I’m a bodybuilder ( think higher volume resistance training with moderate loads 6 days a week) and a cycling enthusiast.
I’m looking to improve my aerobic fitness and cycling performance while mitigating some of the interference effects that occur between resistance/hypertrophy training and endurance training.
I currently train with weights twice a day six days each week using a progressive volume periodization scheme similar to how TrainerRoad structured training macro cycles. So my total training volume starts low and builds over 6-7 weeks so that I’m overreaching on my final week before I deload (use lower weights) and reduce my volume for a week to drop accumulated training fatigue, and then start another training phase.
On the cycling side of things, I’m doing the SSB low-volume training phase as part of a larger low volume plan. I’ve scheduled my TrainerRoad workouts on lower volume weight training days and I do them between weight training sessions so that I have 5-6 hours between cycling and weight sessions (once again to try and mitigate interference as best I can). Fortunately my daily and weekly schedules are flexible enough to allow me to do this.
So far scheduling my weight training and TrainerRoad workouts this way has been effective, and I’ve been able to improve my aerobic fitness and FTP steadily without losing too much muscular size from the weight training. The cardiovascular benefits have more than made up for whatever little bit of strength and size I have lost.
The low volume plan is the most flexible when it comes to scheduling around my weight training but I’m interested in incorporating more volume—something in between the low and mid volume plans but avoiding having to schedule two long hour and a half rides in my already packed training week.
I’ve been toying with adding easier variants (20 second sprints) of the SIT series to the end of my leg workouts to enhance hypertrophy while also getting some bonus aerobic benefits from additional cycling volume.
My understanding of the literature suggests sprint intensity training with shorter intervals (<25 seconds all out) seems to be quite effective at improving aerobic fitness without interfering with hypertrophy and strength training and may even enhance hypertrophic training adaptations by being especially good at stimulating type iix fibres. Also, I really really like sprinting. 
My question is—as long as I can recover properly and don’t fail my prescribed sweet spot TrainerRoad workouts—will adding in an additional 2 short sessions of SIT as I described in the previous paragraph interfere with the goals of the SSB base plan?
Would especially love to hear from other hybrid strength/cycling athletes or physique/cycling athletes if you are out there—and also Chad of course if he has any feedback/insights/caveats to share.