A nice long soak in an Epsom Salts bath. Also, if you're having spasms then ice, ice, ice for the first 12 - 24 hrs. followed by alternating ice & moist heat & gentle stretches to keep the blood supply flowing. Witch hazel truly does work wonders for sore, overdone muscles, bruises, strains, sprains. Keep bathing the area with it. I will soak a washcloth with witch hazel & hold it on the area for 5 or 10 minutes at the time. Witch hazel is cheap too.
Truly though, I think the best thing is to prevent this from happening. Starting in winter do some stretching exercises & as ridiculous as it sounds, things like the "Sit & Be Fit" exercises to prepare for spring. When you get out there, take breaks every 15 or 20 minutes. Stand up, bend over & touch your toes, stretch the kinks out, walk around a bit & let the blood flow back into parts that have been cut off.
Said the kettle to the pot.