Write this down 1000 times:
1. Successful runners are typIcally genetically wired to NOT gain mass.
2. Runners putting in an hour of running a day will not have the protein surplus available to gain muscle.
3. Runners would need to consume massive amounts of calories to even think of gaining muscle.
Someone may have the perception that they gained weight but unless the scale shows an increase over daily fluctuations their perception is not based on reality.
Studies, even some using recreational runners, have shown plyos and heavy weight lifting improves running economy. The issue is the carryover to high level runners. Due to practIcal concers studIes are typIcally done on the untraIned as they provIde a "blank slate". Also, good luck fIndIng a bunch of hIgh level runners to study. HIgh level runners are already close to maxing their performance and you are simply not going to notice a difference in performance because they have already done so much which also improves running economy (sprints, hills, total lifetime mileage). The main benefit for high level runners is reduced injury risk and extended careers due to reduced injury risk and maintaining testosterone levels.
Very low volume. Very high intensity/weight. This will improve max strength. This is why running economy improves...improving the force potential in the working muscles. Other ways of improving running economy (miles, sprints, hills) improve your running efficiency or how your body moves through space.
Here's a simple strength workout that shouldn't take more than 30min
Box jumps: as high as you can go for 3 jumps, increase height by 1-2in each set, max of 5 sets
Squat or Deadlift (alternate from workout to workout): warm up, ramp up to a max set of 5
Dips & pullups: 3 sets max strict reps.
Do the above twice a week on your most intense running days as a secondary workout preferably hours after your run.
Example:
Box jump: 24 x4, 26x3, 28x3, 30x3
Squat: 95 x5, 115x5, 135x5, 155x5, 185x4
Dips 3x10
Pullups 3x10
On your second workout do Deadlifts instead of squats.
For detailed instruction on squats and deadlifts look up Mark Rippetoe'd vids on youtube. Best basic barbell instruction I've seen.
Also, use common sense with nutrition. The more you are breaking down tissues the more you need to repair them..ie: increase protein intake.
Alan