At midday on 9 June this year, my 64-year-old mother was approaching the halfway point of her second Ironman triathlon. I, meanwhile, was eating breakfast in bed (three packets of Quavers, white chocolate Magnum), too hungover to open both eyes at once. We’d both dedicated our weekends to testing the limits of human endurance. It’s just that I’d done so at a festival for gays, watching Samantha Mumba announce, “I refuse to leave this stage without acknowledging Martha P Johnson”, before dropping that train of thought as quickly as it arrived and launching into her 2000 banger Body II Body.

I’m cursed with belonging to a sporty family. It’s not that I am particularly unathletic, more electively idle – a condition that is thrown into sharp relief by the attention-seeking antics of my mother, who once ran 100 miles over the Himalayas in five days, and brother, who has won three cycling gold medals at the Paralympics. Next to them, perfectly reasonable activities – such as eating five Creme Eggs in the bath while listening to Stevie Nicks – begin to look lazy or unwholesome.

Mum has exercised compulsively for as long as I can remember, first swimming, then running, then running marathons. She is not great at directions, so schoolmates would report opening their curtains on winter mornings to be greeted by the sight of her jogging through their garden in a sports bra and head torch, trying to locate a footpath. There was even a short-lived foray into bog snorkelling; she came 13th in the world championships, neglecting to mention that only 14 people had been mad enough to enter. But things stepped up several gears when she discovered the fitness app Strava. Instead of encouraging people to compare their children (Facebook) or thigh gaps (Instagram), Strava tracks users’ run and cycle times and ranks them against others who have downloaded the app. To say that Strava ignited Mum’s competitive spirit would be like saying Donald Trump doesn’t love the people of Mexico.

Once a year I do a day of gym classes with Mum as a kind of annual MOT; if I don’t die, I consider myself to have passed

The app compares your performance across a number of metrics, including age and gender, meaning there is always plenty of urgent data that Mum wants to discuss. A number of missed calls at an unsociable hour used to indicate a family tragedy. Now, it means Mum has won a Strava trophy (she’s in the top 10 fastest women to have completed a particular segment of a race) or – better yet – a “Queen of the Mountain” crown (she is number one, the fastest of all). When she’s displaced from the top spot, lunches are abandoned and conversations halted mid-flow, so that she can rush out on her bike and attempt to reclaim her crown. On a cycling holiday in Colombia, she instructed one of the men to race just ahead of her in order to decrease wind resistance and unseat a rival on the app. “After we finished, we couldn’t get wifi for a couple of hours,” she told me. “It was a tense afternoon.” I could imagine.

My sister’s lack of interest in Mum’s analytics is so violent that she has placed restrictions on how much Strava chat she’ll tolerate (three minutes before she hangs up). I try to be more encouraging, and even joined Mum on a run as she trained for her latest Ironman. I managed 8k, prompting frenzied claims from her that I could probably run a marathon if I trained really hard. Perhaps I could, but what would be the long game? A plastic medal and a JustGiving page to make my colleagues hate me?

Maybe my problem is that a lifetime surrounded by Lycra has rendered sporting achievements unremarkable – encouraging the mistaken belief that I could probably run 100 miles over the Himalayas, too, if only I weren’t so well-balanced. The only sportsperson I’ve ever truly admired is the Olympic figure skater Adam Rippon, and that’s mostly because of a competition where he refused to skate and instead lip-synched to his own heavily Auto-Tuned version of a Rihanna song. Don’t try and tell me that’s less iconic than traditional sporting achievements such as running fast or jumping high.

‘Mum has exercised compulsively for as long as I can remember.’ Photograph: Kellie French/The Guardian. Hair and makeup: Sarah Cherry. Clothes: My Gym Wardrobe

That’s not to say I never exercise. I’ve been known to slutdrop to Little Mix for upwards of five hours at a time, and I cycle to work, inspiring one editor to remark (quite unkindly) that she’d seen me “wobbling along the canal”. Once a year, when I go home for Christmas, I do a day of gym classes with my mum as a kind of annual MOT; if I don’t die, I consider myself to have passed.

I briefly abandoned this homeopathic approach to physical activity in 2017, when a stranger at a house party prodded my belly and told me to “suck it in”. After I’d disposed of his body, I embarked on one of those 12-week transformations that you see advertised on the bus. When the trainer asked me my fitness goal, I said it was to look like Tom Daley, but aged 13, because I wanted to manage expectations. For the next three months I subsisted on dry chicken and rice cakes, going to the gym every evening and dreaming of Minstrels every night. By the second month I was so immune to discomfort that I dislocated my shoulder while using a dumbbell and popped it back into the socket myself. In my protein shake-addled mind I’d become He-Man, minus the Anna Wintour bob.

For someone who sits at a desk all day, it felt good to challenge myself in a way that wasn’t seeing how many packets of crisps I could eat during a single episode of Love Island Australia. But when the 12 weeks ended, I immediately degenerated into my old ways. Exercising every day hadn’t given me more energy, or filled me with endorphins, or made me look like Brad Pitt in Fight Club – it had just driven me dangerously close to becoming the kind of person who posts changing room selfies. Faced with such a sobering prospect, I gave up. Perhaps my mistake was being motivated by vanity alone, whereas my mum is driven by a higher cause: her own immortality.

This year she turned 65, moving her up an age category at events, and so increasing her chances of winning competitions. “It feels like a landmark age,” she told me, “and rather than be defined as someone old, I want to be defined as someone who wins medals.” She’s never been massively tactful (on my boyfriend: “You’re better-looking, but he’s a nicer person”), and in recent years I’ve watched her grow increasingly frustrated with some of her peers. “They’re boring,” she complains whenever she meets someone new. “All they want to talk about is their ailments.” These days, she prefers going on group holidays where the average person is 20 years younger, and upending their expectations of what a grandmother on a bike looks like. In the end, perhaps we’re both motivated by the same spirit of rebellion. As a pensioner, Mum isn’t expected to be hitting the gym five times a week. As a young-ish gay man, I emphatically am.

Watching her compete, I feel proud. But also grateful to have been spared whichever gene compels you to snorkel in a bog.

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