At the population level, meeting and maintaining at least the minimum public health recommendations (150 minutes per week of moderate-intensity physical activity) would potentially prevent 46% of deaths associated with physical inactivity, say the researchers.

Previous studies have linked physical activity to lower risk of death, cardiovascular disease, and certain cancers. But few studies have looked at how changes in physical activity over time are associated with subsequent risk of death.

So to address this knowledge gap, researchers from the MRC Epidemiology Unit at the University of Cambridge analysed how long term changes in physical activity are associated with risk of all-cause, cardiovascular and cancer deaths.

They used data for 14,599 men and women aged 40-79 from the European Prospective Investigation into Cancer and Nutrition-Norfolk (EPIC-Norfolk) study, who were recruited between 1993-1997.

Participants were assessed at the start of the study and then a further three times over an average of 7.6 years, along with other risk factors up to 2004. From this point in time, mortality was assessed up to 2016, for an average of 12.5 years of follow-up.

Physical activity energy expenditure (PAEE) was derived from questionnaires and calibrated against combined movement and heart monitoring measurements.

Overall physical activity included activity at work (e.g. sedentary office work, standing work, physical and heavy manual work) and leisure-time activity, such as cycling, sports and recreational activities.

During the study period, there were 3,148 deaths, including 950 deaths from cardiovascular disease and 1,091 deaths from cancer.

After controlling for existing physical activity and other risk factors such as diet, bodyweight, medical history, blood pressure and cholesterol levels, higher physical activity levels and increases in physical activity over time were associated with a lower risk of death.

For each 1kJ/kg/day per year increase in PAEE (equivalent to being inactive at the start of the study and gradually, over five years, meeting minimum physical activity guidelines), the researchers found a 24% lower risk of death from any cause, a 29% lower risk of cardiovascular death, and an 11% lower risk of cancer death.

Results were similar in those with and without a history of cardiovascular disease and cancer. What’s more, compared with consistently inactive people, those who became more active over time had a lower risk of death from all causes, regardless of past activity levels.

But the benefits were greatest for those with existing high levels of physical activity who became even more active over time, with a 42% lower risk of mortality.

This is an observational study, and as such, can’t establish cause. And the authors point out that the sample was made up of people who were available for follow-up almost a decade after initial recruitment, which may influence generalisability of the results.

But they say that this is a large study with long follow-up and repeat monitoring, that controlled for established risk factors.

“These results are encouraging, not least for middle aged and older adults with existing cardiovascular disease and cancer, who can still gain substantial longevity benefits by becoming more active, lending further support to the broad public health benefits of physical activity,” they write.

“In addition to shifting the population towards meeting the minimum physical activity recommendations, public health efforts should also focus on the maintenance of physical activity levels, specifically preventing declines over mid to late life,” they conclude.

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Physicians have long known that people with ALS experience changes in their metabolism that often lead to rapid weight loss in a process called hypermetabolism. According to the study’s lead author Ernesto Manzo, a UA alumnus and postdoctoral researcher in the Department of Molecular and Cellular Biology, hypermetabolism can be a relentless cycle.

People with ALS use more energy while resting than those without the disease, while simultaneously they often struggle to effectively make use of glucose, the precise ingredient a body needs to make more energy. Experts have not known exactly what happens in a patient’s cells to cause this dysfunction or how to alleviate it.

“This project was a way to parse out those details,” said Manzo, who described the results, published online in eLife, as “truly shocking.”

The study revealed that when ALS-affected neurons are given more glucose, they turn that power source into energy. With that energy, they’re able to survive longer and function better. Increasing glucose delivery to the cells, then, may be one way to meet the abnormally high energy demands of ALS patients.

“These neurons were finding some relief by breaking down glucose and getting more cellular energy,” Manzo said.

ALS is almost always a progressive disease, eventually taking away patients’ ability to walk, speak and even breathe. The average life expectancy of an ALS patient from the time of diagnosis is two to five years.

“ALS is a devastating disease,” said Daniela Zarnescu, UA professor of molecular and cellular biology and senior author on the study. “It renders people from functioning one day to rapidly and visibly deteriorating.”

Previous studies on metabolism in ALS patients have focused primarily on what happens at the whole-body level, not the cellular level, Zarnescu explained.

“The fact that we uncovered a compensatory mechanism surprised me,” Zarnescu said. “These desperate, degenerating neurons showed incredible resilience. It is an example of how amazing cells are at dealing with stress.”

The novelty of the findings partially lies in the fact that metabolism in ALS patients has remained poorly understood, Zarnescu said.

“It’s difficult to study, in part because of limited accessibility to the nervous system,” she said.

Because scientists can’t scrape away neurons from the brain without causing irreparable damage to a patient, the researchers used fruit flies as a model.

“Fruit flies can teach us a lot about human diseases,” Manzo said.

In the lab, he and Zarnescu used high-powered microscopes to observe the motor neurons of fruit flies in their larval state, paying close attention to what happened as they provided more glucose.

They found that when they increased the amount of glucose, the motor neurons lived longer and moved more efficiently. When the researchers took glucose away from the neurons, the fruit fly larva moved more slowly.

Their findings were consistent with a pilot clinical trial, which found a high carbohydrate diet was one possible intervention for ALS patients with gross metabolic dysfunction.

“Our data essentially provide an explanation for why that approach might work,” Zarnescu said. “My goal is to convince clinicians to perform a larger clinical trial to test this idea.”

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Materials provided by University of Arizona. Original written by Emily Litvack. Note: Content may be edited for style and length.

The study took advantage of the unusual seawater chemistry found naturally at sites along the Caribbean coastline of Mexico’s Yucatan Peninsula, where water discharging from submarine springs has lower pH than the surrounding seawater, with reduced availability of the carbonate ions corals need to build their calcium carbonate skeletons.

In a two-year field experiment, the international team of researchers transplanted genetically identical fragments of three species of corals to a site affected by the springs and to a nearby control site not influenced by the springs, and then monitored the survival, growth rates, and other physiological traits of the transplants. They reported their findings in a paper published June 26 in Proceedings of the Royal Society B.

“The good news is the corals can survive and deposit calcium carbonate, but the density of their skeletons is reduced, which means the framework of the reef would be less robust and might be more susceptible to storm damage and bioerosion,” said Adina Paytan, a research professor at UCSC’s Institute of Marine Sciences and corresponding author of the paper.

Of the three species tested, the one that performed best in the low-pH conditions was Siderastrea siderea, commonly known as massive starlet coral, a slow-growing species that forms large dome-shaped structures. Another slow-growing dome-shaped species, Porites astreoides (mustard hill coral), did almost as well, although its survival rate was 20 percent lower. Both of these species outperformed the fast-growing branching coral Porites porites (finger coral).

Coauthor Donald Potts, professor of ecology and evolutionary biology at UC Santa Cruz, said the transplanted species are all widespread throughout the Caribbean. “The slow-growing, dome-shaped corals tend to be more tolerant of extreme conditions, and they are important in building up the permanent structure of the reef,” he said. “We found that they have the potential for persistence in acidified conditions.”

Corals will have to cope with more than ocean acidification, however. The increasing carbon dioxide level in the atmosphere is also driving climate change, resulting in warmer ocean temperatures and rising sea levels. Unusually warm temperatures can disrupt the symbiosis between coral polyps and the algae that live in them, leading to coral bleaching. And rapidly rising sea levels could leave slow-growing corals at depths where they would die from insufficient sunlight.

Nevertheless, Potts noted that several species of Caribbean corals have long fossil records showing that they have persisted through major changes in Earth’s history. “These are species with a history of survival and tolerance,” he said.

He added that both S. siderea and P. astreoides had higher chlorophyll concentrations at the low-pH site, indicating that their algal symbionts were responding positively and potentially increasing the energy resources available to the corals for resisting stress.

Both of the slow-growing species that did well under acidified conditions have internal fertilization and brood their larvae, so that their offspring have the potential to settle immediately in the same area, Potts said. “This means there is potential for local genetic adaptation over successive generations to changing environmental conditions,” he said.

The authors also noted that the differences among coral species in survival and calcification under acidified conditions could be useful information for reef restoration efforts and perhaps even for efforts to genetically modify corals to give them greater stress tolerance.

Paytan said she remains “cautiously optimistic,” despite the many threats facing coral reefs worldwide.

“These corals are more robust than we thought,” she said. “They have the potential to persist with ocean acidification, but it costs them energy to cope with it, so we have to do all we can to reduce other stressors, such as nutrient pollution and sedimentation.”

Paytan and Potts said the collaboration with Mexican researchers was essential to the success of the project, enabling frequent monitoring of the transplanted corals throughout the two-year experiment.