Some data point on speed. Did a fartlek tonight, which included 3 sprints "let the lead out until I start straining".
I guess this is really lame, but the pace for this sprints was at best 4:35 min/mi over ~ 130 meters (0.08 mi).
Top speed reached on those sprints was about 4:25 min/mi. My form was WAY different:
- avg run cadence ~ 220-240 (is that even remotely efficient? I'm at 180 usually)
- vertical oscillation very good ~ 6-8 mm which is way lower than my normal running (~ 10)
- ground contact time very very short ~ 150 (normally 220ish).
Beyond the stats, I ran completely on forefoot, all out, knees came up higher, legs turned very fast. But you know what was weird? All out but not straining was way more efficient than 5k pace, where I tend to sit/saddle (ass back) with poor form.
So I think I know my limitation. For the 5k it's not the lack of pure speed, it's the lack of speed-endurance. I will work on 200m repeats first (or even shorter), and when I can do plenty in 40s I'll move to 400m in 80s before anything longer.
For the marathon my current limitation is mileage and muscular endurance (which creates destruction/cramping).
I'll continue working on form (strides + short hills), speed endurance (200m) and different aerobic workouts at 6:40 (e.g working up to 3x3mi), 7:00 (10mi+), 7:30 (12mi+). Recovery/easy runs will be kept at 8:30-9.
Think this makes sense. Don't you feel sad for someone who after running for 5 years can only run 4:30 pace all out for 30 seconds??? How do you guys run a mile at that pace without resorting to full sprint on forefoot? I don't get it