Episode 128 | The Metabolic Cost of Carrying a Backpack

In what ways do you consider pack design as it relates to your metabolic efficiency or biomechanics – beyond just the weight of the pack or the weight of gear you’re carrying inside of it?

During the episode several articles where referenced. Would it be possible to share a list of these references?

Speaking entirely personally, a hipbelt “matters” because if fitted properly it takes weight off my shoulders and displaces it towards my legs. The leg muscles are by far the strongest muscles in our bodies.

But there’s another thing. Packs with no or poor structure can require weight be carried by the shoulders and/or spinal column. The spine isn’t designed to be an integral aspect of pack structure. Hence, hip belts and frames that can easily transfer weight off the shoulders and spine to the hips and legs–without sagging off the back and throwing the backpacker off balance.

so on Murali’s load lifters, a strange name for them if ever one was devised … if one is to have any kind of wrapping of the shoulder strap around the top are of the shoulder, then for the pack to be held against the body, one needs to have at least some amount of tension on the shoulder straps (sans load lifters). that sounds like a hurt to me, so we have LL’s and they work ok, as long as one adjusts them constantly and every time the shoulder strap length is changed, that gets old when you’re tired and thusly hardly nobody does it. to counter that and help explain the situation, one can look at a McHale pack and see that Dan cleverly (understatement term ) devised a design where he uses an additional independent strap for JUST holding the pack agains the body. it’s works good. one can set the back-to-pack gap/tension and let it sit there all day/week, changing shoulder strap lengths (thusly shoulder load carrying) at will many times a day. all good, especially at loads with like 50# of food, plus a raft, etc.

I suspect I may have shot my self in the foot over the years , because in an effort to load the pelvic area harder, I have bent the McHale stays to pre-load the lower back lumbar area, and this has maybe resulted in making me balance the effect with a bit of excessive pulling-in-the-pack straps tension, which hurts the front of my shoulders more that simply balancing the overhang of the pack might.

I recently returned the to less aggressive curve and we shall see interning how this goes down. the current set-up allows up to 60# to be carried nicely on the hips alone, but as mentioned, does pull on the front shoulders a bit over time.

post trip mods also include reducing the angle of “cant”, or cone angle, allowed by some customs belt mods, in order to gain belt contact area in the rear area of the belt at the lower sides. another thing needing to be tested under load.

cheers,

v.

“I have seen people doing 30+ miles day in and day out with both frameless and framed backpacks (1.5 lbs, 2 lbs, 3lb backpacks) on the PCT – for days/months without any issues” / “Personally, I carried a frameless and 5 lbs in hip packs/fanny packs and didn’t have any shoulder pain or spine issues with 27-30 miles every day – multiple multiple days on the trail.”

With conditioning and adaptation, of course. Without it, or with structural (esp. bone/joint/cartilage) biomechanical issues in the neck or spine, then probably not.

(we have strayed from the original thread – where I was arguing – the issues are too complex and too many factors at play to say there are some factors that will somehow reduce the metabolic cost of carrying a backpack).

I feel this is a misconception – that the spinal cord is not designed to carry lot of weight. We know weight lifters can carry enormous weights (2 to 3x their body weight) without breaking their spines. Of course they are doing it for a short period of time and they have specifically trained for this. But the point is, the spine doesn’t break.

Not trying to show off – but I did 800 miles of the PCT desert section this May 9th/June in 34 days with one zero and a few nero’s. I am 58 and carried a frameless packs (25 oz pack) with no hip belt. There was never a day where I felt fatigue on my shoulders or felt I made a mistake carrying a frameless pack. Remember this is the desert where we were doing frequent 15 to 20 miles of waterless sections carrying 3 to 4 liters several times and it was hot! I encountered one other frameless person (didn’t ask his age – probably late 30’s, early 40’s) doing similar miles as me with a Palante pack – he was faster than me and was a day or two ahead after some time. Met one 24 year old guy with a atom+ pack (with a minimal carbon hoop frame) and a 36 year old guy with REI Flash 55 (2.75 lbs) pack doing similar miles. Your body adapts after some time and doesn’t matter what kind of pack you are carrying – frameless or framed.

Of course we are all carrying similar weights probably 2 to 3 to 5 lbs difference between framed and frameless folks – but we all could do similar miles day in and day out without any issues. Of course we all suffered from lots of blisters on feet – but, legs/body were fine.

I don’t think frameless folks are carrying frameless to reduce weight – as after all the difference between framed and frameless is usually 1 to 1.5 lbs and in my book – 1 to 1.5 lbs saving is not a good reason to go to frameless. There are several other advantages of carrying a frameless – breathe better without hip belt – which will help you go up hills with less effort/fatugue, shoulder and hips not tied together – more freedom of movement. In fact on the SHR, one of my hiking partners with a framed SWD pack was complaining of shoulder pain while I didn’t have any carrying a frameless.