Comparison of predicted and measured physiologically equivalent trot–gallop transition speeds. Comparison of predicted and measured physiologically equivalent trot–gallop transition speeds. (A) Northern breed, (B) hound and (C) retriever dogs. The figure shows stride frequency in relation to locomotor speed while moving on a level outdoor transect. Each data point is a single measurement for a test run by an individual dog. Dash–dot lines represent the minimum and maximum range of the data across speeds. The gray box denotes the difference between measured (dashed vertical line) and predicted (dotted vertical line) (Heglund and Taylor, 1988) trot–gallop transition speeds for each breed. Pseudo-linearity of data within each group is caused by limited variation of speed–stride frequency measurements resulting from the 10 m outdoor transect length used during data collection. Caleb M. Bryce, and Terrie M. Williams J Exp Biol 2017;220:312-321 © 2017. Published by The Company of Biologists Ltd