A mock circulation system has been used to examine the metabolic and hemodynamic responses of untrained and trained latissimus dorsi muscle in a normal animal model. The metabolic response of untrained latissimus dorsi to differing stimulation regimes runs parallel to its mechanical performance. The ratio of power generated to oxidative capacity (a measure of metabolic efficiency) was maintained to a greater extent in muscle trained for 5 months subjected to specific fatigue tests, falling by only 20% (as opposed to 80% observed in untrained control muscle). This approach to studying metabolic and hemodynamic performance may have relevance when skeletal muscle is used for cardiac assistance.