Metatarsal stress fractures tend to be one of the fasted healing fractures [Think of Rooney]. 4 weeks should be more than enough of none weight bearing but is depending on the individual: Sporty/ none sporty, age, weight, general health, cause of fracture, alignment of fracture and so on.
But why do you want to have a shortest possible recovery time? What is the race about? Shouldn`t best recovery be the goal [quantity versus quality]?
I would though use a very simple system [ which becomes more simple the more you use it]: Use pain as an indicator. Use the information you get from the referer.[ not following his instruction makes you liable]
Partly weight bearing [ aquajogging] should be used with care and on indication of pain. I am wondering though about aqua jogging which seems to me rather stressful because it is hard to monitor the amount of stress on the fracture site unlike the use of scales and crutches/bars [patient will focus more on his foot]
You have to let your treatment be guided by the pain:
-use of medication might influence the recovery or hide symptoms like pain.
-No increase of pain over time [all sorts of modalities] unless patient has stopped with medication which influences painlevels.
-Sharp pain indicates something different than dull ache or burning pain. Temporarily increase of dull ache and sharp pain is to be expected after exercising.
-Painlevel will increase on movement and/or weightbearing but should go back to earlier level [pre exercise] within 30 minutes [ I am very generous with this figure take 15 minutes but do not stress your patient with this information].
-Try more weightbearing [stress] only if the pain has subdued at former stress level.
-More weightbearing means using more time at a certain level of weight or more weight during the same amount of time.
- guide the patient , they tend to try to much in general and are going to have a set back. Let them inform you about the discomfort they feel. Inform them about guidelines to pain. In other words let them take [joint]responsibility for their progress.