Hyrox is a fitness craze that shows no signs of dying out - with 1.3 million people expected to compete in an event somewhere in the world this year.

The competition, which is split between running and fitness exercises, has proven particularly popular with young millennials and Generation Z - people in their twenties to early forties.

Its rapidly growing popularity has been attributed to social media.

Fashionable looks are often a non-negotiable for competitors, with many choosing to compete in high-end fitness brands, matching their outfits with their team members.

Allana Falconer, who works in sustainability and started competing in 2023, says she has fallen in love with it.

She has competed in 20 different races across six countries and 12 different cities.

All my holidays revolve around Hyrox or I incorporate events into holidays, she tells the BBC World Service.

The 29-year-old says the most she has spent so far was £2,000, when she travelled to Chicago for the World Championships last year.

Exercise is part of their identity

For competitions abroad, I normally spend approximately £400 per trip for two nights' stay and travel and £120 for a ticket, she adds.

As she is racing so much, she says she needs lots of fitness kit too, adding that I burn through ridiculous amounts of shoes.

Evgenia Koroleva, the founder of ONE LDN gym, says for anyone that takes fitness competitions seriously, the costs can be absolutely astronomical.

She estimates an athlete travelling to compete in a Hyrox competition will spend between £500 to £1,000 in one weekend, with the ticket alone about £120.

Hyrox has created this addiction for people who do it because they never really do one race. When they do their first race they then sign up for another one and because the course is the same it creates this level of competition with yourself, she adds.

The cost of participation is higher than a marathon, and some people have criticized it. Travelling abroad plus the costs involved to run around a bit and get out of breath is a stretch for me, said one former participant on Reddit.

Fran Sirl, a personal trainer, who runs outdoor fitness classes in Richmond Park, says sports like this can feel intimidating and reminds his clients that you don't need specialist kit or equipment to get fit.

Most athletes the BBC spoke to felt the prices for Hyrox were fair due to the cost of hiring large event spaces, specialist equipment and judging panels.

Evgenia says the fact people are willing to pay so much reflects a wider cultural shift in how much people in their 20s and 30s spend on exercise.

Spending money on fitness is a priority for those born between 1997 and 2012 (Gen Z), according to exercise app Strava.

Its survey suggests that a third of them plan to spend more on fitness this year with almost two thirds saying they would rather spend money on new gym clothes than a date.

In Hyrox, UK competitions often sell out quickly, which is why many of those wanting to take part travel further afield.

Hyrox, which hosted its first competition in 2021, has a near 50/50 gender split.

The race involves doing a one-kilometre run eight times, broken up with exercises such as burpee broad jumps, sled pulls and rowing.

Those taking part can compete on their own or with a partner - either in a mixed or same sex team.

Dr Florence Kinnafick, a senior academic at Loughborough University, says the different disciplines can mean competing becomes addictive. While the emphasis on competition isn't attractive to everybody, she warns of the risk of overtraining if people get obsessed with improving their time.

Jorell Hill, who has competed in 10 races so far, says he has definitely caught the bug. He explains that all his holidays now involve fitness retreats and competitions, and he has traveled to numerous countries for these events.

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