Research projects

Activity patterns in the abdominal and back musculature

About this project

Project information

Project status

In progress


Martin Eriksson-Crommert

Research subject

The deepest abdominal muscle – transversus abdominis have gained much attention recently due to findings showing different activity patterns of this muscle when comparing healthy subjects with low back pain patients. Furthermore, this muscle differs from the other abdominal muscles in the way it reacts to arm movements in standing. In addition to the pure biological alterations observed, people with back pain display negative beliefs about pain, catastrophizing thoughts about pain and fear of movement to a higher degree than healthy individuals.

To investigate how the abdominal muscles activates in different situations is imperative to fully understand the connection between muscle function and low back pain. Through comparisons between the different abdominal muscles specific activity patterns in different situations, we want to gain further understanding of the abdominal muscles co-ordination patterns and the specific function of individual muscles. Furthermore, by taking the psychosocial aspects of pain into consideration we want to observe how these aspects can modify the biological responses, i.e. muscle coordination patterns.

Project I: Healthy subjects have been tested. Their muscle activity has been measured through registering the muscles electrical signals. The subjects have in a side-lying position performed a series of manoeuvres that activates the abdominal muscles in different ways. These manoeuvres included; movement of their “upper” arm, with the trunk muscles resist an isometric force that is suddenly released and regaining a neutral trunk position after mild perturbations to the trunk.

Project II: We look into the “normal” activation pattern of the trunk muscles in healthy subjects by having them perform arm movements of different magnitude. As a separate part of the experiment we investigate the activity in different trunk muscles, with electromyography and intra-muscular fine wire electrodes, during different static arm positions.

Project III: The same research question as for the static arm positions in project II, but the muscle activity is measured with ultrasound instead. This does not require penetration of the skin and would allow for the experimental set-up to be more widely used.

Project IV: Due to the association between long lasting back pain and negative beliefs about pain and fear of movement, we want to address the interplay between these psychological and biological (muscle activity patterns) domains of the pain experience. We will identify people that have evident psychosocial issues with pain and study the bodily reactions in response to experimentally induced low back pain and compare to people without or with minimal psychosocial burden.

Current situation: Project I: All subjects have been tested and data analyzed. Two articles are published that treats the two parts; resist an isometric force and mild perturbations to the trunk. A poster reporting the results from the arm movements in side-lying have been presented at an international conference.

Project II: All tests are finished and data have been analyzed. One article regarding the static arm positions has been published and the results from the project have also been presented at several international conferences, both orally and as posters. One article regarding the effect of arm movements of different amplitude on trunk muscle responses have been submitted for publication. Results from this part of the project have also been presented at an international conference as a poster.

Project III: The tests are finished and data are being analyzed.

Project IV: Data collection is in progress




Research funding bodies

  • Region Örebro County


  • Alf Torstensson, Karolinska Institutet
  • Maria Ekblom, Departement of Neuroscience, Karolinska institutet and The Swedish School of Sport and Health Sciences