What's your FTP - 100. You probably can. 1,000. Probably not.

A couple quick thoughts/questions that come to mind -> why the focus on FTP? What are your larger goals/purpose? If goal is to get faster in triathlon, it doesn’t seem to me that sacrificing swim time or run time is necessary - time is given in that case, not taken for focus there. Also, what duration of time are you trying to accomplish this 15% increase in? Do you plan to maintain after, or hit the target and let it fade?


Most important - enjoy the improvement journey!

Need waaaay more info. If you're well bike trained already, you're unlikely to be able to add 15% to your FTP regardless of what plan you follow, pretty untrained, you can probably do it regardless of what plan you follow.

There are FTP builder plans. They usually last 8-16 weeks. You can make big gains in FTP over a few months but after that you plateau and to continue improving as a cyclist you need to change the training focus and goal from building your one-hour FTP to being able to hold higher and higher percentages of your FTP for longer and longer intervals, etc.

I would suggest doing a 3 day a week FTP builder plan with 60-70 minutes power-based intervals on an indoor trainer. Swim and run on days that you don't cycle. After you complete the FTP builder plan you go into your Triathlon Training Plan with your new FPT and use the Triathlon plan to get the endurance rides that you need each week to gain the endurance you need for the distance races your are training for. As you do this you will maintain your new FTP.

I led a 3 day a week FTP builder plan for my triathlon race team last year. We had 15 people in the group training and my goal going into it was to see an average of 6% gain in FTP across the group. Everyone in the group saw at least a 5% gain and some saw more than a 20% gain. I feel that 5-10% is very doable in a short time and that 15% is possible if you have a lot of low hanging fruit.

I see big gains from the beginning of my pre-season to my race season. Then I see drops in my off-season. I focus on where my FTP is at its peak during race season and where it is at the beginning of the preseason. I usually only see a 2-3% increase in race day FTP year over year even though I might see 15-20% FTP increase from the pre-season to the race season.

Depends.

Agree with what others have said -- depends on a lot of factors. Depends on current strengths/weaknesses. If your goal is to make big FTP gains then you're going to have to prioritize the bike. That likely means scaling back on some of your swimming/running. It helps if you're naturally strong in those areas. Design a bike block in the 8ish week range. Test after 4 weeks & again at the end. 15% is a big #. Take whatever gains you make & keep chipping away if you're not there.