Soaking in a hot tub for fifteen minutes, set at a temperature of 95 to 104 degrees F can be an excellent way to prepare for and conclude an exercise session. It will warm up muscles, decrease joint pain and stiffness, an ease movement in joints.
Hot Tub Safety: If you have active inflammation and heat in your joints, high blood pressure, diabetes, a lung or heart condition, skin irritation or other serious illness check with your rheumatologist before using a hot tub or sauna. Pregnant women should not use a hot tub or sauna.
(Source: Koehn, C., Palmer, T., Esdaile, J. Rheumatoid Arthritis Plan to Win. Oxford University Press. Oxford: 2002.)