Cats have flexible spines with great bending and extension. At the same time, the muscles in their torso and back are strong, making their bodies like springs, allowing them to generate power from their entire bodies when jumping. Compared to the somewhat stiffer torsos of humans and dogs, this is a significant advantage in jumping. 
Cats have relatively short thigh bones that can bend significantly towards their abdomen, creating a greater range of motion for power generation. Furthermore, their long metatarsals allow them to generate power from their entire paw. Most importantly, the muscles in their hind legs and paws are very strong. Therefore, cats have excellent jumping ability.
