There are so many reason to do hill repeats. Something to remember is that DOWNHILL running is also really important!
We all know running up hill is hard and makes us strong, but running downhill ALSO makes you strong! And both up and downhill running makes you brave as hell.
Why is uphill running awesome?
it is a kind of strength training, improving muscular force. The faster you produce force, the quicker you can take your next step. Running uphill makes you produce more force on the ground in order to fight gravity. When you run on level ground, you have faster turnover and a quicker cadence.
hill repeats increase the energy output from your muscle fibers that you spent so much hard work and energy developing through your tempo runs, long runs, and interval training! Basically, all those other workouts build up your potential, and hill repeats allow you to unleash it.
hill training uses all 3 muscle-fiber types: slow twitch, intermediate, and fast twitch; it strengthens your connective tissues; it trains you to recruit more muscle fibers; it teaches your muscle fibers to produce and store more energy; it improves your ankle flexibility.
it improves your neuromuscular system: basically it speeds up the communication between your brain and your muscles.
You may have noticed that running uphill makes your heart pound. Hill training also increases your heart's stroke volume.
Hill repeats are hard. Give yourself full recovery before starting the next one.
Uphill running sounds pretty awesome. Why is downhill running awesome?
Just like uphill running improves cadence, downhill running improves cadence. As well as your stride length.
Downhill running is also about eccentric muscle contractions: which basically means your muscles are simultaneously contracting and stretching. You might notice when you run downhill your quads completely blow up. This is because your quads take the brunt of this eccentric load. Downhill running seriously strengthens your quads. Eccentric contractions produce a lot of force, essentially increasing the load for the recruited muscle fibers.
You might have also noticed that running downhill leaves you feeling much more sore the next day. Delayed onset muscle soreness is no joke. This is more likely to happen if you haven't strengthened your muscles to this repeated eccentric contraction. Downhill running helps to leave you less vulnerable to the DOMS over time. This doesn't just protect you from DOMS due to downhill running, it'll also help prevent soreness from a hard speed workout.
Downhill running creates more force, using less muscle. Once you've strengthened the muscles used for downhill running, you'll be able to get a quality workout with way less recovery time. Once you've developed these adaptations from downhill repetitions, you will retain the benefits with low maintenance of maybe one time per month of downhill strides/repeats.
Running downhill strengthens those connective tissues just like uphill running does. It improves your neuromuscular control too, helping to keep your legs aligned so you lose less energy and run more efficiently. Have you have ever seen a picture of yourself running and your hip is dropped, your knee is collapsed in, your ankles are collapsed? Yea, that means you could use some improvement in your leg stiffness, which is basically just another way of saying your strength or resistance to the force your body takes when connecting with the ground.
Now that we understand the physical benefits of uphill and downhill running, how does it make you brave?
Uphill repeats teach you:
You can always do one more.
You are stronger than you know.
Yes, you can get to the top.
The power is within you.
You have the drive.
Downhill repeats teach you:
Your legs will carry you.
You're faster than you thought.
You are in control.
It's easier to be brave than it is hold yourself back.