The latest wave of fitness wearables wants to measure something new this summer: how much you sweat and how well you are staying hydrated. With the UK baking through another heatwave, so-called hydration trackers and 'sweat score' features have jumped from niche sports kit into the mainstream shopping conversation.
The idea is simple enough. Sensors estimate fluid loss from your activity, skin temperature and heart rate, then nudge you to drink before you feel thirsty. For runners, cyclists and anyone training in hot weather, that early warning can genuinely help. Mild dehydration drags down both your performance and your concentration, and most of us are worse at noticing it than we think.
Whether you need a dedicated device is another question. Plenty of mid-range smartwatches now fold hydration prompts into the fitness app you already own, so you may not need to buy anything new at all. Standalone sweat patches and clip-on sensors exist, but they sit at the pricier, more specialist end and suit serious athletes more than casual gym-goers.
If you are tempted, treat it like any other gadget purchase. Decide whether the feature solves a real problem for you, check whether your current watch already covers it, and wait for a sale rather than paying launch-day prices. Fitness wearables discount heavily around the summer sales and again in autumn.
The honest takeaway: a hydration score is a useful nudge, not a medical reading. The cheapest hydration tech of all is a refillable bottle on your desk and the habit of actually using it. Buy the clever gadget if it motivates you, but do not mistake the number on your wrist for a substitute for common sense in the heat.