Running 58:47 [3] 12.62 km (4:39 / km) +113m 4:27 / km
ahr:142 max:171
So I've made it to page 120 of my running form book and it is rather frustrating. While it's readable enough, it doesn't offer much practical advice so you're left hanging a bit.
Having said that, it did mention 'tripod foot landing' (i.e., full foot, not heel or ball) and aiming for 'tall and bouncy', so I tried that out on a park loop in the gloomy evening drizzle.
Overall it worked rather well, mostly because it made me focus on my form more generally - I noticed (and tried to correct) my shoulders droop and my arms flail about in the second half when I got tired. I need to do more shoulder strength work as it was tough keeping the arms working throughout.
As a bonus, focusing on form passes the time more quickly. So a step in the right direction and the right trade-off between speed and endurance.