Lower back ache kills my fast runs.
I started properly running about 2 months ago (built from a base of lots of walking and inclined threadmill).
I mostly run zone 2 (5-10km)
I’m the last 3 weeks I’ve joined 2 different 5K races, in which I did surprisingly well by my standards (24-25mins), but the thing is I felt like I could do better. Every time I slowed down during the race, it was due to lower back ache rather than exhaustion.
When I do z2 runs, I can run a 10k without much noticeable ache, but once I go somewhat fast (eg 5’20 km/min) my lower back decides I’m the enemy. Any ideas why?
I think it might be my weight but I’m not sure. Think could somehow also be form. But then again I don’t have the issues in z2 so I’m confused.
For reference my z2 is like 7-8km/min, depending on the day.
I’m a 187cm male, muscular, 96kg (down from 110 in last 8 months and targeting 88-90).