Hill running is great for developing strength and power, whilst also working on good technique. There's a knack to running hills, which will ensure you get the most benefit. But, even though running hills offers great bang for your buck, you need to be careful when incorporating them into your program because of the higher intensity (compared to running flats), and associated injury risk.
Benefits of Running Hills
1) Great for reducing overstriding, which is a common form fault. It's difficult to overstride when running uphill, because the slope brings the ground closer to you.
2) Great for improving running posture. Getting uphill effectively requires good forward lean, staying tall and looking ahead with your chest and eyes up - all key to good form.
3) Increased strength and power. There's no denying that running uphill is hard. Driving muscles (ie. glutes and calves) are called on for strong propulsion, whilst good knee drive relies on hip flexor activation.
4) Increased load tolerance. The higher force of impact when running downhill requires great activation of stabilising muscles (including glutes and soleus), and more eccentric strength and control from various muscles (differing in some instances depending on strike pattern)
5) Great bang for your buck. The potential benefits of both up and downhill running results in fantastic long-term performance boosts if incorporated into training cautiously and cleverly.
Tips for Running Hills
1) Because pace is more difficult to come by when running uphill, let go of time/pace expectations and regulate effort using other means - ie. heart race or perceived effort.
2) Shallow gradient downhill efforts are fantastic for promoting faster cadence and shorter ground contact time, but good posture (keeping hips forward) is essential otherwise overstriding is likely.
3) The importance and influence of arm action is magnified. Focus on wider and more relaxed arm carry when running downhill to help release tension and improve stability, and strong elbow drive when running uphill encourages knee lift and drive.
4) Efforts of 1-2 minutes at ~8/10 intensity are ideal for ensuring good technique is maintained for each rep and throughout the entire session. Running with some fatigue towards the end of each rep is great for strength endurance and building resilience. But, too long (rep length or entire session) and the benefits will be compromised.
5) Choose gradient wisely. A steady and relatively gentle gradient is best for achieving benefits, both up and downhill. Steep hills become a hard slog and matter of survival, rather than promoting the aforementioned benefits.
Next time you see a hill, embrace the challenge and run yourself over the hill - you will reap the rewards.