Increasing physical activity associated with longer life

*Why extreme fitness rots teeth despite brushing twice daily
*Scientists design blood test that predicts lifespan, expectancy

Research clearly shows that increasing physical activity, regardless of intensity, relates to a significantly lower risk of dying. Even light exercise, such as walking, can make a difference.

Researchers came to this conclusion after analyzing data from published research that had involved the use of wearable trackers to measure the physical activity in adults who were middle-aged and older.

A recent British Medical Journal paper gives a full account of the systematic review and meta-analysis.

The analysis also reveals that sitting for more than 9.5 hours per day is linked to a significantly higher risk of early death. The findings largely confirm those of previous studies on links between physical activity, sedentary behavior, and longevity.

According to the researchers, most health guidelines about minimum levels of exercise have relied mainly on studies that used self-reported levels of activity.

The researchers note that their new investigation is significant because they only included those studies that measured physical activity using accelerometers. These wearable movement sensors can track the amount and intensity of activity during waking hours.

The team also wanted to clarify the effect of sedentary behaviour. The guidelines advise people to spend less time sitting, but they do not specify how much sitting is harmful.

Also, scientists have warned that extreme fitness risk dental decay, as a new study finds half of elite athletes have rotting teeth.

A study of 352 Olympic and professional athletes found high rates of dental problems, even though they brushed their teeth on average twice a day.

Researchers believe the relentless intake of sports drinks, energy gels and bars are to blame, due to their high sugar content. Intensive exercise may also prompt changes in saliva and the immune system that further exacerbates the damage.

The findings, published in the British Dental Journal, highlight potential for improvement as most of the athletes expressed an interest in changing their oral hygiene behaviour to improve their oral health.

The University College London (UCL) Eastman Dental Institute research team surveyed 352 Olympic and professional athletes across 11 sports, including cycling, swimming, rugby, football, rowing, hockey, sailing and athletics, when they provided dental check-ups for male and female athletes measuring tooth decay, gum health and acid erosion.

The researchers also asked athletes what they did to keep their mouth, teeth and gums healthy.

The dental check-ups revealed substantial amounts of oral disease as reported in a 2018 paper, finding that nearly half (49.1 per cent) had untreated tooth decay, the large majority showed early signs of gum inflammation, and almost a third (32 per cent) reported that their oral health had a negative impact on their training and performance.

Elite athletes have poor oral health despite their efforts to care for their teeth: this new study found that 94 per cent reported brushing their teeth at least twice a day, and 44 per cent reported regularly cleaning between their teeth (flossing) — substantially higher figures than for the general population (75 per cent for twice-daily brushing and 21 per cent for flossing).

The researchers found that the athletes regularly use sports drinks (87 per cent), energy bars (59 per cent) and energy gels (70 per cent), which are known to damage teeth.

Meanwhile, the ability to predict how long someone is likely to live would help doctors tailor treatment plans. A new study looking at biomarkers in the blood concludes that more accurately estimating mortality might soon be possible.

As it stands, doctors can predict mortality within the final year of life with some degree of accuracy.

However, predicting it over longer periods — such as five–10 years — is not yet possible.

A group of scientists who recently published a paper in the journal Nature Communications hope that they are now on the path toward developing a reliable predictive tool.

They believe that a blood test might one day be able to predict whether someone is likely to live 5 or 10 more years. The authors explain that this would help doctors make important treatment decisions.

For instance, they would be able to ascertain if an older adult is healthy enough to have surgery, or help identify those in most need of medical intervention.

A test like this might also benefit clinical trials: Scientists could monitor how an intervention impacts mortality risk without having to run trials until enough people die.

Currently, blood pressure and cholesterol levels can give doctors an impression of a person’s likely lifespan. However, in older adults, these measures become less useful.

Counter intuitively, for people aged 85 or over, higher blood pressure and higher cholesterol levels are linked with lower mortality risk.

Scientists from Brunel University London in the United Kingdom and Leiden University Medical Center in the Netherlands set out to identify any biomarkers in the blood that might help tackle this issue.

Their study is the largest of its kind, taking data from 44,168 people ages 18–109. During the study’s follow-up period, 5,512 of these people died.

The team initially identified metabolic markers associated with mortality. From this information, they created a scoring system to predict when a person might die.

Next, the researchers compared the reliability of the scoring system with that of a model based on standard risk factors. To do this, they studied data from a further 7,603 individuals, 1,213 of whom died during follow-up.

After whittling down a long list of metabolites, the researchers settled on 14 biomarkers independently associated with mortality.

Having higher concentrations of some of the 14 biomarkers — including histidine, leucine, and valine — is associated with decreased mortality.

Conversely, having lower concentrations of others — such as glucose, lactate, and phenylalanine — is associated with increased mortality.

The scientists demonstrated that the combination of biomarkers could predict mortality equally well in both males and females. They also tested their findings across several age groups, concluding that “[a]ll 14 biomarkers […] showed consistent associations with mortality across all strata.”

The biomarkers they identified are involved in a wide range of processes in the body, including fluid balance and inflammation. Also, scientists have already linked most of them to mortality risk in previous studies.

However, this was the first time that researchers have demonstrated their predictive power when combined into one model.

This study is just the next step along a path that might lead to a usable blood test. However, the study authors feel encouraged: “A score based on these 14 biomarkers and sex leads to improved risk prediction as compared [with] a score based on conventional risk factors.”

The authors do note certain limitations of their study. For example, they were only able to analyze hundreds of the thousands of metabolites present in human serum.

Including more metabolites in future analyses would, the authors predict, “result in [the] identification of many more mortality associated biomarkers and, hence, improved risk prediction.”

Although this exact test would not be suitable for use by the general public, it could eventually evolve and move into the public sphere in the same way that genetic testing has.

Perhaps, in the future, the question might not be, “How long will I live?” but rather, “Do I want to know?”

Meanwhile, another question that the new study clarifies is the contribution of low intensity activity.

For example, the United States government’s physical activity guidelines recommend a minimum of 150 minutes of moderate or 75 minutes of vigorous activity per week.

While the guidelines mention light activity as a good start to reaching this level and beneficial to health, the emphasis is mostly on moderate and vigorous activity.

Does this mean that light activity has less impact on health and longevity, especially for adults in their middle years and older, than moderate and vigorous activity?

“Answering these questions [has] huge relevance for health promotion,” state two of the authors of ths new study, Ulf Ekelund and Thomas Yates, in an accompanying BMJ opinion article.

Ekelund is a professor at the Norwegian School of Sport Sciences and the Norwegian Institute of Public Health, both in Oslo, Norway. Yates is a professor of physical activity, sedentary behavior, and health at the University of Leicester in the United Kingdom.

For their study, Prof. Ekelund and colleagues set out to examine links between physical activity, sedentary behavior, and risk of death in middle-aged and older adults.

Their analysis included data on a total of 36,383 adults of minimum age 40 years and average age 62 years.

The data came from eight studies that had tracked activity using motion sensors for up to one week and had followed the participants after that for an average of 5.8 years.

The studies had categorized physical activity as light, moderate, or vigorous and had estimated the amount of daily time spent doing each. The researchers give examples of light physical activity as walking, washing dishes, and cooking.

Moderate activity includes mowing grass, brisk walking, and vacuuming, while digging, jogging, and carrying heavy weights are examples of intense physical activity.

The team arranged the results into quarters, ranging from the 25 per cent most active to the 25 per cent least active participants.

Of the participants, 5.9 per cent (2,149 individuals) died during the follow-up. The researchers used these deaths to calculate the risk of death for the most to the least active participants.

After adjusting the results for factors that could influence them, the team found that any level of activity — whether it was light, moderate, or vigorous — related to a significantly lower risk of death during the follow-up.

The 25 per cent most active participants had a 60–70 per cent lower risk of death compared with the 25 per cent least active. There were around five times more deaths in the least active compared with the most active group.

In addition, sitting for a total of 9.5 hours a day or more, not counting time spent sleeping, was linked to a statistically significant raised risk of death.

The researchers suggest the findings reinforce that any level of physical activity — even light exercise that is within reach of most people — is beneficial.

They observe that the effect sizes in their results are about double the size of previous studies that have relied on self-reported data.

Prof. Jochen Klenk of Ulm University in Germany and Prof. Ngaire Kerse of the University of Auckland in New Zealand discuss the findings and the impact that wearable motion sensors are having on this type of research in a linked editorial.

They note that the introduction of wearable sensors has allowed researchers to collect more precise and objective measures of levels and amount of physical activity.

“But,” they caution, “inconsistency and uncertainty remain, especially about the magnitude of any effects and the contribution to health of low levels of physical activity.”

However, the analysis that went into the new findings drew on high quality studies, harmonized methods, and used data on more than 36,000 people. The total scope covered more than 240,000 person-years of followup and 2,100 events.

This gave the authors “sufficient statistical power” to enable them to “differentiate between different levels of intensity – including low intensity physical activity,” note the reviewers.

Meanwhile, researcher Dr. Julie Gallagher (UCL Eastman Dental Institute Centre for Oral Health and Performance), said: “We found that a majority of the athletes in our survey already have good oral health related habits in as much as they brush their teeth twice a day, visit the dentist regularly, don’t smoke and have a healthy general diet.

“However, they use sports drinks, energy gels and bars frequently during training and competition; the sugar in these products increases the risk of tooth decay and the acidity of them increases the risk of erosion. This could be contributing to the high levels of tooth decay and acid erosion we saw during the dental check-ups.”

The study builds on research carried out by the Centre since the London 2012 Olympics, led by Professor Ian Needleman. Previous findings have suggested that elite athletes may also face an elevated risk of oral disease from a dry mouth during intensive training.

Encouragingly, the surveyed athletes said they would consider adopting even better oral hygiene habits to tackle this and an intervention study has already been piloted.

Gallagher said: “Athletes were willing to consider behaviour changes such as additional fluoride use from mouthwash, more frequent dental visits, and reducing their intake of sports drinks, to improve oral health.”

“We subsequently asked some of them and support team members to help us design an oral health intervention study, based on contemporary behaviour change theory and we will publish the results soon.”