Long runs - fast?

[Rob Furness]

, my question is ...
What HR training zone, or what % of Max HR do people tend to run their LSRs at?

I tend to run my long runs at the sharp end of comfortable, this usually equates to an average HR of around 160 (approx 75% max working HR for me). Any slower seems to give me strange niggles, and any faster leaves me too tired to put the hard work in on efforts through the week.