10/03/2026
The Soreness Outside the Muscle: A Different Look at DOMS
For a long time, DOMS was discussed largely as a muscle problem: unfamiliar or eccentric exercise stressed muscle fibers, microscopic damage occurred, inflammation followed, and the muscle became sore.
Delayed onset muscle soreness, or DOMS, is the soreness and stiffness that develops after unfamiliar or unusually demanding exercise. It typically appears hours after the activity rather than during it and is often most noticeable a day or two later.
But the muscle fibers are not the whole story.
Research is increasingly drawing attention to the extramuscular connective tissues associated with muscle—including deep fascia and the connective tissues surrounding and linking muscles—as important contributors to what happens during DOMS.
The connective tissues are being loaded too
When a muscle produces force, that force is transmitted through an interconnected system of intramuscular and extramuscular connective tissues. During lengthening contractions in particular, these tissues are subjected to substantial mechanical loading.
And they change after exercise.
Following eccentric exercise, researchers have measured increased thickness in extramuscular connective tissues. Imaging studies have also demonstrated increased water content and stiffness in deep fascia during the period when DOMS develops.
That changes the way we can think about the familiar “sore muscle.” Some of the tenderness and stiffness we associate with the muscle itself can originate in the connective tissues associated with it.
Fascia can hurt
Deep fascia is richly supplied with sensory nerve endings, including nociceptors capable of responding to mechanical and chemical changes associated with potential tissue threat or damage.
Experimental studies have demonstrated that deep fascia can be a significant source of pain. Its sensitivity can also increase in an inflammatory environment.
After unfamiliar or strenuous exercise, changes in tissue loading, fluid distribution, inflammatory signaling and mechanical stiffness therefore occur in tissues that are quite capable of contributing to soreness.
DOMS involves more than the contractile fibers of skeletal muscle. Muscle and its connective-tissue environment are responding to the same exercise and the forces generated by it.
What does this mean for horses?
Much of the detailed research into DOMS and extramuscular connective tissue has been performed in humans, so the specific findings cannot simply be transferred to horses.
The underlying anatomy and mechanics, however, make the subject highly relevant.
A horse’s muscles are surrounded, separated and connected by extensive fascial and connective-tissue structures. These tissues participate in force transmission and are continuously loaded during locomotion. Exercise doesn’t load the contractile portion of a muscle while somehow sparing everything around it.
Unfamiliar work, an increase in workload, hill work, jumping, changes in terrain and other new physical demands can expose both muscle and connective tissues to loads they are not accustomed to managing.
Afterward, a horse can feel generally stiff, show sensitivity through certain areas, be less willing to use his usual range of movement, or simply seem less comfortable moving freely.
That doesn’t tell us which tissue is responsible, and soreness should never automatically be assumed to be DOMS. Pain, lameness or persistent changes in movement deserve appropriate investigation.
But it gives us a much more complete way of thinking about ordinary post-exercise soreness.
Where massage becomes interesting
Touch and movement interact with the entire region being treated: skin, superficial and deep connective tissues, muscle, local circulation, sensory receptors and the nervous system.
Appropriately timed massage can encourage comfortable movement between tissues, influence local fluid dynamics, provide sensory input and help reduce the perception of soreness. Working with the tissues around and between muscles is just as important as concentrating on the muscle belly itself.
It also helps explain something massage therapists frequently notice: the place that feels restricted or sensitive isn’t always neatly confined to the anatomical boundaries of one muscle.
The horse doesn’t move as a collection of isolated muscles, and neither does the tissue respond to exercise as a collection of isolated structures.
DOMS research gives us another reason to look beyond the muscle—and pay attention to the connective tissues that surround it, connect it and help transmit the forces it produces.
https://koperequine.com/why-hands-on-massage-is-the-best-way-to-for-sore-care-muscles/
