Ice is synonymous with treating many acute running injuries particularly sprains, strains, and bruises. Ice should be applied to injured area as soon as you get home for 20 minutes. It is advised to do this 4 or 5 times a day for acute injuries. Ice reduces blood flow to an injured area reducing both inflammation and pain.
You could reach for a bag of something out of the freezer however ice packs, bags and wraps that are designed specifically for sporting injuries are easier to apply to specific parts of body helping you to recover faster.
Instant ice packs are useful as they don’t need ice to work which is great if you do not have access to a freezer, activated by a chemical reaction triggered when bag is twisted to mix ingredients.