Cooling Down With a Personal Sprinkler

Cooling Down with a Personal Sprinkler

Lowering your skin temperature oentisay help you go faster; here’s one (unusual) way to do it.

This won’t be useful right now if you live in the chilly northern hemisphere, but I wanted to follow up on a post I wrote earlier this year about the best way to cool yourself down on a hot day. Read on if you’re currently experiencing summer.

Back in May, physiologists in Australia wrote a paper pointing out that, thanks to the energy required to evaporate water from your skin, you get far more cooling benefit from a pouring a cup of water over your head than you do from drinking it. There are various caveats (e.g., it’s less helpful on a humid day or if most of the water spills on the ground), but it seemed like a reasonable argument for the commonly seen practice of dumping water on your head during hot races.

To my surprise, I recently heard from someone who is trying to monetise a similar insight. The Spruzza is an “on-board cooling system” for cyclists that sits on the handlebars and allows you to periodically spritz a fine mist of water onto your face.

To be honest, I got a laugh out of it when I first looked at the website. But the developers are serious – in fact, they funded a study by researchers at the University of California, Davis to test the device’s effectiveness. It was presented at least year’s American College of Sports Medicine annual meeting.

As an aside, I get a ton of pitches about products designed to enhance performance. Some (though certainly not all) seem interesting – but if they don’t have any research behind them, I almost never write about them. Lots of ideas are plausible, and they may feel effective in first-person tests (call it the PowerBalance trap), but without studies that at least attempt to isolate the relevant variables, I have no idea whether they really work.

Anyway, since Spruzza is one of the rare ones that has devoted the time and money to conduct some research, I decided to check it out.

The study involved a dozen cyclists who did a pair of 30-kilometre rides (20K at a steady pace at 70 percent of VOmax, then a 10K all-out time trial), with and without the Spruzza, in ~32 C heat.

The results were pretty typical of this type of study: improvement in a bunch of proxy measures like skin temperature, thirst sensation, and perceived fatigue, but no significant improvement in time trial performance.

Would there have been a difference in a larger study, or with more trials? Impossible to know. The researchers speculate that the benefits of feeling less thirsty and fatigued might be more obvious in longer rides lasting several hours, instead of a time trial that lasted a bit more than 15 minutes. That’s not a totally unreasonable speculation, but it is speculation.

Of note, a study on pre-cooling published last year concluded that reduced skin temperature (which in turn makes you feel cooler, regardless of what your core temperature is doing) was the key factor in improving performance in a one-hour time trial. In this case, the skin temperature was averaged from eight sites, including the forehead but also various sites on the arms, legs, chest, back.

Here’s some skin temperature data from the face (in degrees Fahrenheit) for a ride using a Spruzza mister every three minutes versus not using one:

Cooling Down With a Personal Sprinkler
Image courtesy Spruzza


It’s pretty clear that spritzing water cools your face, and depending on where the spray goes I suppose it might also have some effect on your chest and arms.

Is it worth it? As the study found, any measureable performance benefits seem pretty hard to detect. But given the temperature and thirst data, if you live and train in a hot climate, it might well make some of your rides more pleasant.

Next question: Who will buy a specially designed running hat with a small water reservoir that sprays a fine mist of water from the brim onto your face periodically, without soaking your shoes and giving you blisters? I await an infusion of venture capital.


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