And the winner for best packed bag goes to... soldiers!

The infantry gets a bad wrap for being stereotypical ‘knuckleheads’, but alongside their marksmanship training and rucksack marches, they learn the genius behind the physics of packing a bag.

Whether you hate or love maths, lifting and carrying is all about physics. The infantry knows this better than most as they march across rough terrain, forests, and urban operations in full gear. Depending on the job of the soldier, the weight carried varies across their tactical vest and pack. On average, the typical American soldier trains with around 100 lbs of gear. This spans across their rucksack, weapon, canteen, and tactical vest (1). Fighting weights have been recorded anywhere from 53 lbs, for day missions, to 159 lbs. Overall mission weight had an average of 119 lbs for teams that fought in Afghanistan (1).

The physics of weight was briefly described in my article, “What's the deal with different shovels and how can that change my back pain?”. I mentioned that the ‘moment arm’, the distance between a weight and your center of mass, of any object has an impact on how much force you need to lift that object. Picture this: If you hold a 10 lb weight close to your chest and then again with your arm straight out in front of you, that 10 lbs will feel very heavy farther away. It still weighs 10 lbs regardless but by increasing the moment arm between you and the weight, it feels extra heavy. The same thinking is used when adding weight to a march or when you are shipped off to the field. Your vest and bag are packed according to the mission where the heaviest items are generally closest to your torso and the lowest they can be.

In a more relatable world, packing our own backpacks and luggage should take account of this idea. For a typical student, textbooks and laptops should stow away close to the torso as they are heavier items. Our snacks, accessories, etc. should go into the main pocket or on top of anything that outweighs them. Thinking about luggage, a wheeled bag should be packed with the heaviest items by the wheels to make it more stable and easier to pull.

Most moment arm ideas become common sense when you break them down. We can drastically reduce the strain that we feel just by using the Tetris packing skills that we developed from childhood.

Happy packing, happy backs,

Dr. Cole Maranger DC

1. Fish, L. & Scharre, P. (2018). The Soldier’s Heavy Load. Centre for New American Security. Retrieved from: https://s3.us-east-1.amazonaws.com/files.cnas.org/hero/documents/CNAS_Super-Soldiers_4_Soldiers-Heavy-Load-FINAL-2.pdf?mtime=20180926112023&focal=none