Fab abs, Nicole Kidman. But this frantic effort to look half your age is frankly demeaning | Yvonne Roberts

Nicole Kidman, 55, is not only an excellent, award-winning actress and reportedly good company, witty and clever. Next month’s cover of Perfect magazine reveals that she also possesses the latest weapon in the anti-ageing armoury, namely muscles. Furthermore, unlike the deep-frozen facial impact of Botox for holding back the years, these are muscles that move – if Kidman’s reverse plank, also pictured, is any guide.

Since the portrait of the actress was released last week, dressed in what looks like a quilted upmarket nappy, it transpires that she is definitely not alone in acquiring sculpted biceps, washboard abs and banished batwings (upper arm sag) in the elasticated period now known as midlife.

The revelation of her physical transformation has led to a series of articles about older women who have undergone a similar transformation, strong in body and therefore, they say, stronger in mind, creators of a new, healthy femininity that also turns back the clock to grant the fitness they never had in their 20s. What’s not to like?

Particularly as, for instance, a recent survey by Women in Sport revealed that more than a million girls who thought of themselves as sporty in primary school lost interest in physical activity as teenagers. Fear of being judged and a lack of confidence were among the main reasons given. Gymnast Simone Biles, tennis star Serena Williams and many of England’s female football players have also been cruelly judged and “fit-shamed”, criticised as unfeminine and too manly in their physiques. So, won’t this mini-army of fortysomething-plus celebrities, media columnists and influencers, led by Kidman, encourage more women to lift those weights?

Perhaps. Biles, Williams and their fellow athletes are uber-fit because they are dedicated to their sport. What they are not engaged in is a complex strategy to try to deceive Father Time. When body transformation becomes tightly buckled to the impossible quest to look 30 at double that age, the trap of femininity is sprung.

In the 1980s, the feminist Susan Brownmiller wrote an entire book on femininity, a measure by which men and women calculate a female’s alleged assets, demeanour and physical deficiencies. Brownmiller described attempting to acquire femininity as “bafflingly inconsistent at the same time [as]… minutely demanding… Femininity always demands more”. And she warned that “an unending absorption in the drive for a perfect appearance… is the ultimate restriction on freedom of mind”.

Madonna, very fresh faced and alarmingly full of lip, recently celebrated her 64th birthday in fishnet tights and a skirt split to the thigh. And why not? She has travelled from boy toy (emblazoned on one of her first leather jackets) to toy boys apparently without adding a year. But, she has told her fans, she has decades of battle scars including torn ligaments and a hip replacement. Arthritis must surely follow. In those circumstances, “letting yourself go”, the gravest of sins in a youth-obsessed culture, might seem like a blessed relief. “Are the old really human beings?” Simone de Beauvoir asked in her book Old Age. How can we know in a nation of female Peter Pans?

To achieve the Kidman biceps, a fitness instructor estimated, it takes five workouts a week.

Reinvention is Kidman’s profession, but the continual parade of testimonies by others intent on publicising their efforts to allegedly age-proof their lives through diet, exercise, wardrobe, abstinence, camouflage and a dose of self-deception is creepy, a kind of competitive oneupwomanship. “I can do this ageless wonder trick better than you”, the very opposite of sisterly solidarity.

Does a bit of showing off by women old enough to know better really matter? Arguably it does, because it feeds into moralising attitudes about health and ageing that ignore the impact of wealth and class.

Linda Tirado, when holding down two jobs and being the mother of two, wrote an article in 2013 called This Is Why Poor People’s Bad Decisions Make Perfect Sense for the HuffPost. She explained that she smoked because “it’s a stimulant. When I am too tired to walk one more step, I can smoke and go for another hour.” She, and many like her, fighting to make ends meet, have neither the time nor the resources to become a buffed “jacked chick” – but given that these images flood popular culture, they often measure themselves against those who do.

Relentless introspection (as opposed to the insurrection required to challenge life’s inequalities) and an obsession with what has been lost, instead of contemplating the gains that come with age, stops us feeling at ease with the process of becoming ourselves, however flawed and creased. In Natural Causes: Life, Death and the Illusion of Control, the author and activist Barbara Ehrenreich refreshingly writes: “Once I realised I was old enough to die, I decided that I was also old enough not to incur any more suffering, annoyance or boredom in the pursuit of a longer life.”

Exercise can be enjoyable. It boosts mental and physical health. According to research published last week, a 10-minute stroll every day helped Korean octogenarians to live 40% longer during the five-year study than those who hardly moved at all.

That makes sense. But extremes do not. Pursuit of eternal youth voraciously fills the space in which it ought to be possible to see and admire many ways of sailing splendidly into wrinkled old age. Judi Dench, aged 87, was pictured last week visiting the BBC’s The Repair Shop. She didn’t look the least bit afraid of who she is now and what is to come.