Let's start with the general recommendation that a competitive endurance athlete needs 0.5 to 0.6g/lb body weight. The average 150lb male (that's me) would need about 75-90g of protein per day. Since I also weight train, I'll keep my requirement at the 90g per day. On most days I'm sure I get this amount and more, but the two questions are; is it quality protein and did I get it at the right time? Bars and drinks that are balanced with protein, simply make sure that you have a convenient and great tasting way to get the quality protein you need, when you need it (throughout the day and mainly post training).