Running strength isn't quite as definitive as VO2max or LT. It's a bit ambiguous. However,
as I view it, it has two components....physiological and psychological.
The physiological component is related to running economy, but it is also different.
I think of both running strength and running economy as sub-elements of a broader subject that I call running efficiency.
Running economy is a measure of how efficiently you use oxygen while running at a specific pace. Improving running economy
means that you can physiologically sustain a faster pace at a given percentage of VO2max, or a given pace at a lower percentage
of VO2max, for a longer distance. Running strength is a measure of how efficiently your muscles function at a specific pace,
or what percentage of muscular capacity is used to run a given pace. Increasing muscular strength permits you to sustain a
given pace longer with less percentage of your muscular capacity. In the latest (1999) edition of his book, "The Competitive
Runner's Handbook", Glover calls running strength, muscular fitness. Some runners refer to "core strength", which I view as
largely synonymous with running strength.
Hill running, fast continuous runs (like tempo runs and long MP runs) and higher mileage
are all good ways to improve running strength physiologically. By hill running, I don't just mean periodic hill repeat workouts.
Even on easy days, if you have a choice between hilly and flat routes, the hilly one will be the more beneficial choice. It
isn't necessary to run the hills hard on an easy day. But, just having to lift yourself up them will contribute to strength
development. You can even find ways in your everyday life that will benefit running strength. For example, if you have to
go to an upper level of a building and have a choice between stairs and elevator, choose the stairs. Anything that contributes
to muscular strength improvement, without building bulk (i.e., weight) will contribute to running strength. An excellent non-running
way to contribute to the development of running strength is weight training. Some runners believe that leg weight training
isn't particularly beneficial for a runner. I strongly disagree! It will contribute significantly to running strength improvement,
which makes you a more efficient runner. You say that you don't have access to a fitness center for weight training? That's
no excuse. Most forms of weight training can be improvised using items commonly found around the house. Heck, for leg presses,
just put a kid on your shoulders and do 50 squats every evening. ;-)
Also, upper body work should not be ignored. Improving upper body fitness might be
an obtuse element of improving running strength, but it is a real one. As one tires in a long race, such as a marathon....even
a half marathon....form can deteriorate, which results in a decrease of running efficiency. A stronger upper body will help
in maintaining form in the late stages of a race. It's all part of our strength as a runner.
I mentioned a psychological element of running strength. That relates to our ability
and willingness to race outside of our "comfort zone". Again, that's a bit nebulous. Just as different people have different
thresholds of pain, so to do different runners have different "comfort zone" boundaries.
Also, comfort zone has different meanings depending on race distance. For instance,
I think the discomfort of a marathon and a 5k are quite different. That of a marathon is one of extreme weariness and muscular
"deadness". I just want to stop and rest....or stop completely. My legs get sluggish and want to stop functioning. A lot of
the discomfort battle is mental. My mind nags at me constantly over several miles for relief and I have to fight it. The discomfort
is symptomatic of glycogen depletion. OTOH, the discomfort of a 5k is gut-wrenching, lung searing pain. Through most of the
race, I want to ease the pace just a little just so I can breath again and get ready for the final push. That type of discomfort
doesn't occur for me in a well paced marathon until I am in the final push to the finish line. As we learn to deal with and
overcome discomfort, our "comfort zone" is expanded. That makes us stronger....and faster....racers.
Some forms of training workouts help us to work on our comfort zones. However, the
best way to expand them is by racing. That's the only way we sustain a level of discomfort long enough to make it a really
good "workout". The discomfort of 10k-half marathon distances are some combination of the marathon and 5k extremes. Probably,
the longer the distance, the greater the test of the marathon comfort zone and the better for working on our "marathon comfort
zone". However, you can run 10-15k races a lot more frequently than half marathons. And I think that race frequency is more
important than race distance for "comfort zone" training. That's why I always tried to run about 20 races/year with most of
them 10 miles or less.