I've been continuing to experiment with my run training over the past couple of months. Since none of the races I plan to enter have any significant hills on the run course, I had been doing all of my run training on level ground. (You know: "Train like you race, Race like you train.") Unfortunately, I live in a hilly area, so I had been driving to a flatter area for my runs.
Which is really silly, when you look at the time and gas cost involved. So I decided to start running closer to home. On my first run, I thought I was going to die after the first hilly kilometer.
My pace on level ground has been gradually getting faster, going below 26 minutes for 5K, and 55 minutes for 10K (which is fast for me!). But it took me 45 minutes to do my first 5K run with rolling hills, with at least 5 minutes of that spent resting, gasping for air.
Over the next three runs I was able to eliminate the rest stops, and now my average speed is slowly starting to improve, though it is nowhere close to my speed on level ground.
Clearly, my prior run training wasn't doing much for my cardio conditioning. I was going as fast as I thought I could go while adequately monitoring my gait, and I wasn't worried too much about conditioning. My intent was to not push my run too hard, maintain comfort and form, and build my conditioning by doing hill repeats on the bike.
Aside from the loss of breath, the main difference I noticed when changing to running hills was that my knees were taking more of a beating during the first kilometer. My solution has been to do more of my warm-up on a small level area near my house. I now run back and forth on my block until my heart rate just enters Zone 3, then I head for the hills.
Not surprisingly, 'comfortable running' can also be done on hills. It's just not quite as 'comfortable' as it is on level ground! It is certainly more of a diaphragm workout, and I'm also recruiting more quads and glutes. Using different muscles, or using them in different ways, means I'm also using a slightly different gait in the hills.
What are the changes to my gait? I've kept my metronome set at 190 bpm. I've kept my body nearly vertical, with only a slight forward lean. My decreased average speed with constant turnover means my average stride length is decreasing, which is expected. I'm obviously doing far more work per kilometer. This is also indicated by my having a higher average heartbeat during hilly runs.
Since my calves feel about the same after my hilly runs, nearly all the extra work and effort must be coming from my quads and glutes. Were that happening on level ground, it would mean I'm running closer to the ground, due either to running in a slight squat or over-striding, otherwise those muscles wouldn't be recruited as much.
I expect to use more glutes going uphill, since I have to lift each foot higher to place it up the hill, meaning my quads and glutes have to do more to straighten the leg.
But I also found I'm using more quads and glutes going downhill. Since I can't tolerate significant heel impact, by the time my forefoot touches the ground when going downhill, the ground is already close to my heel. To avoid heel impact, I must use my quads to absorb much of my downward momentum, since the elevated ground beneath my heel means my calves will have less distance to do so.
I also find my back is a bit more tender after hill runs, which I believe means I'm not absorbing downhill impacts as well as I need to, despite increased quad and glute use.
For me, this means I'm not yet able to 'fly' downhill. Something to work on, since this should be where I'll make the easiest improvement to my average speed. Yet it is also where my legs are absorbing the greatest forces, meaning injury is easier.
I'm not worried about running comfortably uphill: Keep the cadence high, take smaller steps, and improve my conditioning. I believe staying comfortable downhill will be the real challenge. I'm wondering if it will be possible to improve my downhill speed while simultaneously reducing impact. That's my current research project.