An interesting study by (Huang et al, 2013) has found that myofascial trigger points (MTrP) are significantly more likely to develop in muscle tissue subjected to repetitive eccentric loading and blunt trauma. The muscle tissue showed characteristic increases in myoelectrical potential activity as well as changes in the shape of the myofibrils which became large and round in cross section and enlarged tapering shapes in longitudinal section.
The study was performed on rats, however we can certainly hypothesise that a similar causative mechanism may apply in humans who play regular sports. In particular contact sports such as rugby, American football as well as other sports where acceleration results in high levels of eccentric muscle loading combined with direct blows by various parts of the opponents anatomy.
So what we have here is a working model which may be another way to explain the development of muscle pain in sports. The difference is the pain may be arising from trigger points and not necessarily torn or 'strained' muscle.
We need to consider this possibility, and consider what mechanisms may have been at play when the sports person presents with muscle pain. This is important as trigger point pain would need to be managed differently to an acute or chronic muscle strain. For example if your patient presented with fairly acute onset muscle pain that was due to the activation of a trigger point - a simple local needling approach, performed gently and specifically may be sufficient to provide relief (Baldry, 2005). If however there was evidence of local swelling, inflammation and possibly discolouration associated with a muscle tear - local needling into the most tender area of muscle in the more acute phase may not be the best option?
It all comes down to assessment and this study should make us more aware of what pathophysiology may be at play in the development of muscle pain in sports people.
