Don’t bother with 4×100 splits.
If you already agree with this sentiment, I’m probably not going to say anything you haven’t already a millions times yourself.
If you do still try to take 4×100 splits, I apologize for all the times I’ve snickered behind your back. The biggest question to ask is: What are you timing?
If you time how long each athlete carries the baton, odds are you are not timing even 100m increments. So you could time one athlete for 95m and the next for 105m. That may all sound like “about” 100m, that ten meter difference is 1.15 seconds for an 11.5 100m runner. This is the same reason why you time the baton, not the runner, in the 4×400 and 4×800. Accuracy of distance is vital for taking any kind of split.
If you are timing the baton over even 100m increments, there are still two major problems: 1) unless you are high in the stands, you can’t accurately judge when the baton crosses the center of each exchange zone, and 2) even if you are, the portion of a particular athlete’s leg that is run by teammates (by virtue of early zone or late zone exchanges) is far more significant than it is when taking 4×400 splits.
Basically, the standard error of ±1 second on a split that is acceptable in longer relays, renders 4×100 splits worthless. Not to mention that one of your four legs is starting out of blocks while the other three get rolling starts. Time can also be lost in bad versus good exchanges.
Some coaches will say, “but my athletes like to know anyway.” My response is educate them as to why it’s a meaningless stat and avoid giving them any misleading information that could disrupt team unity.
Rich
Note: I have to confess, we had HUDL this year and I may have used it to time rolling 80s from the end of one exchange zone to the beginning of the next (you can go frame by frame and use the video counter to calculate time). But this also was taken with a grain of salt as it’s hard to get a great angle (even on video taken from the stands) and not have other teams in the way.