Improved Hold Time, Unproven Benefit: Reassessing the Cervical Endurance Hold as an Outcome Measure in Fighter Pilots.

Abstract

Improvements in cervical endurance hold (CEH) time have been used as evidence that training interventions reduce neck pain risk in Air Force fighter pilots. This assumes that a longer hold time reflects a meaningfully lower risk of neck pain in this population, an assumption that remains unvalidated. We examine the reliability and validity evidence for the CEH and argue that its use as a surrogate for training success should be reconsidered. The CEH, known as Grimmer's test, shows strong intra-rater reliability but considerably weaker inter-rater reliability, particularly where test cessation depends on subjective examiner judgment rather than pain or exhaustion. No reliability data exist for this test in fighter pilots specifically. Validity evidence in this population was absent until a 2026 study of Royal Air Force Typhoon pilots found no significant correlation between neck flexor endurance and flight-related neck pain, despite high pain prevalence in the cohort. This is the first direct test of the assumption underlying the test's current use as an outcome measure, and it does not support that assumption. Prior evidence further suggests that neck pain in military pilots is more associated with coronal plane strength than the sagittal plane flexion this test assesses, and evidence that training cervical endurance reduces neck pain incidence remains mixed. An improvement in hold time is weak evidence that an intervention reduced neck pain risk. We recommend that the CEH be reported as a measure of endurance, not a proxy for pain outcomes, with future work evaluating coronal plane and extension-based alternatives.