mmma Previous studies on cycling cadence have focused on the economy of the cadence. in search of the optimal pedal cadence. The purpose of this study was to determine the hemodynarnic changes associated with varylng pedal cadence at a constant workload. It was hypothesized that increased pedal cadence would enhance the skeletal muscle pump, resulting in elevation of cardiac output. Seven cycllsts were enlisted to cycle at 200 watts at pedal cadences of 70.90 and 110 rpm (random order). Oxygen uptake. heart rate. stroke volume, cardiac output. blood pressure. and vascular resistance were determined. As has been previously shown, oxygen uptake increased with increased cadence (70. 90. 110 rpm) at this workload. Heart rate. stroke volume. cardiac output and blood pressure were increased. and vascular resistance decreased, with increased cadence. Cardiac output increased (34 %)in excessof theincrease in oxygen uptake (15 %) as shown by the decrease (-14.5 %) in the arterial-venous oxygen difference occurring with increasing cadence. Apparently, even though the workload was constant, the increase in pedal cadence resulted in a more effective skeletal-muscle pump which increased muscle blood flow and venous return. It is not known if this might contribute to the natural selection of higher cadences by cycling athletes. even though there is reduced economy.a Key words: Pedal frequency, cardiac output, skeletal-muscle pump, cycling economy, cardiovascular l ntrod udion The cadence used by cyclists has been investigated as to the most efficient or economic pedal frequency required for performance (3.7.12.18,19,24). A non-linear reltionship appean to exist between oxygen uptake and pedal cadence (3). In general, investigations have indicated that oxygen uptake increases at pedal cadences both below and above an "optimum" pedal cadence during a constant workload (3,24). This "optimum" pedal cadence increases linearly with increasingworkInt.

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Increased regularity, or decreased variability, of organ functions is a generalized response to systemic inflammation that occurs in widely divergent systems during endotoxemia.