Strength Training for Hilly Marathon Success

While I'm writing this in the context of preparing to race a hilly marathon course, the same could be said for hilly 5-10km races, XC races, half marathons, and ultra marathons... not to mention tough triathlon courses.
Neil and I often talk to our athletes about training specificity. This is as true for pacing and nutrition as it for today's topic: strength training.
I'm often asked a couple of important questions by athletes looking to race over hilly or mountainous marathons. These questions often cover topics such as the specific type of regular hill sessions, or footwear choices for the particular course.
One question many runners don't think of:
'...what kind of strength work can I do to prepare my body to dominate the hills?'
This is equally important for runners tackling the Snowdonia Marathon as it is Boston Qualifiers looking to stay strong in the face of Heartbreak Hill!
Three Key Muscle Groups
Most of us know that as a rule we aim to build runners with optimal running technique, mobile hips, strong glutes, and great general leg and core strength... but what do we emphasise in the gym if we know that the runner has many hills to contend with during an upcoming race and in training?
Please note: focusing on the following key muscle groups is recommended in addition to a full running specific strength and conditioning program, including compound lifts, functional core strength work etc...
Hamstrings
The hamstring muscles are one of the most important muscle groups for runners as they cross both the knee and the hip. Given that running uphill requires both more knee and hip flexion during swing phase, and more hip extensor torque during stance phase, than running on the flat at the same pace, strength-endurance of the hamstrings becomes an even more important factor.
To maintain good running form on a hilly marathon course hamstring strength-endurance becomes a determining factor for success. The good news is that there are plenty of exercises you can use to work on this particular facet of your physical preparation. Below is a collection of hamstring exercises for runners:
Spinal Erectors
We've all seen the runner who looks bent in two, hunching forward from the waist as he or she runs up the seemingly never-ending hill. They seem to collapse further forward as they progress up the hill and fatigue further. Many of us will have certainly experienced this ourselves!
The postural muscles that work to maintain spinal extension (Erector Spinae, Quadratus Lumborum, etc...) have to work overtime to maintain an effective running torso position.
Research (Koblbauer et. al., 2013) tells us that it is normal for trunk angle to increase as a runner fatigues. Intuitively, we know this gets worse as hills are thrown into the mix as the fatiguing factor! The more we can do to strengthen the back and core muscles an avoid this fatigued, bent-over position, the better.
Calf Complex
Hill work is tough on the calves! Uphill especially. It's natural for most runners to strike the ground further forward on the foot when running up an incline. Particularly for habitually heel striking runners, this can be a big change of loading pattern for the muscles of the lower leg.
Here are a couple of simple yet great exercises to help develop the appropriate calf strength:
References
Koblbauer, I., van Schooten, K., Verhagen, E., & van Dieën, J. (2013). Kinematic changes during running-induced fatigue and relations with core endurance in novice runners. Journal of Science and Medicine in Sport