Elastic modulus (A), viscous modulus (B), work (C), and power (D) for active IFM fibers across muscle oscillation frequencies for young and median-aged flies. Dashed lines in (C) and (D) represent frequency of maximum work and power, respectively, from the article. Asterisks indicate a significant difference (p < 0.05) between young and median-aged flies at a particular frequency range (horizontal line). Temperature = 15°C.