The "tolt", by definition, is a gait of one foot / two foot support sequence. When it switches to two foot / three foot support, it is no longer a "tolt" by definition. It becomes a "saddle" gait.
Nicodemus, M.C and Clayton, H.M. (2003)
Temporal variables of four-beat, stepping gaits of gaited horse
Applied Animal Behavioural Science 80, 133-142
Gaited horse breeds perform a variety of four-beat stepping gaits that are
recognized and distinguished by the sequence and timing of the footfalls and
by the limb support sequences during the stride. The popularity of the
gaited horse breeds is increasing and accurate descriptions of limb
kinematics are needed both to define the performance characteristics of the
different gaits and to assist in identifying gait pathologies. The objective
of this study was to measure the temporal stride variables of 16 four-beat
stepping gaits using frame-by-frame analysis. The gait sequences used for
analysis were selected by the breed associations as being representative of
correct performance of each gait. The results showed that all gaits were
classified as symmetrical. A regular four-beat rhythm was present in the
classic fino, coon rack, marcha picada, mountain pleasure rack, paso llano,
rocky mountain rack, style rack, road gait, and tolt. An irregular rhythm
with diagonal couplets characterized the fox trot, marcha batida, paso
corto, and paso largo, while lateral couplets were found in the running
walk, curly rack, and sobreandando. Three distinct limb support sequences
were identified, with only the marcha batida demonstrating a period of
quadrupedal support. Hind limb stance was longer than forelimb stance in the
paso corto, paso largo, style rack, and running walk.
A recent study (M. Nicodemus, MSU; H. Clayton, MSU, College of Veterinary Medicine; McPhail Equine Performance Center, AABS 80, 2003), analyzes the symmetrical four-beat gaits of gaited horses as each performs their signature smooth gait. Video tapes of these horses were used in the study to examine each breed's recognized gait. These videos, showing correct movement, according to the associations, were supplied by the appropriate breed associations. Breeds included were: Paso Fino, Florida Cracker, Gaited Curly, Missouri Fox Trotter, Mangalarga Marchador, Mountain Pleasure, Peruvian Paso, Rocky Mountain, Racking, Singlefooter, Tennessee Walker, and Icelandic Horses.
Three horses representing each breed, selected by the breed associations, were ridden by professional gaited horse trainers, at speeds appropriate for the gait. This was determined by the respective trainers and breed associations. Each horse was currently competing at a national level for their breed association.
Five strides from each horse were analyzed. Each of the strides used in the study were approved by the respective trainers and breed associations as correct for the gait being demonstrated. The videos were analyzed frame by frame for ground contact and lift-off. Support phases consisted of quadrapedal, tripedal, diagonal bipedal, lateral bipedal, and unipedal.
The results showed the "tolt" to have a regular four-beat rhythm, with two foot / three foot support, rather than the described one foot, two foot support. In discussion of the results, a previous study (abstract below) was referenced, which revealed only seven of 23 horses showed the accepted tolt pattern (one foot / two foot support) at one or two speeds, and all horses showing one to three gait variations at different speeds.
The gait might have been a pacey tolt, but the study says it was a regular four-beat, so that leaves us with a saddle gait.
From the McPhail study: "It might be concluded that the tolt can be performed in many ways and that the present definition may be too narrow to encompass the natural variability of this gait."
In summary, the tolt exhibited in videos supplied by the breed association, performed by horses at national competition level, ridden by professional riders, was determined to be in actuality a two foot / three foot saddle gait. Additionally, according to the previous study referenced, the one foot / two foot tolt (as defined for the gait), was found only within a small segment of the horses surveyed, and then only within a limited speed range.
The following is an abstract of a study done on the tolt, which reflects that true tolt "is present only over a narrow speed range".
Motion pattern of the toelt of Icelandic horses at different speeds.
Zips S, Peham C, Scheidl M, Licka T, Girtler D
Equine Vet J Suppl 2001 Apr :109-11
"The toelt of the Icelandic horse is a symmetric 4-beat gait, with alternating single and double support phases. By definition, the duration of the diagonal and ipsilateral stance phases should be similar. The aim of this study was to investigate the stride characteristics of horses ridden at toelt, and to compare these to previous descriptions of this gait. The kinematics of 23 Icelandic horses was measured using the Expert Vision System. Mature and sound horses, used for pleasure riding and / or competitions, were ridden at toelt at 3 different speeds. For each horse, 10 strides were measured at toelting speeds of 2.9 m/s (s.d. 0.28), 3.7 m/s (s.d. 0.29) and 4.7 m/s (s.d. 0.53). Seven horses showed true toelt pattern at one or 2 speeds. At the highest speed, 60% of all motion cycles showed the pattern of 4-beat pace. This investigation shows that the previously described toelt pattern is present only over a narrow speed range, and toelt at extended speed is, in fact, a 4-beat pace or rarely a 4- beat trot."