[quote author="Matt Norquist (WashedupDec)" date="1259377482"][quote author="Jay Turner" date="1259369217"]Here’s an extension of what irish100m asked…
Can you still get the intended work you need when doing a SE1 or SE2 session if running in trainers? Or must you wear spikes only to get needed effect?
I don’t think it makes a huge difference, but for in-season SE1 or SE2, probably better to wear spikes. But the shoes you wear doesn’t seriously influence stride length, running form, etc – for runs at under 90% effort.[/quote]
Ok, but what about runs at 90-95% effort?[/quote]
I think for 90% and beyond, you need spikes. Not necessarily for training effect, but for ability to run quickly enough without expending more than 95% effort.