The "strut" sound, as in the words up, supper, and love, is quite different in the US than it tends to be in the UK. Americans tend to make it very much like the schwa sound, so that the vowel in both syllables of "above" sound possibly identical. Coaching ESL speakers may require a shift from what they're used to so that Americans more clearly understand them - and Americans need to make a subtle shift in this vowel for most British accents as well.
Jim covers these concepts in this video:
View Video Files