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Rubber bands reduce the cost of carrying loads

An Author Correction to this article was published on 05 April 2019


Vertical movement of the hip during locomotion causes a loaded backpack to be accelerated with each step1, which imposes large peak forces on the wearer. Here we show that using bungee cords to suspend the load from a backpack frame reduces not only its vertical movement, and hence its vertical force on the carrier, but also the energetic cost of walking with the pack. This permits larger loads to be carried while moving rapidly, and at the same time reduces the risk of orthopaedic and muscular injury.

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Figure 1: Suspended-load ergonomic backpack.
Figure 2: Vertical position of, and force exerted by, a 27-kg load carried by a hiker walking at 5.6 km h−1.


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Corresponding author

Correspondence to Lawrence C. Rome.

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Competing interests

L Rome formed an entity (Lightning Packs LLC) in 2004 to hold intellectual property (one patent issued 2006 and others pending), and eventually develop the electricity-generating backpack. L Rome and his family own all the equity in this entity. This entity remained dormant until 3 months ago (after the completion of the work in this manuscript), when it received modest small business grants from the US government to pursue commercialization of the electricity-generating backpack. The other authors, Louis Flynn and Taeseung Yoo are not involved in the entity, nor do they have any financial interest in the entity.

Supplementary information

Supplementary Information

Contains supplementary methods, supplementary tables and reference lists.

Video 1

Running with locked backpack

Video 2

Running with suspended backpack

Video 3

Suspended and locked backpack Side by Side

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Rome, L., Flynn, L. & Yoo, T. Rubber bands reduce the cost of carrying loads. Nature 444, 1023–1024 (2006).

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