So which generation really is the fittest? We put our six guinea pigs (from Gen X to Gen Z) to the ultimate test - with VERY surprising results

Conventional wisdom is this: the body hits its physical peak at 25 and it’s an uphill struggle from there. But in the race for longevity with its supplements, Oura trackers, reformer pilates and sleep scores, conventional wisdom is looking a little off the pace.

The buzz phrase of the moment is ‘fitness retention’: keeping your peak performance for years longer than your parents would have done. Better access to sports science, with more ‘total health bundles’ and ‘fitness DNA tests’ than you can shake a class pass at, means that Generation X (44- to 59-year-olds) is holding its own. 

There are now 6.3 per cent more active people aged 55+ in the UK than there were seven years ago (at the same time, 320,000 fewer 16- to 34-year-olds are classed as active).

For example, at 48, I am fitter and stronger than I was in my 20s. My weight-training gym is increasingly busy with superfit people in their 50s, 60s and 70s, nailing deadlifts and burpees (although they don’t do gym selfies – you have to draw a generational line somewhere).

So, which generation on the YOU staff has the greatest fitness retention? To find out, we had to borrow a lab. ‘It’s never too late to get on your health and fitness journey, and I say that to patients in their 80s,’ says Dr Gaurav Sabharwal, a private GP specialising in sport, and founder and CEO of One5 Health.

He gave us the use of his preventative health clinic to run the gamut of blood tests measuring hormones, vitamins, cholesterol levels and diabetes risk, analysis of body fat and muscle percentages, balance challenges and grip-strength tests (a key indicator of general health). 

What is the longevity test that everyone with an eye on ‘fitness retention’ is banging on about? A VO₂ Max. Sabharwal describes it as the ‘one of the strongest predictors of health span’, as well as ‘the strongest independent predictor of future life expectancy’.

You’d be forgiven for not having heard of a VO₂ Max. Six months ago, only running nerds had. But Sabharwal swears by it. It has been touted as the most useful measure for all exercisers by fitness professionals and wellness experts – among them Peter Attia, the Canadian doctor and podcaster who wrote the 2023 book Outlive: The Science and Art of Longevity. Searches for the test have since rocketed.

A VO₂ Max is a numerical score that expresses how effectively your body metabolises oxygen. To work it out, you are put on a treadmill with your face strapped into a mask that measures the amounts of oxygen inhaled and utilised, and are asked to run to the point of exhaustion (hence ‘max’).

The more oxygen you efficiently consume, the more energy your muscles will have, increasing the time and intensity that you can exercise.

The most useful thing about it is that this score can be adjusted for genetics, sex, age and body composition: the same score might be considered high for one person and low for another. And, as we’re a competitive bunch at YOU, that’s how we decided to test which generation of our staffers is most at its peak. For fun, we awarded each a school exam-style lettered grade loosely pegged to their VO₂ Max score.

GEN Z 

Maggie: Top and leggings, Goodmove by M&S; Socks, The Sock Shop; Trainers, Asics at Schuh

‘Poor hips mean that I can’t squat’

Name Maggie John

Age 23

VO₂ Max score (ml/kg/min) 43.1 (this puts Maggie in the top 25 per cent of VO₂ scores when adjusted for age and gender).

Health bio Recently I’ve started to walk 8km-10km a day – I love the positive impact it has on my mental health.

Fitness brag The tests show my strength levels are totally fine and, astonishingly, I scored top marks for fitness.

Fitness fail Social media is full of people doing extreme fitness challenges, and this always makes me feel I’m not doing enough. The testing team told me that walking is the best form of exercise for me, in terms of maximising fat burn.

Hidden health flaw I can’t squat very low due to poor hip mobility. I’m now trying to fix this with daily(ish) pilates sessions.

Scarlett: Top and shorts, New Era;  Socks, The Sock Shop; Trainers, Nike at Schuh

‘I’m a spin-class fan who vapes’

Name Scarlett Dargan

Age 25 

VO₂ Max score 52 (this puts Scarlett in the top 10 per cent of VO₂ scores).

Health bio I’m a spin-class fanatic and marathon runner who loves a drink, vapes and can’t cook, won’t cook.

Fitness brag My VO₂ Max rating was high. Thanks to my marathon training, I’m probably fitter than the average Gen Zer.

Fitness fail I like to drink alcohol five nights a week; more than almost all of my Gen Z friends, lots of whom are teetotal – still, apparently my liver’s OK.

Hidden health flaw My strength levels were very poor – I mean, ‘bottom 20 per cent for my age’ poor. This means that I’m more prone to injury during exercise and proves that I need to diversify my training. 

Millennial

‘My muscle to fat ratio is terrible’

Name Luisa Avietti

Age 30 

VO₂ Max score 46 (this puts Luisa in the top 5 per cent of VO₂ scores).

Health bio Naturally slim but I do absolutely no exercise – I don’t like how it feels when you sweat and if I ever go to the gym with my friend we just end up talking rather than working out.

Fitness brag During the VO₂ Max test on the treadmill, I felt as though I could keep going forever. I used to swim competitively as a teenager so maybe my body remembered it once had good endurance levels.

Fitness fail I’m only on the 3rd centile for strength, so virtually everyone else my age is stronger than me.

Hidden health flaw My muscle to fat ratio, it turns out, is terrible – I’m skinny-fat, in a nutshell.

Samuel: T-shirt and shorts, Goodmove by M&S; Socks, The Sock Shop; Trainers, New Balance at Schuh

‘At a push, I could lift a suitcase’

Name Samuel Fishwick

Age 33

VO₂ Max score 34 (this puts Sam in the top 50 per cent of VO₂ scores).

Health bio Pudgy millennial who snacks a lot.

Fitness brag When I run, I burn lots of fat calories at lower heart rates – but also, alas, far fewer the harder I run. So, I need to do steady cardio rather than, say, HIIT training.

Fitness fail I’m a heavyweight weakling. I knew this already – my wife beat me in an arm-wrestle – but no one likes to have these things spelled out.

Hidden health flaw The tests showed I could, at a push, muster the level of strength you need to lift a suitcase. Adjusting for my weight and height, 94 per cent of other men can outdo this. I am also overweight. Hmm.

Kerry: Top, bralet and leggings, Sweaty Betty; Trainers, Saucony at Sweaty Betty 

Gen X

‘I was pathetic at the jumping test’

Name Kerry Potter

Age 48

VO₂ Max score 43 (this puts Kerry in the top 5 per cent of VO₂ scores).

Health bio Stereotypical Gen X hedonist who got healthy – I swapped raving for running and am now a dedicated gym bunny (and eater of biscuits).

Fitness brag My cardio fitness and strength were impeccable. All that pumping iron is bearing fruit: my grip strength is excellent, my muscle mass is good and my squat power is in the 65th centile for my age.

Fitness fail As someone who was always slow-clapped by other pupils during high jump in school PE, it came as no surprise that I was pathetic at the jumping test.

Hidden health flaw I’m iron-deficient so need a supplement.

Rosie: Top and leggings, Vuori; Trainers, New Balance at Schuh

‘I run with my dog three times a week’

Name Rosie Green

Age 50

VO₂ Max score 45 (this puts Rosie in the top 5 per cent of VO₂ scores).

Health bio I’m committed to exercise. I run with my dog three times a week and do twice-weekly strength sessions. But – full disclosure – I never push myself too hard.

Fitness brag The team said I have ‘impressive’ fitness and recovery levels plus the heart age of someone seven years younger. My stroke risk is half that of the average 50-year-old.

Fitness fail My grip strength was normal to low.

Hidden health flaw Despite my super-healthy diet, it turns out that I have significantly high cholesterol. On reflection, I do like to see teeth marks in my buttered toast.

And the winners are… Gen X! the midlifers have it 

By Dr Gaurav Sabharwal

To compare the different generations’ health and fitness, we used the following parameters: VO₂ Max, muscle-mass percentage, grip-strength score and average blood- glucose levels.

The Gen Xers are in excellent health, and there are several better-outcome scores in this group – in terms of both health and fitness parameters – compared to Gen Z and the millennials. VO₂ Max tends to peak in adults in their 20s and then declines by around 10 per cent a decade. Gen Z had the highest scores, as you would expect.

However, there is a 25-year age gap between the pairs in Gen X and Gen Z, so we’d expect to see a VO₂ Max score at least 20 per cent lower for the older women – yet it was only eight per cent.

As a result, when adjusted for expected age-related decline, the Gen X duo are maintaining a higher level of cardio-respiratory fitness than their younger counterparts.

Interestingly, Gen X had by far the highest grip strength of all generations – clearly Kerry and Rosie’s weight-training is paying off. The key takeaway from the project? Age should not be a barrier to adopting and maintaining health and fitness. 

A One5 Health Well Woman or Well Man screening starts from £250; the fitness testing package costs £450. For more details see one5.health

Stylist: Sairey Stemp

Hair: Julie Read at Carol Hayes 

Make up: Levi-Jade Taylor at Carole Hayes