Have I committed a sin, or fraud and deception, by absenting myself from the sports class to perform prayer, while my friend confirms my presence in the college, whose system does not allow departure except on Thursday evening and return on Saturday night?

Registering attendance without being present is considered a lie and is forbidden, except in cases of necessity or a need deemed legitimate by Islamic law. If the punishment for absence is running around the college, this is a beneficial exercise and not a punishment, unless the running causes you hardship. In that case, it is permissible for you to falsely register your attendance due to need, as lying is permitted to achieve a legitimate objective that cannot be attained otherwise.