So how much difference is there in times on say, 100's when diving versus pushing off the wall for those that have good diving starts? I don't hop out of the water when training to do a lot of dive-in starts (though I know I should do it more), but I'm just so familiar with my times from starting from the wall. I've just started masters, former age grouper with 15 year hiatus...
it's hard to say how much help a dive is in a 50 or a 100, but when comparing 25 times I'd say at practice a dive start save 1-2 secs depending on the stroke.
in breaststroke from a push I tend to finish my pull out a few meters shorter than when diving.
if you have someone timing you from a dive compared to you looking at a clock from a wall start, then your time will be more accurate as well.
There is a teen boy on our year round team who recently had ear surgery and cannot dive for 18 months. He has to push off in races. Based on what he was swimming before and his results now, I'd say about 3 seconds is the difference. He would consistently win his heat/race and now is coming in about 2 seconds behind kids he previously beat with ease.
I actually did a set this morning with my group where we did some 50 sprints--the odds I did from the blocks, the evens from a push. I was about 2 seconds faster on the ones off the blocks.
Assuming that you get off of the blocks fairly fast, and have a good reaction time, you will see a few seconds difference between the ones from a push and from a start.
I only rarely push myself to racing speed off the wall, and generally would do a "fast" 100 free about 8-10 seconds behind a normal race time. That being said, I still think a dive would account for 3-4 seconds difference at that distance.
I think this is a highly individualized number based on each individual's start, push, and push off from turn. My push off after a flip turn is much more efficient and stronger.
My time is usually about 4 seconds faster from a block as opposed to a push off.
it's different for each person
TEST IT
do a fast 25 from a push for time
rest 5 minutes
do a fast 25 from a dive for time
compare the your times
Test it again several days in a row.
Do the dive 1st & the push 2nd
compare times
average times
the diff is probably 1 - 3 seconds
figure it out for you.