The factor that is NOT directly related to efficiency in movement or energy usage is D. digestion. While digestion is critical for energy supply, it doesn't directly affect how efficiently muscles work or how energy is utilized in movement. Therefore, digestion is the correct answer to the question. ;
D. digestion is the factor that is NOT a direct measure of efficiency in movement or energy usage. While important for energy supply, it doesn't impact how efficiently muscles and movement utilize that energy. The other options directly relate to how energy is expended and utilized in physical activities.
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