Israel Hayom is reporting on an interesting psak by Rabbis Dovid and Avrohom Stav, father and son rabbis in Israel.

They recently publicized the psak in the Tchumin halachic periodical published by the Tzomet Institute. According to the psak, one could use exercise equipment on Shabbos, as long as it is not electric.

According to the psak, opposition to exercise on Shabbos was due to the approach that causing one to sweat is a medical need and a medical benefit. Exercise and fitness for the purpose of retaining a level of fitness and/or for burning energy was never prohibited. To that end they pasken that exercise at home, including using non-electric equipment such as a stationary bike (with no electricity) for non medical purposes, is allowed on Shabbos.

In the article they add that some have tried to ban it using the explanation of uvdin dchol - being similar to a weekday activity - but Rabbis Stav reject that opinion saying most opinions reject this, especially when the exercise machine is purely mechanical with no prohibition in its use.

Regarding running on Shabbos, it is more complicated. While technically one could run for fun/pleasure or for other, not solely health, reasons, running outside in sports clothes on Shabbos is problematic as it is damaging to the Shabbos atmosphere. One should preferably wear clothes special and designated for Shabbos the entire Shabbos, and not wear weekday clothing. Showering or bathing, likely to be done after such a run, would also be a problem as it can involve various prohibitions - so one should avoid activities that will cause one to need a shower if one does not know how to do so properly on Shabbos following the relevant halachos.

Rav Stav says everything is base don established opinions and no chiddushim were introduced for this psak. It used to be that Shabbos was a day of rest, but today that has sometimes become, for some people, a day of suffering and burden. Shabbos was given for enjoyment and not to be a challenge. Today part of the day off includes moving one's body, being active and not feeling tied down or imprisoned.

This does not include going to a gym to exercise, as that is disrespectful to Shabbos, butsomebody who wants to exercise at home and has equipment at home that would be allowed, is allowed to use it. Shabbos is not a day of sport, Rav Stav says, but if someone needs 30 minutes of physical activity as part of his enjoyment for the day, that is fine. He adds that now with the return of Corona to our lives and the possibility of more closures with limited activities and people feeling imprisoned at home, this psak halacha is very relevant.

I would only note that Macy's sells formal dress shirts made from Dri Fit material, and they aren't the only one, and there are also companies making dress suits in moisture wicking and breathable materials. An executive from one such company, Gihan Amarasiriwardena, ran a half marathon in 2015 wearing such a suit and held the world record for running the half marathon in a suit. So perhaps the problem of running in public in tshirt and shorts being inappropriate can also be solved by wearing Shabbos dress suits and shirts and going for a run like that. Perhaps one should run in all black running shoes on Shabbos, or maybe there are dress shoes that can be run in, but the shoes seem to be less of a problem.