Physiological indicators of lower neck strain with reduced levels of vibration and a novel vibration mitigating cushion

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Proceedings titleSAFE Symposiums
Conference54th Annual SAFE Symposium, Oct. 31st-Nov. 2nd, 2016, Dayton, Ohio
AbstractINTRODUCTION: Whole-body vibration during helicopter flight can result in adverse health effects, such as neck strain, which can impact performance and safety. The current ISO-2631 whole-body vibration standard does not account for vibration effects on the head and neck. Furthermore, it is unclear as to the extent to which vibration mitigating countermeasures, such as seat cushions, affect vibration transmission to the pilot and reduce head movement and neck strain. This study examined the impact of vibration level and a mitigating cushion on pilot neck strain and head movement. METHODS: Using a human rated shaker facility, the physiological responses of 12 pilots were examined during 15-minute exposures to three levels of vibration (Low=0.23, Normal=0.30, High=0.36 grms) which are representative of forward flight in NRC’s Bell 412 and CF Griffon helicopters. Responses were also compared using either a standard original equipment manufacturer (OEM) or vibration mitigating (MIT) cushion at each vibration level. Electromyography (EMG), as an indicator of neck strain, and seat and head acceleration were recorded continuously. RESULTS: Normalized EMG amplitude was significantly higher during High (OEM= 0.201±1.023, MIT= - 0.008±0.983) compared to Low (OEM = -0.197±0.859, MIT= -0.193±0.991) vibration for both cushions, and amplitude was also higher during Normal (OEM= 0.245±0.914, MIT= -0.048±0.947) compared to Low vibration for the OEM cushion. During Normal and High, the EMG amplitudes were significantly lower, and median frequency significantly higher, with the MIT compared to OEM cushion. Head acceleration was significantly lower with the MIT (1.187±0.261 m∙s⁻ ²) compared to the OEM (1.108±0.234 m∙s⁻ ²) cushion. DISCUSSION: The EMG changes occurring with increased vibration may be indicative of higher neck strain, highlighting the deficiency in ISO-2631 which suggested that the tested vibration levels and durations were within accepted exposure limits. The vibration mitigating cushion was effective in reducing such effects, as well as reducing head acceleration
Publication date
AffiliationAerospace; National Research Council Canada
Peer reviewedYes
NPARC number23001455
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Record identifierad7c2782-f7ea-4351-a4b1-c96b742c8df3
Record created2017-02-12
Record modified2017-02-12
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