You are not correct about 60 fps.
And I believe it is you that is in error!
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I was quite clear on my position. Is it your position that
all meaningful serve analysis requires 240fps? That seems to be your assertion, and if so it is simply wrong and easily falsifiable. 60fps can identify many serve flaws; from a very high toss, a poor racquet drop, a waiter's tray error, a low elbow at or around trophy position, a tossing arm that isn't raised properly, and an incorrect grip, to name but a few. That would still make 60fps a rather valuable tool for those that don't have the magic 240 number available to them. To suggest that, just because frames are missing (when aren't they?) one can believe anything they want, is a red herring, and you have proven this yourself by making observations and interpretations based on 480p @ 30fps, right here:
Rec player here that would classify himself as an "improver" that just wants to develop some good technique, learning most of the technical stuff from youtube. Can I get some advice on which elements of the serve I need to focus my attention. I've recently started practicing a pinpoint stance...
tt.tennis-warehouse.com
At lower frame rates, analysis should be limited to the frames that
are visible, and I never suggested otherwise, but I didn't think that needed mentioning.
[..]I've spelled this frame rate issue out on the forum many times so why don't you think about whether you are spreading false information to some readers, who in turn...........[..]
This is a major edit:
Once again, if it is spreading false information to suggest a 60fps video can be useful for the purposes of a serve analysis, then how did you manage to reach your conclusions in the above
serve critique thread, based on much lesser quality? There are several more examples on these forums where you offer an analysis of videos filmed at 30fps.
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The problem as I see it is this: your beginning premise appears to be that every serve, no matter what the level or how many technical flaws it may have, requires, or at least benefits greatly from a detailed analysis of ISR. I asked that question above but the answer seems to be a resounding yes. The articles you cite - in particular the Marshall & Elliot article on long axis rotation, which finds ISR as
the major contributor to racquet head speed on the high level serve - say nothing about how deliberate this ISR actually is. While the ISR contribution itself is undoubtedly a scientific fact, note that it is also based on an analysis of the aforementioned
high level serve. That analysis in no way, shape, or form tells you how to
develop a high level serve.
Based on your first premise above, you then proceed to the next logical step; which is to claim that high speed video is an essential part of this process, and since 60fps can't adequately identify ISR (true enough) it is therefore useless for any meaningful serve analysis (a waste of time, or wasting time, were your words I believe). That however assumes your first premise is correct, and as you may have noticed, not everyone (including myself) agrees with that assessment, which is why you get so much pushback on your ad nauseam "high speed video ISR" pontifications.
And herein lies the problem; to me it is not logical to take the most significant contributor of racquet head speed from a high level serve (something that isn't even referenced as a conscious act), and then attempt to apply a detailed analysis of that single feature to each and every amateur serve that happens to come through the door, especially those with quite obvious technical flaws. Flaws that don't need 240fps to identify. It is my belief that the
8 stage serve model by Kovacs and Ellenbecker is an excellent tool for evaluating the tennis serve at all levels (where ISR is briefly mentioned as a key part of the contact phase, and also recognised as the key power contributor, along with wrist flexion). It covers and outlines many aspects that can be examined and compared to a high level serve using frame rates that don't require high speed video.
Is it not possible that as a serve begins to develop and take shape at a lower level, as certain aspects of the 8 stage model are successfully implemented, by getting the tossing arm up nice and high, by reaching a strong trophy position, and by learning to throw the racquet at the ball while correctly timing the leg drive, that ISR begins to appear as a result of these things rather than a forced act? Higher level serves that are in the minority would certainly be better served with 240fps, and I never argued against that either (for the record).
That is my argument against why 240fps is a
requirement, and perhaps you might want to reflect on that, while peering through the looking glass.
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And now, back to your regular viewing experience.