Like many men in their mid-30s, I run a bit. It's nothing serious, but 40 minutes round the park a few times every week seems to keep the worst consequences of a two-a-week curry habit and the occasional drinking binge at bay. Last year I decided to up the stakes, training for and running a 10km race. Then I did another, after less preparation and a couple of late nights. In the middle of it, I broke down.
Actually, to say that I "broke down" is overstating it. I was forced to stop, after about six kilometres, by a racing, skipping, fluttering heartbeat. After a minute or two of abject terror, it returned to normal, so I trudged back to the start line, collected my stuff and went home. A couple of weeks later an electrocardiogram (ECG) showed a vaguely abnormal heart rhythm, but a battery of further tests showed no obvious cause and I was told that unless it happened again, there was no need for action. A cardiac nurse said that perhaps I had been "overdoing it a bit".
Meanwhile, a couple of weeks ago, a friend of mine had what appeared to be a heart attack, after a week of late nights, overwork, exercise and the combined stress of moving house and a lively toddler. After tests, it was downgraded to a less dangerous condition, involving bruising to the heart muscles. After more tests, it was upgraded again to a mild heart attack. Whatever it eventually turns out to be, it's not something a man in his mid-30s should really be having.
Is there a connection between the two? If there is, it's not that people in their mid-30s have started dropping like flies after a tough week, a couple of pints and an hour of gentle exercise. Despite fears over binge drinking and obesity, only 0.8% of heart attacks happen to people between 35 and 44.
What they may well be evidence of, however, is a small but significant crisis in the health of those in the second half of their 30s. It is not documented well, because healthcare messages tend to be aimed at the self-destructive young, or those who have reached an age when illnesses of the ageing body can start to kick in. But doctors and psychiatrists report an increase in thirtysomethings with conditions related to exhaustion, overindulgence, or simply a desire to keep up a lifestyle that our systems are no longer so adept at handling. More generally, doctors believe that the 30s are becoming an increasingly key decade in determining how our lives, and health, will pan out.
"For many people, their 30s becomes the decade that can most influence their future health and wellbeing," says Professor Ian Gilmore, President of the Royal College of Physicians. "For example, by continuing to drink more than the recommended number of units of alcohol, they may be slowly damaging their livers without realising it.
"It is also a time when many people give up sporting activities or exercise due to work and family commitments, leading to weight gain and raising their risk of heart disease and other conditions later in life. The stressful pace of many lives can also lead to a poor work/life balance, and people should be aware of that and take early action to avoid what is a detrimental combination of factors."
Alcohol is often a factor in thirtysomething health problems, as another of my friends, Dan, can testify. Dan is 35, works as a social worker and has a small child. When his partner and son went away for a weekend, he took the opportunity to party like it was 1999 (when he was still in his 20s). He ended up on a life-support machine for 10 days with acute kidney failure, and it was through luck alone that his kidneys started to work again.
"It was a heavy weekend," he says, "and a stupid one. But to be honest, I wouldn't have got into that state after a weekend like that 10 years ago. I didn't get into that state after many weekends like that 10 years ago."
The difference between 25 and 35 is 10 years of ageing, of course. Can it really make such a difference? "Yes, the 21-year-old who got in at 3am and dragged himself into work the next morning is physically less able to do so at 35," says Dawn Harper, a GP based in Gloucestershire. "You also have to take the cumulative effect into account. At 21 you might have been bingeing for a couple of years. At 35, you could be looking at 15 years of cumulative damage."
And other factors tend to accumulate in your 30s, that are absent in your 20s and less pressing in your 40s. Many of us have young families, for example. Most of us take on more responsibility at work. But we refuse to settle into sedate middle age. The belief that we can do it all, encouraged by the popular idea that youth can be delayed almost indefinitely, means we keep up hectic social lives, and often take up punishing exercise regimes, too.
"Thirtysomethings now are juggling more on a day-to-day basis than thirtysomethings of previous generations," says Harper. "Work, social lives, keeping fit, perhaps young families. For women, in particular, there's a tendency to reach for the glass to help them cope. The result is an increase in alcohol-related conditions, such as liver disease and mouth cancer, in people in their 30s and 40s."
Dr Bill Shanahan, a consultant psychiatrist and medical director of Capio Nightingale Hospitals, is seeing many people in their 30s with problems associated with do-it-all lifestyles.
"For many, the 30s are the best days of their lives," he says. "But for some who lived life to the full and partied hard in their 20s, and then try to keep that going in their 30s, their tolerance is less and they just can't cope. Especially when they are marrying that lifestyle to added responsibilities."
Dawn Harper identifies another reason why thirtysomethings often push themselves too hard. "There's a competitive edge that seems to take over from the late 20s," she says. "Who's doing best, who's earning most, who lives in the nicest house. By your mid-40s, on the other hand, you're pretty much where you're going to be."
The upshot of this do-it-all, have-it-all attitude is that, for many of us, our mid-to-late 30s represent a uniquely hectic and stressful period. And by taking on board all the stuff about "middle-youth", and "40 being the new 30", we've come to view our less-than-youthful bodies as indestructible. A 21-year-old thinks that too, of course, but a 21-year-old has a lot more justification.
And that's what links my friends and me with a growing number of thirtysomething patients with damaged livers and depression. Diabetes is on the rise in thirtysomethings, too. And Shanahan believes that many people in their 30s are simply "burning out".
"There's another group in their 30s that I see, a group who haven't necessarily been partying hard for 15 years, but who take on too much at work, maybe have family responsibilities, and think they can cope," he says. "When they find they can't cope, they often turn to alcohol."
"The idea that they just can't cope can be quite a shock for people in their 30s," he adds, "because they are only trying to keep up lifestyles that may have been quite normal for them 10 years before."
Until my heart scare, my life was pretty much the same as it had been 10 years before, only with more work and a mortgage to pay. Recently, I've added a newborn son to the equation. Something will have to give, and I'm determined it won't be my health.
