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Ergonomic shoulder straps that reduce shoulder pain


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  • #3740407
    Nenta WAKO, Dr.Eng.
    BPL Member

    @nentaw_backpackresearcher

    Companion forum thread to: Ergonomic shoulder straps that reduce shoulder pain

    Two methods for reducing backpack shoulder load have been well known.
    One is the load distribution to the lower back with hipbelt or lumbar pad. The other is the load distribution within the shoulder area…

    #3740615
    Rex Sanders
    BPL Member

    @rex

    Interesting! If I understand your video correctly:

    – Keeping heavy weight close to the back is very important for reducing pain.
    Good to know that measurements confirmed conventional backpacking wisdom.

    – Changing shoulder pad thickness can also reduce pain.
    The diagram looks like pad thickness and pressure was less over the clavicle, transferring more pressure across the top of the shoulder, and just below the clavicle.

    As you noted, with only 8 male subjects, hard to know if this design works for a wider range of people. Are you planning any more tests?

    — Rex

    #3740790
    Nenta WAKO, Dr.Eng.
    BPL Member

    @nentaw_backpackresearcher

    Rex,
    Thank you for your comment.

    In the experiment, the strap didn’t have an buffering effect by itself as it was made of solid PVC sheet. And the pad for padded level was the same material. The purpose was to investigate the effect of load separation.

    Regarding the small number of subjects, I couldn’t perform the experiment fully owing to Covid pandemic.
    Now this research has closed, but when the product whose spec is applied is developed, I will confirm this effect, again.

    For the loading on the clavicle, some adverse effects are reported. So, its load needs to be reduced. What I have to investigate is the adverse effect due to loading on the portion under the clavicle.

    #3741313
    Russell Biser
    BPL Member

    @rbiser

    Have you compared this to Klattermusen’s butterfly bridge / carry on bone system which seems to do the same thing?

    #3741321
    Johan
    BPL Member

    @johan-river

    Locale: Cascadia

    Interesting stuff. As someone who suffers from spinal birth defects and can’t hold much weight on my shoulders regardless of strap design, I have found that once a pack is beyond the 20lb mark, using a front pack eliminates all of my shoulder and back pain. It does require a more robust hip belt to then take the load, but the system works great. My front pack only adds 1 ounce of weight because I modified my bear bag to clip to my shoulder straps and hip belt.

    I personally think not anywhere close to enough people are using chest/front packs that hook into either the shoulder straps or go around under the armpits and connect directly to the main pack. Beside shoulder pain, there is also a lot of energy loss in trying to keep one’s body balanced with a huge imbalance in the load.

     

    #3741371
    Nenta WAKO, Dr.Eng.
    BPL Member

    @nentaw_backpackresearcher

    Russell,

    Thank you for your comment.
    I haven’t tried butterfly bridge.
    It seems easy to establish the strap position onto the clavicle when users wear the backpack to place V-shaped frames over the clavicle.

    And regarding the clavicle load, it would be designed for applying larger in lateral part than in medial part. It might be reasonable design for the clavicle to avoid moving downward that compress the brachial plexus and axillary artery, relatively.

    But, on the whole, it is designed to support the load on the clavicle positively. So, I think it would be an opposite concept for my suggestion.

    #3741381
    Nenta WAKO, Dr.Eng.
    BPL Member

    @nentaw_backpackresearcher

    Johan,

    Thank you for your comment!
    Even if shoulder load is distributed within shoulder area, the compressive load of intervertebral discs can’t be reduced. So, in your case, I think that distributing to the lower back is necessary. Also, it is necessary for your lumbar spinal moment to be reduced by way of keeping load balance between front and back even.

    Contrarily, the constraint due to hip belt generally brings compensation in walking motion.
    It reduces the relative phase between thorax and pelvis in walking with backpack and hip belt, comparing to that in natural walking. And, to keep the same walking speed, it’s necessary for stride larger, regardless of less range of pelvic rotation.

    Considering both aspects, users should choose a better way to reduce shoulder load depending on their situation.

    #3741388
    Russell Biser
    BPL Member

    @rbiser

    Nenta,

    “But, on the whole, it is designed to support the load on the clavicle positively. So, I think it would be an opposite concept for my suggestion.” It doesn’t feel like it. Having used it myself it does seem to deload the clavicle itself if one side of the V is on each side of the clavicle, and the stiffening provided by each arm of the V accomplishes something like the thickened padding does in your straps.

    “it would be designed for applying larger in lateral part than in medial part.” I have not noticed this in actual use.

    Achieving this with differing padding thicknesses is more elegant, manufacturable, and ultralight though, so style points to you.

    #3741389
    Nenta WAKO, Dr.Eng.
    BPL Member

    @nentaw_backpackresearcher

    Russell,

    Thank you for sharing user review!
    Sorry, I haven’t actually try it.
    Therefore, my comment was a design review only based on the description of official site. The actual performance seems to be different.

    I want to try it, one day! Thanks.

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