The potential effects of a biofeedback writing exercise on radial artery blood flow and neck mobility

Background: 

It has been suggested that sustained contraction of the deep neck muscles may reduce axial cervical range of motion (CROM) and radial artery blood flow velocity (v_rad.art.mean). No studies have reported both phenomena in relation to acute hand, shoulder or neck trauma. 

Procedures: 

the CROM and v_{rad.art. mean} were measured in 20 police officers prior to and immediately after a 2-hours drive on a motorcycle and immediately after a 1-minute writing exercise using biofeedback. The CROM was measured using separate inclinometers and the v_rad.art.mean was measured in both arms just proximal to the wrist using echo-Doppler. 

Findings: 

During the study, one officer had a motorcycle accident resulting in acute symptoms of neck trauma. His v_rad.art.mean was acutely reduced by 73% (right arm) and 45% (left arm). Writing with biofeedback increased his v_rad.art.mean by 150% (right arm) and 80% (left arm). In the remaining 19 officers, the CROM to the right was significantly increased after the 2-hours driving task (p<0.05; paired subject t-test). Writing with biofeedback increased their CROM in both directions and v_rad.art.mean in both arms (p<001). 

Conclusions: 

A 2-hours drive showed modest physical changes in the upper extremities. Biofeedback in writing tasks might relate to the influence of relaxation and diverting attention for neck mobility and arterial blood flow improvement.