Redefining Pain Origins: Comparing DOMS and Fascia Pain to Muscle Pain in Lumbar Studies

Delayed onset muscle soreness (DOMS), commonly used in studying acute low back pain (aLBP), is traditionally thought to originate from muscle damage. However, recent research suggests that the deep fascia, part of the extramuscular connective tissue (ECT), plays a significant role in DOMS. This challenges previous beliefs about its causes, moving away from muscle-centric theories to include fascial involvement.

Verbal pain descriptors like the Pain Perception Scale are key in characterizing aLBP, helping to distinguish pain qualities between muscle and fascia.

Fascia pain descriptors are similar to skin pain, such as  “burning,” “scalding,” and “hot.” In contrast, descriptors for muscle pain are significantly different, e.g., “deep pain”.

Given these insights, the role of DOMS, traditionally thought to mimic muscle pain, is being reevaluated, with a focus on the involvement of the ECT and deep fascia in DOMS pain. The study explored the effect of an eccentric trunk extension exercise on pain descriptors related to fascia and muscle pain.

In a new study, published in European Journal of Physiology, sixteen healthy individuals (L-DOMS group) were compared with participants from a prior study (L-PAIN group, 16 individuals) who experienced selective electrical stimulation of the thoracolumbar fascia and the multifidus muscle.

The L-DOMS group underwent a regimen of eccentric trunk extensions to the point of exhaustion, specifically targeting the lower back area to induce DOMS.

In the days following the exercise, the research team closely monitored the sensory characteristics in the L-DOMS group. They employed several methods, including pain on palpation measured on a 100-mm analogue scale, pressure pain threshold (PPT), and the Pain Sensation Scale (SES). Notably, 24 and 48 hours after the eccentric training, there was a significant increase in pain on palpation in the L-DOMS group, while pressure pain threshold remained unchanged.

The study took an analytical approach to understand the nature of the pain experienced. Factor analysis of the sensory descriptors (SES) used by both L-DOMS and L-PAIN groups revealed a stable three-factor solution. This analysis distinguished between superficial thermal pain (described as “heat pain”), superficial mechanical pain (“sharp pain”), and “deep pain.” Intriguingly, the descriptions of “heat pain” and “deep pain” in the L-DOMS group closely mirrored those from the L-PAIN group, who had undergone electrical stimulation of fascial tissue. These descriptions were significantly different from those typically associated with muscle pain.

The study’s findings challenge conventional understanding of DOMS. The differences in sensory description patterns, combined with the pressure pain threshold and self-reported DOMS for palpation pain scores, strongly suggest that the origin of DOMS is more closely linked to fascial tissues rather than muscular tissues. This insight could have significant implications for how DOMS and related conditions are approached in both clinical and fitness settings, emphasizing the need to consider the role of fascial tissues in pain management and rehabilitation strategies.