Comparison of girth materials, girth tensions and their effects on performance in racehorses

Objective To compare the effect of girth materials and commonly used girth tensions on athletic performance of racehorses and to test the length tension properties of commercially available girths. Procedure Seven horses were exercised at speeds to produce 95% of maximal heart rates on 15 occasions using a randomised block design, and girthed with 5 different girths at 3 nominal tensions of 6, 12 or 18 kg. The girths used were a standard elastic race girth, an ‘American’ elastic race girth, an elastic race girth twice the normal width, a standard canvas race girth and a canvas race girth at twice the normal width. Tension in the girth was recorded continuously using an in‐line load cell connected to a physiograph. Horses ran to fatigue on a treadmill inclined at 10% slope. Tensions were measured at peak inhalation (T/inh) and exhalation (T/exh), recorded at rest (rest) and during exercise (ex). An analysis of variance was used to compare the mean run to fatigue times (RTFT) between girth types and tensions, multiple pair‐wise comparisons were then carried out using Tukey's test where significant differences were found. The length‐tension relationships of five commercially available girths for training and racing of Thoroughbred racehorses were studied by the application of standardized weights in series to multiple samples of each type of girth. Measurements were taken in a controlled environment and analysis of variance was used to compare the means for length‐tension of each girth type. Results The elastic and the ‘American’ elastic girths produced significantly longer RTFT when compared to the standard canvas girth (P=0.01 and P = 0.001 respectively). Also girths tensioned at Texh rest 6 kg and Texh rest 12 kg produced significantly longer RTFT than when girthed at Texh rest 18 kg (P=0.03 and P = 0.08 respectively). There were significant differences between the commercially available girth types at each tension (P < 0.05), but differences were not significant between girths of the same type. Girths with an elastic component reached their peak for maximum extension at 14.5 kg and thereafter their extension declined. Conclusion The type of girth and the tension at which it is applied affects athletic performance. Lower girth tensions and the use of elastic materials in the girth would appear to optimise performance. However according to this study and our previous study, none of the commercially available girths studied would adequately protect against the potentially detrimental effects of overtightening on athletic performance.