Third Stress Fracture in 1 year, Do I hang them up?

In the US, there are few chances/places to have a solid training group after college. It sounds like you have done some over-training, RED-S situation and I think this takes time to develop out of. Add that you have reduced your impact training (and need the impact to build bone density) and it can be a bit of a spiral. But you are early in your college career. I think most of the bright-minded (not me) will tell you that the best runners develop slowly over time. You have plenty of time. And you are that great teammate who knows how to suffer and knows the pain and disappointment that running/injury can bring. You bring a wisdom and shared knowledge that will be good for your team overall. So many college recruits have lived a life blissed by ignorance of injury ... but their day may come and having someone there to help them will be invaluable to team spirit and give you greater purpose. For you: build slowly, take a day or three off when you have those little niggles, put yourself in position to train consistently and do great things. Save your tri-career for LA Olympics.

if you want to run, run and keep fighting for it. follow your dreams

May I ask after fracture #1 and #2, what steps did you, coach, and doctor make to determine when and how to resume training? Assume you had a 6-8 week break, how did you/coach/doctor know you are cleared to resume training?

up to you but you need to figure out the cause for the bone issues or it'll just keep happening.

Sounds like you work hard so don't feel bad about taking up resources

Femoral stress fractures are not common. Get consult with nutritionist if possible and start taking Vit D3/K2 supplement. Your mileage is relatively low to have fractures of this type, and you need entire blood work up to figure it out.

Ask about blood tests: serum calcium and phosphate levels, parathyroid hormone (PTH), thyroid-stimulating hormone (TSH), alkaline phosphatase, albumin, pre-albumin, Vitamin D, bone mineral density study.

I have tested these multiple times. All normal. Have also tested bone density and had low scores. Low testosterone is believed to be a result of overtraining/stress. I have been working part time serving as well.

HGH may help you and those frighteningly weak bones. Good luck.

Fracture 1 (first femural in highschool) the return was very slow and didn't top the 35 mpw range for many months. I then had a full winter of 50 mpw and didn't get my second until after the week off following track season. It occurred during my first week back. I was in Flagstaff and California on a road trip and had a couple 10-13 mile days but kept it at 50 still. I then took a full 8 off while slamming hours on the eliptical/bike (10-13) and working full time. I built back up relatively slowly over freshman xc season with last month around 50mpw again. Foot was a little sore but I was in great shape. Took a week off at the end, and then once again my first week back to training the foot developed a really sharp pain. This was just halfway through the week following a slow 4 mile tempo. My mistake this past build was hitting high 40s/50s and racing. I didn't implement a full day off. But I ran 30-35mpw for a couple months before this, and implemented a gravity assist treadmill as well. I would like your opinion on this. But my plan next time is to not top 35 and run 4 days a week while doing intense cycling/ swimming.

I wouldn’t hang it up just yet. As another poster mentioned, you’ll have a cycling/tri career after college, even as you use them to crosstrain now. College running is a once-in-a-lifetime opportunity, and it will be over soon enough.

But you need to take more time off and just get back to establishing a real base before you start implementing hard workouts. This might mean missing or redshirting a full fall or spring season. Just get out there and get your body in a position to absorb enough miles.

Also, you may need to throttle the hard workouts back in terms of volume and frequency. This is where I think Tinman has it right, where all you really do in the course of a week is a CV workout w hills afterward, a Tinman tempo (not hard) w 200s afterward, and a long run.
So, during racing season, you essentially have the Wednesday workout and the Saturday race and that is it.

I second the D3/K2 advice. K2 is an unsung hero that helps build bone and shuttles calcium away from your arteries. You need 100 mcg for every 1000 IUs of D3 so like 500mcg and 5000 IUs. Start doing this immediately when you start building base.

On the other hand, a FTP of 350w is really good. You could probably be a very good time trialer, and most runners make good climbers, so, perhaps cycling is your future. If money or scholarship isn’t an issue, you will probably get a similar experience on a collegiate cycling team, maybe not quite as good but pretty close.

You said you love cycling. Do you love running? Your heart knows the answer to this. You could always give running one more year, and if you haven’t figured it out, then make the switch.

I realized when I got this last diagnosis that I wasn’t ready to give it up. Recently listened to a podcast about the best Norwegian Ironman guys only doing 35mpw on 4 days. I still love it and think I can be successful. But I think my love for both could lead to success in triathlon later.

At 19, when you should be in peak health, you have low testosterone, low bone density, and you've had three stress fractures!

I think you need someone in your life, not an internet stranger, to tell you that your life is out of whack. You're addicted to exercise, or something like that, but you're in it too deep to see for yourself. (That's not a criticism, just an observation.)

Your long-term health is more important than the next race, and it's severely at risk right now.

Anecdotally, check out what Ryan Hall has to say (nowadays) about how unhealthy he was as an elite runner.

You want my opinion? Stop running. Stop biking. Stop training. Just stop. Go back to being a normal healthy human before it's too late.

350 watts with a runners build is very solid. You should focus on cycling and will upgrade quickly. As you gain racing experience, Cat2 (maybe 1) shouldn't be an issue, then go compete in Collegiate nationals.

Do you train in alpha flies or vapor flies? Some correlation is starting to emerge connecting them to femoral sfx. great for feet, unsafe up the chain...

Could you explain more about this, I'm genuinely curious

Yes. Do that.

This is a very interesting take. It is not the first time someone has told me something similar I'm not going to lie. I really enjoy this stuff though man. I don't think I can just quit. I've thought about what you are saying. Training for something gives me a goal and a hope. And it's a lifestyle that keeps me out of trouble/ focused on the wrong stuff. I will definitely check Ryan Hall's stuff. I have some in the past and remember him saying having around 100 T levels which made me feel better.