My twin! Same ftp and 5k numbers but I'm on an injury induced swim block. Foot is feeling better so I'm going to use TrainerRoad and some short easy runs to keep some bike/run fitness. My swim block is modest...right now just 12-15k a week but I'd like to graduate up to 15-20k over the next few weeks.

I'm swimming around 12-13K now. Would love to bring it up to 15K-20K, but at my pace I need more time in the pool, or do doubles. Maybe in a few months.

Let's say you are swimming 5x per week, you can easily add a 15-20 min run on your swim days at some point in the day. That leave 2 days a week to do a normal run and normal bike. During one of your 5 swim days, just add a 45 min trainer ride with 30x(40 second hard-20 second easy spin). That should keep your biking "alive" and not losing much. Assume during all the swimming there will be a decent amount of kick sets too (let's say with fins, on your back, doing dolphin kick etc....so the same muscles used for biking should be aerobically well conditioned).

All this to say, you won't lose "much" if you do enough swimming. The short runs will keep the weight bearing chain in your body active. I've been on a year long swim focus for a number of reasons and everytime I get on the bike I am stronger than last year, but this could have something to do with not running, but I am certain the swim aerobic conditioning is superior to anything I can consistently achieve on the bike or run. Just can't do that much intensity everyday in those sports.

Judging on your times and the length of a sprint distance swim, unless your swim is extremely shocking, you may get bang for buck with a bike/run focus?

An efficient approach is to get in the short runs on the treadmill either right before or right after your swims.

This would be the logical thing to do, especially since I'm sticking with short course... but I still would like to be a better swimmer. The bike I think is where I should concentrate next, as the run as always been my Achilles Tendon and I end up getting injured one way or another; I think maybe I can shave off another minute off of my 5K over the course of next season, but I don't think I will be able to go lower than 22... but who knows..

Thanks, I will try it this week.