Those lactate sessions were the worst. I'd be in a lab on a turbo trainer and I'd do four 30-second efforts at 100% effort. It sounds so innocuous but the difference between 99% and 100% is huge. You can finish at 99% and you'll be hurting but if you push a tiny bit more – and that's the bit that makes the difference to your training – your legs just grind to a halt. It's like your engine is seizing up. My coach would unclip my feet and pull my leg over the saddle so I could just slide off onto a mat and curl up in a ball.