Correlation of symmetrical gaits and whole body mechanics: debunking myths in locomotor biodynamics.

Independent maturation of gait (Hildebrand) and whole body mechanics (Cavagna et al.) traditions in locomotor analyses has led to conflicting terminology. Re-evaluation of these traditions yields three primary insights. First, walking and running should be recognized by their fundamentally different mechanics. Because duty factor fails to consistently distinguish these mechanics, its use in discriminating walks from runs should be abandoned in preference to parameters that more accurately reflect the movements of the center of mass (COM; phase difference in external mechanical energy or Froude number). Second, "trot" should be reserved as a descriptor of a particular footfall pattern. This and all gait terms lack explicit information about limb compliance and thus COM movements. Third, symmetrical gait definitions should be broadened to reflect the four primary footfall patterns: the lateral-couplet dominated pattern of the pace, the diagonal-couplet dominated pattern of the trot and the more independent sequencing of footfalls of the two singlefoots. Intermediate gaits (perennially confusing and a mouthful to pronounce) are thereby subsumed by these four discrete gaits. Confusion between gait terminologies would be avoided if limb phase were consistently reported.