From Longman Dictionary of Contemporary Englishheavy breathingheavy breathingBREATHEbreathing that is slow and loud → heavy breather → heavy
Examples from the Corpus
heavy breathing• The staff relaxed, until the building started expanding and contracting - an effect they described as akin to heavy breathing.• They heard heavy breathing and a figure appeared round the corner, clothed in the grey garb of Godstowe Priory.• The cabin was full of heavy breathing and the stink of our sweat.• There was no sound except the heavy breathing around him; the whole world seemed asleep.• The rustling of bushes and the sounds of heavy breathing at the sandbar to the north deepened the stillness of dusk. 