Routine determination of oxygen consumption by means of treadmill tests have achieved great popularity as an assessment of exercise metabolic function. Treadmill testing allows for precise measurement of oxygen consumption with minimal effects from the subject's skill.3 The use of treadmill testing to diagnose cardiac disease, to determine progression of cardiac disease, and to prescribe exercise programs for patients and athletes requires an awareness of all factors that may influence test results.A subject evaluated in the Oklahoma State University Human Performance Laboratory suggested that a difference in leg length influenced oxygen consumption values obtained by means of treadmill testing. In order to more precisely determine the effect of leg length differential on oxygen consumption, this subject was tested with two leg length conditions, one test with a difference of 28.6 millimeters and a second with no difference in leg length. The two leg length conditions were used for three work loads: 1) progressive increase in the elevation of the treadmill during a 20-minute test; 2) constant elevation of the treadmill at a 20% grade for 20 minutes; and 3) a constant treadmill elevation of 16% for 20 minutes.The subject was a 30-year-old female who at an early age suffered damage to the distal epiphyseal plate of the right tibia. Due to the disruption in growth, the right leg was 28.6 millimeters shorter than the left as measured from the anterior superior iliac spine to the distal end of the medial malleolus. The 154-centimeter-tall 44.5-kilogram female was on a daily running program averaging 90 points per week based on the Cooper aerobic point system.'The subject reported to the laboratory for testing on the same day and at the same time for 4 consecutive weeks. The subject had not exer- cised during the preceding 36 hours and had not eaten during the preceding 8 hours. A 4-day period elapsed between each test. The order of testing was randomized with respect to the leg length variable and workload.The leg length was determined with the subject standing with feet positioned together. The vertical distances from the right and left anterior superior iliac spines to the floor were determined with a plumb line. In this manner, it was possible to determine the amount of shoe lift needed to establish equal leg length. The measurements obtained were validated by utilizing calibrated blocks of 2-millimeter thickness added under the heel of the short leg until the anterior iliac spines were level. A shoe lift constructed of cork and foam rubber was devised to compensate for the 28.6-millimeter difference in leg length.Prior to testing, the subject rested in a supine position until the heart rate stabilized at a constant rate for 5 minutes. The heart rate was monitored by telemetry and recorded on a paperpen recorder. When the heart rate stabilized, a 2-minute pulmonary gas sample was collected. This sample and all subsequent gas samples were corrected to standard atmospheric conditions prior to analysis for oxygen con...

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