From the FAQ:

Training points for defending and fitness training regimes are distributed as follows;
50% of all the training points received by the player go to the first randomly selected defensive (if training defence) or fitness (if training fitness) skill
35% of all the training points received by the player go to the second randomly selected defensive (if training defence) or fitness (if training fitness) skill
the last third defensive (if training defence) or fitness (if training fitness) skill gets 15% of all the training points received by the player.

Stamina = Fitness Skill. So, yes