I am a Cat3 road racer here in Colorado. I am in the "Build" phase of my program and at this time of year typically do Cruise Intervals, which are 4-5 x 6mins in Zone 4+ with 2 min recoveries. I like this workout and feel that it definitely benefits me. However, I am interested to hear if anyone could suggest any variations on this workout. I have begun my racing season but only have low-priority races at this time.

Thanks!