The Influence of the American Football Helmet on Neck Flexor Endurance and Clinical Postural Assessment in Adolescents

Date

2021-12

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Abstract

Protective helmets cause postural changes to the head and neck that may increase the risk for helmet-to-helmet contact in football and prevent the neck muscles from controlling the head. Concussion and whiplash are both common football injuries caused by acceleration and deceleration events to the head and neck. Decreased neck musculature strength and endurance have been proposed to play a role in preventing concussion and whiplash. The deep neck flexors (DNF) are important muscles responsible for maintaining head and neck posture, and, when compromised, play a role in neck pain, headache, whiplash associated disorders and reduced postural control. It is unknown whether the DNF can maintain neck posture with the additional football helmet weight. Concussion causes altered postural control and has been associated with lower extremity musculoskeletal injury after concussion resolution. Military and commercial protective equipment has been shown to alter postural control in healthy individuals. This dissertation examined the influence of the football helmet on neck flexor endurance and postural and balance control measures. Phase-one of this dissertation took place at the Musculoskeletal Laboratory at Texas Tech University Health Sciences Center and evaluated a sample of convenience from the school’s student population. Phase-two of this dissertation took place at an SSM Health Sports Medicine Clinic and evaluated healthy, adolescent football players. This cross-sectional study established reliability for the novel Neck Flexor Endurance Test (NFET); evaluated the football helmet’s influence on NFET, Postural Stability Test (PST), Limits of Stability (LOS), modified Clinical Test of Sensory Integration on Balance (mCTSIB) and the Balance Error Scoring System (BESS); evaluated the association between NFET and PST, LOS, mCTSIB and BESS; and evaluated the association between PST and BESS. Phase-one evaluated 20 healthy adult males (26.4 ± 4.56 years old) to establish NFET inter-rater reliability. To establish NFET intra-rater reliability, 10 subjects returned for additional testing. For Phase-two, 26 healthy adolescent football players (16.42 ± 1.58 years old) were evaluated with and without a football helmet on for NFET, PST, LOS, mCTSIB and BESS. Good NFET inter-rater reliability was established (ICC (2,2) = 0.899 (95% CI, 0.76 - 0.96)). NFET intra-rater reliability coefficient for rater-one reproducibility was excellent (ICC (3,1) = 0.903 (95% CI, 0.66 – 0.97)) and good for rater-two (ICC (3,1) = 0.878 (95% CI, 0.59 - 0.97)). The average intra-rater reliability coefficient for both raters’ reproducibility was good (ICC (3,2) = 0.891 (95% CI, 0.62 - 0.97)). Wearing a football helmet significantly decreased NFET (p < 0.001), LOS (p < 0.001) and BESS (p < 0.001) performance. A fair relationship (r(52) = 0.354, p=0.010) was found between NFET and LOS composite scores. A fair, negative relationship (r(52) = -0.380, p=0.005) was observed between NFET and BESS test results. No other significant associations were found, including no significant relationship between PST and BESS. The NFET is a reliable test and further research is necessary to determine its clinical benefits. The football helmet has a negative influence on NFET performance and should be considered when determining an individual’s return to football following a head or neck injury. The football helmet exhibited a negative influence on dynamic postural control. This finding suggests that both dynamic postural assessment and testing with football equipment are valuable considerations when assessing an individual’s readiness to return to football following cervical and concussive injury. Additionally, there is a fair association between NFET performance and dynamic postural control. This finding is an important first step to better understanding the role of football equipment on injury risk. Finally, there is no association between PST and BESS. BESS should be evaluated against dynamic postural control assessments that are more consistent with the BESS than the PST.

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Keywords

concussion, balance, posturopraphy, protective equipment, football, football helmet, static balance, cervical spine, cervical flexors, deep neck flexors, neck flexor endurance test

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