We’re turning into a nation of middle-aged weaklings, experts say, and need to step up the exercise intensity to overcome the "sitting disease".
“We’re the undermuscled generation,” says Auckland University nutrition professor David Cameron-Smith. For too long, he says, we’ve focused on our heart and brain health at the expense of what he calls our most significant tissue – our muscles. The modern world makes it easy for us to go through life without the intensity of exercise our ancestors did: we are rarely required to lift, pull or push. The result, he says, is “an epidemic of frailty. We are just puny compared to previous generations.”
In middle age – which he categorises as 30 to 60 – we’re embracing a false sense of wellness, he says. We’re juggling a job, child or senior care, and increasingly complex lives, but most of us are fortunate enough to have no obvious disease. At the same time, however, we’re beginning to lose muscle mass and strength. The loss begins in our thirties and accelerates from our mid-forties. And for many years, we hardly notice.
“You feel there’s nothing wrong with you but you could be better,” says Cameron-Smith. “You could be fitter, you could be stronger, you could have more muscle, you could have greater concentration. But it’s false wellness because if you carry on, you’re going to slide, little by little, breath by breath. Without actively doing something about it, you’ll end up with some element of chronic disease.” Isn’t that just called ageing, and inevitable for us all? Nope, says Cameron-Smith. What’s important is the pace at which we’re ageing, and that will depend largely on not only our cardiovascular fitness, but also our physical strength. In otherwise similar individuals, that varies enormously.
Cameron-Smith and a team at the university’s Liggins Institute have been researching muscle mass and strength in healthy, middle-aged men and discovered a four-fold difference among them in muscle size, and a three-fold difference in muscle strength. The men, aged between 50 and 52, had all let their physical fitness slide. They were “average Joes”, he says, none of whom had done much if any exercise for the past year, or had a history of sportiness that might have explained the varying results.
All had similar BMIs (body mass index), and similar diets. “Middle-aged men have a very similar diet – they are all partial to a bit of meat, and like a beer on occasions. None had a particularly unhealthy diet, but nor were they particularly healthy.”
He says if there was a four-fold difference in, say, memory among average 50-year-olds, “we’d have a national crisis to try to understand why, because the ones with the lowest memory scores would be at significant risk of cognitive impairment. The variation in muscle strength should be treated in the same light because those at the bottom end of the curve are clearly going to be at much greater risk of falling, and of age-related illness as they get older.”
Weak as kittens
Cameron-Smith was alarmed at just how weak the bottom 20% proved to be. “It’s staggering how frail some otherwise healthy 50-year-olds are. They were weaklings – far weaker than I would ever have imagined. These are men who live normal lives in the community, hold down jobs and don’t have any advanced disease. They’re just profoundly weak.” Less than 10% of the group of 50 men studied were “noticeably strong”, and the rest were “mediocre”.
Weakness matters, he says. “At some point in your life, the hardest thing you will have to do is get up out of your chair or get yourself up off the floor after a fall and your maximum strength determines whether you can or can’t do that … whether you lie on the floor and have to wait for the paramedics to come and get you, or whether you’re stuck on the toilet and can’t get up. Weak people at 50 are going to be the weakest people at 70, unless they can shift themselves quite dramatically.”
Walking five times a week for 30 minutes each time, week in and week out, just isn’t going to fix that. “Two things will happen: you get very good at walking. You get faster and better and you don’t expend as many calories. Your muscles adapt to the point to allow you to become more efficient.” But unless you do more – double the distance, add more hills, carry a backpack, you won’t keep improving. “Exercise is always a process of adding and adding and adding; that’s how your muscles grow, adapt and repair.”
The fittest men in the study were twice as fit as the least fit, but Cameron-Smith says it’s staggering that “in the 21st century, we still can’t explain why otherwise similar people are fitter and stronger than others”.
Genes are part of the answer, with several international studies showing that certain mutations are associated with strength in leg muscles and grip. Most of those genetic variants, known as SNPs, fall outside the genes, in the non-protein coding area of the genome formerly described as “junk DNA”. A mutation inside a gene, which switches it off, for example, can have a dramatic effect, but an accumulation of many different mutations outside the genes, as in this case, causes much smaller effects.
Justin O’Sullivan, a genomics expert also at the Liggins Institute, has applied for $1.2 million in Health Research Council funding in a bid to work out a genetic risk score that can predict grip strength and frailty. “If we have a person’s genome sequence, can we work out how strong their grip and leg strength is going to be later in life and, from that, how frail they’ll be in their old age,” says O’Sullivan. The study, a collaboration with colleagues in Southampton, England, will also try to understand how the gene expression is being altered as a result of the mutations. “If we can understand that, perhaps we can modify it, either through nutritional or other changes – for example, exercise training that might modify the expression of the genes. If you apply the right training, you can moderate the effects; to some extent overcome the predisposition to weakness.”
GPs treating patients who’ve had their DNA mapped in direct-to-consumer tests have told him the patients are keen to do what they can to offset the predisposition dictated by their genes. There’s no sense that people use it as an excuse to throw up their hands in surrender, believing their destiny is set.
Auckland exercise physiologist Matt Wood, who manages the Auckland University of Technology exercise science clinic and runs fitness programmes for heart and cancer patients, says we may need to reframe the key messages in the “five days/30-minutes-a-day” recommendations for a more “multipronged approach”. “Walking from A to B will only get you so far, and so far is not bad, but it’s not great. Intensity matters.”
Many international guidelines now include an alternative to five days of moderate exercise, of three days of 20 minutes’ moderate-to-vigorous exercise, “hence the trend towards intensity training”.
The Ministry of Health (see sidebar) recommends we do strengthening exercises targeting muscles in our arms, legs, chest, abdomen and back on at least two days each week, and at least two and a half hours of moderate physical activity weekly (about 30 minutes a day over five days). But the experts we spoke to believe the strength message is not well signalled and often overlooked. The ministry knows how many of us are achieving the physical activity side – only about half – but it’s a measure of the lack of emphasis on the strengthening component that it hasn’t got accurate statistics on that aspect yet. It says getting stronger doesn’t mean you have to go to the gym. You can achieve the same results doing push-ups, sit-ups and squats at home, carrying children or heavy bags of shopping, or doing activities such as aqua aerobics, hill walking, climbing stairs or digging in the garden.
The AUT exercise programme, although individually tailored for participants, combines structured strength/resistance exercises with physical activity, ideally taking the least time to achieve “bang for buck”. “We’re not trying to give people traditional, slow, long-distance training because 95% of people don’t like that stuff. Usually, we’re not prescribing more than eight repetitions of an exercise,” Wood says. The basic regimes involve 10 minutes’ resistance work with 20 minutes’ cardiovascular exercise.
People referred to the programme typically have one or more heart-risk factors, and are often in sedentary jobs and overweight. But Wood says weight loss is not a focus. “Psychologically, the primary focus on obesity is one of our biggest problems. BMI has no predictive ability for cardiovascular fitness. There’s nothing worse than saying to someone, ‘Your BMI is this’ and they lose 2kg and think they’ve failed. The recommendations for weight loss involve 60 minutes [exercise] five days a week. Well, who the heck is going to do that? Setting people up for failure is not going to solve the problem. Protecting what is evidence-based and meaningful is a heck of a lot better.”
Programme participants are often surprised to discover that as a risk factor for coronary disease, cardiorespiratory fitness (CRF) is more important than hypertension, smoking, cholesterol, diabetes or obesity. CRF is measured by the amount of oxygen consumed during exercise – the less consumed, the less fit you are. A person in their eighties in a rest home, for example, would probably consume about a fifth of the oxygen of a moderately fit middle-aged person.
Resting on our laurels
Wood says people often talk about their history in sports or fitness as a much younger person, but it’s difficult to say how much an active childhood protects us in later years. “From a broad perspective, it’s important, but things can get bad pretty quickly.”
Cameron-Smith agrees, saying although an active childhood is beneficial, it isn’t a magic bullet. “Just because you played competitive sport as a teenager isn’t going to significantly buffer you in later years. Look at how quickly things turn to custard for competitive athletes when they stop. People who are used to training hard but eating hard often give up training but continue to eat hard.”
He fears for the current generation, shackled to its screens. “They’re going to be worse than us, sitting around a keyboard forever, their physical activity in decline. It’s a workforce that has to be 24/7 online and there is no downtime and no separation between home and work. Their ability to turn devices off, be physically active, have ‘me’ time, will vanish.”
Cameron-Smith, who leads a research team investigating the best nutritional strategies to limit muscle loss with ageing, says there’s still much to be learnt about the amount and types of protein that best help muscles grow and repair. Comparatively, exercise wins hands down. “If you don’t exercise, you could drink power smoothies and eat protein bars all day without ever being able to get out of a chair more easily.”
One of the world’s leading experts on the so-called “sitting disease” is Melbourne professor of physical activity and public health David Dunstan, whose research has focused on how desk-bound workers can offset the perils of a sedentary lifestyle.
He talks to the Listener by phone while he’s walking to work, so he doesn’t have to sit at his desk. There are downsides: the line repeatedly cuts out as he moves out of range, or is rendered inaudible by wind noise, but he perseveres – the upside of being regularly on the move is too important to give up lightly. He also has a height-adjustable desk at which he can stand or sit.
“We suspect a lot of the relationship between sitting and ill health is because those large muscles in the legs are switched off for long periods during the day and that’s not favourable for many of the body’s regulatory processes, such as clearing blood sugar levels. We need to start thinking about ways of switching those muscles back on more often.”
A meta-analysis published in the Lancet in 2016, involving more than one million men and women in 16 published studies, examined links between sitting and deaths from all causes. This showed it took 60-75 minutes of moderate physical activity a day to mitigate the harmful effects of sitting. “Very few people would achieve that,” says Dunstan.
Stand up and be counted
The ability to stand from sitting is a major predictor of quality of life and well-being because it’s related to functional independence, and Dunstan says the key for desk-bound office workers is to alternate sitting and standing throughout the day, doing either walking or resistance activities every half hour. “If I’ve been sitting for 30 minutes, it’s too long.”
Dunstan’s work has monitored the impact of walking breaks every 30 minutes, but he says that’s been criticised as unrealistic in some offices where it’s disruptive to have staff regularly circulating the room. In a more recent study, they’ve looked at simple resistance exercises including squats and knee and calf lifts for three minutes every 30 minutes that can be done while standing beside their desk. The exercises brought a 40% improvement in blood-sugar control over the day, which he says is “huge” for people with diabetes.
Cameron-Smith, who joined a gym and upped his resistance training after discovering his muscle strength was “at the lower end” of those in the Liggins study, says the importance of sarcopenia, or muscle weakness, is now top of mind for many scientists in the field. “International groups have got together to argue about the formal diagnosis and that’s led to a vanguard of researchers who’ve said, ‘Hello, this is a major health condition that costs a large amount of money. It’s the thing that most people in assisted care have, so what causes it, how do we treat it and how can we prevent it?
“The modern environment is pulling us down. None of us are where we should be. Every one of us should be significantly stronger. You may never be a masters athlete or break a world record, but you can certainly have a significant impact on your quality of life.”
What the doctor ordered
The Ministry of Health says we SHOULD:
- Sit less, move more. Break up long periods of sitting.
- Do at least two and a half hours of moderate or one and a quarter hours of vigorous physical activity spread throughout the week.
- For extra health benefits, aim for five hours of moderate or two and a half hours of vigorous physical activity spread throughout the week.
- Do some muscle-strengthening activities on at least two days each week.
- Do some physical activity – any is better than none.
What we ARE doing:
- 46% of us do at least five hours of moderate activity spread over five or more days a week. 51% do at least 30 minutes a day spread over five or more days. (2013/14 figures)
- 14% do little or no physical activity each week.
- Men are more likely to be very physically active than women from the same age group. Women are more likely than men to do little or no physical activity in a week.
- People in the most socioeconomically deprived areas are more likely to do little or no physical activity compared with those in the least deprived areas.
- Asian and Pacific people are less likely to be very physically active than non-Asian and non-Pacific people.
- People sit for an average of four hours a day, with higher-educated people sitting longer.
This article was first published in the August 11, 2018 issue of the New Zealand Listener.