What Is a Step Test at KER?By Kentucky Equine Research Staff · January 1, 2015
At Kentucky Equine Research, studies are designed to measure various exercise parameters in horses. One tool used to measure conditioning is a step test. This test is performed to determine maximum aerobic capacity and to estimate the fitness level of a horse.
During a step test, a horses runs on a high-speed treadmill, with the speed being gradually increased until maximum oxygen consumption is reached. Indirect calorimetry is used to measure oxygen consumption and carbon dioxide production to determine when maximal oxygen consumption occurs.
Throughout the step test, heart rate is measured. Blood samples are pulled during the last 15 seconds of each speed interval, and plasma from the blood is analyzed for certain metabolites, commonly glucose and lactate.
Two fitness parameters are ascertained during a step test, V200 and VLA4. V200 is the speed at which the heart rate reaches 200 beats/minute. VLA4 is the speed at which plasma lactate concentrations reach 4 mmol/L.