Myokines are molecules that facilitate some of the benefits of exercise

Complex molecular reactions in our tissues cause muscle contraction

When we want to move a muscle, a signal travels from the brain and into the muscle cells in question, sparking a chemical reaction that causes the muscle's smallest contractile units—sarcomeres—to shorten, forcing the muscle to contract.

The reason some people love exercise may be because of their microbiome

Certain gut microbes in mice trigger dopamine release and drive motivation to exercise more. Scientists are investigating whether humans carry similar microbial patterns that influence our natural inclination towards movement, exploring how unseen microbial ecosystems may shape mammalian fitness behavior and reinforce innate reward pathways. (Some users may experience a paywall.)

Optimal human functioning requires movement

There is now ample evidence to back the centuries-old hypothesis that exercise is critical to human health. This review article explores the latest discoveries in exercise science, including how exercise is intrinsic to maintaining our organ systems throughout life.

Exercise releases chemicals that enhance cognitive function

Neurotransmitters like dopamine, serotonin, and norepinephrine, along with increased brain-derived neurotrophic factor levels, enhance a wide range of brain functions. New research demonstrates a direct link between movement and numerous cognitive benefits, including memory, learning, and stress resilience.

Exercise changes your genes without changing your DNA

Physical activity can turn beneficial genes on and harmful genes off, without altering the underlying DNA code. This engaging article explains the epigenetic mechanisms that take place with exercise and ultimately result in improved metabolism, lower inflammation, and optimized brain function.

Microtears in muscles from exercise cause fibers to grow back larger

Placing muscle under increased load or stress causes damage that requires rest to repair, leading to stronger, more enduring muscle over time. Muscles adapt to such increasing demands by improving their efficiency with approaches that include increasing the number of mitochondria housed in hundreds of thousands of muscle cells.

Muscles fatigue due to the loss of energy like ATP and glycogen

Adenosine triphosphate fuels muscle contraction, and with each contraction (like during exercise), the amount of ATP reduces. ATP helps potassium and sodium move across muscle membranes, generating ions and helping to contract the muscle.

Exercise helps make your arteries more elastic

Regular aerobic exercise releases nitric oxide, a key molecule that relaxes blood vessel walls and improves vascular function. These exercise-induced adaptations make the heart work more efficiently and blood vessels become more elastic, leading to improved circulation and lowered cardiovascular risk.

'Viscoelasticity' allows muscles to be elongated briefly after stretching

The protective tissues around skeletal muscles consist of elastic proteins like collagen. Stretching them expands their length while retaining strength, ideal for athletes.

One minute of exercise correlates to five extra minutes of life (on average)

Doctors increasingly view exercise as the single most powerful medical intervention available. Observational studies suggest one minute of exercise correlates to an additional five minutes of life as humans age. Stanford researcher Euan Ashley discusses our current understanding of how exercise provides benefits at the cellular level.

Can humans delay or reverse old age?

We're not sure yet. Researchers at the University of California San Francisco are studying why some conditions and behaviors, such as low-oxygen environments and exercise, benefit the aging process, hoping to reveal potential health applications. Some of this research focuses on klotho, a naturally occurring age-regulating hormone named after the Greek Fate Clotho. Animal studies on klotho brain injections found subjects had improved memory recall and age-related degeneration resistance.

Physiological muscle memory allows us to quickly regain lost musculature

The term "muscle memory" is most often associated with the neurological kind, which involves the development of strong and efficient neural pathways in the brain and spine. Physiological muscle memory also slows the loss of muscle mass, with both types affected by genetics and diet.

What does the muscular system do?

The muscular system is responsible for movement by and throughout the body. Smooth muscle contractions push food and blood through the digestive tract and blood vessels, respectively. Skeletal muscles are responsible for voluntary movement or lack thereof by the body. Cardiac muscle controls the beating of the heart, which is the pump that powers the circulatory system responsible for distributing energy and nutrients to cells across the body.

Strength training appears to make for a healthier, youthful-looking brain

A study from 2025 links having higher amounts of muscle with a more youthful-looking brain age. Scientists analyzed data from more than 1,100 healthy adults around their mid-50s after they underwent full-body MRIs, comparing muscle, fat, and brain age appearances from the scans.Their findings link strength training and controlling visceral fat with improved brain health. The research didn't tease apart why this benefit occurs.

Too little stress can be as problematic as too much stress

Hormesis—mild or moderate stress followed by recovery—helps make us more resilient. A stress expert speaking during this roughly 30-minute CNN special explains that our bodies depend on periodic mental and physical challenges to activate our innate defense mechanisms, spurring cellular repair and regeneration.

How ALS (Lou Gehrig’s Disease) might work, and what scientists are learning about it

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that affects the nerve cells (neurons) controlling muscle movement. As the motor neurons degenerate, they stop sending signals to the muscles, causing progressive muscle weakness and, eventually, death. This three-minute animation focuses on the mechanisms within the motor neurons that cause them to degenerate. By understanding these mechanisms, researchers hope to one day find a cure for ALS.

Peptide TB-500, promoted for regenerative healing, is not FDA approved

Watch a board-certified sports medicine therapist detail his thinking about this synthetic peptide; he says it's "promising but unproven." He notes that this product is designed to mimic the natural protein thymosin beta-4, found in human and animal tissues, which promotes wound healing. TB-500 is classified as a research peptide for recovery, meaning it's not approved for human use and has not yet undergone rigorous human trials on its safety and efficacy.

How to think yourself into health

Can the right thoughts lead to a stronger immune system? Neuroimmunologists like Hai Qi study how drugs targeting the brain, as well as thought exercises, can prompt stronger immune responses to infection. This six-minute video investigates the radical claims.

Can microdosing improve mental health?

Animal studies involving microdoses of psilocybin, the psychoactive component in magic mushrooms and ketamine, found it helped to alleviate anxiety and inflammation, an immune response that can cause damage when chronically active. Human studies are ongoing. In at least one double-blind study, where researchers and patients don't know who got a placebo versus the real thing, about half of the participants incorrectly guessed they had been given placebos.

Inflammaging is chronic low-level inflammation as we age, and it may be a key disease driver

The term refers to the idea that largely invisible but consistent low-level inflammation as humans age fuels chronic diseases and cellular aging. Inflammaging, this article says, is due to lifestyle factors like poor sleep, low levels of activity, and poor diet, acting in concert to cause cellular damage and trigger inflammation.

Limb regeneration research may lead to treatments for arthritis

For scientists pursuing the cure for arthritis, the holy grail of discoveries lies in how to regrow healthy cartilage inside human joints. While this feat has so far resisted our best scientific attempts, there are plenty of other human tissues—such as the liver and fingertips—that will successfully regenerate.

Using fitness wearables to track muscle wasting in astronauts

All that exercising, and astronauts still are likely to lose a large amount of muscle mass while in microgravity. Astronauts can lose up to 20 percent of their muscle in as little as five days in space. Currently, tracking muscle loss means waiting until astronauts land to remeasure their muscle density post-trip. This article explains a NASA-backed fitness wearable that may be able to track muscle atrophy as it happens.

An experimental bionic knee has been directly integrated into the user's muscle and bone—not an external socket—marking a significant prosthetic advancement.

Collagen supplements have become a multibillion-dollar industry

Beginning in our 20s, the amount of this protein in our skin, muscles, and connective tissue declines. But independent, high-quality studies—like those that are double-blind—have not yet shown a significant association between their use and evidence of it improving skin elasticity, reducing wrinkles, or combating hair loss. Some collagen supplements do seem to help with joint pain and knee function, but NPR cautions that studies on that purpose are industry-funded.

Goose bumps may play a role in hair growth

Research in mice suggests that the same muscles that contract to create goose bumps act as the bridge for the sympathetic nervous system’s connection to hair follicle stem cells. This raises questions about how this knowledge could be used to reactivate the sympathetic nerves in hair follicles to boost hair growth in people.

MS Drugs reduce inflammation, helping reduce relapses and slow disease progression

Disease-Modifying Drugs calm the body's inflammatory response to help stave off relapses—when new or existing MS symptoms show up for a day or longer. Avoiding smoking, exercising, reducing stress via mindfulness, checking for vitamin D deficiencies, drinking more water and eating well, all can slow disease progression. [The jury's still out on if HRT around the time of menopause may reduce dementia risk](https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(25)00122-9/fulltext) Estrogen can reduce inflammation and support neural growth in the brain, and some research has suggested that beginning hormone replacement therapy around menopause—versus later in life—reduces Alzheimer's disease risk. Still, a recent systematic review concluded that taking HRT didn't affect dementia risk, regardless of when women started taking it, so the science remains unsettled.

What do vitamins actually do?

Vitamins are molecular tools the body needs to carry out regular cellular processes, such as wound healing. This 45-minute video dives into the science behind vitamins and their role in the body. There are 13 essential vitamins that must be...

How muscles get their names

There are more than 600 muscles that crisscross the human body, and each has a name that's more than a simple label. Muscle names also typically communicate the muscle's size, behavior, length, location, appearance, direction, and attachments to bone. These names usually have Greek or Latin roots, such as in the case of the deltoid muscles, which are named in reference to the Greek letter delta (𐤃).

Targeting cholesterol metabolism may help address macular degeneration

Research published in 2025, based on human plasma samples and mouse models, indicates that boosting the levels of a molecule called apolipoprotein M in the blood can improve cholesterol processing, helping prevent some cellular damage that contributes to age-related macular degeneration.

World records are often broken later in the day—and scientists wonder if muscle clocks explain the difference

For reasons that are still not entirely clear, on average, people tend to lift more weight and achieve other exercise feats later in the day. Theories to explain this discrepancy include muscle clocks are at peak performance in the afternoon and that there's morning-to-afternoon variation in core body temperature, hormones, and neural activity.

Research suggests Ozempic has benefits beyond weight loss

Semaglutide, the key ingredient in Ozempic, is proving to be more than just a diabetes and weight loss drug. Research suggests it may also help prevent strokes, improve heart health, and slow Alzheimer’s.

Stem cell therapies

Stem cells' special attributes interest researchers developing new therapeutic tools for a variety of health problems. Much of this research is done with support from the National Institutes of Health (NIH). This page offers a snapshot of research programs funded by the NIH and the health problems those programs focus on.

Positive role models are a benefit of support groups

Meeting individuals who are going through similar life experiences or navigating similar health journeys can provide inspiration and be a benefit of attending in-person or online support groups.

Adhesion molecules and intercellular junctions allow cells to connect together

While some organic structures are mostly composed of non-cellular components (e.g., collagen and calcium phosphate minerals in bones), tissues and organs composed of connected cells rely on specialized proteins and connections to create watertight seals that protect cells within the interior from environmental molecules.

Learn how colorectal cancer is linked to the American diet and chronic inflammation

A University of South Carolina colon cancer researcher offers insights from his own research and notes that more exercise, social support, and eating fruits, vegetables, legumes, and foods like fish and olive oil—often called the Mediterranean diet—are associated with better health—and could improve our colons.

Snake venoms are repurposed proteins responsible for other bodily functions

Just as saliva aids digestion in humans, proteins responsible for bioactivities such as digestion and blood clotting were eventually secreted in the glands and fangs of snakes across evolutionary history. Organisms that could not withstand the effects of these molecules (e.g., excessive bloodstream clotting) became ideal prey for snakes.

Modern bodybuilding evolved in the 19th century

The origins of modern progressive resistance exercise are traced to ancient Greece, where a repeat Olympic victor carried a calf every day until it grew into a full-sized ox. This 56-minute comedy and history podcast journeys through the rise of modern bodybuilding, which took off during the 19th century.

Mitochondria—only inherited from mothers in most animals—have their own DNA

Mitochondrial DNA, or mtDNA, typically takes the shape of a circle and contains genes that code for proteins essential to the production of energy-containing molecules called ATP. When mitochondria fuse, the mixing of healthy and damaged mtDNA helps alleviate the effects of mutations that may have occurred during mitochondrial division or environmental interactions.

Explore the abundance of different types of cells in the human body

Lacking a nucleus and other organelles to maximize space for oxygen-carrying hemoglobin and enhance maneuverability through narrow capillaries, there are about four times as many red blood cells and platelets as all other cell types in the body combined. However, about half of the body's cell biomass consists of skeletal myocytes, or muscle fibers.

How medical robots could cure cancer

Medical robots are on the verge of being able to be injected into the body, where they will be responsible for semi-autonomous behavior, such as detecting cancer cells and distributing medication. This six-minute video dives into the science of these nanorobots, which are smaller than blood cells. Applications of these nanobots could range from disease discovery and condition monitoring to tissue repair and artificial blood delivery.

Understanding insulin

Scientists Daniel and Kelly talk with researcher Dr. Katrine Whiteson about diabetes, the history of insulin production, and Dr. Lydia Villa-Komaroff—an essential member of the team who discovered that bacteria could be induced to produce insulin. Listen to discover interesting facts about the life-saving medicine and how it works in the human body.

Multiple sclerosis means 'many scars'

That's a reference to the scarring or lesions that occur in the brain, spinal cord, and elsewhere whenever the immune system has a flare-up. The immune system attacks the myelin because it incorrectly responds as if it's a threat, damaging the body's ability to transmit electrical signals effectively from areas of the body to the brain.

A macrophage can eat 100 bacteria, on average, before it's exhausted

These specialized immune cells are first responders during inflammation, responding to a threat or injury and then performing other inflammatory response tasks, including summoning neutrophils to help attack invaders.

The hormone that spreads love and helps fish share fear

Scientists consider emotions like fear and empathy to be among the oldest evolutionary behaviors observed in mammals. Yet to date, how these reactions are processed in the brain, regardless of species, is not well understood. A new study reveals how the chemical oxytocin—known as the "love hormone" in humans—helps let fish know when their friends are in danger.

Why one runner believes Stoic philosophy is important for marathoners

There's plenty of time for thinking while training for a marathon, and Matt Fitzgerald suggests it'd be wise to study the Stoic philosophers to navigate the many frustrations that come with that training. Fitzgerald may be talking about running, but his advice can apply to any seemingly impossible goal.

The anatomy of 'Mashle,' as described by a doctor

"Mashle: Magic and Muscles" is a manga and anime in which a seemingly magicless man performs outsized feats he blames on "muscle magic." In this 15-minute video, a doctor breaks down the anatomy and biomechanics of some of the feats performed by Mash, the series' main character who's spotted flying a broom via leg pumping and reading magical texts while sitting in an invisible chair (i.e., single-leg squat).

The marvels of mucus

Mucus—otherwise known as snot or phlegm—has a gross reputation, but the substance is actually of vital importance, lining the moist surfaces of our nose, intestines, lungs, and more. It plays a constant role in keeping our tissues from drying out and acts as a line of defense, but if it gets too sticky or thick, it can cause problems. Read about the marvels of mucus here.

Umami synergy—combining glutamates and nucleotides—can amplify a meal

While glutamates are known for triggering the umami taste through specific taste receptors, nucleotides like IMP and GMP can bind alongside glutamates to enhance the receptor's response. This union explains why certain classic food combinations like bacon and eggs taste exceptionally savory.

A visualization of mycoremediation, where fungi extract toxic and radioactive pollutants from soil

As organisms such as mushrooms grow, they develop large networks of root-like structures called mycelium that spread underground and release enzymes that break down contaminants. By absorbing these chemicals, fungi limit the damage caused by these toxins and localize them within the organism for easier collection and disposal.

'Endoevolution' refers to the Darwinian selection happening continually inside us

The term, coined by Roxanne Khamsi in her 2026 book "Beyond Inheritance: Our Ever-Mutating Cells and a New Understanding of Health" describes the idea that evolution does not just occur across generations of humans. Instead, mutated cells continuously compete with healthy ones in our bodies, with implications for our tissues and health. Khamsi says these autocorrections are essentially natural gene therapy.