Soon enough, training camp will be kicking off for NFL teams. This will ignite fiery competitions between players who must earn the right to start or retain a roster spot.

Running back competitions in particular will be compelling. This summer will pit some aging veterans against younger, fresher legs. Who will come out ahead when new Denver Broncos running back Jamaal Charles attempts to salvage his NFL career in Denver with C.J. Anderson and Devontae Booker nipping at his heels?

Several quarterbacks will also be under tremendous pressure to prove their value. As usual, there are several teams conducting competitions to sift out which quarterback is best suited under center.

With a month to mentally and physically prepare to perform their best, the following 10 NFL players have the most to prove during training camp.