Neck muscle activity and perceived pain and discomfort due to variations of head load and posture

Knight, James F.; Baber, Chris

Affiliations

¹School of Electronic, Electrical, and Computing Engineering, The University of Birmingham, Birmingham, UK

Abstract and keywords

Background: The increasing use of helmet-mounted displays in aviation raises issues of head-supported weight and neck musculoskeletal function, especially during acceleration.

Objectives: This study aimed to quantify musculoskeletal stress as weight was added to the front of the head in different head positions and determine the effectiveness of a counterbalance in reducing stress.

Methods: There were 20 subjects who participated. The study required that the subject move his head every 10 s for 10 min to one of five positions that were assumed to represent those readily adopted in everyday situations: neutral, 30° extended, 30° flexed, 35° left rotated, and 35° right rotated. Of the subjects, 10 repeated the test while wearing a GSMK6 helmet, and when 0.5 kg, 1.0 kg, or 2.0 kg was added to the front of the helmet. The other 10 subjects repeated the test but with counterbalances. During testing, EMG was recorded from the neck extensors and sternocleidomastoid muscle. Pain levels were recorded using the Borg-CR10 scale.

Results: Changes in head position from neutral resulted in significant increases of EMG amplitude (mean ± SD) in the neck extensors of up to 18 ± 13% (p < 0.05), and due to head load by 46 ± 33% (p < 0.05) with a frontal load of 2 kg. Sternocleidomastoid EMG showed little change due to increases in load but increased significantly by up to 265 ± 227% of the neutral position (p < 0.05) when the head was rotated.

Conclusions: The use of head-mounted displays presents the risk of detrimental effects to the musculoskeletal system. Determining the effect of added weight requires a knowledge of working head postures.

Keywords: head-mounted displays; head load; head position

Links

PubMed: 14960047

WoS: 000188384000005

History

Received: 2002-11

Revised: 2003-03

Revised: 2003-06

Revised: 2003-08

Accepted: 2003-08

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Cited By (8)

Year	Entry
2014	Sovelius R. Cervical Loading Analysis of Fighter Pilots: Studies on Cumulative Loading, Contributing Factors and Interventions [PhD thesis]. Tampere, Finland: University of Tampere School of Medicine; February 21, 2014.
2008	Sovelius R, Oksa J, Rintala H, Huhtala H, Siitonen S. Neck muscle strain when wearing helmet and NVG during acceleration on a trampoline. Aviat Space Environ Med. February 2008;79(2):112-116.
2008	Brolin K, Hedenstierna S, Halldin P, Bass C, Alem N. The importance of muscle tension on the outcome of impacts with a major vertical component. Int J Crashworthiness. October 2008;13(5):487-498.
2012	Van den Oord MHAH, Frings-Dresen MHW, Sluiter JK. Optimal helmet use and adjustments with respect to neck load: the experience of military helicopter aircrew. Int J Ind Ergon. January 2012;42(1):73-79.
2018	LeClair B, O'Connor PJ, Podrucky S, Lievers WB. Measuring the mass and center of gravity of helmet systems for underground workers. Int J Ind Ergon. March 2018;64:23-30.
2014	Godwin AA, Eger TR. Ergonomic and usability ratings of helmets and head-mounted personal protective equipment in industry. Work. 2014;47(1):23-31.
2009	Green JWN. The Effects of Added Mass on the Dynamic Motions of the Head and Trunk During Running and Walking [Master's thesis]. Drexel University; September 2009.
2015	Ibrahim E. The Effects of Neck Posture and Head Load on the Cervical Spine and Upper Extremities [Master's thesis]. Hamilton, ON: McMaster University; November 2015.