Ariadne - the problem with the elbow is, most probably, a repetitive strain injury. My OH had a similar problem when using a strimmer for lengthy periods. After a visit to a specialist because he was in so much pain, he was told to "pace himself" with the strimmer and only do a little at a time with gaps of a week or so between - allows the arm to recover. Just be careful. I'm not sure, but is "Tennis Elbow" a similar condition?
Meggie