Connect with us

Science

How many calories will the Tour de France winner burn?

Published

on

Enlarge / Jumbo-Visma team’s Belgian rider Wout Van Aert cycles to the finish line during the first stage of the 109th edition of the Tour de France cycling race in Copenhagen, Denmark, on July 1, 2022.

Imagine you begin pedaling from the start of Stage 12 of this year’s Tour de France. Your very first task would be to bike approximately 20.6 miles (33.2 km) up to the peak of Col du Galibier in the French Alps while gaining around 4,281 feet (1,305 m) of elevation. But this is only the first of three big climbs in your day. Next you face the peak of Col de la Croix de Fer and then end the 102.6-mile (165.1-km) stage by taking on the famous Alpe d’Huez climb with its 21 serpentine turns.

On the fittest day of my life, I might not even be able to finish Stage 12—much less do it in anything remotely close to the five hours or so the winner will take to finish the ride. And Stage 12 is just one of 21 stages that must be completed in the 24 days of the tour.

I am a sports physicist, and I’ve modeled the Tour de France for nearly two decades using terrain data—like what I described for Stage 12 – and the laws of physics. But I still cannot fathom the physical capabilities needed to complete the world’s most famous bike race. Only an elite few humans are capable of completing a Tour de France stage in a time that’s measured in hours instead of days. The reason they’re able to do what the rest of us can only dream of is that these athletes can produce enormous amounts of power. Power is the rate at which cyclists burn energy and the energy they burn comes from the food they eat. And over the course of the Tour de France, the winning cyclist will burn the equivalent of roughly 210 Big Macs.

Cycling is a game of watts

To make a bicycle move, a Tour de France rider transfers energy from his muscles, through the bicycle and to the wheels that push back on the ground. The faster a rider can put out energy, the greater the power. This rate of energy transfer is often measured in watts. Tour de France cyclists are capable of generating enormous amounts of power for incredibly long periods of time compared to most people.

For about 20 minutes, a fit recreational cyclist can consistently put out 250 watts to 300 watts. Tour de France cyclists can produce over 400 watts for the same time period. These pros are even capable of hitting 1,000 watts for short bursts of time on a steep uphill—roughly enough power to run a microwave oven.

But not all of the energy a Tour de France cyclist puts into his bike gets turned into forward motion. Cyclists battle air resistance and frictional losses between their wheels and the road. They get help from gravity on downhills but they have to fight gravity while climbing.

I incorporate all of the physics associated with cyclist power output as well as the effects of gravity, air resistance and friction into my model. Using all that, I estimate that a typical Tour de France winner needs to put out an average of about 325 watts over the roughly 80 hours of the race. Recall that most recreational cyclists would be happy if they could produce 300 watts for just 20 minutes!

Turning food into miles

So where do these cyclists get all this energy from? Food, of course!

But your muscles, like any machine, can’t convert 100 percent of food energy directly into energy output—muscles can be anywhere between 2 percent efficient when used for activities like swimming and 40 percent efficient in the heart. In my model, I use an average efficiency of 20 percent. Knowing this efficiency as well as the energy output needed to win the Tour de France, I can then estimate how much food the winning cyclist needs.

Top Tour de France cyclists who complete all 21 stages burn about 120,000 calories during the race—or an average of nearly 6,000 calories per stage. On some of the more difficult mountain stages—like this year’s Stage 12—racers will burn close to 8,000 calories. To make up for these huge energy losses, riders eat delectable treats such as jam rolls, energy bars, and mouthwatering “gels” so they don’t waste energy chewing.

Tadej Pogačar won both the 2021 and 2020 Tour de France and weighs only 146 pounds (66 kilograms). Tour de France cyclists don’t have much fat to burn for energy. They have to keep putting food energy into their bodies so they can put out energy at what seems like a superhuman rate. So this year, while watching a stage of the Tour de France, note how many times the cyclists eat—now you know the reason for all that snacking.

This article is republished from The Conversation under a Creative Commons license. Read the original article. You can subscribe to The Conversation’s newsletter here.

The Conversation

Continue Reading

Science

Jumping spiders may experience something like REM sleep

Published

on

Enlarge / This little guy looks too perky to need a nap.

Our sleep is marked by cycles of distinct brain activity. The most well-known of these is probably rapid eye movement, or REM sleep, which is characterized by loss of muscle control leading to twitching and paralysis, along with its eponymous eye movements. REM sleep is widespread in vertebrates, appearing in many mammals and birds; similar periods have also been observed in lizards.

Figuring out what might be going on beyond vertebrates can get a bit challenging, however, as identifying what constitutes sleep isn’t always clear, and many animals don’t have eyes that move in the same way as those of vertebrates. (Flies, for example, must move their entire head to reorient their eyes.) But an international team of researchers identified a group of jumping spiders that can reorient internal portions of their eyes during what appears to be sleep.

And according to this team, the spiders experience all the hallmarks of REM sleep, with periods of rapid eye movements associated with muscle twitching.

Spider napping

Spiders, and specifically jumping spiders, may have more going on mentally than might be assumed based on their tiny size and correspondingly tiny nervous system. But the key to this new study was the discovery that, apparently, they sometimes just need a nap. A year ago, some of the same team members were authors of a publication that reported sleep-like behavior in these spiders. At night, they’d find some overhanging vegetation, attach a single thread to it so they could dangle from it, and then stay there until light returns in the morning. By all appearances, they’re sleeping.

And that gives the researchers a chance to avoid one of the bigger challenges in cross-species sleep studies. The eyes of jumping spiders contain structures called retinal tubes, which can be moved to direct the spider’s vision to specific locations. These tubes aren’t visible in adult spiders due to the pigment in the spider’s cuticle. But newly hatched spiders take some time to develop that pigment, having translucent bodies that allow the movements of the retinal tubes to be tracked.

And so the researchers decided this was the perfect opportunity to see whether spiders might have an REM-like phase to their overnight rests. “The most salient indicator of REM sleep is the movement of eyes during this phase,” they write. “Movable eyes, however, have evolved only in a limited number of lineages—an adaptation notably absent in insects and most terrestrial arthropods—restricting cross-species comparisons.” For these jumping spiders, that restriction doesn’t apply.

So, they shut the lab lights off, let the spiders enter their sleep-like state, and then tracked any movement using an infrared camera.

Are rapid eye movements REM?

Just as you might see in a mammal, the spiders experienced periodic periods of rapid eye movement—albeit involving the movement of retinal tubes. Although these events varied a bit from instance to instance and between individuals, they generally lasted similar amounts of time, and they repeated with a period that was similarly consistent.

Perhaps more significantly, the retinal tube movements were frequently associated with twitching or curling of the spiders’ legs. Only about 40 percent of the periods of eye movement were associated with leg twitching, but every leg twitching that happened over the sleep period was associated with eye movement.

It’s not clear that this behavior represents REM because it performs the same function as REM sleep does in humans (something we’re still working to understand). But physically, the hallmarks seem to be there, which has some significant implications. “That these characteristic REM sleep-like behaviors exist in a highly visual, long-diverged lineage further challenges our understanding of this sleep state,” the researchers note. This is especially true given that other researchers have published findings of REM-like behavior in distantly related animals like cuttlefish.

But the spiders at issue here provide a distinct possibility of testing how deep the parallels go. People have proposed that the eye movements of REM are a product of replaying visual memories during sleep. In a lab environment, it’s possible to expose these spiders to visual stimuli that force them to perform specific patterns of eye movements. After which, you can shut the lights off and see whether the same pattern is repeated during sleep.

PNAS, 2022. DOI: 10.1073/pnas.2204754119  (About DOIs).

Continue Reading

Science

Scientists hid encryption key for Wizard of Oz text in plastic molecules

Published

on

Enlarge / Scientists from the University of Texas at Austin encrypted the key to decode text of the The Wizard of Oz in polymers.

S.D. Dahlhauser et al., 2022

Scientists from the University of Texas at Austin sent a letter to colleagues in Massachusetts with a secret message: an encryption key to unlock a text file of L. Frank Baum’s classic novel The Wonderful Wizard of Oz. The twist: The encryption key was hidden in a special ink laced with polymers, They described their work in a recent paper published in the journal ACS Central Science.

When it comes to alternative means for data storage and retrieval, the goal is to store data in the smallest amount of space in a durable and readable format. Among polymers, DNA has long been the front runner in that regard. As we’ve reported previously, DNA has four chemical building blocks—adenine (A), thymine (T), guanine (G), and cytosine (C)—which constitute a type of code. Information can be stored in DNA by converting the data from binary code to a base-4 code and assigning it one of the four letters. A single gram of DNA can represent nearly 1 billion terabytes (1 zettabyte) of data. And the stored data can be preserved for long periods—decades, or even centuries.

There have been some inventive twists on the basic method for DNA storage in recent years. For instance, in 2019, scientists successfully fabricated a 3D-printed version of the Stanford bunny—a common test model in 3D computer graphics—that stored the printing instructions to reproduce the bunny. The bunny holds about 100 kilobytes of data, thanks to the addition of DNA-containing nanobeads to the plastic used to 3D print it. And scientists at the University of Washington recently recorded K-Pop lyrics directly onto living cells using a “DNA typewriter.”

But using DNA as a storage medium also presents challenges, so there is also great interest in coming up with other alternatives. Last year, Harvard University scientists developed a data-storage approach based on mixtures of fluorescent dyes printed onto an epoxy surface in tiny spots. The mixture of dyes at each spot encodes information that is then read with a fluorescent microscope. The researchers tested their method by storing one of 19th-century physicist Michael Faraday’s seminal papers on electromagnetism and chemistry, as well as a JPEG image of Faraday.

Other scientists have explored the possibility of using nonbiological polymers for molecular data storage, decoding (or reading) the stored information by sequencing the polymers with tandem mass spectrometry. In 2019, Harvard scientists successfully demonstrated the storage of information in a mixture of commercially available oligopeptides on a metal surface, with no need for time-consuming and expensive synthesis techniques.

A molecular encryption key was embedded in ink (left image) of a letter (right image), which was mailed and analyzed to decrypt a file.
Enlarge / A molecular encryption key was embedded in ink (left image) of a letter (right image), which was mailed and analyzed to decrypt a file.

ACS Central Science 2022/CC BY-NC-ND

This latest paper focused on the use of sequence-defined polymers (SDPs)  as a storage medium for encrypting a large data set. SDPs are basically long chains of monomers, each of which corresponds to one of 16 symbols. “Because they’re a polymer with a very specific sequence, the units along that sequence can carry a sequence of information, just like any sentence carries information in the sequence of letters,” co-author Eric Anslyn of UT told New Scientist.

But these macromolecules can’t store as much information as DNA, per the authors, since the process of storing more data with each additional monomer becomes increasingly inefficient, making it extremely difficult to retrieve the information with the current crop of analytic instruments available. So short SDPs must be used, limiting how much data can be stored per molecule. Anslyn and his co-authors figured out a way to improve that storage capacity and tested the viability of their method.

First, Anslyn et al. used a 256-bit encryption key to encode Baum’s novel into a polymer material made up of commercially available amino acids. The sequences were comprised of eight oligourethanes, each 10 monomers long. The middle eight monomers held the key, while the monomers on either end of a sequence served as placeholders for synthesis and decoding. The placeholders were “fingerprinted” using different isotope labels, such as halogen tags, indicating where each polymer’s encoded information fit within the order of the final digital key,

Then they jumbled all the polymers together and used depolymerization and liquid chromatography-mass spectrometry (LC/MS) to “decode” the original structure and encryption key. The final independent test: They mixed the polymers into a special ink made of isopropanol, glycerol, and soot. They used the ink to write a letter to James Reuther at the University of Massachusetts, Lowell. Reuther’s lab then extracted the ink from the paper and used the same sequential analysis to retrieve the binary encryption key, revealing the text file of The Wonderful Wizard of Oz.

In other words, Anslyn’s lab wrote a message (the letter) containing another secret message (The Wonderful Wizard of Oz) hidden in the molecular structure of the ink. There might be more pragmatic ways to accomplish the feat, but they successfully stored 256 bits in the SDPs, without using long strands. “This is the first time this much information has been stored in a polymer of this type,” Anslyn said, adding that the breakthrough represents “a revolutionary scientific advance in the area of molecular data storage and cryptography.”

Anslyn and his colleagues believe their method is robust enough for real-world encryption applications. Going forward, they hope to figure out how to robotically automate the writing and reading processes.

DOI: ACS Central Science, 2022. 10.1021/acscentsci.2c00460  (About DOIs).

Continue Reading

Science

Locked-in syndrome and the misplaced presumption of misery

Published

on

In 1993, Julio Lopes was sipping a coffee at a bar when he had a stroke. He fell into a coma, and two months later, when he regained consciousness, his body was fully paralyzed.

Doctors said the young man’s future was bleak: Save for his eyes, he would never be able to move again. Lopes would have to live with locked-in syndrome, a rare condition characterized by near-total paralysis of the body and a totally lucid mind. LIS is predominantly caused by strokes in specific brain regions; it can also be caused by traumatic brain injury, tumors, and progressive diseases like amyotrophic lateral sclerosis, or ALS.

Yet almost 30 years later, Lopes now lives in a small Paris apartment near the Seine. He goes to the theater, watches movies at the cinema, and roams the local park in his wheelchair, accompanied by a caregiver. A small piece of black, red, and green fabric with the word “Portugal” dangles from his wheelchair. On a warm afternoon this past June, his birth country was slated to play against Spain in a soccer match, and he was excited.

In an interview at his home, Lopes communicated through the use of a specialized computer camera that tracks a sensor on the lens of his glasses. He made slight movements with his head, selecting letters on a virtual keyboard that appeared on the computer’s screen. “Even if it’s hard at the beginning, you acquire a kind of philosophy of life,” he said in French. People in his condition may enjoy things others find insignificant, he suggested, and they often develop a capacity to see the bigger picture. That’s not to say daily living is always easy, Lopes added, but overall, he’s happier than he ever thought was possible in his situation.

While research into LIS patients’ quality of life is limited, the data that has been gathered paints a picture that is often at odds with popular presumptions. To be sure, well-being evaluations conducted to date do suggest that up to a third of LIS patients report being severely unhappy. For them, loss of mobility and speech make life truly miserable—and family members and caregivers, as well as the broader public, tend to identify with this perspective. And yet, the majority of LIS patients, the data suggest, are much more like Lopes: They report being relatively happy and that they want very much to live. Indeed, in surveys of well-being, most people with LIS score as high as those without it, suggesting that many people underestimate locked-in patients’ quality of life while overestimating their rates of depression. And this mismatch has implications for clinical care, say brain scientists who study wellbeing in LIS patients.

Eleven US states and several European countries, for example, have legalized various forms of assisted dying, also known as physician-assisted suicide or medical aid in dying. In these places, families and clinicians are often involved in fraught decisions about whether to actively end a person’s life or pursue life-extending interventions such as mechanical ventilation. Advocates for the right to die, a movement that dates back to the 1970s, have historically raised concerns about the potentially dehumanizing nature of these interventions, which can lengthen a person’s life without improving its quality. They specifically argue that LIS patients should be able to decide whether to end their lives or stop life-extending treatment.

Brain scientists do not disagree, but they worry that inaccurate and negatively-skewed ideas about what it means to live with LIS could unduly tip the scales. “It’s important to not project our thoughts and feelings” onto others, said Steven Laureys, a neurologist and research director of the Belgian National Fund for Scientific Research. While non-disabled individuals might say, “‘this is not a life worth living,'” he added, the evidence doesn’t necessarily bear this out.

He and his colleagues want to ensure that their research is shared with LIS patients, their families, and physicians. The researchers are also trying to better understand which factors contribute to a patient’s overall sense of satisfaction.

Continue Reading

Trending