Determination of health status during aging using bending and pumping rates at various survival rates in Caenorhabditis elegans

Alongside recognizing the importance of extending lifespan, an emerging focus has appeared on improving health in longevity, defined as healthspan. Aging is a process for all animal species; however, due to the time limitation in aging studies, Caenorhabditis elegans is an established model used for studying aging. In the current study, we evaluated various markers of muscle functions and determined that bending or pharyngeal pumping rate can represent worms' healthiness. A new concept named 'dynamic-scaled value' was developed, rescaling health markers to the corresponding markers in the control group at the same survival rate. Using these dynamic-scaled values of bending or pumping rates, we determined the health status of various treatments, including whether health improvement over aging depended on lifespan extension. Co-treatment of cranberry juice with Lactobacillus plantarum significantly improved health status during the mid-late life stage, while cranberry juice alone did not improve compared to the control. The dynamic-scaled value can be used as a complementary indicator to the quality-adjusted values to determine the health status. In addition, the dynamic-scaled values would allow us to compare results from others based on adjustments using their respective controls and relatively simple measurements to obtain the results.