Effects of different head-loading masses on the posture and neuromusculoskeletal profile of pubescent girls living in the ILembe district of KwaZulu-Natal, South Africa

Abstract

Head-loading is a longstanding traditional method of transportation commonly practiced in rural African communities. This method of  transportation is necessary but has adverse health concerns. This study was conducted to determine the effects of different head-loading  masses on the posture and neuro-musculoskeletal health of pubescent porters living in ILembe District of KwaZuluNatal, South  Africa. A cohort (n=120) of pubescent girls (aged 9-13 years) voluntarily partook in a pretest-posttest cross-over study. The participants’  craniohorizontal angle (CHA), craniovertebral angle (CVA), and selected kinanthropometrical heights were measured when they carried  headloads equivalent to 25% and 50% of their body mass as well as during an unloaded state. Furthermore, participants completed a  cranial loading health questionnaire. The CVA (18.5±3.0vs15.8±3.2°) and CHA (36.1±4.2vs33.6±4.5°) increased when the participants  headloaded 25% of their body mass compared to the unloaded state (p<0.01). Similarly, CVA (20.7±3.2vs15.8±3.2°) and CHA  (38.3±4.5vs33.6±4.5°) increased when head-loading 50% of their body mass in contrast to the unloaded state (p<0.01). During 25% head- loading, standing vertex height (SVH) (1.34±0.07vs1.42±0.1m) diminished (p<0.01), while shoulder height (1.17±0.08vs1.16±0.1m)  increased (p>0.05) as compared to the unloaded state. The participants’ SVH (1.43±0.08vs1.42±0.1m) and shoulder heights  (1.14±0.08vs1.16±0.1m) significantly changed when head-loading 50% of their body mass compared to the unloaded state (p<0.01). Head- loading produced neuro-musculoskeletal pain in the neck (30.5%), lower back (28.5%), shoulders (24.8%), and knees (10.6%) (X 2=0.001).  When head-loading 25% of body mass, the CVA and CHA increases were accompanied with a diminished SVH, suggesting that  participants experienced cervical intervertebral disc compression and posterior cervical vertebral translational movement. However,  when the participants head-loaded 50% of their body mass, CVA, CHA, and SVH increased, while shoulder height decreased. This  indicated that the girls presented with posterior cervical vertebral translation and cervical, thoracic, and lumbar intervertebral disc   compression, producing neuro-musculoskeletal pain and postural misalignment.