| Objective: To review current scientific knowledge pertaining to backpacks and various other modalities employed to carry loads. A second objective of this paper is to comment on current methods of assessing the effects of load and carriage on the human body. The reviewers have contrasted the potential benefits of surface electromyography (s-EMG) over metabolic assessment measures in preparing this review. Data Sources: The current scientific literature was examined using the MEDLINE® database and was accessed using the PUBMED® online search engine. The MANTIS® database was also searched for additional material. Study Selection: Sixty-three journal articles were chosen from a selection of 104. Of these, 38 that pertained to the aims of this discussion were included. Data Extraction: The journals were selected based on relevance to the topic discussed, i.e. results pertaining to EMG, metabolic measurement approaches, assessment of different load carriage methods, load placements on the spine as well as effects loads have on the spine, gait or general biomechanics of the human frame. Data Synthesis: From the literature, we find that EMG is a valid but poorly utilised tool in assessing the effects of load on the human frame. There is yet little evidence to suggest a clear rationale behind the determination of an ideal backpack weight that can be used as a guideline for advising wearers. Conclusion: Ideal load placement on the human frame requires further and more detailed study. The relationship between the level of perceived exertion and the EMG trace still requires further large-study investigation. The literature supports the notion that Mean Power Frequency (MPF) analysis can be used as a reliable and repeatable method of determining fatigue in smaller muscle groups. Its use should be favoured against more global and less specific metabolic measures. Observations in both children and adolescents have found that painful syndromes may occur because of overloaded backpacks. Longitudinal observations are needed to confirm a causative link between these loaded states and painful syndromes. This abstract is reproduced with the permission of the publisher; full text (print only) by subscription.
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