The Effects of Bag Style on Muscle Activity of the Trapezius, Erector Spinae and Latissimus Dorsi During Walking in Female University Students
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The University of San Francisco USF Scholarship: a digital repository @ Gleeson Library | Geschke Center Kinesiology (Formerly Exercise and Sport Science) College of Arts and Sciences 2015 The ffecE ts of Bag Style on Muscle Activity of the Trapezius, Erector Spinae and Latissimus Dorsi During Walking in Female University Students R. Hardie R. Haskew J. Harris Gerwyn Hughes University of San Francisco, [email protected] Follow this and additional works at: http://repository.usfca.edu/ess Part of the Kinesiology Commons, Sports Sciences Commons, and the Sports Studies Commons Recommended Citation Hardie, R., Haskew, R., Harris, J. and Hughes, G. (2015). The Effects of Bag Style on Muscle Activity of the Trapezius, Erector Spinae and Latissimus Dorsi During Walking in Female University Students. Journal of Human Kinetics, 45(1), pp. 39-47. https://doi.org/ 10.1515/hukin-2015-0005 This Article is brought to you for free and open access by the College of Arts and Sciences at USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. It has been accepted for inclusion in Kinesiology (Formerly Exercise and Sport Science) by an authorized administrator of USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. For more information, please contact [email protected]. Journal of Human Kinetics volume 45/2015, 39-47 DOI: 10.1515/hukin-2015-0005 39 Section I – Kinesiology The Effects of Bag Style on Muscle Activity of the Trapezius, Erector Spinae and Latissimus Dorsi During Walking in Female University Students by Rebecca Hardie1, Rachel Haskew1, Joel Harris1, Gerwyn Hughes1 Back pain is common in adolescents which has been associated with carrying a bag. However, there is little research examining the effects of bag style in female adolescents. The aim of the study was to investigate the effects of different bag conditions on muscle activity of the trapezius, erector spinae and latissimus dorsi muscles in female university students during walking. Twelve female university students walked on a treadmill for 5 minutes at 1.1 m/s during five conditions; control, 1 strapped rucksack, 2 strapped rucksack, ipsilateral shoulder strap and contralateral shoulder strap, each containing 10% bodyweight. Electromyography for the trapezius, erector spinae and latissimus dorsi was recorded for the last 30 s of each condition. Two-way ANOVA and paired t-tests were used to identify differences between right and left muscles and between bag conditions. Results showed that muscle activity of the left trapezius was significantly higher than the right trapezius during the 1 strap rucksack condition. For the left trapezius, the 2 strapped rucksack and the control condition had significantly lower muscle activity compared to the 1 strapped rucksack and the ipsilateral shoulder strap. For the left erector spinae muscle, there was significantly greater muscle activity when wearing the contralateral shoulder strap compared to the control. For the right erector spinae, significantly lower muscle activity was observed when wearing the 2 strapped rucksack compared to the ipsilateral shoulder strap and contralateral shoulder strap. There were no significant differences in muscle activity of the latissimus dorsi muscles between any of the bag conditions. These findings suggest that a two strapped rucksack should be used when carrying loads to reduce spinal muscle activity which may, in turn, reduce reports of back pain in female adolescents. Key words: electromyography, bag style, spinal muscles. Introduction Adolescent back pain complaints are causes muscular fatigue (Ibrahim, 2012; Piscione increasing with up to 75% experiencing back pain and Garnet, 2006). Reports of back pain are higher (Jones and Macfarlane, 2005; Skoffer, 2007). Bag in adolescent females compared to adolescent carrying has been associated with back pain males (Dockrell et al., 2006; Korovessis et al., (Grimmer et al., 2002) with 50% of adolescents 2005), which may be due to females having with back pain reporting links to bag carriage decreased upper body strength (Haselgrove et al., (Dockrell et al., 2006; Haselgrove et al., 2008; 2008). Skoffer, 2007). Back pain due to carrying a bag University students commonly carry a may occur as a result of increased activity of the bag for more than 30 min daily (Haselgrove et al., back muscles (Elfving et al., 2003) which, in turn, 2008) with the average bag load being 1 - Sport, Health and Exercise Subject Group, University of Hertfordshire, UK. Authors submitted their contribution to the article to the editorial board. Accepted for printing in the Journal of Human Kinetics vol. 45/2015 in March 2015.Brought to you by | University of San Francisco Authenticated Download Date | 3/10/17 10:29 PM 40 The effects of bag style on muscle activity of the trapezius, erector spinae and latissimus dorsi approximately 10% body weight (BW) (Heuscher examining muscle activity for a wide range of et al., 2010). The weight carried has been shown to different bag styles and there is a lack of research have little effect on posture or muscle activity in the current literature examining an all-female (Brackley et al., 2009; Grimmer et al., 2002), population, which is the population most at risk whereas the bag type and carrying method have of back pain (Dockrell et al., 2006). Therefore, the been shown to significantly affect muscle activity aim of this study was to investigate the effects of and posture (Hong and Xian Li, 2005; Kim et al., different bag conditions on muscle activity of the 2008; Korovessis et al., 2005; Motmans et al., 2006). trapezius, erector spinae and latissimus dorsi Common carrying methods used by adolescent muscles bilaterally in female university students teenagers are a 2 strapped (Dockrell et al., 2006; during walking. Motmans et al., 2006) or 1 strapped rucksack (Feingold and Jacobs, 2002), a shoulder bag (bag Material and Methods hangs from one shoulder strap on the same side of Participants the body) (An et al., 2010), a satchel (bag hangs Following institutional ethical approval, a from one shoulder strap across to the opposite convenience sample of 12 female university side of the body) (Hong and Xian Li, 2005) and a students (age = 20.6 ± 1.16 yrs; body height = 1.65 handbag (An et al., 2010). ± 0.04 m; body mass = 69.7 ± 11.3 kg) volunteered Asymmetrical bag carrying has been to participate in the study. Subjects were free of shown to cause an asymmetrical gait (Cottalorda any lower limb or back injuries at the time of et al., 2004) and decreased stride length (An et al., testing and provided written and verbal informed 2010). Also, previous research has concluded that consent before the commencement of the study. single strapped bags affect posture by causing, Procedure increased cranialthoracic spine rotation (Vacheron Subjects attended a single testing session et al., 2000), increased shoulder elevation wearing suitable trainers and sport’s clothing. (Korovessis et al., 2004) increased pelvic tilt Muscle activity was measured using surface (Vacheron, 2000), increased trunk lateral flexion, electromyography (EMG) (Biometrics Ltd, due to weight being on one side of the spine Newport, UK) with a sampling rate of 1000 Hz. (Pascoe et al., 1997) and increased lumbar flexion The EMG was pre-amplified and set at a and lordosis of the spine (Betanny-Saltikov and bandwidth of 20-450 Hz, noise ratio of<5 µV and Cole, 2012). These postural changes will likely rejection ratio of 60 Hz (dB>96dB). Surface cause an increase in muscle activity of the back electrodes were bilaterally fixated to skin parallel muscles responsible for maintaining posture in an to the muscle fibres (using adhesive stickers and attempt to maintain the location of the centre of tape) to the anatomical locations recommended by mass over the base of support during the gait SENIAM and Motmans et al. (2006). Integral dry cycle (Grimmer et al., 2002). This increased muscle reusable surface electrodes (SX230 Biometrics) activity has been linked with increased back pain with a fixed inter-electrode distance of 20 mm and injury (Chow et al., 2011). However, previous were attached using adhesive pads (T350). The research examining the effects of single strapped skin of each electrode site was cleaned using bags on muscle activity presents conflicting alcohol wipes. The trapezius electrode site was findings. For example, Quereshi and Shamus located 2 cm lateral to the third thoracic vertebrae, (2012) reported increased contralateral muscle erector spinae was located 2 cm lateral to first activity with asymmetrical bag carriage compared lumbar vertebrae and latissimus dorsi was located to symmetrical bag carriage, whereas Piscione and 2 cm distal to the inferior angle of the scapula Garnet (2006) reported no difference in muscle (Figure 1). An earth electrode was placed on the activity between symmetrical and asymmetrical wrist. carriage. The subjects were required to complete a Therefore additional research is required walking task during five bag conditions; 1) a 2 to further investigate the link between bag styles strap rucksack condition, 2) a 1 strap rucksack and activity of the muscles which maintain condition, 3) an ipsilateral shoulder strap posture of the body and may be associated with condition, 4) a contralateral shoulder strap back pain. Furthermore, there is little research condition, and 5) a no bag condition (control) Journal of Human Kinetics - volume 45/2015 Brought to you by | Universityhttp://www.johk.pl of San Francisco Authenticated Download Date | 3/10/17 10:29 PM by Rebecca Hardie et al. 41 (Figure 2). Bags were loaded to be equal to 10% of Results each subject’s BW. A bag of 10% BW replicates a university student’s load more accurately when Trapezius using male and female subjects, however, there is Muscle activity of the left trapezius was no female only guidance on bag weight (Dockrell significantly higher than the right trapezius et al., 2006). The order in which subjects were during the 1 strap rucksack condition (t(11) = 3.70, p ɳ2 required to perform the bag conditions was = 0.004, = 0.55).