Using physiologically based models to predict in vivo skeletal muscle energetics.

Area of Science:

• Biomechanics
• Skeletal Muscle Physiology
• Energetics

Background:

• Understanding skeletal muscle energy consumption is crucial for animal locomotion.
• In vivo muscle energetics are difficult to measure experimentally.
• Physiologically based muscle models are used to estimate energy use but often lack validation against whole-body measures.

Purpose of the Study:

• To evaluate the capability of physiologically based muscle models to predict in vivo muscle energy use.
• To refine models using isolated muscle data and account for ATP recovery inefficiencies.
• To assess model sensitivity to mechanical and energetic parameters.

Main Methods:

• Developed and refined a physiologically based muscle model.
• Incorporated data from isolated muscle experiments.
• Simulated muscle energetics under varying contraction frequency, duty cycle, and fascicle length.

Main Results:

• The model successfully captured the dependence of energetic cost on muscle mechanical state.
• Model predictions tended to underpredict the magnitude of in vivo energetic cost.
• Model sensitivity was highest for force-velocity parameters and energetic parameters.

Conclusions:

• Muscle mechanics are the primary drivers of skeletal muscle energy use.
• Current physiologically based models show promise but require further refinement for accurate in vivo energetic predictions.
• Precise physiological parameters for human skeletal muscle require detailed investigation.