The "booty" aspect is often tied to the "fit at any age" movement. Mature women are increasingly visible in the fitness world, specifically in strength training.
Programs focused on building and maintaining muscle mass (hypertrophy) help counter age-related muscle loss (sarcopenia), leading to the toned, athletic look associated with the term. matures and booty
Fashion for mature women has become significantly more daring. The "booty" aspect is often tied to the