Regardless of whether it's a gel, a drink, a bar or even just sweets that you're knocking back on the move, you're doing it for one very visceral reason - the wall. The wall is what marathon runners hit in the second half of the race, usually somewhere between 18 miles

late."Products Of Your TimeWhat you take on is more than a matter of taste. A myriad of sport-specific products exists, each one vying for that place in your race-day kit bag. You can choose from carbohydrate gels to isotonic drinks; energy bars

of stored energy are released as the spring recoils."The further you can stretch those springs and the quicker they can reach full extension, the more power they will generate each and every time they snap back.That sort of instant energy sounds ideal