My sports masseur, Vinny Power, who is just great, told me of his “magic cups” way.
Fill some disposable polystyrene coffee cups with water and freeze. Because they are ‘styrene, you can easily tear off a strip and apply it, without it getting too cold to hold or the ice falling out.
Apply the ice directly to the area BUT keep moving it all the time, never stopping in one place or you may burn the skin. I give about 5 minutes per shoulder/upper arm, when I’m icing, until the skin is bright red. It always feels great after.
Polystyrene cups are harder to find these days as they are non-biodegradable, but I recently got 2 packs of 40 in a €2 shop in Clonmel for …€2. Enough to do me for a few years.
I’ve used paper cups and they are ok also though the ice tends to fall out. Plastic cups are useless. I always keep one cup full in the staff fridge in the pool, just in case.
Ice is also good for lactic acid reduction on days when you are beat. Ice immediately if you think you have strained or overworked a muscle.
Some people like gel packs/frozen peas but you need to protect the skin from them and I don’t know if they make the area cold enough. Bio-freeze is good for short term use, about 5 days, no more as it’s very hard on the skin. It feels particularly effective right out of the pool, through some weird after-effect of the chlorinated water..