Pain-Induced Changes in Motor Control Revealed by Muscle Imaging
Deborah Falla, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Denmark
Take Home Message:
- Although neuromuscular impairments are well documented in patients with musculoskeletal pain, the relationship between pain, altered motor strategies and changes in muscle properties are not fully understood.
- High-density surface EMG (muscle imaging) has shown that muscles with complex architecture display variations in activity among different regions. For example, during fatiguing contractions, the relative activity of the cranial region of the upper trapezius muscle increases more with respect to the caudal muscle region.
- Variation in activation within regions of the same muscle seems an efficient strategy for avoiding accumulation of metabolites within the same muscle region; accordingly, this strategy is associated with a reduction in fatigue.
- In contrast, in the presence of acute and chronic pain, patients perform sustained contractions with negligible changes in the relative activation of different muscle regions.
- A long term consequence of this strategy is an overload of muscle fibers and as a further consequence, alterations in the biochemical status of the muscle. This knowledge provides new insight into the development of altered muscle properties which may play a key role in the chronicity and recurrence of pain.
Click to read Deborah Falla's biography