MECHANICAL ENERGY MANAGEMENT IN CYCLING - SOURCE RELATIONS AND ENERGY-EXPENDITURE

Conservation of energy suggests that during cycling the constrained lo wer extremity is capable of delivering energy to the bicycle without e xpending energy to move the limbs. The purpose of tills study was to c haracterize the management of mechanical energy during cycling and, sp ecifically, to evaluate the potential for system energetic conservatis m. Mechanical energy contributions derived from lower extremity energy sources were computed for 12 experienced male cyclists riding at five combinations of cadence and power output The knee joint dominated (>5 0%) in contributing to system energy and a moderate amount of energy w as derived from hip joint reaction forces (>6%). Energy generations an d dissipations at the sources were sensitive to power output and, with in the range of conditions studied, insensitive to cadence. Two energy models estimated mechanical energy expenditure under hypothetical sin gle-joint and multijoint muscle operating conditions. When multijoint muscles were incorporated into the energy management analysis, a signi ficant reduction in mechanical work relative to the single-joint muscl e operation occurred. Energy savings associated with multijoint muscle energy transfers were enhanced at higher bicycle power levels, sugges ting that conservation of mechanical energy is plausible given appropr iate actions of two-joint muscles.