Indirect flight muscles in Mhc¹⁰/Mhc¹⁰, Mhc^R146N/Mhc^R146N females show normal sarcomere organization at late pupal stage and in 2h-old adults, minor disruptions of thick and thin filament packing in 2-days old adults, and disorder in myofibril morphology in 7-days old adults, including gaps in the hexagonal packing of thick and thin filaments and disruption in the Z- and M-lines, as compared to controls. These muscles also show significantly decreased power generation and work, significantly increased active tension, but do not show a significant change in passive tension, as compared to controls; under optimal power producing conditions, there are further significant decreases in power generation, net work (likely due to decreased work generated:work absorbed ratio), and in relative muscle length amplitude, as compared to controls. These muscle defects are associated with a progressive decrease in flight index and a lower wing beat frequency, as compared to controls. Mhc¹⁰/Mhc¹⁰, Mhc^R146N/+ individuals display similar, albeit more modest, flight ability defects and indirect flight muscle morphology and performance defects.

The hearts of Mhc¹⁰/Mhc¹⁰, Mhc^R146N/+ individuals display significant decreases in cardiac dimensions (diastolic and systolic diameters) and in fractional shortening, and a significant increase in systolic interval, but do change in heart period, as compared to controls; the heart has an essentially normal myofibrillar integrity and organization in 1-week old adults, but displays myofibrillar discontinuities in 3-weeks old adults, as compared to controls; cardiomyocyte thickness in both young and aged mutant adults shows no statistically significant differences, as compared to controls.