Originally Posted by chroma

One risk factor for aggravating TOS, which I personally experienced, is brisk walking with the arms held straight. This pulls on the shoulder girdles and can add to the compression.

If you google for "power walking" you will see every article on power walking recommends keeping your arms bent. I've seen different reasons cited including "to avoid traction injuries" and to avoid finger swelling.

Something to keep in mind when you're hiking.