What CSS Training Means In Practise

For distance swimmers - including open water athletes and triathletes - one physiological factor is all important: your lactate threshold. If you can improve your speed at threshold then your race times will drop. Your ability to sprint or work anaerobically above threshold is largely irrelevant in distance swimming and triathlon.

Compared to traditional master's swim sets, CSS training involves swimming at a slightly (only slightly!) slower pace but with much shorter recoveries between each swim. This keeps things focused on developing your aerobic system, which is what you need to become a better distance swimmer.

The problem with sprinting hard and then recovering is that it focuses much more on your anaerobic system, which is great for sprinters but far from ideal for distance swimmers and triathletes.

CSS is an acronym for Critical Swim Speed. It's an approximation of your lactate threshold speed and you can find it by doing a couple of swimming tests (no messy and invasive blood lactate tests involved - just a stopwatch!). It's not precisely the same as lactate threshold but it will be extremely close and plenty accurate enough to guide your training.

(the above was taken from "Swim Smooth")

Hope this helps

Best

Coach Audrey