Parameters of forelimb ground reaction force in 48 normal ponies

Abstract

Recordings of forelimb ground reaction forces were made from 48 normal ponies moving at the trot, to evaluate the relationships between bodyweight, vertical ground reaction forces, the timing of individual events within the stance phase and the total contact time. There were highly significant correlations between the mean vertical ground reaction forces and bodyweight. The mean vertical ground reaction forces, corrected for bodyweight, were inversely correlated with the total contact time suggesting that higher trotting speeds may be associated with greater vertical ground reaction forces. The ponies' bodyweights were positively correlated with the contact time, implying a reduced stride frequency with increasing size. The ground reaction force events in the mid and late stance phases occurred at consistent fractions of the total stance time. The ground reaction forces and time parameters were highly symmetrical.

Use of a stand-alone pressure plate for the objective evaluation of forelimb symmetry in sound ponies at walk and trot

“…The mean PVF and VI measurements of five trials of the sound ponies in the present study had a high symmetry ratio (>95%), which is comparable to those obtained using a force plate in horses with PVF symmetry ratios of 94-99% at walk and 97% at trot (Merkens et al, 1986(Merkens et al, , 1993 and in ponies, with PVF symmetry ratios of 99-100% at trot (Barr et al, 1995). Merkens et al (1993) used leftto-right symmetry quotients in horses, while Barr et al (1995) calculated the symmetry ratio in ponies by dividing the value from one randomly chosen forelimb by the value from the contralateral one.…”

“…Absolute kinetic values Barr et al (1995) only supplied quantitative ground reaction force date in his study on 48 ponies, whereas in the present paper, a graphical representation of the vertical ground reaction force at walk and at trot is shown. Although it was not our aim, the possibility of detailed analysis of the four individual quadrants, as quantitatively assessed by Back (2003, 2007), is another distinct advantage of the pressure plate over a force plate, as it demonstrates the subsequent loading of the different portions of the foot during a complete stance period.…”

“…The aims of the study were to investigate whether pressure plate measurements and their symmetry ratios recorded on different days in a group of sound ponies using a stand-alone system were repeatable, and whether absolute values were similar to previously reported force plate data in ponies (Barr et al, 1995).…”

“…* 'dimple' in the vertical ground reaction force curve in the early stance phase ( Barr et al, 1995). Although the mean BW of the five ponies in the present study (279 kg) was higher than that of the 48 ponies (189 kg) in the study of Barr et al (1995), the slightly higher forelimb PVF in ponies at trot compared to other breeds such as Dutch Warmbloods (118% BW) (Merkens et al, 1993), Standardbreds (113% BW) (Seeherman et al, 1987), Thoroughbreds (108% BW) (Dow et al, 1991) and Quarter Horses (101% BW) was confirmed.…”

“…Merkens et al (1993) used leftto-right symmetry quotients in horses, while Barr et al (1995) calculated the symmetry ratio in ponies by dividing the value from one randomly chosen forelimb by the value from the contralateral one. In the present study, we used lowest highest mean value of five valid trials per pony  100% to be independent of handedness of a leading limb and so keep values <100%.…”