His research on the intertidal zone of wave-swept shores has led to increased understanding of this habitat. His most publicized research is his work on locomotion of water striders, which led to the coining of the term "Denny's paradox" to explain a discrepancy between physics and previous understanding of how surface-dwelling animals such as these insects move.
In 2008 he examined greyhounds, thoroughbred horses and human athletes trying to find their maximum running speed. He predicted the fastest possible time for men's 100 metres will be 9.48 seconds.
