Quick Dip: What Is Lactic Acid?

A short read for the car journey

Category: Training | Read time: Under 2 minutes

Near the end of a fast swim, your arms or legs might feel heavy and keeping your speed becomes harder. You may hear someone blame “lactic acid”. What does that mean?

The substance we usually mean is lactate. Your body makes it as it breaks down sugar to release energy for your muscles.

During hard swimming, you can produce lactate faster than your body uses it, so the amount in your blood rises.

Does this start at a certain age?

You already make lactate as a young child. Younger children generally build up less during hard exercise than adults. As you grow through your teenage years, that response gradually changes. There is no particular birthday when it switches on.

Lactate is useful fuel. Your muscles and heart can use it for energy.

So why can hard swimming burn? Several changes inside working muscles trigger signals from nerves. Lactate alone does not explain that feeling or why you become tired.

It also does not stay trapped in your muscles causing tomorrow’s aches. Soreness after unfamiliar or demanding exercise is linked to how your muscles respond and repair.

What does this mean for training?

Check whether you are holding the target times and keeping your stroke together. A stronger burning feeling does not prove you have trained better.

Use the recovery your coach has set. If it includes an easy swim, keep it easy.

Did you know? What pace and technique should I aim to maintain through this set?

Created by Basingstoke Bluefins Coaching Team