Walking during the Nine Days
Question
If a woman is accustomed to walking for sport, which causes her to sweat profusely, can she do her walks during the Nine Days and then bathe in lukewarm water, limb by limb / and wash her head? And is there a difference between the Nine Days and the week in which Tisha B ’Av falls?
Answer
Shalom!
It is permitted to engage in sports activities during the Nine Days for health and similar purposes, even if it is known that the person will sweat afterwards and will need to bathe.
The permission to bathe for those who sweat is according to their need: those for whom it’s sufficient to wash just a part of the body, should not bathe the entire body, and those for whom cold water will suffice [or lukewarm water that is not enjoyable to the body, which has the same status as cold water] should not bathe in hot water, and those who do not need soap to cleanse, should not bathe with soap.
For Ashkenazim, there is no difference in this matter between the week in which Tisha B’Av falls and the Nine Days. For Sephardim, the prohibition is only in the week in which Tish B’Av falls.
Source
Shulchan Aruch, section Orach Chaim, chapter 551, paragraph 16