How do you prevent sacrificing stroke length when you increase stroke rate?

Through recent trainings, I think I have been able to increase my stroke length. I can tell this by the hissing sound getting louder that I hear when I pull, as well as the number of strokes per yard. :laugh2: But when I try to increase the stroke rate as well, this time my stroke length suffers and the overall speed doesn't get as much boost from my recently increased stroke length. Is it because I am not executing the stroke technique in exactly the same manner when I'm sprinting as when I am just cruising? Or are there other things to watch out when I sprint?