Short hill sprints have the final goal to help to recruit the most part of fibres in your muscles. That's the reason because is an important training NOT CONNECTED with the distance of the event, but with a physiological target.
Normally, I use this work as second training of the day, after a long run (may be 1:15 - 1:30) at good pace, but not too much fast (in the case of Marathon runners of 2:08, for example, about 5:30 / 5:40 per Mile pace).
Of course, if there are athletes training once a day only, we cannot use short sprint as full training session.
The development of this training (that remains for all the season, without any difference between general period and specific period)is to move for longer distances (for example, 10 x 150 or 10 x 200), only after reaching a very good level of speed and specific speed endurance (not before 2 months of short sprints). In this way, we can move from a MECHANICAL and NERVOUS goal, to a METABOLIC goal, maintaining the other goals too.
About the guy writing that with these workouts every athlete cannot last more than 2 years, I can give the following examples :
Shaheen (from 2002 to 2006, 26 competitions of steeple without losing, 5 full years, and his injury is due to an impact against a door)
Mark Bett, lasting 10 years at top level from 12'55" to 26'52"
Manyim, 10 years from HM, pacer of 3000 steeple and full Marathon with 2 performances every year about 2:08 - 2:09
Moses Mosop, with me from 2002
James Kwalia, with me from 2002
Wilfred Bungei, Olympic Champion 2008, using short sprints uphill from 1999
I can continue with a lot of other athletes. But when you speak, you must know what are you speaking about. Too many times, when American or European people see that a top Kenyan disappears, they suppose this fact depends on training.
Instead, the most part of times are problems not connected with their athletic activity, but with their normal life, to provoke a break in their career.
Normally, a top Kenyan athlete, going home, becomes the referement for all his village, not only his family, and goes to be disturbed by a lot of problems of other people. As is very difficult for an African to have in his mind at the same time more than one problem, the first effect is they become confused, and quit training.
This was, for instance, the reason of the stop of Nicholas Kemboi,one of the greatest talent I saw in my life, able to move from 28'19" to 26'30" in less than 2 months of continuous training with me in St. Moritz in 2003, after affected by a lot of personal problems, in part connected with his change of citizenship.
So, nothing to do with short sprints.
Instead, when you exceed in lactic training, giving too much importance to that area against the aerobic area, you really goes to short your career.