Why you feel so good after a hot class, it isn't just the endorphins

There's a particular kind of quiet that happens about ninety seconds into savasana after a hot class. You'll know it if you've felt it. It isn't sleep, it isn't quite meditation, it's the body finally letting go of something it had been carrying since Tuesday. I get asked all the time what's actually happening in there. So here, the short version.

Your circulatory system has a pump, your heart. Your lymphatic system doesn't. Lymph is the clear fluid that drains waste products, old immune cells and excess interstitial fluid out of your tissues, and it relies almost entirely on muscle contraction, breath and movement to circulate (British Society for Immunology overview). Sit at a desk for nine hours and very little of it moves. Spend an hour doing sun salutations in a warm room and a lot of it does.

The heat does a few specific things. Skin blood flow increases substantially to dissipate the warmth, which lifts cardiac output even in mild postures, a 2018 study at the University of Texas at Austin found that 12 weeks of regular hot yoga improved endothelial (blood-vessel lining) function in sedentary middle-aged adults, comparable to moderate aerobic exercise (Hunter et al., Experimental Physiology, 2018). Translation: the inside of your blood vessels gets more elastic, which matters enormously for long-term cardiovascular health.

Slow breathing matters too, possibly more than the postures themselves. A 2018 systematic review in Frontiers in Human Neuroscience concluded that slow breathing techniques (around 4-6 breaths per minute) reliably shift the autonomic nervous system toward parasympathetic dominance, the "rest and restore" state, and are associated with lower anxiety, lower blood pressure and improved heart-rate variability (Zaccaro et al., 2018).

So the post-class glow isn't a vibe. It's a measurable shift in how your body is operating. Fluid is moving. Vessels are relaxing. The nervous system has finally exhaled.

A couple of practical notes from twenty-odd years on the mat:

Hydrate before, not during. Drink 400-500ml in the hour before class. Sipping constantly during practice dilutes your sodium and tends to leave people dizzier, not fresher.

Replace electrolytes after a hot class, especially if you've come more than twice in a week. A pinch of sea salt and a squeeze of lemon in water does the job. You don't need a brightly coloured sachet.

Don't shower in cold water straight afterwards if you can help it. Lukewarm is kinder. Your cardiovascular system has just done some real work.

And if you're new, go gently. One hot class a week for the first month is plenty. Your body will tell you when it wants more.

, Linzy