Originally Posted by
Christobevii3
For people who do 2x20' builds, if I break that up into say 5x8' does it give similar work? Is it just about time in that zone overall from that workout to get a benefit? I ask this because I live in a very limited area for riding during the week. I can usually get two 8 minute hits in a loop with a couple two minute relaxations between due to the route. Is this ok or should I be looking at something else?
5x8 would not have the same effect as 2x20. That's not to say you can't boost threshold with shorter intervals, but in order to do so you need to modify the workout more than just breaking it up. Usually by increasing intensity and/or reducing rest intervals. Two minute rest intervals sounds good, but you'll also want to slightly bump your intensity. Maybe 103%-106% of FTP? One FTP workout protocol that's been popular around here is to do 6x5' at 105%-108% of FTP with one minute rest intervals. These are supposedly more effective at boosting FTP than traditional 2x20s. By messing around with the intensity level you might be able to make it work with an 8 minute work interval, but I'm no coach or physiology expert.