The Relation Between Biomechanical Stiffness and Feeling Stiff

Andy Peloquin

Personal Training


The Relation Between Biomechanical Stiffness and Feeling Stiff - Fitness, fitness, biomechanics, mobility, lower back pain, Trending, erector spinae


Back pain and back problems are surprisingly common in our modern day and age. According to the American Chiropractic Association, low back pain is one of the most common reasons for missed work and is the single leading cause of disability around the world. Roughly 50% of working Americans experience back pain every year, with more than 31 million suffering back pain at any given time.



Pretty scary, right? Thankfully, most of the problems are non-organic or mechanical, due to an injury or strain rather than cancer, arthritis, spinal infection, or fracture. That stiffness in your back may not be as serious as you might fear.


In fact, according to a new study, the stiffness may not even be all that stiff. Confused? A professor from the University of Alberta's Faculty of Rehabilitation Medicine explains, "“A conscious experience of feeling stiff does not reflect true biomechanical back stiffness. When we use the same word, stiffness, to describe a feeling and how we measure actual stiffness, we assume these words are describing the same thing. But that is not always the case.”


To prove the point, the researchers gathered participants and asked them how stiff their backs felt. The participants gave their answer, and the researchers used a customized device to measure the true stiffness of their backs. According to the lead researcher, "There was no relation between biomechanical stiffness and the reported feeling of stiffness. What people describe as stiffness is something different than the measurement of stiffness.”


That makes a bit more sense, right? The sensation our brains translate as "stiffness" isn't the same as the actual measurement of how stiff our spines and spinal muscles are. In fact, as one Australian doctor believes, "the feeling of stiffness may be a protective construct that is created by our nervous system."

The spinal erector muscles do more than just keep your spine upright—they also provide a protective cushion around the spine joints and bones. In cases of injury, the muscles will often swell up and stiffen as a means of protecting the spine from not only further strain and injury but even pain.


What's the point of this study? As the lead author said, “Words are important. The words patients use to describe a problem in the clinic may not be the same thing we as clinicians measure in the clinic. We need to find out what it means exactly when someone says they have a stiff back. We now know it might not mean that their back is mechanically stiff. It could mean they feel their movements are slower and more painful.”



1. Tasha R. Stanton, G. Lorimer Moseley, Arnold Y. L. Wong, Gregory N. Kawchuk. "Feeling stiffness in the back: a protective perceptual inference in chronic back pain." Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-09429-1.

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