world application, however, this is a challenging endeavor. The first challenge is to accurately measure the grip strength required for the job. In research laboratories, sophisticated instrumented tools or handles are used to replicate the force required for specific functions. Unfortunately, most employers lack the resources to acquire this kind of technology for a one-time job analysis.

Implementing an Effective Grip Force Test

In the real world, the most objective method available for measuring grip force in the workplace is to ask a worker, one who performs the job regularly, to replicate the grip force required to accomplish the tasks of the job using a commonly available instrument called a grip dynamometer. While on the surface this may sound like a very subjective method, research shows that it’s actually fairly objective and reliable, provided that:

  • Enough employees are asked to replicate the grip
  • Enough grip repetitions are done per employee
  • The correct verbal instructions are provided to the employees participating
  • The handle position of the strain gauge replicates the size of the tool used
  • The forearm and hand are positioned similarly to what the job requires

Considerations for Compliant Screens

Once the grip force required for the job has been determined, the challenge is to develop a screen that is EEOC and ADAAA compliant. To replicate the job requirement, the test developer must consider factors like:

  • The duration of each grip
  • The grip vs. rest cycle or pace for repetitive gripping
  • The maximum number of continuous repetitions made at that pace without stopping for a more extended rest
  • The handle position of the grip dynamometer
  • The forearm and hand position for testing (should replicate the job demand)

Addressing Common Grip Strength Testing Mistakes

While the science is sound and the protocol straightforward, grip strength test implementation in pre-hire testing often falls considerably short of the state of the art. For example, some test developers will assume that if the task involves lifting 50 lb., the grip requirement should be set at 50 lb. More often than not, the force grip force required to hold an object is not equivalent to the weight of the object -it can be lower or higher - depending on the hand -object interface. In an inconsistent implementation, applicants can be excluded who could do the job where others are included when they really can’t, depending on the direction of the error.

Another common mistake we see is that employers will set the grip pass-point at an average of the maximum grip of their existing workforce rather than at the grip force required for the job. This is a practice that is not approved by the EEOC or ADAAA and is likely to produce adverse impact for women.

The bottom line is that if you have a significant number of hand/wrist/elbow cumulative trauma injuries, you need to consult with a test developer who truly understands the technology, procedures, test development, and EEOC and ADAAA guidelines for pre-employment testing in order for your grip strength testing to be defensible.

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Topics: Pre Employment Screening

Deborah Lechner

Written by Deborah Lechner

Deborah Lechner, ErgoScience President, combines an extensive research background with 25-plus years of clinical experience. Under her leadership, ErgoScience continues to use the science of work to improve workplace safety, productivity and profitability.