Legs burning? Good! Why lactic acid is NOT your enemy

Lactic acid, properly known as CH₃CHCOOH, has had a bad rap.

Burning thighs when you’re walking hard? ‘Lactic acid’ isn't to blame – in fact it’s doing your body a whole host of good. Here’s what you need to know.

1 It’s not lactic acid

‘Lactic acid’ has been blamed for tired, painful legs for decades, but scientists increasingly think we’ve got it all wrong. First, they discovered lactic acid isn’t produced at all during exercise, next that ‘lactate’ (which is) isn’t a waste product that stings your poor muscles, but a nutrient they desperately want. 

2 It’s not hurting you

Muscles working at intense levels do naturally become more acidic, which interferes with their ability to ‘fire’ and do their work. But lactate doesn’t cause this acidity, it alleviates it, serving as a fuel for the muscles, reducing acidity, delaying fatigue and preventing injury. 

3 It helps your heart

Keep walking and you’ll produce more lactate – and when you’ve got more than your muscles need, it spills over into other parts of the body. Among its uses, scientists found lactate limited inflammation following injury, and that during rest it becomes a major fuel for the healthy heart, improving its function. 

4 It feeds your brain

Lactate produced by exercise is your brain’s fuel of choice – preferred because it can be directly consumed, unlike glucose which has first to be converted to lactate – and studies reveal brain fuelling with lactate improves clarity of thought, long-term memory formation and neuron production.

5 It doesn’t stop there

Repeated exposure to lactate from walking causes the body to adapt in ways that are at once very sciency (like mitochondrial biogenesis and whole-body homeostasis), and powerfully good (like better circulation, metabolism, stress-management, learning and resilience). Scientist George Brooks Ph.D, a pioneer of the reassessment of lactate, says “It’s like the VISA of the body – accepted by cells everywhere it goes. It’s a revolution.” So if you’re feeling that ache in your legs, rejoice! You’re preparing a feast for body and mind.