TABLE 1.

Potential Cervical Spine Examinations and Clinical Considerations in Reducing SRC Risk.

Factor of Interest	Potential Examinations to Consider	Measurements to Consider	Clinical Relevance	Avenues for Future Research
Neck Strength and Girth	Isometric neck strength  measures in all three  planes of motion to  quantify flexion,  extension, lateral  flexion, rotation, and  flexion in rotation  (sternocleidomastoid).	Isometric strength  measurements   with a: •  Hand-held  dynamometer5, 10, 19, 68, 70. •  Fixed  dynamometer16, 19, 51, 57. •  Hand-held tension   scale11.	Lower neck strength is  associated with  increased head linear  and rotational  accelerations during  impact5, 8, 9, 20 as well as  increased SRC risk11.  Additionally, every one-  pound (approximately   0.45 kilogram) increase   in neck strength,   decreased concussion   risk by 5 percent11.	• Development of age- and sex- specific strength normative values. • Relationship between neck strength and SRC risk, including reducing linear and rotational head acceleration. • Relationship between neck strength and clinical outcomes post- SRC.
	Neck circumference   measurement.	Circumference  measurement  above10 or below11   the thyroid   cartilage.	Lower neck girth is   associated with   increased head linear   and rotational   accelerations during   impact5, 8 as well as   increased SRC risk11.	• Relationship between girth and SRC risk, including reducing linear and rotational head acceleration. • Relationship between girth and isometric neck strength.
Neck Endurance	Neck muscle endurance   measures.	Cervical flexor24, 28, 34   and extensor35, 59   endurance tests.	Since increased activation   of the deep cervical   flexors is thought to   enhance stability and   posture in the cervical   spine22, 39 and possibly   play a role in controlling   head accelerations32, 61, 72, there is potential for   increases in neck   endurance in these   muscles to be   associated with   decreased risk of SRC.	• Relationship between deep muscle endurance and SRC risk. • Relationship between deep muscle endurance and clinical outcomes post- SRC.
Strength Imbalances	Asymmetry in neck   strength measures   across the three   planes of motion.	Calculation of a  strength  imbalance score   within planes of   motion16.	A flexion-extension ratio   that is close to one   correlates with lower   head accelerations   during impact16 which   may allow for more   neck protection16, 29.	• Relationship   between neck   muscle   asymmetries and   SRC risk.
Posture	Observation for forward   head posture (FHP).	Craniovertebral angle   measurement56.	It is speculated that since   FHP is associated with   a decreased flexion-  extension strength   ratio3, more extreme   postural impairments   may be associated with   SRC risk. Obtaining this   specific measure may   be important as smaller   craniovertebral angles   are associated with   FHP impairments73.	• Relationship between head-neck posture and linear and rotational head acceleration. • Relationship between head-neck posture and severity of clinical outcomes post- SRC.