I've been criticized multiple times by various forum members for trying to combine sport specific training with strength/vert/speed training. The way I see it, I might as well add in as much sport specific component as I can or else my training will be inefficient. There's soo much to work on but your body/schedule can only handle a few things at a time, might as well try to get the most out of your training.
The criticism is fair. You are also right that your body can only handle so much. But the solution is not to confuse your speed training with sports specific training. The solution may be to do MORE sports specific training, rather than muddy your speed specific training with sports specific training. I mean why run 40's without a frisbee catch? Why not before every 40 have you or a friend throw the frisbee 50 yards down field so it gets to 50 yards in about 6 seconds after you start, that way run 40 yards and go and catch the frisbee? Wouldn't that be better? Or would it make your speed training less efficient?
You're right about standing left/right starts not ever happening in frisbee. But even if there's a countermovement, accelerating out of it can be similar to a sprint start. Let's say I put in 1000 sprint start reps, all starting with a right leading leg, and then I attempted that movement (from the video) in a game, using left and right legs. Even though it's not the exact same movement, wouldn't the movement with the right leading leg end up being considerably faster than left leading leg?
You are asking an unfair question. IF you are asking me to train you to make you the best ultimate player possible AND you are limiting the tools I can use to 40 yard sprint work, then you may have a point... BUT I would never train you using only 40 yard sprints! That would be silly. The countermovement you see in the video is actually VERY different than a 40 yard sprint start. I'm not going to argue that there is zero carryover, but the carryover is very little.
I don't know much about frisbee, I know only one athlete who played professionally for the seattle sockeye and from what I understand from him the game is becoming a little less a leisure sport and starting to become a bit more like football and that they now have a combine where players are tested in the 40 yard dash. If this is true and it is going in the direction of the NFL where they put far too much weight on the 40 yard dash time - you have to accept it and get the best 40 yard dash time possible. IF the powers of frisbee are stupid and make athletes test their 40 yard dash with both lead legs... Then yeah you gotta practice both. You have to get as good as possible at combine tests that are part of tryouts - no matter what they are or how silly they are because your performance can make or break your ability to make a team... It's my understanding that they are including a 40 yard dash like football where you can use either lead leg. So you need to get as good as possible at this drill. Not make your performance suffer by using both lead legs...
Think about training efficiency like this. You can only do so many reps. Lets use the number you gave of 1000 total reps in some training period. Here are your options.
Your starting ability:
1) 40 yard PR = 5.0 seconds (left/right lead leg = 5.0, 5.1)
2) Left lead leg countermovement ability and right leg (in game skill ranked 0-10) = 5,4
So in these skills we are going to call you a 5.0 (5.0, 5.1), 5, 4 guy. Obviously we want these all to get better.
Now here are some training options are results:
Option A: 1000 dominant (left leg) 40 yard sprints.
Result A: 4.6 (4.60,4.90), (8,5)
Option B: 500 left, 500 right 40 yard sprints (both done alternating)
Result B: 4.75, 4.80 ( 7,6)
Option C: 500 left (focus on speed without confusion of switching leg) and 500 reps of 60 yard short shuttlee (NFL combine drill for change of direction).
Result C: 4.65 (4.65, 4.85) ( 9,8)
Who makes the team? IMO Athlete B is the worst one at the tryout. Whether it's fair or not the coaches are going to see the 4.75 first and foremost and brand him as "Not that quick". Additionally, because he countermovement ability has been trained in a really not specific way he is only slightly better at change of direction that athlete A. Athlete B is first to get cut. He is slow.
Athlete A has overemphasized the 40 at the expense of other drills but may make the team over both A and C if the coaches are anything like NFL coaches and put a ton of emphasis on the 40 yard time.
However, if the coaches are good and can recognize talent then athlete C will make the team (and apart from making the team athlete C is the best). He has trained specifically for his 40 and achieved a very respectable time of 4.65 which is only slightly worse than what he would ran if he only trained for the 40... Additionally by spending time working on his 60 yard shuttle he has far better performance on this test (if it is included in the combine) which allows him the specific change of direction skill to get open better than his competitors and outperform them in the tryout.
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This is how you need to structure your training. Get your 40 yard time as good as possible without obsessing over it so much that you neglect your sport (how much neglect you should do depends on the weight put on it at tryouts). Also train sports specific skills. But don't hinder your ability to get better int he 40 by adding a non-specific variable that will have marginal carryover to the ability you are training... Does that make sense?