Heat: what to use tonight

If you have nothing, in order of preference

1. A hot shower. Water directly onto the low back, as hot as you can comfortably take, for ten to fifteen minutes. The best option most people already have, though getting in and out is the hard part — put a chair or a mat down first and move slowly.
2. A hot water bottle. Wrap it in a tea towel, lie on it or against it. Refill every half hour or so.
3. A wheat or rice bag microwaved for a couple of minutes. If you don't own one, a clean sock filled with dry rice and tied off does the same job.
4. A warm bath, if you can get in and out safely. Some people find the getting out costs more than the bath gives. Judge honestly.
5. A towel run under hot water and wrung out, swapped every few minutes. Crude, but it works.

Why heat and not ice

Heat opens up blood flow to tissue that is compressing its own circulation, and it feeds the nervous system a safety signal rather than a threat signal. Cold does the opposite of the first part: it makes muscle contract, which is the exact thing you're trying to reduce while the segment is locked.

Ice has its uses — an acutely inflamed joint, a fresh impact injury — but not on an active muscular spasm in the first 72 hours.

Using it safely

• Check the skin every twenty minutes. Reduced sensation plus a heat source is how people get burns they don't feel.
• Don't sleep directly on an electric pad unless it's specifically designed for overnight use.
• Never apply heat over numb skin, broken skin, or an area you can't feel properly.
• If heat increases the pain, produces tingling, or feels strange rather than soothing, stop and reassess.