Metrics of Natural Muscle Function

3.1 Caution about Copying and Comparisons / 74 3.2 Common Characterizations—Partial Picture / 75 3.2.1 Maximum Isometric Force Production Depends on the Level of Neural Activation / 75 3.2.2 Rate of Force Production and Relaxation Varies Among Muscles / 75 3.2.3 Maximum Isometric Force Depends on Muscle Length / 75 3.2.4 Force Development Decreases with an Increase in Shortening Velocity / 77 3.2.5 “Blocked Stress” Calculations Overestimate a Muscle's Capacity to do Work / 78 3.3 Work-Loop Method Reveals Diverse Roles of Muscle Function during Rhythmic Activity / 79 3.3.1 Work-Loop Method Provides Better Estimate of Maximum Power Output during Rhythmic Activity / 80 3.3.2 Mass-Specific Work Output Decreases with Cycle Frequency / 81 3.3.3 Mass-Specific Power Output is Independent of Cycle Frequency / 82 3.3.4 Work-Loop Method Shows Muscles have a Role in Energy Management and Control / 82 3.4 Direct Comparisons of Muscle with Human-Made Actuators / 85 3.4.1 Evaluating Musclelike Properties of Electroactive Polymers (EAPs) Using the Work-Loop Technique / 85 3.4.2 Activation, Stress, and Strain during Cyclic Activity / 86 3.4.3 Mass-Specific Power Output of an EAP can Fall within the Range of Natural Muscle / 86 3.5 Future Reciprocal Interdisciplinary Collaborations / 86 3.6 Acknowledgments / 87 3.7 References / 87