Immediate effect of maximum voluntary isometric contractions of the cervical flexor and extensor muscles on ultrasound-based muscle size and mechanical properties

Sports-related concussion (SRC) and concurrent neck pain (NP) is one of the most common and serious injuries in the United States. Prevention strategies to target modifiable intrinsic risk/protective factors are lacking. From a joint stability perspective, it is of interest to examine whether neck muscles are capable of changing tissue properties immediately after repeated maximal voluntary isometric contractions (MVIC). A total of 24 healthy subjects participated in the study. One examiner (T.N.) scanned select cervical flexor and extensor muscles with diagnostic ultrasound (US) to obtain muscle properties [cross-sectional area (CSA), thickness, and stiffness with shear wave elastography (SWE)]. These US-based muscle properties were compared before and after MVIC trials. Results show that the CSA of the longus colli (LC) and sternocleidomastoid (SCM) thickness was significantly increased post-MVIC. No other significances were observed.