Naval Special Warfare (NSW) crewmen demonstrate diminished cervical strength and range of motion compared to NSW students.

Background: Cumulative effects of high-impact vertical forces, like those experienced on an open-ocean mission, could be an injury concern for the cervical spine.

Objective: Compare cervical range of motion (ROM) and strength measures between students and NSW Crewmen and secondarily to compare these measures between students and Crewmen separated into three groups based on years of service.

Methods: A volunteer sample of 186 students (age: 22.8±3.1 years) and 167 Operators (age: 26.9±5.1 years) completed cervical isometric strength (% BW) and ROM (°) measurements using a handheld dynamometer and CROM-3 device, respectively. Independent samples t-tests were done to evaluate differences between students and Crewmen. Analysis of Variance and appropriate post-hoc tests were calculated to compare students to Crewmen separated into three groups based on years of service. Data is reported as mean±SD and (student mean vs. Operator mean).

Results: Students demonstrated higher flexion strength (21.7±4.9 vs. 19.1±5.0) and greater ROM: flexion (54.3±10.6 vs. 51.2±9.2), and extension (77.0±14.4 vs. 71.3±11.4) than Crewmen. Students demonstrated greater flexion strength than Crewmen with ≤2 (19.4±5.1), 3-6 (19.4±5.3), and ≥7 (18.6±4.7) years of service.

Conclusions: Students demonstrated greater cervical strength and ROM. A trend of decreasing ROM/strength in Crewmen with greater years of service was also observed.