I agree with Christian,
"Hormonal responses from training are overrated. They are transient at best and WILL NOT have a significant impact on performance and recovery. Fastors such as post workout nutrition, restoration techniques and means of training should be emphasized".
For the athlete, the key to training is finding the appropriate training effect that will improve specific components (speed and so on), eat well and rest appropriately. Logic tells you that if this criteria is met, the body's hormonal response will take care of itself.
I am also in agreement with Christian's comments referring to so-called gurus who "like to use strength training exercises to burn fat by using long series (15-20+ repetitions) and short rest intervals (30-60 seconds)". A friend once did such methods (high reps, light weights) in preparation for the Mr Universe in England and lost about 25?% strength and a lot of muscle. The next year, I recommended he train the same way when dieting as he did when trying to build muscle, that being heavy and fairly long rests. While he lost about 5% strength, he came in 10kg heavier weighing 104kg (178cm) ripped, after beign 116kg, and placed second.
Again, while I would argue that there are many ways to train in terms of exercises and reps used, I believe it is absolutely crucial that any athlete never get away from the training methods that enabled the improvements in the first place.
In relation to sprinting, this demands that the prime emphasis is always on speed and power. It is far easier to get fit for a training distance than improve speed and power. In fact, for a 100-200m sprinter I would argue that optimal speed endurance can be achieved in around 6 weeks given that such events are primarily anaerobic. In contrast, as I am finding out with my athlete, who is now just focusing on 60m speed and strength, it is extremely difficult to improve power and speed.