Using Critical Swim Speed in triathlon Training

Use Critical Swim Speed (CSS) in your triathlon swim training

As triathletes we now have equipment to show, heart rate, power, stroke rates, distance and even where you’ve been when you were lost. This also give us the ability to train smarter. Every 4 – 6 weeks my swim squads complete a CSS test. Critical Swim Speed. The result is a pace per hundred meters. This is a guide to your lactate threshold when you swim. CSS Blog Ok forget the clever stuff. This is you optimum swim pace for long distance swim races. You need to ‘know’ this pace by the time you get to next triathlon season.


Use CSS to train for Open Water Swims

Even though you’ve calculated your CSS you need to know how to use it. I’ve used the word ‘know’ several times. I don’t just mean you have a number on a piece of paper. To ‘know’ is to be able to intuitively swim at this pace. Your body ‘knows’ what it feels like. In open water swimming you will not have convenient markers every 25m to help you stick to the pace. You won’t be able to look at your watch because your arms will be flailing around. This means you need to ‘feel’ what this pace is like.

I’ve been using a swim set to help swimmers develop this feel. Give it a try.

Learn to swim at your CSS pace

Warm up: 10 minutes

Main Set: 100m at your CSS pace x 5 20 seconds rest to check the time. Each interval should be exactly your CSS time. (This takes practice) You can use a Finnis tempo trainer to help or the big pace clock.

75 m at CSS x 5 20 seconds rest. No clock. No Finnis Tempo Trainer. Swim just on feel. You don’t normally swim 75m intervals so this will change your perception.

F.A.Q’s: Yes. In most pools this is 3 lengths. Yes. You can rest at the other end of the pool. No. Don’t swim back to this end between intervals.

100m at CSS x 2 20 seconds rest. Check the pace you have been swimming.

Cool Down: 5 minutes



No two athletes are the same. You have a busy and deserves our very best. We take the time to get to know you so we can help you experience tri – sports at your best.

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