I’m 63 and shooting for my last IM before knee replacement so I know a thing or two about your situation.

Given that you are a very good swimmer, my first recommendation is that you do the minimal amount of swimming necessary to maintain your current 1/2 IM swim. Then, I’d heavy up on the bike, especially given it will represent about 80% of your race time, and it is now your relative weakness.

For me, bike “heavy-up” principles are:

1. Ride as many miles as you can....when I’m in IM build mode, I push 350 miles/week. That may not be you, for a variety of reasons, but I’d look at your bike volume in the past and aim to grow it 50% or more this year (you don’t have to run after all)

2. 56 miles is, at the end of the day, high Z2 riding, endurance oriented. So in addition to #1 above, I’d make sure I was riding a 50-60 mile time-trial every 7 or 10 days. You should be striving to maximize your average or normalized power and expect to improve them as you build your bike fitness.

3. Ftp intervals. Basically, if you don’t know your FTP,I’d aim for 120-125% of the power in #2 above and do interval sets such as 6x10 minutes w/ 3-5 min easy in-between or 10x6 minutes, w/ 2 min easy...

4. Some faster stuff, say 50% more power than 2 above and do 15x1 min or 10x2 min with equal amounts of rest

5. Try to ride every day or a minimum of 6 days/week...

You can do this every week or 10 days depending on what you can handle/manage. The other days should be easy endurance rides (Z1 or low Z2).

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Randy Christofferson(http://www.rcmioga.blogspot.com

Insert Doubt. Erase Hope. Crush Dreams.

Thanks Randy. I'm not sure I can heavy-up to your biking volume standards, but 5-6 days of riding per week shouldn't be too difficult given that I am retired :-)

I swim with my masters team 5x/week and once pool racing resumes, I will add an additional day of swimming.

As of last month, my FTP is 197W. My sweetspot interval session right now consists of 3x20min with 8min recoveries. I will continue to up that to get to a point during my build where I can do a minimum of 75-90min in that sweetspot. I've done some over/unders as well (or criss-cross intervals whatever they are called). The vast majority of my rides are on zwift these days. Time trialing shouldn't be too hard although a 50-60mile TT may not be on zwift's offering atm. I'll have to check that out.

While I agree that a 56 mile ride may be Z2 oriented, at the end of the day, I'd like to be able to push the limits a bit more and see what's doable and that is why I was especially questioning the value of a weekly long base ride.

Agreed. I’ve been able to average 80% of ftp on some bike 1/2 him bikes...which is really z3 (depends on if you have 5 or 6 zones I guess). My best was 225 watts when my ftp was around 280...yielded a 2:22....usually though, I’ve averaged 75-77% and 70% or so for my IM distancerides

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Randy Christofferson(http://www.rcmioga.blogspot.com

Insert Doubt. Erase Hope. Crush Dreams.

You have it all backwards. Stop thinking about intensity first with the occasional base ride, and instead it should be endurance riding first with the occasional intensity. Depending on how your race schedule looks, I'd structure it something like this: 2 or 3 blocks of base, doing almost entirely z2 with maybe 1 VO2 max workout and one sweet spot/tempo workout per week just to build general fitness. Then, one block where you do 2 high intensity workouts per week, maybe throw in some tabatta style 30/30s, or just the classic 5x5. These workouts raise FTP, although your TTE st threshold won't be super high. Then a block focusing on threshold, doing 2 threshold rides per week, working on trying to build that TTE towards 60+ min. Surround these with 4 or 5 Z1/Z2 rides per week. These Z2 rides are what gives you the fitness to actually push what's possible while racing

Thanks for the recommendations imswimmer328. Not being a biker, I'll have to google tabatta style 30/30s. Can you please elaborate on the "classic 5x5'? Are these above threshold or below?

I think 2021 will be an experimental racing year with no running after the bike. I did an aquabike in November and felt that I still had something left after finishing the bike.

Sorry, I just felt like my post was getting a little too long, so I didn't explain those. 30/30s are basically where you do 30 seconds hard, 30 seconds recovery. A workout incorporating those will look like 3 rounds of 7 sets of the 30/30 intervals, with the on sets done at the highest power you can make while still keeping it consistent for the whole workout, and the off will be somewhere in low z2, and a longer rest between each set.

5x5 can be done a couple of ways. I really like doing it with the on intervals targeting a best average power output, so as hard as I can go while making sure the last interval is about the same as the first. These I do with the same amount of rest as work, so 5 min on, 5 min off. You can also change up the duration as you see fit, so 6x4, 4x8, exc. Another way is to target a lower power output with lower rest. This isnt how I do this workout though, so hopefully someone with more experience can chime in, or you can find more info online.

My understanding is that the 30/30s are better for increasing power output in the short term because they really are more of an anaerobic capacity workout. The longer 5x5 sets are more of a true vo2 max workout and are good for increasing vo2 max over time by producing structural changes in your heart to increase stroke volume, so it takes a while to really reap maximum benefits, although you will see some short term gains as well.

As for you feeling you had more to give after the bike, I think these workouts are also really good for teaching you how to push hard on the bike, especially since they shouldnt be done with erg mode. Also, for an aquabike, I'd think you'd target a much higher percentage of threshold than the 80ish% I think you mentioned earlier? Usually for a 70.3 i'm more in the 85%-90% range, although it's kinda all relative