If you belong to the second group, we have some tips for you that will help you glide up hills that much easier. Hill training builds leg strength. The main driver muscles in the quadriceps and the calf muscles are developed.
Strength is important later in speed training.
And you'll need a fair amount in any race, particularly the marathon. Another ingredient that hills bring is a thing called character. It should go easily. We have all seen runners attacking hills with their heads down and arms pumping away. But if you bend your head and lean forward, you are constricting the flow of oxygen to your lungs at the very time when your heart needs it most.