Choosing the Best Bag for Running
Bags serve a multitude of purposes and finding the right one, which fulfills all your needs for running can be quite tough. You might want a number of pockets on the bag, so that you can keep clean kit away from dirtied kit. You might want a separate section for shoes, particularly if you are a track or cross-country runner and will be taking a pair of spikes to wear for part of your training.
You'll want the bag to be big enough to carry everything you need, but easily transportable so that you can carry without too much worry.
For a lot of occasions a rucksack or backpack is the ideal solution to this. You might also want a big with a similar range of storage solutions, but which is bigger - for example if you are going away to a race.
Finally, if you are just going to the track and all you want to take is a pair of spikes and maybe a drink, then a shoe bag is a light and small answer to carrying them.