Thursday, August 18, 2022

Do winners cheat more? New research refutes previous high-profile study

New large-scale research led by the University of Leicester shows that winning does not cause people to cheat, in stark contrast to a previous high-profile study.

Peer-Reviewed Publication

UNIVERSITY OF LEICESTER

New large-scale research led by the University of Leicester shows that winning does not cause people to cheat, in stark contrast to a previous high-profile study.

A 2016 paper1 by Israeli researchers reported a series of experiments, which claimed that winners of skill-based competitions are more likely to steal money in subsequent games of chance against different opponents, as opposed to losers or people who did not see themselves as winners or losers.

This highly-cited study of relatively small sample sizes proposed that competitive winning induces a sense of entitlement that encourages cheating.

But now, an expanded and enhanced study by researchers at the University of Leicester (UK) and the University of Southern California (USA), published today (Wednesday) in the journal Royal Society Open Science, has refuted the original findings.

The international team of researchers found that people with a strong sense of fairness cheat less – regardless of whether they had previously won or lost.

They examined the behaviour of 259 participants in a lab-based dice-rolling game – identical to the original study – and 275 participants undertaking a basic coin-tossing game in an additional online experiment. The results were then analysed using standard statistics plus a mathematical technique called structural equation modelling.

Researchers found that a small but significant amount of cheating occurred for the financial rewards on offer, just as in the original study. However, winning did not increase subsequent cheating or increase people’s sense of entitlement – and neither did losing.

Instead, the only factor investigated which could account for the small (but significant) amount of the cheating that occurred was low ‘inequality aversion’.

People with inequality aversion dislike unequal outcomes. Those with a strong sense of fairness tend to be inequality averse, and they avoid cheating because they view the practice as a form of unfairness.

Andrew Colman is a Professor of Psychology within the University of Leicester’s Department of Neuroscience, Psychology and Behaviour, and also served as lead author for the new study.

Professor Colman said:

“Cheating and general dishonesty are of growing concern in the light of academic dishonesty in the digital age, problems of tax avoidance and evasion by wealthy people in developed economies, and more generally effects of widening inequality in wealth and income on corruption and crime.

“We were surprised by the findings in the 2016 study, and that’s why we wanted to replicate it with substantial sample sizes. The original study’s small samples do not have the statistical power to generate firm conclusions.

“We were amazed when it turned out that neither winning nor losing had any effect on cheating although a significant amount of cheating occurred. We have at least provided scientifically sound data that give a clear answer to the question.”

Does competitive winning increase subsequent cheating?’ is published in Royal Society Open Science.

Researchers reveal how an insect-eating plant uses rain energy to power its traps

Peer-Reviewed Publication

UNIVERSITY OF BRISTOL

Image 1 

IMAGE: GRAPHIC SHOWING MECHANISMS OF NEPENTHES GRACILIS view more 

CREDIT: ANNE-KRISTIN LENZ

Scientists at the University of Bristol have uncovered the deadly workings of a carnivorous plant.

In the steaming jungles of Borneo, plants have evolved innumerable tricks to help them survive and outcompete their neighbours. The Slender Pitcher Plant, Nepenthes gracilis, is amongst the most ingenious: its elaborate cup-shaped leaves are equipped with a canopy-like hanging lid that turns into a deadly springboard for ants when it is hit by a falling rain drop.

The findings, published today in Biology Letters, reveal for the first time, how the lethal spring works.

The team were surprised to find that, rather than bending in the lid itself or in the narrow constriction between pitcher cup and lid, the spring is located far down in the back of the tubular pitcher wall. The off-centre location at the rear of the tube has two effects.

First, it makes the spring direction-dependent and as a result, the lid moves easily down, but not up. When a rain drop hits, the lid is accelerated quickly downwards, flicking any insects sitting on its underside into the fluid-filled trap below. On the way up though, the increased resistance of the spring slows the lid down, so that it stops moving sooner and the trap is quickly ready to capture again.

Second, the off-centre spring prevents the lid from twisting or wobbling, thereby maximising the transmission of impact energy into downward movement.

Lead author Anne-Kristin Lenz of Bristol’s School of Biological Sciences explained: “If you look at the pitcher shape you would assume that the deformation happens at the smallest cross section, which is the transition point from lid to pitcher tube, but in fact it also deforms further down at the back of the pitcher tube.

“Pitcher plant traps are lightweight, but sturdy. Nepenthes gracilis uses small changes in the trap shape to transmit impact energy with astounding efficiency. We can learn from these plants how to optimize structures geometrically, which could help to save material and weight, while still having a functional spring. The springboard trapping mechanism might even provide inspiration for designing new mechanical devices for harvesting energy from rain or hail.”

This clever use of geometry makes Nepenthes gracilis the only known plant to exploit an external energy source to achieve extremely fast movement – entirely free of metabolic costs.


CAPTION

The Slender Pitcher Plant known as Nepenthes gracilis

CREDIT

Dr Ulrike Bauer


  

CAPTION

The Slender Pitcher Plant known as Nepenthes gracilis

CREDIT

Dr Ulrike Bauer

Paper:

Pitcher geometry facilitates extrinsically powered 'springboard trapping' in carnivorous Nepenthes gracilis pitcher plants by Anne-Kristin Lenz and Ulrike Bauer in Biology Letters.

 

Suspended sediment reduced by rapid revegetation after Fukushima decontamination

Peer-Reviewed Publication

UNIVERSITY OF TSUKUBA

image 

IMAGE: IMAGE view more 

CREDIT: UNIVERSITY OF TSUKUBA

Researchers from the University of Tsukuba find that soil decontamination efforts in Fukushima result in constant, high levels of suspended sediments and a rapid decline in radiocesium particles, and that rapid vegetation recovery reduces the duration of unsustainable turbidity effects

Tsukuba, Japan—The effects of increased sediment load in rivers during the recovery phase after a nuclear accident are a key consideration in decontamination efforts. Researchers from Japan have discovered that with some planning, unsustainable effects from these efforts could be mitigated.

In a study published this month in Nature Sustainability, a research group led by the University of Tsukuba has revealed that although the initial effects of increased sediment load in rivers caused by the Fukushima decontamination efforts were unsustainable, several factors worked in the region's favor to reduce these effects.

On 11 March 2011, the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in Japan released a large amount of radiocesium into the landscape, resulting in long-term radioactive contamination of large nearby water catchments. Mechanical decontamination, used to recover contaminated regions such as Chernobyl, was conducted by the Japanese government at Fukushima in the year following the accident.

"Previously, the focus has mostly been directed at understanding on-site decontamination effects and issues caused by the resuspension of atmospheric particles," says corresponding author of the study, Professor Yuichi Onda. "Not much was known about whether these disturbances have long-term, secondary effects on downstream catchments."

To investigate these effects, the researchers conducted a comprehensive impact assessment. They found that the potential for regional erosion increased during the decontamination phase, but declined in the following revegetation stage. The suspended sediment level increased by just over 237% in 2016 compared with 2013. Modeling indicated that the slow increase in sediment from decontaminated areas resulted in a rapid decline in particulate radiocesium, but that there were no significant changes in radiocesium discharge downstream after decontamination.

However, because constant, high levels of turbidity (the measure of water cloudiness or haziness) in rivers affects water use by local residents and the structure of regional aquatic food chains, the unsustainable downstream effects caused by upstream decontamination are of major importance. Vegetation recovery following land development depends considerably on local conditions; both Fukushima's high rainfall level and the soil used for decontamination enabled fast vegetation recovery, shortening the duration of such effects.

"Our results showed that mechanical decontamination upstream caused continuous high levels of suspended sediment downstream, but with reduced radiocesium concentrations, and that quick vegetation recovery can reduce how long these unsustainable effects persist for," says Professor Onda.

This study highlights the need for future remediation projects to include measures such as a pre-assessment of the natural restoration capacity of local landscapes and, where necessary, the addition of suitable revegetation steps in catchment regulatory frameworks, which would reduce the effects of long-term decontamination activities on downstream environments.

###
We acknowledge funding support from the commissioned study from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) FY2011-2012, Nuclear Regulation Authority FY2013-2014, Japan Atomic Energy Agency-funded FY2015-2021, Grant-in-Aid for Scientific Research on Innovative Areas grant number 24110005, Grant-in-Aid for Scientific Research (A) 22H00556, Agence Nationale de la Recherche ANR11-RSNR-0002 and the Japan Science and Technology Agency as part of the Belmont Forum.

Correspondence

Professor ONDA Yuichi
Faculty of Life and Environmental Sciences
Center for Research in Isotopes and Environmental Dynamics (CRiED), University of Tsukuba

Related Link

Faculty of Life and Environmental Sciences
Center for Research in Isotopes and Environmental Dynamics (CRiED)

World-first study reveals physical toll on law enforcement recruits

Australian research is the first to examine training injuries among law enforcement agencies in detail

Peer-Reviewed Publication

EDITH COWAN UNIVERSITY

Police recruits 

IMAGE: A STUDY HAS EXAMINED THE PHYSICAL TOLL LAW ENFORCEMENT RECRUIT TRAINING HAS ON ITS PARTICIPANTS. view more 

CREDIT: WA POLICE.

For the first time, a new study has identified the number and type of injuries commonly experienced by police recruits whilst undergoing their academy training, an important step towards ensuring new officers can in the future meet physical standards whilst reducing the risk of injury. 

Edith Cowan University (ECU) researchers analysed the injuries suffered by Western Australian police recruits between 2018 and 2021 – making WA Police the first police organization in the world to look at injuries among recruits in such detail.

The team identified the most common injury types and body regions affected, while also identifying which injuries were most disruptive to recruit training and which demographics were most susceptible. 

Lead ECU researcher Dr Myles Murphy said the information could be used to help agencies across the globe.

“We found less than ten studies on injury profiles in law enforcement recruits around the world, including organisations such as the FBI,” he said. 

“And that’s just the injuries they get, let alone risk factors.  

“From an injury prevention point of view, police recruits around the world have not been front of mind. Until now.” 

Military-like injury risk 

WA Police Force recruits undergo vigorous physical training to ensure they are capable to perform the more strenuous aspects of policing. 

However, of the 1316 recruits included in the study, 20 per cent needed to modify their recruit training due to injury, reflecting injury rates seen in military recruits.

And the injuries could be significant: 87.4 per cent required more than eight days of modified training, and 34 per cent resulted in more than 28 days.  

WA Police Force Academy Principal, Superintendent Kate Vivian, said the organisation recognised the physical toll training could have on recruits and funded the ECU study to find ways to ensure graduates met the appropriate standards of physical fitness relevant to operational policing, while at the same time reducing the risk of injury. 

“Understanding injury risk and ways to prevent injury occurrence in our recruits is a top priority for the WA Police Force, and we have a number of effective injury prevention processes in place to help identify and mitigate injury risk for recruits both prior to and during their physical training program,” she said. 

“In addition to these strategies, the WA Police Force continues to support and collaborate with ECU on an initiative to screen pre-inducted police recruits before entering the Academy, providing important benchmarking and physical profiling information.  

“This will assist the agency with developing a screening tool and software platform to identify injury risk to future recruits prior to commencing their physical preparation programs at the Police Academy, and operational deployment.” 

Who and what is most susceptible? 

The study looked at each type of injury’s prevalence and how many days of disrupted training it caused, to calculate an overall injury burden score. 

Knee injuries had easily the greatest impact on training, ahead of injuries to the shoulder and lower leg. 

Ligament and joint injuries had the largest burden for injury type, closely followed by muscle and tendon injuries. 

Similarly to other intensive training programs such as military basic training, men under the age of 30 had a substantially reduced injury risk.  

When training loads were accounted for, men were 40 per cent less likely to be injured and recruits under 30 years of age were 50 per cent less likely to be injured.   

Next steps 

Dr Murphy said the next step is to conduct body scans of recruits using cutting edge technology at ECU’s High Performance Centre, which would allow training programs to be adjusted where necessary to reduce injuries. 

“For example, if muscle mass isn’t shown to be protective and just adds weight and contributes to stress fractures, then we’d know getting recruits to put on a bunch of muscle wouldn’t be wise; you’d be better off focusing on nutrition and cardio-based exercise,” he said. 

“But if we find muscle is really protective against injury, it would be reasonable to try and bulk them up.” 

‘Injury Profiles of Police Recruits Undergoing Basic Physical Training: A Prospective Cohort Study’ was published in the Journal of Occupational Rehabilitation.’

 Stickers and a smartphone for easy nitrite detection on foods

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

Stickers and a smartphone for easy nitrite detection on foods 

IMAGE: A NEW FILM REACTS TO NITRITE ANIONS THROUGH A COLOR CHANGE, TURNING DARKER WITH HIGHER NITRITE LEVELS. view more 

CREDIT: ADAPTED FROM ACS APPLIED MATERIALS & INTERFACES 2022, DOI: 10.1021/ACSAMI.2C09467

Nitrates and nitrites give processed meats their characteristic pink color and robust flavor. Although many consumers want to limit consumption of these preservatives because the substances can form potentially cancer-causing compounds, knowing how much is in a food has been difficult to determine. Now, researchers reporting in ACS Applied Materials & Interfaces have developed a color-changing film that consumers can stick onto foods and easily analyze nitrite levels by snapping a picture with a smartphone.

Cured and processed meats, such as salami and bacon, are often treated with nitrite or nitrate salts to keep them looking and tasting fresh. Though nitrate is relatively stable, it can be converted to the more reactive nitrite ion in the body. When in the acidic environment of the stomach or under the high heat of a frying pan, nitrite can undergo a reaction to form nitrosamines, which have been linked to the development of various cancers. Some methods to determine nitrite levels in foods already exist, but they are not very consumer-friendly and often require expensive and laborious techniques and instruments. To help consumers make more informed decisions, Saúl Vallejos, José M. García and colleagues wanted to develop an easy-to-use nitrite quantification system.

To accomplish this, the researchers developed a film they called “POLYSEN,” which stands for “polymeric sensor,” made of four monomers and hydrochloric acid. Disks punched from the material were placed on meat samples for 15 minutes, allowing the monomer units and acid in the film to react with nitrite in a four-step azo coupling reaction. The disks were then removed and dipped in a sodium hydroxide solution for one minute to develop the color. When nitrite was present, the film’s yellowish hue deepened with higher nitrite levels in the food. To quantitate the color change, the researchers created a smartphone app that self-calibrates when a chart of reference disks is photographed in the same image as the sample disks.

The team tested the film on meats they prepared and treated with nitrite, in addition to store-bought meats, and found that the POLYSEN-based method produced results similar to those obtained with a traditional and more complex nitrite detection method. In addition, POLYSEN complied with a European regulation for migration of substances from the film to the food. The researchers say the new approach could be a user-friendly and inexpensive way for consumers to determine nitrite levels in foods.

The authors acknowledge funding from La Caixa Foundation and the Spanish Agencia Estatal de Investigación. They also acknowledge the support and collaboration of the company Inforapps.

The paper’s abstract will be available on Aug. 3, 2022, at 8 a.m. Eastern time here: http://pubs.acs.org/doi/abs/10.1021/acsami.2c09467.

For more of the latest research news, register for our upcoming meeting, ACS Fall 2022. Journalists and public information officers are encouraged to apply for complimentary press registration by completing this form.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

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Ditching the toothbrush for whiter teeth, fewer cavities (video)

Peer-Reviewed Publication

AMERICAN CHEMICAL SOCIETY

Ditching the toothbrush for whiter teeth, fewer cavities 

IMAGE: A NEW HYDROGEL TREATMENT BREAKS APART CAVITY-FORMING BIOFILMS AND WHITENS TEETH WITHOUT DAMAGING ENAMEL. view more 

CREDIT: AMERICAN CHEMICAL SOCIETY

The first thing people notice when they meet you is your smile. To be more confident when giving wide-mouthed, eye-crinkling smiles, people want healthy, pearly white teeth. But toothpastes only remove surface stains, and whitening treatments can harm enamel, leading to cavities and discoloration. Now, researchers in ACS Applied Materials & Interfaces report a new hydrogel treatment that breaks apart cavity-forming biofilms and whitens teeth without damaging them. Watch a video of the treatment here.

Daily toothbrushing and flossing are good ways to prevent cavities from forming, according to the American Dental Association. However, these methods don’t effectively whiten teeth. For better whitening, consumers often turn to over-the-counter or professional treatments that combine hydrogen peroxide-containing gels and blue light, producing a chemical reaction that removes stains. This combination removes most of the discoloration, but generates reactive oxygen species that can break down enamel. Previously, Xiaolei Wang, Lan Liao and colleagues modified titanium dioxide nanoparticles for a less destructive tooth-whitening treatment. This method still required high-intensity blue light, which can damage nearby skin and eyes. So, the team wanted to find a material that would be activated by green light — a safer alternative — to both whiten teeth and prevent cavities.

The researchers combined bismuth oxychloride nanoparticles, copper oxide nanoparticles and sodium alginate into a thick mixture. Then, they evenly coated the mixture onto the surface of teeth stuck to a slide and sprayed the concoction with a calcium chloride solution, forming a strongly adhering hydrogel. Next, the team tested the material on teeth that were stained with coffee, tea, blueberry juice and soy sauce and placed in a lab dish. Following treatment with the hydrogel and green light, the teeth got brighter over time, and there was no damage to the enamel. In another set of experiments, the team showed that the treatment killed 94% of bacteria in biofilms. To demonstrate that the treatment could work on teeth in vivo, the team used the new method on mice whose mouths were inoculated with cavity-forming bacteria. The green-light activated hydrogel effectively prevented moderate and deep cavities from forming on the surface of the animals’ teeth. The researchers say their safe, brush-free treatment both effectively prevents cavities and whitens teeth.

The authors acknowledge funding from the National Natural Science Foundation of China, Key Youth Project of Jiangxi Province, Key Research and Development Program of Jiangxi Province, Natural Science Foundation of Jiangxi Province and the Graduate Innovation Special Fund Project of Jiangxi Province.

For more of the latest research news, register for our upcoming meeting, ACS Fall 2022. Journalists and public information officers are encouraged to apply for complimentary press registration by completing this form.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

To automatically receive news releases from the American Chemical Society, contact newsroom@acs.org.

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Daily cannabis users less likely to view heavy cigarette smoking as dangerous

Peer-Reviewed Publication

COLUMBIA UNIVERSITY'S MAILMAN SCHOOL OF PUBLIC HEALTH

A growing number of Americans are using cannabis as it becomes legalized for recreational adult use in a rapidly increasing number of U.S. states. Questions abound about what impact legalization will have on adult and youth health.

In a new study at Columbia University Mailman School of Public Health, findings show that increased cigarette use is one possibility. While cigarette use has been declining for decades in the U.S., the study finds that adults who use cannabis daily do not perceive smoking a pack a day as being as harmful as those who do not use cannabis in the U.S. The findings are published in the journal Nicotine & Tobacco Research.

“In the context of recent findings that perception of risk plays a key role in predicting substance use, and that perception of risk associated with cannabis use has declined steadily along with legalization, these findings were somewhat of a surprise,” said Renee D Goodwin, PhD, a professor in the Department of Epidemiology at Columbia Mailman School of Public and professor of Epidemiology at The City University of New York of New York, and lead author.

The researchers used data from adults age 18 and older in the 2020 National Survey on Drug Use and Health, a representative survey of U.S. individuals. Participants’ responses to a question about how much people risk harming themselves physically and in other ways by smoking one or more packs of cigarettes per day were compared between those who use cannabis daily and those who did not use cannabis in the past year; 62 percent of adults who use cannabis daily perceived pack a day cigarette use to be of “great” risk to health, compared with 73 percent of those who did not use cannabis in the past year.

“Tobacco control has done a tremendous job in public education on the physical health risks associated with tobacco use, and cigarette smoking in particular, over the past several decades,” noted Goodwin. Her prior work shows that cigarette use, however, is much more common among those who use cannabis and that cannabis legalization may contribute to observed increases in cannabis use and cannabis-cigarette co-use among adults.  “We wondered why that might be. Our findings suggest that diminished risk perception of pack a day cigarette use might be one contributing factor.”

At a recent Suffolk County Legislature Public Hearing on Introductory Resolution 1417 A Local law to Regulate the Packaging of Cannabis (Marijuana) Products to Dissuade its Appeal to Children, Goodwin discussed her work and, in particular, that of Canadian colleagues. The resolution, proposed by Legislator Kara Hahn, aims to ban cannabis packaging that appeals to children in Suffolk County, New York (NY01). Findings from Canada, which made cannabis legal federally show increases in adult cannabis use but as of the most recent study in 2022, no significant increases in cannabis use among adolescents. “Data from Canada suggests that plain packaging is one measure that can maximize the safe and effective rollout of cannabis legalization that ensures and protects the health, safety and wellbeing of all members of our community,” Goodwin said.  

“Enacting legislation on the local and state level that reduces the appeal of cannabis products to youth vis-a-vis prohibiting product packaging that mimics foods and candies that are traditionally marketed to children (e.g., pop-tarts, Oreos) may reduce potential unintended harms to the most vulnerable members of our community via accidental ingestion/poisonings, which have exploded in number in recent years in the U.S., with child and adolescent intentional use of these products,” Goodwin suggests.

Co-authors are Meng Xi, Columbia Mailman School of Public Health; and Keely Cheslack-Postava, Vagelos College of Physicians and Surgeons and the New York State Psychiatric Institute.

Columbia University Mailman School of Public Health

Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the fourth largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master’s and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit www.mailman.columbia.edu.

 

 

 

Physical activity affects boys and girls differently

Being physically active has major health benefits. But physical activity affects boys and girls differently

Peer-Reviewed Publication

NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY

Being physically active has major health benefits. But the physical activity affects boys and girls differently. New research has examined the relationship between body fat and physical activity in children.

“We looked at the connection between objectively measured physical activity and the proportion of body fat in girls and boys,” says Silje Steinsbekk, a professor at NTNU’s (the Norwegian University of Science and Technology) Department of Psychology.

The researchers measured participants’ body composition rather than their weight and height. They posed such questions as:

Does increased physical activity lead to a lower percentage of body fat over time? Or is it perhaps the other way around, that people who gain more body fat over time become less physically active?

Body fat and physical activity in girls are unrelated

The researchers examined the children every two years from the age of 6 until they were 14 years old. They found that the level of activity affects the sexes differently.

“In girls, we found no connection between their physical activity and amount of body fat. Increased physical activity didn’t lead to less body fat in the girls, and body fat had no effect on changes in their physical activity,” says Tonje Zahl-Thanem, a former research fellow and first author of the article.

But for boys, it's different. The amount of body fat influences their physical activity.

More body fat in boys results in less physical activity

“Increased body fat in boys led to less physical activity two years later, when they were 8, 10 and 12 years old,” says Zahl-Thanem.

With one exception, increased physical activity had no effect on changes in body fat.

“We found that boys who are more physically active when they’re 12 years old have a lower proportion of body fat when they’re 14. This wasn’t the case at an earlier developmental stage,” Steinsbekk says.

Several possible reasons for differences between the sexes

The study did not investigate the reasons for these differences, but the researchers point out that large bodies are heavier and require more exertion when exercising, which may explain why boys whose body fat increases become less active over time. But why isn’t this the case for girls?

“Here we can only speculate, but boys are generally more physically active than girls, so when boys reduce their activity level, the physical impact is greater,” Steinsbekk says.

We also know that children with large bodies are less satisfied with their bodies, and body dissatisfaction is associated with less physical activity in boys, but not in girls.

“Boys’ physical activity is probably even more competitively oriented than girls', and more body fat makes it more difficult to succeed. Both of these conditions can help explain why increased body fat leads to less physical activity in boys, but not girls,” says Lars Wichstrøm, a professor in NTNU’s Department of Psychology and also co-author of the study.

It could also be that girls are more likely to maintain physical activity when their proportion of body fat increases, because more attention is paid to girls' bodies and appearance.

Body fat affects sedentary activity in boys

The researchers also examined the link between inactivity or a sedentary lifestyle and body fat. In the same way that they objectively measured physical activity, they also measured how long the participants were sedentary during the day.

“The results show that boys who had an increase in the proportion of body fat had a corresponding increase in sedentary activity two years later. This carried through all the age groups studied, from the age of 6 through age 14.

In other words, boys whose proportion of body fat increases become more sedentary.

For the girls, however, there was no link here either. The percentage of body fat did not affect their level of inactivity over time, and they did not become less active by gaining more body fat.

“In sum, we found a link between physical activity, sedentary lifestyle and fat percentage in boys, but not in girls,” Steinsbekk says.

Trondheim Early Secure Study

The researchers used figures from the Trondheim Early Secure Study (TESS). They followed almost 1000 children at two-year intervals from when they were 4 years old. The participants are now 18 years old, and the eighth survey is underway.

In this study, the research group used data at five different times, when the participants were 6, 8, 10, 12 and 14 years old. The Trondheim Early Secure Study has provided data for a number of studies on children's development and health. 

References:

Zahl-Thanem T, Wichstrøm L, Steinsbekk S. Relations between physical activity, sedentary time, and body fat from childhood to adolescence: Do they differ by sex? Int J Obes (Lond). 2022 Jun 3. doi: 10.1038/s41366-022-01156-6. Epub ahead of print. PMID: 35662270.  DOI: 10.1038/s41366-022-01156-6

Zahl-Thanem, T., Wichstrøm, L. & Steinsbekk, S. Relations between physical activity, sedentary time, and body fat from childhood to adolescence: Do they differ by sex?. Int J Obes (2022). https://doi.org/10.1038/s41366-022-01156-6