الجواب حامدا و مصلیا
In the related matter, the perpetrator has become a grave Sinner due to his evil act during Ramadan al Mubarak for which it is incumbent on him to repent and make Isthighfaar and Thowba. However his fasting is accomplished and no Kaffara {Expiation} or Qadha {Repetition} is due on it. If the ejaculation was due to the stress of the legs on the basis that it could have been evaded had the stress of the legs been withdrawn, then in such a condition, although Kaffara does not become compulsory due to ejaculation but it will be necessary for him to make Qadha for nullifying the Fasting.