Delayed-Onset Muscle Soreness Mimics a Tendency Towards a Positive Romberg Test

The exact mechanism of delayed-onset muscle soreness (DOMS) is far from entirely known for more than 120 years. A recent bi-phasic neurocentric DOMS theory proposes that DOMS is a non-contact acute compression axonopathy initiated on the intrafusal proprioceptive Type Ia terminal, in the form of an autonomously acquired transient Piezo2 channelopathy under unaccustomed and/or strenuous eccentric/isometric contractions and allostatic stress. The current study applied this theory as a working hypothesis and it was executed by involving a dynamometer-based DOMS-inducing eccentric exercise protocol on seventeen young elite male handball players in the Hungarian National Handball Academy. Stabilometry was used to measure postural sway before and right after the DOMS-inducing protocol. The findings of this DOMS study is in contrast to fatigue related ones, since it decreased sway with open eyes. Furthermore, closed eyes did not reduce antero-posterior postural sway due to DOMS effect, like it is observed in fatigue, but rather increased it. Hence, both open and closed eye related DOMS findings are in contrast to the fatigue related ones, where sway was increased when eyes were open and antero-posterior postural sway was reduced when eyes were closed. Accordingly, the closed eye finding due to DOMS effect is an analogous tendency towards a positive Romberg test. Indeed, a positive Romberg test is indicative of impaired proprioceptive signaling in neurology and Piezo2 is the principal mechanosensory ion channel responsible for proprioception. In summary, our study suggests that a reflex-like compensatory postural control enhancement may be initiated in response to closed eyes when fatigue is the underlying factor, however this reflex-like compensatory mechanism may be impaired due to Piezo2 channelopathy and DOMS effect, resulting in enhanced antero-posterior and left-right postural sway.