The weak link: do muscle properties determine locomotor performance in frogs?

Area of Science:

• Comparative Physiology
• Biomechanics
• Locomotion

Background:

• Muscle performance is crucial for movement, but its direct link to locomotor performance is not well understood.
• Frog jumping offers a model system to study muscle capacity and locomotor output due to its discrete nature and reliance on mechanical power.

Purpose of the Study:

• To investigate the relationship between interspecific variation in muscle power and jump performance.
• To test the hypothesis that differences in jump distance are explained by variations in available muscle power.

Main Methods:

• Measured jump performance and peak power output using force plate ergometry in three frog species: Osteopilus septentrionalis, Rana pipiens, and Bufo marinus.
• Assessed peak isotonic power output of isolated plantaris muscles for each species.

Main Results:

• Significant differences in jump performance were observed across species, with O. septentrionalis exhibiting approximately five times the peak power output of B. marinus.
• Interspecific differences in jump power were not correlated with differences in available muscle power.
• Available muscle power varied less across species than did jump power.

Conclusions:

• The dissociation between available muscle power and jump performance suggests that non-muscular mechanisms, such as elastic energy storage, are critical in determining locomotor performance.
• Elastic mechanisms can significantly influence or mask the direct contribution of muscle mechanical properties to overall locomotion.