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Understanding Force

  • Issued: December 2009
  • Content last reviewed: December 2009

Force is the amount of effort exerted by the muscles. All work tasks require workers to use their muscles to exert some level of force. However, when a task requires them to exert a level of force that is too high for any particular muscle, it can damage the muscle or the related tendons, joints and other soft tissue. This damage can occur from a single movement or action that requires the muscles to generate a very high level of force. However, more commonly, the damage results when muscles generate moderate to high levels of force repeatedly, for a long duration, and/or while the body is in an awkward posture.

The activities that often involve high force requirements include:

  • Lifting, lowering, and carrying
  • Pushing or pulling and
  • Gripping and manipulating objects

Some job tasks result in high force loads on different parts of the body. For example, lifting a heavy load that is far from the body increases the load on the lower back. This can potentially damage both the spinal discs and the vertebrae.

Another source of force on the body comes from working with hand tools that have hard or sharp edges, i.e. resting the forearms on the hard edge of a desk, can also potentially cause damage to tendons, muscles, blood vessels and nerves under the skin. This is often referred to as contact stress.

The following parameters are important to understand the impact of force:

  • Weight of objects
  • How long a forceful effort has to be exerted
  • How many times in a given period it has to be exerted
  • The posture the body is in

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