Physiological and biochemical profiles of six elite Canadian 800 meter runners are presented. Anthropometric data was recorded. Aerobic capacity was assessed on a treadmill run to fatigue; the initial treadmill velocity was 2.22 m X s-1 increasing by 0.22 m X s-1 each minute. VO2max was determined by the mean of the four highest consecutive 15 second values. The Anaerobic Speed Test (AST) (20 degrees incline, 3.52 m X s-1 to fatigue) was used to assess anaerobic performance characteristics. Two minute post-AST blood samples were analyzed for lactate. Needle biopsies were obtained at rest from the vastus lateralis muscle. The muscle fibers were classified and a homogenate of the muscle was used in the determination of buffering capacity. These are young athletes with a low percentage body fat. The mean VO2max was 63.6 +/- 2.9 ml X kg-1 X min-1. The anaerobic capacity is striking with the mean AST time of 114.3 +/- 16.3 seconds and post-AST lactate values of 22.0 +/- 1.4 mmol X l-1. The skeletal muscle buffering capacity was elevated above normal by 50% indicating an enhanced capability of resisting changes in intracellular pH which may affect performance.