Effects of a pre-moistened multilayered breathable fabric in promoting heat loss during recovery after exercise under hot conditions

Reasons for performing study: Horses generate considerable internal heat burdens when exercising. Although common practice for a trainer or groom to place a wet blanket or towel on the dorsum of a hot horse post exercise, there are no data supporting the efficacy of this cooling method. Objective: To test the hypothesis that a pre-moistened blanket designed with a multilayered breathable fabric would enhance heat loss in horses post exercise. Methods: Eight treadmill-trained horses performed a standardised exercise test (SET) weekly for 3 weeks, with 3 different recovery treatments administered randomly. Pulmonary artery temperature (PAT) was measured via Swan-Ganz catheter. The SET consisted of 10 min at 3.7 m/sec, 3 min at 11.0 m/sec, 25 min at 3.7 m/sec and 20 min of recovery walking at 2.0 m/sec (58 min exercise and recovery under laboratory conditions of 35.0-40.6°C and 27-49% RH). From 3-7 min during recovery, the treadmill was stopped and horses randomly received either: (a) no bath (negative control); (b) a bath consisting of 32 1 of 1-4°C water split into 3-4 cycles of bilateral water application (positive control) followed by water removal ('scraping'); or (c) application of a multilayered fabric blanket soaked in 16-19°C water, wrung out, and placed over the dorsum and sides of the horse. PAT was compared using RM ANOVA with the Student Neuman-Keul's test used post hoc to discriminate between treatments at specific points in time. Results: Mean PAT rose with each phase of exercise (P<0.001) and peaked at a mean of 40.2 ± 0.2°C. During recovery, the cold bath decreased HR and PAT for 9 min after walking resumed (P<0.001-P<0.05). The blanket did not decrease HR or PAT compared to negative control (P>0.05), and both were hotter than the cold bath treatment through 16 min of recovery (P<0.05). Conclusions: A specially-designed cooling blanket failed to reduce PAT when compared to negative control. Cold water bathing decreased HR and PAT but was not effective throughout all of recovery. Potential relevance: A specially-designed, pre-moistened multilayered breathable fabric failed to promote evaporative cooling compared to negative control. Cold water baths may need to be repeated throughout recovery to optimise their effect.