Your 5-wk timeframe and your built up run base as well as the fact that this is a Half, not full race, makes me optimistic you'll keep most of your run gains, if you put in legit deep water running sessions and a smattering of runlike elliptical to keep the neuromuscular recruitment there.
The race day run you'll have to pace conservatively, expect some real suffering at the end due to a lack of pounding conditioning, but I think you can capture the bulk of your fitness on the run by continuing to bike and swim hard, and do pool running at a legit effort to keep everything 'but' the pounding in shape.
I'd say differently if this was a much more long-term problem that would have you permanently reducing running (like for arthritis, which doesn't get better), but for 5-wks, I think despite its disappointing timing, you can still look forward to a reasonable run effort (just not PR land.)
I've been forced to investigate alternative runinng schemes due to some ankle arthritis that I'm managing, and certain ellipticals are actually decent for the run motion, like the Precor Adaptive motion elliptical, or the Arctrainer, although it's def still not running (lower cadence, higher force, feels kinda like biking, actually.) I'd def put some of that in there as well just for some nonimpact weightbearing training (if your doc ok's it - note that they are super conservative though.)
I def haven't had enough experience to really figure out the right mix to maintain run ability, but my hunch so far from experience is that water running is the #1 alternative - you can readily get your HR and run cadence to legit hard-effort speed, and aside from the impact, it really does translate to on-road higher leg turnover and more comfort with high aerobic effort on the roads. I've actually come to also like adding the runlike ellipticals as well for the weightbearing and even leg force training - I suspect they'll help some as the race gets longer. I also wouldn't discount the benefits of high-cadence cycling - on your lower-watt sessions, pushing up your bike cadence to near your upper limits is also very good training for hip leg turnover that for me seems to have some benefit to running, and definitely seems close to the run motion than low-cadence but higher watt grinding on the bike. I'm doing all 3 right now as I've had to cut back running due to arthritis, and I've been happy with how well things seem to be working so far. I'm probably at 50% low-mileage run sessions (<4 mi right now), 35% water run, and 15% runlike elliptical for running, as well as adding real focus to high bike cadence on my bike workouts whenever possible.
Whatever you do though, don't just try and return to running too fast and then just 'run through the pain.' Even on race day, if the pain is flaring up and getting more than mild, shut it down and walk, or even DNF if if you're having problems walking. THe worst thing to do as an AGer is to take a major injury because you overdid it and end up sitting out months. Unlike the pros (for whom it also sucks) who have time and access to added recovery tools, we AGers often fall completely off the regular building or even regular exercise curve once we can't exercise at all for months as we fill that time with lots of fluffy nonessential waste-of-time stuff that make it super hard to get back to that regular 1-2 hrs/day of working out.
The race day run you'll have to pace conservatively, expect some real suffering at the end due to a lack of pounding conditioning, but I think you can capture the bulk of your fitness on the run by continuing to bike and swim hard, and do pool running at a legit effort to keep everything 'but' the pounding in shape.
I'd say differently if this was a much more long-term problem that would have you permanently reducing running (like for arthritis, which doesn't get better), but for 5-wks, I think despite its disappointing timing, you can still look forward to a reasonable run effort (just not PR land.)
I've been forced to investigate alternative runinng schemes due to some ankle arthritis that I'm managing, and certain ellipticals are actually decent for the run motion, like the Precor Adaptive motion elliptical, or the Arctrainer, although it's def still not running (lower cadence, higher force, feels kinda like biking, actually.) I'd def put some of that in there as well just for some nonimpact weightbearing training (if your doc ok's it - note that they are super conservative though.)
I def haven't had enough experience to really figure out the right mix to maintain run ability, but my hunch so far from experience is that water running is the #1 alternative - you can readily get your HR and run cadence to legit hard-effort speed, and aside from the impact, it really does translate to on-road higher leg turnover and more comfort with high aerobic effort on the roads. I've actually come to also like adding the runlike ellipticals as well for the weightbearing and even leg force training - I suspect they'll help some as the race gets longer. I also wouldn't discount the benefits of high-cadence cycling - on your lower-watt sessions, pushing up your bike cadence to near your upper limits is also very good training for hip leg turnover that for me seems to have some benefit to running, and definitely seems close to the run motion than low-cadence but higher watt grinding on the bike. I'm doing all 3 right now as I've had to cut back running due to arthritis, and I've been happy with how well things seem to be working so far. I'm probably at 50% low-mileage run sessions (<4 mi right now), 35% water run, and 15% runlike elliptical for running, as well as adding real focus to high bike cadence on my bike workouts whenever possible.
Whatever you do though, don't just try and return to running too fast and then just 'run through the pain.' Even on race day, if the pain is flaring up and getting more than mild, shut it down and walk, or even DNF if if you're having problems walking. THe worst thing to do as an AGer is to take a major injury because you overdid it and end up sitting out months. Unlike the pros (for whom it also sucks) who have time and access to added recovery tools, we AGers often fall completely off the regular building or even regular exercise curve once we can't exercise at all for months as we fill that time with lots of fluffy nonessential waste-of-time stuff that make it super hard to get back to that regular 1-2 hrs/day of working out.