Canine elbow changed from allowing paws to swivel — which is important for grabbing and tackling prey — to keeping the paw more stable, which is important for long-distance running.
Meanwhile, cats maintained their tried-and-true method of ambushing prey, using quick bursts of sprinting to tackle startled beasts.(ref)
Cats and dogs diverged about 60 million years ago, and endurance adaptations for dogs started at least 40 Ma from mongoose like ancestors.
The forelimbs of African wild dogs show a combination of adaptations to endurance running, including a vestigial first digit and reorganized wrist muscles, passive spring action from a powerful ligament, and bigger muscles that store energy and provide stability. (ref)
You can see for yourself if you examine a dog's wrist and paw and check it's springiness, length, agility, grabbing ability... it's straight and springy for running.
Another know fact is that:
canines maintain a high mitochondrial protein turnover facilitating rapid adaptation to environmental extremes and energetic challenges (Miller et al, 2017, PLOS ONE 12:e0174874).
The cat's nasal channels are also less adapted to humidifying warm/cold air and tracking down prey for exhaustive predation.
Cats are typically forest animals and can climb trees better and specialize in fast attacks, including razor sharp claws where the chitin flakes a bit like flint.
You can see the cat's running adaptations when you consider it's jumping ability, climbing ability, reaction speed, attack poise, claw vs bite ferocity, limb agility, speed of movement, night vision.
They comprise a spectrum of ecological specialties that place them at different ends of the performance chart for much of their anatomy and biochemistry.