Determination of the lactate breakpoint during incremental exercise in horse adapted to dietary corn oil

Objective-To determine lactate breakpoint of horses and test for effects of training and dietary supplementation with corn oil on that breakpoint. Animals-7 healthy Arabian horses. Procedures-Horses received a control diet (n = 4) or a diet supplemented wi th 10% corn oil (4). A training program, which comprised two 5-week conditi oning periods with 1 week of rest, was initiated. Submaximal incremental ex ercise tests (IET) were conducted before the first and after both condition ing periods. Blood samples for determination of blood lactate and plasma gl ucose concentrations were collected 1 minute before IET and during the 15 s econds immediately preceding each speed change. Data collected were fit to one- and two-slope broken-line models and an exponential model. Results-Good fits were obtained by application of the broken-line models (a djusted R-2 > 0.92) to blood lactate concentration versus speed curves. Lac tate breakpoints increased 41% after training, After training, slope 2 and peak blood lactate concentrations were greater in the corn oil group, compa red with controls. Mean blood lactate concentration at the breakpoint was n ot affected by training or diet. Plasma glucose concentration versus speed curves also fit the broken-line models, and glucose breakpoints preceded la ctate breakpoints by approximately 1 m/s in the second and third IET. Conclusions and Clinical Relevance-Lactate breakpoints can be determined fo r horses, using blood lactate concentration versus speed curves generated d uring submaximal IET and may be useful for assessing fitness and monitoring training programs in equine athletes.