From Longman Dictionary of Contemporary Englishfighting fitfighting fitBritish English extremely fit and healthy → fight
Examples from the Corpus
fighting fit• Masie had responded brilliantly to treatment and seemed fighting fit.• She was taken in by Maggie Taylor and now five month old Teka is fighting fit and lapping up all the attention.• Consequently, it hosts an excellent wild brown trout population and fish are pink-fleshed and fighting fit, averaging 10oz in weight. 