Chapter 90:1
Non-Melacha Prohibitions
1. There are actions which are forbidden on Shabbos even though they do
not resemble a "melacha" (one of the 39 forbidden activities), nor is it
likely that they will lead to the performance of a "melacha." [If so,] why
were they forbidden? Because [Isaiah 58:13] states: "If you restrain your
feet because of Shabbos, and [refrain' from] tending to your affairs on My
holy day...honoring it by [refraining] from your ways, pursuing your
affairs, and speaking [of weekday] matters...I will let you ride the
heights of the earth and enjoy the inheritance of your father, Jacob..."
Based on the phrase, "honoring it by [refraining] from your ways," the
Sages stated [Shabbos 113a]: "The way you walk on Shabbos should not
resemble the way you walk during the week." Therefore, it is forbidden to
run on Shabbos (1). [This does not apply to] matters involving mitzvot. In
that instance, it is permitted - indeed, it is a mitzvah - to run
(2). (This can be inferred from the verse itself: "YOUR ways," implies
that the prohibition applies only when you are involved in YOUR ways,
whereas when involved in the ways of Heaven (that is, mitzvot), it is
permitted).
FOOTNOTES:
(1) People are generally rushing during the week to take care of their
business, and thus not running on Shabbos would be considered "refraining
from your ways," that is, the regular way you do things during the week. It
is also forbidden to jump or skip (Mishna Berura 301:1,2).
(2) Youths are permitted to run around for pleasure on Shabbos, since it is
a mitzvah to have pleasure on Shabbos ("Oneg Shabbos"), and these sort of
activities are what gives them pleasure. It is even permitted for an adult
to run to see something that will provide him with pleasure (Shulchan Aruch
301:2 and the Mishna Berura).
It is also permitted to jump over a puddle (if walking around it would be
difficult) or to run to get out of the rain (Shulchan Aruch Harav and
Minchas Shabbos).