Swim 40 100’s

Learn to Pace Yourself Properly

The power of the "Swim 40 100's" workout is that it teaches you to pace yourself properly. This will have a huge carryover to your race performances.

The principles can easily be carried over to swimming, cycling or even kettlebell swings and snatches.

This workout was rumoured to be one of Chrissie Wellington's favourites. I've never had the opportunity to ask her but, with its effectiveness, it wouldn't surprise me.

Almost anyone can swim three or four 100m intervals fast with a reasonably long rest interval and they'll be fine.

This workout takes away rest as a set variable. You only get to rest for the amount of time left over before the end of the interval: rest and work are combined. If you swim faster, you get more rest, if you swim slower, you get less rest. 

The problem is that if you swim too fast, the extra rest you get is too little. So that's not a solution. If you swim too slowly, the workout turns into a 4k long swim at a pace faster than your 4k personal best. Either way, pace it wrong and you don't finish.

In order to make the workout work properly, you have to figure out how long your intervals need to be. To do this, take your best recent 400m time, work out the average 100m time and add 10 seconds.

Now, you have to swim close to your best 400m pace for 4000m. Pace it right and you'll get just enough rest to be able to complete it. If you can't do it on this interval, add another 5 seconds to the interval next time. Over time, you should be able to reduce the interval even swimming the same pace.

If 40 intervals are too many, the workout is just as effective if you do just 10, 20 or 30. 

How to do the "Swim 40 100's" workout...

Warm up thoroughly for about 800m using a combination of easy/steady swimming and your swim drills (that means the drills you need, not the ones you like!).

Wait until the pace clock hits the top and set off swimming...

40 x 100m Freestyle swimming, setting off every time the pace clock gets to the end of your interval. Focus on hitting the same split every time.

Cool down by swimming 200m very easy, ideally incorporating a bit of backstroke to stretch out.

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Will Newton


In over twenty years of coaching, Will has coached everyone from absolute beginners to world champions. His interest in getting the best results for athletes who compete for the love of the sport, rather than as professionals, drives him to find the most effective ways to get results.

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