I recall having seen people on here mention that they use foam rollers for post run muscle relief. I have finally decided to take the plunge and invest in one. The array of variants on Amazon and every other website is bewildering though. Long ones, short ones, knobbly ones, ribbed ones, different degrees of firmness. I won't mention what it all reminds one of. The price range seems quite wide too. Could anyone enlighten as to what the difference is, or more to the point, which is the most suitable for runners?