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Pool faster in one direction than the other?
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I did a bunch of 25's today, which I don't do very often, and almost every time I was faster by about one second going from the deep end to the shallow end of the 25 yd pool I swim in. I'm not a gifted swimmer by any means, but virtually every time leaving from the shallow end would net a time in the low 19:xx range and leaving from the deep end was in low 18:xx range. These were with a pretty quick 3-4 sec rest at around 90% effort. Any reason this would happen??

I think this was the first time I've swum 25's since I started wearing a watch to keep track of pool intervals - I'm assuming there was this discrepancy in the past, but I didn't notice it by just glancing up at the pace clock.


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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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There's a pretty significant current where I swim (Tosa WAC in Milwaukee). The current runs counterclockwise around the whole pool, so the outside lanes have a stronger current than the interior ones. In the outside lanes it can be 1-2 seconds different between the two directions. I'm guessing that it just has to do with the way that the jets are oriented coming out of the filter pumps.
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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natethomas wrote:
I did a bunch of 25's today, which I don't do very often, and almost every time I was faster by about one second going from the deep end to the shallow end of the 25 yd pool I swim in. I'm not a gifted swimmer by any means, but virtually every time leaving from the shallow end would net a time in the low 19:xx range and leaving from the deep end was in low 18:xx range. These were with a pretty quick 3-4 sec rest at around 90% effort. Any reason this would happen??

I think this was the first time I've swum 25's since I started wearing a watch to keep track of pool intervals - I'm assuming there was this discrepancy in the past, but I didn't notice it by just glancing up at the pace clock.

is this an outdoor pool?
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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In my home pool that happens in lane 2 in the shallow end. There’s a wicked current that slows you down coming into the wall, it’s very noticeable if you are sprinting against someone in lane 3 (no current)

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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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Isn't it obvious? If the pool runs north/south, one direction you're swimming uphill and the other way downhill. Or if its east/west, one way you're swimming with the Earth's rotation, and the other way against it...

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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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There's an outdoor long course pool near me that is faster in one direction in the middle lanes by about 4 seconds and the opposite in the outer lanes.
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Re: Pool faster in one direction than the other? [Warbird] [ In reply to ]
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Warbird wrote:
Isn't it obvious? If the pool runs north/south, one direction you're swimming uphill and the other way downhill. Or if its east/west, one way you're swimming with the Earth's rotation, and the other way against it...

Where was the moon ? It's pulling you.
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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is it an outdoor swimming pool? if yes, wind also plays in this game

is there a significant depth difference between both sides? if yes, normally you will swim slower when finishing at deeper side, why? you swim faster in shallow swimming pools the floor of the swimming pool also plays in your speed, so.. it is like swimming uphill versus downhill, or better said run in two differents tracks both of them uphills, the first with a increasing gradient from easy to difficult, versus a decreasing gradient from difficult to easy. (*)

(*) and in this case also psychological aspects play because the postive feedback of swimming faster and faster, help you to swim even faster. A negative feedback make the opposite, you will note that you are moving less and less water because the deep and you will swim even slower.

In a short pool this is not a big issue, but in 50m pools you can see even more. And if there is a jump platform in the pool... so extra depth... you will realise the most.
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Re: Pool faster in one direction than the other? [PMo] [ In reply to ]
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I have felt that same thing in that pool. It always seems faster heading back to the shallow end. However, now that I'm swimming with the Masters group there, I haven't really had the time to sense that as I'm usually just trying to hang on to the group. Have you joined in on Wednesday or Saturday?
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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natethomas wrote:
I did a bunch of 25's today, which I don't do very often, and almost every time I was faster by about one second going from the deep end to the shallow end of the 25 yd pool I swim in. I'm not a gifted swimmer by any means, but virtually every time leaving from the shallow end would net a time in the low 19:xx range and leaving from the deep end was in low 18:xx range. These were with a pretty quick 3-4 sec rest at around 90% effort. Any reason this would happen??

I think this was the first time I've swum 25's since I started wearing a watch to keep track of pool intervals - I'm assuming there was this discrepancy in the past, but I didn't notice it by just glancing up at the pace clock.


Could you unconsciously be pushing off harder from the deep end, since you are not standing?

edited to add:
Turbulence must be variable in pools, but I can certainly see that jets aimed a certain way or in one lane or another, can make a difference. This is N=1 and you now must repeat the experiment in a different lane.
Last edited by: dtoce: Apr 2, 19 4:31
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Re: Pool faster in one direction than the other? [dtoce] [ In reply to ]
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As I remember there were faster lanes in the pool at the Rio Olympics.

A person got a medal in the 50 free that wasn't expected to.
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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Many pools draw half the circulation water from the gutter system The other half via the bottom drains. A current exists. It is this principle that allows the floor cleaning systems to work in residential pools. At the college pool I swim in there is a solid 1" time difference.
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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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Happens to me all the time when I swim down hill
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Re: Pool faster in one direction than the other? [jaretj] [ In reply to ]
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Fina has maintained the jets were turned off durring the sessions, but I am skeptical. However there was a wold championship a few years back where the results were undisputable. I tried googling it but kept coming up with billiard results...
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Re: Pool faster in one direction than the other? [ajthomas] [ In reply to ]
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This covers what you're looking for:
https://www.washingtonpost.com/...m_term=.631e396e0dfc

Happened at 2013 worlds and 2016 Olympics.

edit - tried to attache the image but it was too big:
https://img.washingtonpost.com/...chart.png&w=1484
Last edited by: tallswimmer: Apr 2, 19 6:27
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Re: Pool faster in one direction than the other? [ivantriker] [ In reply to ]
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The shallow end is 3’ and the deep end is 10’ - finishing in the deeper end was consistently slower. I guess you wouldn’t really notice this discrepancy unless doing 25’s or if you look at data after a swim and break it down by 25’s.


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Re: Pool faster in one direction than the other? [tallswimmer] [ In reply to ]
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That picture is definitive proof that ONE LAP IS ONE POOL LENGTH!!!
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Re: Pool faster in one direction than the other? [jaretj] [ In reply to ]
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You're right. And although no current should be "acceptable" for a world-level swim meet, it's especially unacceptable why you're swimming a 50 as there is no chance for it to supposedly "even out" over the course of the race. I've been to short course pools with circular currents and your lane 1 and lane 8 splits per length can vary wildly. If you count strokes, you could be 1-2 spl difference per 25 depending on your direction.
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Re: Pool faster in one direction than the other? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
In my home pool that happens in lane 2 in the shallow end. There’s a wicked current that slows you down coming into the wall, it’s very noticeable if you are sprinting against someone in lane 3 (no current)

This must be centennial....I hate that lane!
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Re: Pool faster in one direction than the other? [Birch] [ In reply to ]
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Birch wrote:
JasoninHalifax wrote:
In my home pool that happens in lane 2 in the shallow end. There’s a wicked current that slows you down coming into the wall, it’s very noticeable if you are sprinting against someone in lane 3 (no current)

This must be centennial....I hate that lane!

Yup. Centennial. Currents and waves.

In a weird way, I love that pool because it makes every other pool seem faster.

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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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Maybe bring a level next time to make sure one end of the pool isn't higher than the other.
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Re: Pool faster in one direction than the other? [JasoninHalifax] [ In reply to ]
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I miss my old outdoor SCM pool in Portland. It only maxed out at 5.5 feet deep with concrete walls, no gutter, and old school lane lines. It did a great job prepping you for open water.

My current YMCA has two lanes (2 and 5) that are dirt slow compared to the other 4. Probably 2 seconds/100. It was crazy to see the difference between there and swimming even in the warm-up lanes at Harvard a few weekends back.

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Re: Pool faster in one direction than the other? [natethomas] [ In reply to ]
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How do you know it's faster? Some pools I swim in have a clock at either end. I wonder sometimes if they aren't out of sync by a second or two. Are you using one clock or is it by watch?
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Re: Pool faster in one direction than the other? [BobAjobb] [ In reply to ]
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BobAjobb wrote:
Warbird wrote:
Isn't it obvious? If the pool runs north/south, one direction you're swimming uphill and the other way downhill. Or if its east/west, one way you're swimming with the Earth's rotation, and the other way against it...


Where was the moon ? It's pulling you.
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Glad you guys cleared that up. I figured the pool was just a bit shorter in one direction.
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